Section 4 Flashcards

Question

A 72-year-old man presents with a one-year history of lower back pain that is gradually getting worse. He now describes the pain as a six out of ten. He has a past medical history of lumbar disc herniation for which he had a discectomy one year ago, and the pain got better at first, but it never resolved completely. He also says he was prescribed several analgesics during this time with no relief. A spinal cord stimulator (SCS) is considered as a treatment option for this patient. Which of the following is a rare complication of the procedure? 1. Lead migration 2. Lead fracture 3. Cerebro-spinal fluid leakage 4. Seroma

Answer 1

**3. Cerebro-spinal fluid leakage** ## Footnote * The complication rate following spinal cord stimulator implantation is relatively high. The most common complications are due to the hardware malfunction, such as lead migration. * The puncture of the dura can occur during lead placement, causing a cerebrospinal fluid leak, but it is rare. * The puncture of the dura can occur during lead placement, with headaches occurring in up to 70 percent of cases. * Lead fractures can occur in above nine percent of cases being a strenuous physical activity, one of the causes.

Answer 2

**2. Diplopia** ## Footnote * The individual with Wernicke Korsakoff syndrome will usually present with ocular disturbances which may include diplopia, painless vision loss, or strabismus. * Gait abnormalities include a wide-based short stepped gait and an inability to stand or ambulate without assistance. * Mental status changes include apathy, paucity of speech, and indifference to the environment. * As the disorder progresses, other symptoms that may develop include agitation, anger, hallucinations, and confabulations.

Answer 3

**2. Continue observation** ## Footnote * If the eye with the optic nerve sheath meningioma (ONSM) is blind, and the tumor is confined to the orbit, the patient should be observed as they grow very slowly. Some surgeons advocate surgically resecting the tumor to avoid extension to other areas, but this patient is 76-year-old. * Observation is the acceptable measure in cases where the visual function is intact or remains stable, especially in patients who maintain a central visual acuity of 20/50 or better. * Stereotactic radiotherapy has been used as an alternative to surgery. * Surgical resection can be justified in cases of disfiguring proptosis where the visual function has significantly decreased or in cases of intracranial extension.

Answer 4

**1. Previous radiation** ## Footnote * Glioblastoma multiforme is the most common aggressive primary cranial nervous system tumor. Usually more common in older men and African American race. * Studies have shown that a previous history of irradiation in early life is a risk factor for GBM. Although, in most cases, risk factors are not identified. * It is important to take a careful history, including a prior history of irradiation, to assess for risk factors. * No convincing evidence exists regarding associations of GBM with family history, smoking, or alcohol history.

Answer 5

**2. L5/S1 right-sided microdiscectomy** ## Footnote * While conservative management is generally best in young patients, this must be taken on a case by case basis. Here, the patient's activities of daily living are severely impaired, and he has a clear, localized pathology to explain his symptoms. Hence, surgery is reasonable. * For cases with isolated, unilateral disc herniations without facet degeneration or instability, decompression alone without fusion is a suitable choice. * An anterior approach may not fully address his symptoms as his disc space height was preserved on imaging. Hence, posterior microdiscectomy is a better choice for direct pathology access. * Microdiscectomy does carry a small (~10%) risk of recurrence, which may need further discectomy and fusion (TLIF) in the future, but given his radicular symptoms and isolated imaging findings, microdiscectomy now is more appropriate than TLIF.

Answer 6

**3. Administration of 100 percent oxygen** ## Footnote * The clinical vignette is classical of a tension pneumocephalus. * The first step in treatment should be 100 percent oxygen. * Using 100 percent oxygen allows for the reduction of pneumocephalus owing to its diffusion mediated by nitrogen gradient (80% in pneumocephalus) towards blood (0% in 100% oxygen) and its subsequent disposal of the lungs. * Craniotomy or burr bole is justified in tension pneumocephalus with significant brain herniation encompassing a major threat to the patient's life.

Answer 7

**3. Bulbocavernosus reflex monitoring** ## Footnote * The preservation of bladder and bowel function is of paramount importance while operating on an intramedullary tumor in the conal region. * Intraoperative assessment of the bulbocavernosus reflex is a valid tool in safeguarding the bowel function while performing surgical excision of such a tumor. * Electromyography from anal sphincters following bulbocavernosus reflex helps in the intraoperative assessment of the integrity of the bowel function. * Motor and somatosensory evoked potentials can be used as an adjunct, but they play no role in assessing bladder bowel function. Intraoperative MRI is technically demanding and also requires tractography in safeguarding the relevant tracts.

Answer 8

**3. Arcade of Frohse** ## Footnote * The posterior interosseous nerve is an extension of the radial nerve as it course on the posterior side of the forearm. The posterior interosseous nerve is motor to the wrist, finger extensors as well as the supinator muscle. * Sometimes the posterior interosseous nerve can become entrapped at the arcade of Frohse. The nerve often gets entrapped during repetitive supination and be associated with lateral epicondylitis. * The patient may present with weakness in wrist and finger extension without any sensory loss. Management includes rest and modification of hand activities. * If there is no improvement after 3-6 months of extensive conversative management, surgical decompression may be indicated.

Answer 9

**2. Hyperintensity posterior to the dens in T2W and STIR sequences** ## Footnote * The most important factor governing the management of C1 fractures is the intactness of the transverse atlantal ligament (TAL). The TAL can be assessed indirectly on plain radiographs and CT scans. However, the direct assessment of the ligament can only be made on MRI. * Axial CT scan can reveal bony avulsion injuries of the lateral mass. MRI cervical spine is the best modality to diagnose any damage to this vital ligament. T2WI and STIR (short tau inversion and recovery) sequences can reveal hyperintensity of the ligament at the insertional or intrasubstance level. * The rule of Spence is based on the assessment of the unilateral or bilateral overhang of the C1 lateral mass over the C2 superior articular process on an open mouth anteroposterior (odontoid) radiograph. If the combined overhand exceeds 6.9 mm (or 8.1 mm after correction for magnification errors), it indicates a rupture of TAL. * On lateral plain cervical radiographs, atlantodens interval (ADI) greater than 3 mm in adults and 5 mm in the pediatric population indicates TAL injury.

Answer 10

**4. Schwannoma** ## Footnote * Schwannoma commonly have a dumbbell-shape due to their propensity to grow out through the neural foramina. * A spinal epidural abscess usually arises as a complication of discitis or vertebral osteomyelitis. Symptoms can be acute as they can cause venous thrombophlebitis with ischemia of the spinal cord. * Massive herniated lumbar disc is one of the principal causes of cauda equina syndrome, but it is usually associated with the intervertebral disc space and does not exit through the foramen forming a dumbbell-shape appearance. * Meningioma may arise anywhere along the lumbar spinal canal and often have a dural tail.

Answer 11

**3. Osteophyte formation** ## Footnote * The patient’s symptoms are likely caused by nerve root compression in the setting of cervical spondylosis. * Disc desiccation leads to a loss of disc height and can be accompanied by a disc herniation. * Alteration in load distribution across the cervical spine results in loss of cervical lordosis, which in turn contributes to overloading of the uncovertebral and facet joints, triggering osteophyte formation. * Altered load balance leads to bony and ligamentous hypertrophy and ossification.

Answer 12

**2. Weakness of great toe extension** ## Footnote * Lumbosacral spondylolisthesis is seen in 4% to 6% of the population, particularly in people engaging in sports requiring back hyperextension activity (gymnasts, footballers, weight lifters). The majority of the slips occur at the L5/S1 level as the forces going through the lumbar spine are the greatest at that level, and facets are oriented in a more coronal fashion. * As the lumbar spine L5 nerve root exits below the L5 pedicle, it is most commonly affected by the slip. The reduction of high- grade slips is controversial; nevertheless, the same nerve root is usually affected. The weakness of the ankle extension would correlate with L4 nerve root weakness. * The clinical scenario suggests a higher grade of spondylolisthesis that was possibly treated with reduction and fusion. As the L5 nerve root exits below the L5 pedicle, it is at greatest risk of injury and would present with a weakness to great toe extension. * Ankle plantarflexion is mainly supplied by the S1 nerve root and is not the most commonly affected in cases of L5/S1 spondylolisthesis. Although bowel and bladder dysfunction may occasionally be present in patients with advanced L5/S1 spondylolisthesis, if it presents as a new finding in the postoperative period, it should be immediately investigated to exclude postoperative causes of cauda equina syndrome like a hematoma.

Answer 13

**2. Hyperintense region just adjacent to the right lateral mass of atlas on T2WI MRI** ## Footnote * The most important factor governing the management of C1 fractures is the intactness of transverse atlantal ligament (TAL). The TAL can be assessed indirectly on plain radiographs and CT scan. However, the direct assessment of the ligament can only be made on MRI. * Axial CT scan can reveal bony avulsion injuries of the lateral mass. MRI cervical spine is the best modality to diagnose any injury to this vital ligament. T2-WI and STIR (short tau inversion and recovery) sequences can reveal hyperintensity of the ligament at the insertional or intra-substance level. * The rule of Spence is based on the assessment of the uni- or bilateral overhang of the C1 lateral mass over the C2 superior articular process on open mouth anteroposterior (odontoid) radiograph. If the combined overhand exceeds 6.9 mm (or 8.1 after correction for magnification errors), it indicates a rupture of TAL. * On lateral plain cervical radiographs, atlanto-dens interval (ADI) greater than 3 mm in adults and 5 mm in pediatric population indicates TAL injury.

Answer 14

**3. Preoperative spinal drain placement** ## Footnote * Spinal drain placement, often by neurosurgery, allows for decompression of the spinal cord. In this patient, an extensive stent graft is required that will cover many branches from the aorta to the anterior spinal cord. * This places the patient at high risk for spinal cord ischemia and resultant paralysis. The best practice to minimize this complication is spinal drain placement, allowing for decompression postoperatively. * During the assessment of the blunt trauma patient, bilateral chest tubes may be placed for pneumothorax or hemothorax. A left-sided effusion on an initial chest X-ray is a non-specific finding that, with a widened mediastinum, may represent an aortic transection. This should be verified with a CT angiogram. * Placement of the chest tube would not treat the aortic injury. Lumbar puncture would not provide a long enough benefit of spinal decompression. Although carotid-subclavian bypass may be required in about 40% of patients following coverage of the left subclavian artery during stent-graft placement, this is often a staged procedure. Additionally, this patient's injury is distal to the great vessels. Occasionally, coverage of the left subclavian is necessary for a distal injury to obtain an adequate seal at the proximal stent graft.

Answer 15

**1. Liposomal amphotericin B** ## Footnote * This young patient in diabetic ketoacidosis with evidence of sinus/ orbit and cavernous sinus involvement merits a high consideration for rhino-orbital cerebral mucormycosis. The suspicion or diagnosis of rhino-orbital cerebral mucormycosis is a medical as well as surgical emergency since it carries high morbidity & mortality even with appropriate treatment. IV liposomal amphotericin is initiated immediately at a dose of 5 mg per Kg body weight per day, with many clinicians going up to a dose of 10 mg per Kg body weight/day. Surgical debridement is planned immediately. * Extensive surgical debridement is to be planned at the earliest. This will help to arrive at an early tissue diagnosis via frozen section specimens. Tissue PCR techniques also will help in reaching a diagnosis. Surgical debridement is also expected to reduce the fungal load. Extensive exploration and debridement of sinuses along with orbital decompression or exenteration is usually done. Local installation of amphotericin is often done in debrided cavities. The intracranial disease is also debrided as much as feasible. The role of surgical exploration and debridement in intracranial involvement is a bit controversial since many experts believe that mortality is inevitable. However, there are case reports of survival in early intracranial involvement. * Liposomal amphoterin B has better tissue penetration and minimal renal toxicities compared to parenteral amphotericin B. * IV posaconazole or isavuconazole is used only when the patient is not tolerating amphotericin or is not responding to amphotericin. They are used as a step-down oral continuation therapy agent, only after many weeks of IV amphotericin therapy has resulted in clinical improvement in the given patient.

Answer 16

**1. Digital subtraction angiography** ## Footnote * The patient most likely has hydranencephaly. Most studies suggest that the damage caused to the brain is related to early internal carotid artery occlusion. As such, hydranencephaly is categorized into a group of circulatory developmental encephalopathies. * Digital subtraction angiography is used in some cases to evaluate the patency of the internal carotid arteries. * The anomaly presenting in hydranencephaly follows the anatomic distribution of the brain supplied by the internal carotid artery. Structures supplied by the posterior circulation (cerebellum, brain stem, thalamus, basal ganglia, and choroids plexus) are preserved. * Brainstem auditory evoked response test is used to confirm the loss of cortical function but with preserved brainstem function.

Answer 17

**2. Exosomes derived from the same differentiated tissues** ## Footnote * Stem cells have been used for regenerative therapy which gave hope to patients of what was considered before as incurable diseases such as spinal cord injury, systemic sclerosis, Alzheimer disease, and myocardial infarction. One disadvantage of stem cell therapy is its carcinogenic potential. * The regenerative effect of MSCs is due to their paracrine action rather than the direct replacement of the injured tissue. So, the administration of conditioned medium or EVs derived from the stem cells has a similar regenerative capacity equivalent to that produced by the stem cells themselves. * MSCs derived EVs improved several conditions in experimental animals, including diabetic nephropathy and diabetic retinopathy. * Exosomes derived from immune cells or the same differentiated tissue have not been tried as regenerative therapy and are not expected to have a positive effect. Autologous engineered stem cells have the same oncogenic potential of the olfactory stem cells.

Answer 18

**3. Type 3** ## Footnote * The patient has clinical signs and symptoms consistent with ulnar nerve neuropathy. * Ulnar neuropathy at the wrist and hand can range from pure sensory to pure motor deficits. Ulnar neuropathies of the wrist and hand are divided into 3 types. * Type III lesion is limited to the superficial branch, causing purely sensory deficits to the palmar aspect of the medial half of the fourth digit and the fifth digit. * Type I is a lesion of the ulnar nerve just proximal to or within the Guyon canal involving deep and superficial branches; this causes mixed motor and sensory deficits and subsequent weakness of all the ulnar hand muscles. Type II is a lesion involving the deep branch which causes a pure motor deficit with a varied pattern of weakness based on the compression site.

Answer 19

**3. Cross-face sural nerve graft and gracilis muscle free flap** ## Footnote * Six months after denervation, the muscles suffer irreversible atrophy due to the loss of nerve stimulation. After this period, even if the nerve input is restored, the muscles will not be able to contract. * In this context, the atrophied muscles must be replaced with a functional muscle, and its innervation is secured by a sural nerve graft extension from the contralateral (unaffected) facial nerve. * This is because the dissection of the affected facial nerve in the presence of scarred tissue is complicated and even impossible in many cases. * Although physical and occupational therapy can generate some improvement, they won't be able to reanimate the face or generate smiling or mouth angle movement.

Answer 20

**2. Radiotherapy** ## Footnote * The patient has a pineal region tumor with hydrocephalus. * The cerebrospinal fluid (CSF) positivity for placental alkaline phosphatase (PLAP) and histopathological features are suggestive of germinoma. * Germinomas are highly radiosensitive. * Resection of germinomas is difficult due to high collagen content.

Answer 21

**1. Polycystic kidney disease** ## Footnote * Patients with berry aneurysms present with the most severe manifestation of a major aneurysmal rupture, such as a subarachnoid hemorrhage to minor hemorrhage, also known as a sentinel bleed, non-hemorrhagic scenarios, or asymptomatic situations in which the aneurysm is found incidentally. * Seizures present in twenty-five percent of aneurysmal subarachnoid hemorrhage. They may be focal or generalized. * Genetic factors in the development of the berry aneurysm include connective tissue disorders that weaken artery walls, polycystic kidney disease, arteriovenous malformations, and a history of an aneurysm in two or more first-degree family members. * Other risk factors are untreated high blood pressure, cigarette smoking, drug abuse, including cocaine and amphetamines, which via their toxidrome, increases blood pressure extremely, heavy alcohol intake, and heavy caffeine intake.

Answer 22

**3. Patient's age** ## Footnote * Definitive diagnoses can only be made through a postmortem examination of the brain. However, "probable cerebral amyloid angiopathy (CAA)” diagnosis can be made during life utilizing imaging or tissue sampling. * Probable CAA (with imaging) must include multiple hemorrhages restricted to the cortical, lobar, or cortical- subcortical regions, absence of another diagnostic lesion, and age of 55 years old. * Gradient-echo magnetic resonance imaging (MRI) is one of the most important techniques used for diagnosis. * Brain biopsies are rarely utilized in the diagnosis of CAA, except when CAA-related inflammation is suspected. Hypertensive bleeds mostly involve the basal ganglia and the brainstem regions.

Answer 23

**4. Reassurance** ## Footnote * Genitofemoral neuralgia is the most common complication following chemical lumbar sympathectomy with an incidence of 5-7%. It is the most common complication following lumbar sympatholysis and symptoms usually resolve on their own within a few weeks. * Associated symptoms of genitofemoral neuralgia are usually transient and last up to 6 weeks. * The genitofemoral nerve lies directly anterior to the psoas muscle. * Genitofermoal neuralgia can occur due to the spread of neurolytic agents on the genitofemoral nerve.

Answer 24

**3. Pneumocele** ## Footnote * Pneumocephalus, also known as pneumatocele or intracranial aerocele, is defined as the presence of air in the epidural, subdural, or subarachnoid space within the brain parenchyma or the ventricular cavities. * Pneumorrhachis denotes intraspinal air. * Pneumocele is a focal or diffuse enlargement of any paranasal sinus, usually frontal, associated with thinning its bony walls and hyperpneumatization. * Pneumosinus dilatans is the same as pneumatocele, but the sinus walls are intact and normal.

Answer 25

**2. Grade II isthmic spondylolisthesis subtype B** ## Footnote * Meyerding classification for spondylolisthesis is based on the percentage of slippage. Grade I is 1-25%, grade II is 26-50%, grade III is 51-75%, grade IV is 76-100%. * Isthmic spondylolisthesis is divided into subtype A (stress fractures of the pars), subtype B (elongation of the pars without overt fracture), and subtype C (acute fracture of the pars). * Pathologic spondylolisthesis is divided into subtype A (systemic causes) or subtype B (focal processes). * Failure of conservative management can lean one toward possible surgical stabilization of the affected spondylolisthesis.

Answer 26

**3. 7, Surgical intervention** ## Footnote * The thoracolumbar injury classification and severity score (TLICS) is used to guide treatment and uniformity to spine fractures in the trauma setting. It evaluates fracture injury morphology, neurologic status, and posterior ligamentous complex integrity. * For this patient, the fracture type is burst +1, the neurologic status shows incomplete spinal cord injury +3, and posterior spinal cord injury +3, for a score of 7. * The TLICS treatment implications for a score of fewer than 4 points is usually nonsurgical management. A score of 4 points may be nonsurgical or surgical management. A score greater than 4 points indicates surgical management. * Initial management should be spine precautions, log rolling of the patient only, and application of a brace or special stabilization bed until the patient can be cleared for surgery.

Answer 27

**3. Nicardipine** ## Footnote * The headache need not be the worst of the patient's life. Even a headache that is different from past headaches should raise one's suspicion for subarachnoid hemorrhage. NSAIDs are generally avoided in brain bleeds due to the risk of increased bleeding. * Although analgesia is important to provide in this situation, blood pressure control is the most important measure while preparing for definitive treatment, possibly invasive. * Nicardipine and labetalol are fist line agents for blood pressure control in these patients. Systolic pressure should be kept lower than 140 mmHg. * Hydrochlorothiazide is a good medication for hypertensive patients not having a hypertensive emergency or SAH. HCTZ is not indicated acutely for pressure control in this pressure with SAH.

Answer 28

**1. Aqueductal stroke volume of 45 microliters** ## Footnote * The patient has idiopathic normal pressure hydrocephalus (iNPH). * The surgical treatment of iNPH is the insertion of ventriculoperitoneal shunt. * Factors suggesting favorable outcomes following shunt surgery are aqueductal stroke volume greater than 42 microliters, lack of white matter lesions on magnetic resonance imaging, B-waves longer than 50% of intracranial pressure monitoring time, and resistance to cerebrospinal fluid outflow over 18 mmHg/ml/min. * In this scenario, the patient presented with dementia as the initial symptom, which is a poor prognostic factor following surgery.

Answer 29

**3. Posterior inferior cerebellar artery** ## Footnote * The lateral medullary syndrome is caused by a vascular event in the lateral part of the medulla oblongata. The arteries commonly involved in lateral medullary syndrome are the posterior inferior cerebellar artery or the vertebral artery. The lateral medullary syndrome is characterized by varied neurologic manifestations. Patients generally have a sudden onset, but approximately 25% may show a gradual onset. * The usual symptoms of lateral medullary infarction include vertigo, dizziness, nystagmus, ataxia, nausea and vomiting, dysphagia, and hiccups. Atherosclerotic disease is the leading cause. Other causes include cardiac embolism, arterial dissection, small vessel disease, etc. * Patients have impairment of pain and thermal sensation over the contralateral side of the trunk and limbs, impairment of pain and thermal sensation over the ipsilateral face, ipsilateral Horner syndrome, and ipsilateral limb ataxia. * Anterior inferior cerebellar artery pathology can lead to lateral pontine syndrome. Anterior spinal artery infarct causes bilateral pain and temperature loss and quadriparesis. Posterior cerebral artery infarct can lead to diplopia, visual field defects, dysphagia, vertigo, alteration in consciousness, memory impairment, or difficulty reading.

Answer 30

**2. FAIR test** ## Footnote * The FAIR (flexion, adduction, and internal rotation) test can reproduce symptoms of piriformis syndrome. * This involves placing the patient in the supine position and having them flex their hip and bring it across the midline and internally rotating the lower extremity, which will place tension on the piriformis muscle. * The one major difference between sciatica and piriformis syndrome is that the latter rarely presents with neurological deficits. * On the physical, localized tenderness around the buttock area is very common.

Answer 31

**4. Medial longitudinal fasiculus** ## Footnote * The patient has signs and symptoms characteristics of internuclear ophthalmoplegia (INO). * Medial longitudinal fasciculus allows for cross-communication between CN III and CN VI. It is extensively myelinated and coordinated both eyes to move in the correct direction. * The most common causes of INO are multiple sclerosis and ischemic stroke. Her risk factors of type 2 diabetes mellitus, hypertension, and family history of cardiovascular disease make the diagnosis of brainstem infarct highly likely. * Edinger-Westphal (EW) nucleus is the parasympathetic efferent for the eye. A lesion in the EW nucleus results in an ipsilateral fixed and dilated pupil. Cranial nerve III lesions would result in a "down-and-out" gaze, ptosis, and absent light reflex. Trochlear nerve lesion would result in a palsy of the superior oblique muscle of the eye.

Answer 32

**4. Passive cervical extension with rotation to the affected side and axial compression that results in the reproduction of radiculopathy symptoms in the upper extremity ipsilateral to the direction of head rotation** ## Footnote * In current literature, the Spurling test is described as a passive cervical extension with rotation to the affected side and axial compression that results in the reproduction of radiculopathy symptoms in the upper extremity ipsilateral to the direction of head rotation. * The Spurling test was originally defined as passive lateral flexion and compression of the head, though this is no longer recognized as the proper technique. * Passive cervical flexion resulting in electric shock-like paresthesia is Lhermitte sign and may indicate multiple sclerosis plaques or other intramedullary pathology. * The Spurling test is designed to exaggerate cervical nerve root compression to recreate radiculopathy symptoms, and a positive result should prompt further testing and imaging.

Answer 33

**3. Kocher's point** ## Footnote * The placement of the ventriculostomy point at the Kocher's point has been shown to decrease the risk of its subsequent obstruction by at least 33%. * The chandelier pattern of the proximal shunt prevents its contact with the choroid plexus, thereby minimizing its obstruction following the risk of it being ensheathed by the same. * This phenomenon has been shown to increase the lifespan of the shunt while compared to those that have been placed from the posterior points like Keen, Dandy, and the Frazier points. * In posteriorly placed proximal shunts, the tip seems to lay on the floor of the ventricles close to the choroid plexus, thereby increasing the odds of its subsequent occlusion.

Answer 34

**3. He had a transient episode of neurological dysfunction that is expected to improve within weeks** ## Footnote * Preserved nerve conduction distal to the injury site, and no evidence of fibrillations potential indicate that the injury is neurapraxia. * Neurapraxia is a transient conduction block with no disruption of external or internal nerve continuity. * In neurapraxia, there is no Wallerian degeneration (which is seen in axonotmesis or neurotmesis). Regeneration of the nerve is not required for recovery. * The loss of function is temporary and tends to recover within weeks to months at most. No surgical intervention is typically required.

Answer 35

**3. Inability to fully close the eye** ## Footnote * The patient had an iatrogenic transection of the facial nerve as it courses through the parotid gland as she can not close the eye. * Direct end-to-end coaptation offers the best chance of functional recovery in a facial nerve injury. * The facial nerve innervates the orbicularis oculi muscle. It also innervated the muscles involved in facial expression. * The motor function of the trigeminal nerve is for the muscles of mastication, the tensor tympani, mylohyoid, tensor veli palatini, and the anterior belly of the digastric.

Answer 36

**3. Rhinorrhea** ## Footnote * Nasal fractures are the most frequent facial fracture in adults with midface blunt trauma as the most common mechanism. It is usually the result of road traffic accidents, sports injuries, falls, and physical fights. * The presence of rhinorrhea may raise the suspicion of cerebrospinal fluid (CSF) leak, and thus the cerebral fluid must be examined, and neurology consulted. * Typical physical findings in nasal fractures include tenderness, crepitus, nasal shortening or depression, step-offs, and nasal base widening. * Diagnosis is usually made upon clinical evaluation, by history taking and physical examination, while imaging is rarely needed.

Answer 37

**2. Worsening neck pain** ## Footnote * A transient increase in radicular pain was seen in up to 18% of patients following injection. * The possible mechanism of the transient increase in pain may be the epidural needle coming in contact with associated nerve roots and spinal nerves. * This complication is more commonly reported with a transforaminal cervical epidural steroid injections. * The four most common side effects following a cervical epidural are neck pain (6.7%) headache (1.7%), insomnia (1.7%), and vasovagal reaction (1.5%).

Answer 38

**4. Posterior cord brachial plexopathy** ## Footnote * Weakness of shoulder abduction (deltoid, C5/C6, upper trunk, posterior cord) and elbow extension (triceps, C6/7/8, upper and mid trunk, posterior cord) fits best with a posterior cord injury as elbow flexion (primarily controlled by the biceps brachii and brachialis, C5/6, upper trunk, lateral cord) is intact arguing against a C5 or C6 radiculopathy or an upper trunk brachial plexopathy. A radial neuropathy would not be expected to cause weakness in shoulder abduction. * Acute radial neuropathies at the spiral groove are sometimes difficult to distinguish from a central nervous system lesion producing arm weakness. Most central disorders that cause arm weakness tend to affect the extensors greater than the flexors. Thus, weakness in extension of the wrist (ie, wrist drop) and fingers may be an ambiguous finding. Relative preservation of triceps strength and sensory loss isolated to the dorsum of the hand are helpful findings indicative of radial neuropathy at the spiral groove. Most importantly, the brachioradialis should also be weak in a radial nerve lesion, but is typically less affected in a central disorder. * Conservative treatment is generally the rule for patients with a one-time compression injury to the radial nerve (such as a radial Saturday night palsy). Physical therapy, wrist splinting (to maintain function), and pain management are most important. Prognosis for full recovery is generally good. * In patients with severe injury secondary to trauma, follow-up examinations and electromyography (EMG) may be warranted. Severe ongoing nerve compression or transection may be difficult to distinguish from a single episode of injury that occurred at the time of trauma. Lack of any improvement, either clinically or electrophysiologically, warrants further imaging or surgical exploration.

Answer 39

**2. Ipsilateral warming of more than 2 C** ## Footnote * The blockage of T2 sympathetic ganglion is imperative in assuring complete sympathetic denervation of the upper limb. Ipsilateral warming more than 2 C was observed in more than 70% of patients following the complete sympathetic blockade. * The ipsilateral warming of more than 2 C is taken as the definitive sign of complete sympathetic denervation in the upper arm. The studies have shown the temperature varaibility between one and a half to seven and a half degrees Celcius. * The greater rise in temperature is seen in the late stages of complex regional pain syndrome owing to the concurrent presence of vasoconstriction in the patients. This temperature variability also increases with the number of procedures within the patient. * Horner syndrome only helps in confirming the presence of the stellate ganglion. The horner syndrome can also occur without the sympathetic blockage, even if only the upper half of the ganglion is blocked. The flushing and lacrimation are only additional and no conclusive signs to confirm a sympathetic block. Drop in the temperature of the ipsilateral tympanic membrane is also a reliable sign, but the increase in the temperature within 10 minutes of the procedure is the limiting factor.

Answer 40

**2. Flexion/distraction type injury** ## Footnote * A chance fracture of the spine is a flexion/distraction injury of the spine that can result in a bony or ligamentous injury centered at the abdominal viscera. * In a chance fracture of the spine, the anterior column fails under compression, and the middle and posterior columns fail under tension. * Ligamentous bony chance fractures are more difficult to heal and require surgical decompression and stabilization. This is most appropriately managed from a posterior approach. * Bony chance fractures are more stable than ligamentous chance fractures and may be treated non-operatively. Despite this, providers should still follow closely for evidence of nonunion or kyphosis.

Answer 41

**1. Admit the patient, contact the neurosurgical and neurology team, arrange for admission blood tests, and arrange vascular imaging, i.e., a CT angiogram +/- MRI/MRA** ## Footnote * A young patient with intracerebellar hemorrhage (ICH) and no bleeding diathesis should always raise suspicion of an underlying lesion such as a vascular abnormality. The increased attenuation within the clot on the CT head may be areas of calcification within vessels and increases the likelihood of a vascular malformation being the cause of the ICH. This patient is currently stable and does not need to be rushed to the theater for surgery. In stable patients, it is important to complete investigations that may assist with their further care. * Posterior fossa arteriovenous malformations (AVMs) are rare and account for 7 to 15% of all intracranial AVMs. AVMs within the cerebellum make up the majority of posterior fossa AVMs. * An appropriate investigation of a possible vascular malformation includes an MRI/MRA, CT angiogram, and a cerebral catheter angiogram or digital subtraction angiogram (DSA). The latter studies are more invasive. However, their dynamic nature allows for the investigation of vessel filling at different times and helps identify feeding and drainage vessels, which is very useful in surgical planning. * Although this patient is currently stable and does not have an altered conscious level, she has just had a significant ICH that requires admission for frequent neuro-observations as the ICH could progress and the patient could deteriorate. The patient also requires further investigations for the cause of her ICH, and these should initially be done as an inpatient. Though she has a history of a sudden-onset headache, her CT head revealed the cause of this and did not show signs of subarachnoid blood.

Answer 42

**3. Factor V Leiden mutation** ## Footnote * An empty delta sign is seen in cerebral venous thrombosis. * Risk factors for this include dehydration with resultant decreased intravascular volume, malnutrition, sepsis, and thrombophilias. * Cerebral venous thrombosis can be caused by Factor V Leiden mutation, antithrombin III deficiency, hyperhomocysteinemia, prothrombin gene mutation, and deficiencies of proteins S and C. * A young, active marathon runner is unlikely to have carotid vessel disease or a lower extremity deep venous thrombosis. A transesophageal echocardiogram would be useful in working up a patient with an ischemic stroke or if there is a concern in the setting of sepsis for endocarditis.

Answer 43

**4. L4/L5** ## Footnote * The L4/L5 disc level is the most common spinal segment to be affected by degenerative spondylolisthesis. * This is where the L4 vertebral body has a true displacement forward in relation to the L5 vertebral body, referred to as an anterolisthesis. Posterior displacement or retrolisthesis is also possible but is much less common. * Degenerative spondylolisthesis occurs as part of the aging process, resulting in disc degeneration and arthritic changes that cause the anterior slippage. * This is in contrast to other forms of spondylolisthesis, such as congenital, traumatic, or isthmic, where there is typically disruption of the posterior elements such as the pars interarticularis or pedicles.

Answer 44

**1. -1000** ## Footnote * The patient has a fracture involving both tables of the frontal sinus. * The next day he developed cerebrospinal fluid (CSF) rhinorrhea. * CSF rhinorrhea can cause pneumocephalus formation. * The Hounsfield unit of air is -1000.

Answer 45

**1. Elevated opening pressure, WBC 3 cells/mm3, 100% lymphocytes, glucose 55 mg/dL, protein 150 mg/dL** ## Footnote * Malignancy from the breast, lung, melanoma, or even a primary brain cancer may cause carcinomatous meningitis. The survival rate is only a few weeks at best. * The most common manifestations are headaches and seizures. * Lumbar puncture is the standard diagnostic procedure. Common findings include elevated opening pressure and elevated protein levels. Malignant cells are seen in 60% to 70% of cases after three attempts. * The contrast-enhanced MRI is the imaging of choice as a CT scan may not be sensitive enough to pick up leptomeningeal enhancement.

Answer 46

**4. Genetic testing** ## Footnote * Pseudohypertrophy of the calves and suggestive Gowers sign leads to the diagnosis of Duchenne muscular dystrophy. * Duchenne muscular dystrophy is an X-linked recessive disorder associated with muscle weakness. * It is caused due to the deletion of the dystrophin gene. * Creatinine phosphokinase is usually elevated. Genetic testing will assist in diagnosing the patient. Muscle biopsy is also diagnostic.

Answer 47

**1. Left anterior cerebral artery** ## Footnote * In this patient, the most likely diagnosis is anterior cerebral artery syndrome causing contralateral hemiparesis and sensory loss, which are more in lower extremities than the lower extremities and disconnection syndrome. * The major blood supply of the brain is by two sets of arteries, the vertebral arteries, and the carotid arteries. Inside the skull, the carotids divide into two major arteries, the anterior and the posterior cerebral arteries, and many smaller arteries like the ophthalmic artery and the anterior choroidal arteries. These arteries supply blood to the anterior two-thirds of the brain. The ophthalmic artery supplies the structures of the orbit while the posterior communicating artery acts as an anastomotic ‘connecting vessel’ in the Circle of Willis. Anterior choroidal artery supply structures in the brain important for motor control and vision, and the anterior cerebral artery supplies part of the cerebrum. * The vertebral arteries join to form a basilar artery which is located near the base of the skull. They give off many small branches in the brain stem and forms the posterior cerebellar and the posterior meningeal arteries. Meningeal branch supplies the falx cerebelli, a sheet of dura mater, while the anterior and posterior spinal arteries supply the spinal cord, spanning its entire length. The posterior inferior cerebellar artery supplies the cerebellum. * The anterior cerebral artery supplies the anteromedial portion of the cerebrum, whereas the middle cerebral artery is situated laterally, supplying the majority of the lateral part of the brain. The posterior cerebral artery supplies both the medial and lateral parts of the posterior cerebrum.

Answer 48

**4. Cribriform plate of the ethmoid bone** ## Footnote * The cribriform plate of the ethmoid bone forms the central portion of the roof of the nasal cavity, which separates the cranial vault from the external environment. On either side of the cribriform plate are the lateral lamellae, which extend vertically towards the foveae ethmoidalis, which in turn rise obliquely to join the roofs of the orbits. * The olfactory bulbs send projections through the cribriform plate to the olfactory mucosa at the apex of the nasal cavity. Because these nerves are very thin, they are prone to shearing injuries in the setting of blunt force head trauma. Shearing of these nerves will produce hyposmia or anosmia, depending on the severity of the injury. * Cerebral spinal fluid (CSF) is a clear watery liquid that main drain directly into the nasal cavity if the integrity of the anterior skull base is compromised. Testing the fluid for glucose, ß-2 transferrin, or ß-trace protein can identify CSF. Alternatively, if watery sanguineous rhinorrhea is present, placing a drop on a piece of filter paper and noting a halo sign may increase suspicion for a CSF leak. * An acute CSF leak is not a surgical emergency but may require lumbar drainage and bed rest in the short term and potentially surgical repair if conservative measures fail to resolve the leak within a week. The usefulness of antibiotic prophylaxis to prevent meningitis in these patients is controversial.

Answer 49

**1. CD99** ## Footnote * Astrocytoma and ependymoma are the most common intradural and intramedullary lesions of the spine. However, ependymoma (myxopapillary variant) is by far the most common lesion found in the conus medullaris. * The homogeneous enhancement and the sign of bleeding (T1 hyperintense region) suggest the diagnosis of ependymoma. * Myxopapillary ependymomas are usually positive for these immunophenotype markers: GFAP, S100, vimentin, CD99, AE1/AE3, and NCAM1. * Myxopapillary ependymomas are usually negative for these immunophenotype markers: CK5/6, CK20, E-cadherin, cytokeratin.

Answer 50

**2. It typically arises from the vermis and the roof of the fourth ventricle** ## Footnote * Medulloblastomas are invasive embryonal tumors of the cerebellum and tend to metastasize along the craniospinal axis. * Tumor growth starts along the floor of the fourth ventricle and occupies the entirety of the ventricle, subsequently invading both the cerebellar vermis and the brainstem, causing ataxia and signs of hydrocephalus early on. * The peak incidence of medulloblastoma is in the first decade of life, with an annual incidence of 0.5 per 100,000 children. * The mainstay of treatment for medulloblastoma is maximal surgical resection followed by chemotherapy and whole neuroaxis radiation.

Answer 51

**4. Leave it as it is, provided the rest of the spine is in contact with the board, and support her with pillows** ## Footnote * Hard collars and longboards can produce significant complications, and the quality of evidence in their use is very low. Increased intracranial pressure (even in normal subjects), skin breakdown, and an inability to access the airway are some issues with hard collars. * Clinical algorithms in determining spinal immobilization should be used. * The patient may be bending the spine due to spinal injury at that level. * The patient should not be forced to position such that the spine board will be in contact.

Answer 52

**3. A skull resembling a parallelogram, without synostosis** ## Footnote * The clinical scenario is in favor of deformational plagiocephaly (DP). In DP, there is no synostosis. The skull shape is that of a parallelogram. * Assisted labor and first-born male child are risk factors for DP. * Torticollis and preferred supine sleep position are also risk factors for DP. * In case of craniosynostosis, a palpable bony ridge can be felt.

Answer 53

**2. Intravenous corticosteroids** ## Footnote * The most important goal of treatment is the stabilization of neurological symptoms. * Corticosteroids, especially dexamethasone, are the most common initially prescribed treatment for children with newly diagnosed (or suspected) diffuse intrinsic pontine glioma (DIPG). * Dexamethasone serves as a temporary measure for brain edema before undergoing stereotactic biopsy. * Surgery has a limited role in the management of DIPG due to its location. While the brain MRI may provide more detail, there is no need to delay administering steroids because the CT demonstrates brain edema. Radiotherapy is a mainstay of DIPG treatment and can lead to symptom relief, but administering steroids is the best next step in management.

Answer 54

**1. CT of head and lumbar puncture to rule out meningitis** ## Footnote * A basilar skull fracture allows communication between the nasopharynx or middle ear and the meningeal space. Fractures that involve the petrous ridge of the temporal bone will cause blood to pool behind the tympanic membrane causing it to appear purple. This usually appears within hours of injury and maybe the earliest clinical finding. * Altered mental status and fever with known basilar skull fracture require evaluation of the CSF. CSF leak is not easy to diagnose and the fluid should be sent for analysis of beta transferrin. * The majority of CSF leaks resolve spontaneously within 5-10 days but some can persist for months. Meningitis may occur in less than 5% of patients but the risk increases with the duration of the CSF leak. * Pulmonary emboli are rare in children but a fat embolus could occur. Hypoventilation and atelectasis would have more respiratory symptoms.

Answer 55

**4. Lower down the external ventricular drain (EVD) below the level of the tragus** ## Footnote * The clinical scenario, as depicted in the ICP waveform analysis, is typical of rising ICP pressure; therefore, there is an urgent need for intervention to reduce the same. * The intraventricular ICP monitoring system, in addition to being the gold standard for measuring the same, allows for the immediate release of CSF, thereby counteracting any rise in ICP. * So the best immediate management plan would be to allow for egress of CSF by lowering the transducer and the EVD bag below the level of the tragus (external auditory canal). * After combating this sudden rise in ICP only, we can ask for other interventions like repeating CT scans and preparing for damage control surgery.

Answer 56

**2. Ultrasound guidance** ## Footnote * Pre-procedural ultrasound helps in assessing the relevant anatomic study and relationship between the carotid sheath, esophagus, longus colli muscle, tubercle of the transverse of the C6, and the vertebral artery. This helps in assessing the safe trajectory of the injection during the procedure. * The ultrasound also provides continuous and real-time images of the trajectory of the tip of the needle, thereby preventing any vascular injuries and inadvertent damages to the esophagus and thyroid gland. * It also helps in determining the precise subperiosteal location of the tip of the needle while injecting the drug and also of the pattern of the distribution of the drug, to ensure its maximum efficacy. Moreover, it has a low learning curve and avoids the risk of radiation exposure. * The blind manual approach has the risk of causing injury to the vertebral artery and damage to the pleura, causing a pneumothorax. The efficacy of the procedure is also low compared to that of the ultrasound-guided procedure. Fluoroscopic guidance has the risk of radiation exposure. It also cannot predict inadvertent vascular injuries.

Answer 57

**4. Basivertebral nerve neurotomy** ## Footnote * Basivertebral nerve ablation/neurotomy would be clinially indicated in this scenario. The procedure is indicated when patients meet the following indication criteria: chronic axial low back pain (greater than 6 months of duration); pain refractory to conservative nonsurgical treatment for at least six months of duration; and evidence of vertebral endplate changes on diagnostic images (MRI). * MRI findings compatible with vertebral endplate changes indicated in basivertebral nerve ablation include Modic type I and/or Modic type II changes; vertebral endplate changes with inflammation, edema, disruption, and/or fissuring; fibrovascular bone marrow changes (hypointensive signal for Modic type I changes); fatty bone marrow replacement (hyperintensive signal for Modic type II changes). * Basivertebral nerve ablation/neurotomy is the only intervention to directly target chronic axial low back pain of vertebral nature when other anatomical structures are not involved, such as facet joints, intervertebral discs, central canal, etc. * Lumbar epidural corticosteroid injection is clinically indicated for lumbar radiculopathy. Lumbar medial branch block is indicated for facet arthropathy, and vertebroplasty is clinically indicated in vertebral compression fractures.

Answer 58

**3. Smaller suture line** ## Footnote * A smaller suture line correlates with proper shunt function in children with open sutures. * Signs of obstruction include enlargement of the infant’s head, fontanelle full and tense when the infant is upright and quiet, prominent scalp veins, swelling along the shunt tract, vomiting, sleepiness, irritability, downward deviation of the eyes, poor feeding. * When an abrupt malfunction of a shunt occurs, symptoms can develop very rapidly and lead to coma or death. * Ventricular shunting for obstructive hydrocephalus secondary to a tumoral mass decreases ventricle size but does not decrease tumor size.

Answer 59

**4. Flow 800 study** ## Footnote * There is a risk of vasospasm in the postoperative period in patients undergoing surgery following subarachnoid hemorrhages from aneurysmal rupture. The release of bilirubin for the lysed blood and inadvertent clipping of the perforators and parent vessels predisposes to vasospasm. * Flow 800 is an automated software that displays flow mapping generated from the indocyanine green angiography of the parent vessels, their branches, and the perforators. It also analyzes the pattern of a flow velocity as well as transit time through them. * The difference in flow velocity of more than 50% between the parent and the branching vessels and the significant increment in the transit time through them are factors that predict a high risk for postoperative vasospasm. * Intraoperative angiography is technically demanding, along with the risk of radiation exposure. Indocyanine green only gives a qualitative analysis of flow patterns through the vessels. Endoscopy helps in evaluating the blind corners of the operating fields but will not give any information with regard to patterns of flow dynamics.

Answer 60

**3. Transvenous embolization via the ipsilateral inferior petrosal sinus** ## Footnote * Transvenous embolization via the inferior petrosal sinus is the preferred treatment modality for indirect carotid-cavernous fistulas (Barrow type B, C, D). The inferior petrosal sinus may be accessed via the jugular vein. * The superior ophthalmic vein is a potential route to the cavernous sinus, most commonly employed in scenarios in which the inferior petrosal sinus is stenosed or in discontinuity with the jugular system. It may be accessed endovascularly through the facial vein, the preferred method. * Direct surgical cannulation of the superior ophthalmic vein is typically reserved for cases in which other transvenous approaches to the cavernous sinus have been exhausted, and transarterial access is not appropriate or sufficient. Endovascular access via the facial vein is preferred but may be technically challenging. * Transarterial embolization via the internal carotid artery is appropriate for direct carotid-cavernous fistulas (Barrow type A). Indirect and mixed-type fistulas require at least partial venous access.

Answer 61

**4. Isocitrate dehydrogenase 1 and 1p19q co-deletion** ## Footnote * Infiltration along with moderate cellularity and branching capillaries that give a chicken-wire appearance are the main microscopic feature of oligodendroglioma. The presence of vascular proliferation or necrosis should raise concern for higher tumor grade such as anaplastic oligodendroglioma. * The typical histologic appearance of oligodendroglioma demonstrates nuclei with a rim of clear cytoplasm, resulting in the classic fried egg appearance due to artifactual cytoplasmic retraction that happens as a result of the fixation process. * Isocitrate dehydrogenase (IDH) mutation with 1p19q codeletion is the defining genetic marker for oligodendroglioma. These two mutations are predictive of a better therapeutic response to chemotherapy (temozolomide) and combined chemoradiotherapy, with longer overall survival compared to patients with other types of glioma without these genetic changes. * The tumor histology, grade, size, and anatomic structures involved are all very important considerations to determine patient prognosis because complete tumor resection is the goal for optimal treatment. If the tumor cannot be completely resected, the tumor can continue to be a seizure focus and may later undergo degeneration to more malignant glioma. Metastasis is very rare in oligodendroglioma, but when present portends a poor prognosis.

Answer 62

**2. Head and neck CT scan with contrast** ## Footnote * This patient is presenting with unilateral headache and same- sided partial Horner syndrome after a motor vehicle accident resulting in a whiplash neck injury (a forceful, rapid, back-and- forth movement of his neck). * Unilateral headache and same sided partial Horner syndrome (no ptosis or anhidrosis) indicated internal carotid artery dissection until proven otherwise. * Internal carotid artery dissection can be caused by trauma (e.g., neck whiplash injury) or can occur spontaneously. It leads to the formation of an intramural hematoma that can obstruct blood flow and compress the sympathetic nerves that travel alongside the internal carotid artery. Anhidrosis is typically absent because the sweat fibers branch of the superior cervical ganglion and travel alongside the external carotid artery. * The diagnosis is made by a CT or MR angiography. Treatment is similar to the treatment of a stroke, entailing thrombolysis within four and a half hours of symptom onset and antiplatelet therapy. Cluster headache has a very similar presentation, but the headache is usually short-lived (30 mins-2hrs). Given this constellation of symptoms occurring after a neck whiplash injury, ruling out carotid artery dissection is the best next step in the management of this patient.

Answer 63

**2. No clinical sequelae** ## Footnote * Cavum veli interpositi (CVI) is usually an incidental finding at an MRI or CT scan mainly asymptomatic. * Transient increased intracranial pressure related to CVI is a rare occurrence. It is related to the ball-valve mechanism between the cisterna CVI and the cisterna venae magnae Galeni with transient increased intracranial pressure. * Hydrocephalus related to CVI is a rare occurrence. It is also related to the ball-valve mechanism between the cisterna CVI and the cisterna venae magnae Galeni with a severe increase of the intracranial pressure. * The presence of the CVI in children has been related to the development of psychosis spectrum disorders; however, further studies are needed to confirm this association.

Answer 64

**3. Maxillary artery** ## Footnote * This patient has trigeminal neuralgia and could benefit from a sphenopalatine ganglion radiofrequency ablation. * The needle entry point is nearest to the maxillary artery, which is a branch of the external carotid artery. * The maxillary artery is the most likely vessel to be injured with a sphenopalatine ganglion radiofrequency ablation procedure due to its anatomic location being near the site of needle entry, which is anterior to the mandible and inferior to the zygomatic arch. * The internal carotid artery is less likely to be injured compared to the maxillary artery when performing a sphenopalatine ganglion radiofrequency ablation. The superficial temporal artery is potentially in the territory of the needle entry point for a sphenopalatine ganglion radiofrequency ablation; however, the maxillary artery is closer to the needle entry point and is more likely to be injured.

Answer 65

**4. Symptomatic care only** ## Footnote * The existing literature does not support routine prophylactic antibiotic use in nonoperative facial fractures. * Most surgeons use perioperative antibiotic therapy (defined as 2 hours before surgery to 24 hours post-surgery) when managing facial fractures. * There may be a role for postoperative prophylactic antibiotic use, but this is very controversial. * If one chooses to prescribe antibiotics, an antibiotic that covers sinonasal flora should be selected.

Answer 66

**1. Higher pore density** ## Footnote * Iontophoresis is affected by individual patient physiology. * Pore size, blood flow, temperature, and pigmentation can all affect the permeation of iontophoretic meds. * Pores offer routes of least resistance to transdermal delivery. * Medications are more likely to permeate in patients whose skins have higher pore densities.

Answer 67

**2. A well-circumscribed enhancing lesion at the cerebellopontine angle** ## Footnote * An acoustic neuroma is a benign tumor that may be locally destructive. It typically produces a unilateral, progressive, nonfluctuating, neurosensory hearing loss with unilateral tinnitus and unsteadiness. * The diagnosis of an acoustic neuroma is made with a contrast magnetic resonance imaging (MRI) or a computed tomogram scan. Contrast is essential; otherwise, the non-enhanced scan can miss small tumors. * These tumors usually occur adjacent to the cochlear or vestibular nerve. Anatomically, acoustic neuromas tend to occupy the cerebellopontine angle. * The majority of acoustic neuromas present with unilateral hearing loss due to cochlear nerve interruption or impairment of blood supply to the nerve. Other clinical features include tinnitus, decreased word understanding, vertigo, headaches, and facial numbness. With enough growth, the mass of the cerebellopontine angle will eventually compress the brainstem and cause gait abnormalities.

Answer 68

**1. Catheter migration and twisting around a nerve root** ## Footnote * A patient with an intrathecal catheter showing new-onset neurological symptoms has a high percentage of suspected catheter migration. First of all, imaging of the spinal axis is necessary to exclude stenosis or the formation of a granuloma. Intrathecal catheter-tip granulomas are rare and are formed progressively over time. * Neuroimaging allows visualization of the catheter and possible compression of nerve roots. * Although the worsening of the painful manifestations may be suggestive of catheter occlusion or catheter twisting, the appearance of new neurological symptoms (pain radiating to the buttocks, groin, and back of the lower limbs) can be better explained by the compression of nerve roots. * Opioid toxicity occurs mainly as respiratory depression and somnolence.

Answer 69

**2. Decompression with anterior fusion** ## Footnote * The above-mentioned patient has significant cervical spondylosis with kyphosis. * The appropriate treatment option is spinal canal decompression and anterior cervical fusion. * In kyphosis, anterior fusion is recommended. * Decompression and laminectomy without fusion lead to poor results.

Answer 70

**1. A dosimeter under and over the apron and optional dosimeters in various locations above the apron to estimate doses in potentially- exposed areas** ## Footnote * Dosimeters are devices that measure the absorbed dose of radiation that contacts the caretaker. These devices should be worn by all hospital staff who encounter planned ionizing radiation. This allows the radiation safety department to audit exposure for individual staff and inform them of their occupational exposure levels. Staff should be aware of their dose levels and the dose limits set forth by their institution. * Dosimeters should be worn both outside and inside the leaded apron for comparison of doses, and the dosing should be analyzed by the facility’s radiation safety department. * Raising awareness of the importance of dosimetry should be a priority for the occupational safety or radiation safety departments in health systems. * Sanchez et al. reported that as much as 50% of physicians do not wear or incorrectly wear dosimeters. Unfortunately, in a significant number of healthcare settings, there is a paucity of monitoring and, thus, a lack of reliable data.

Answer 71

**1. Saccadic visual exploration** ## Footnote * The clinical significance of LWs could be to demonstrate the physiological functioning of the saccadic visual exploration processes. In other words, as LWs are probably related to an oculomotor visual integration mechanism. * Lambda waves are physiological, sharp, and triangular transients seen over the occipital regions when the eyes are open. * Lambda waves typically present with saccadic eye movements during visual scanning. * They disappear when the eyes are closed and during sleep.

Answer 72

**4. Phenytoin** ## Footnote * Phenytoin is a commonly used anticonvulsant and rarely causes nephrotoxicity. * Phenytoin is associated with gingival hypertrophy. * Phenytoin can induce the P-450 enzymes in the liver. Thus, reducing the bioavailability of other drugs. * Ethosuximide is primary for the absence of seizures occurring in children.

Answer 73

**3. Mastoiditis** ## Footnote * The patient initially had an upper respiratory tract infection, which led to Eustachian tube dysfunction. Decreased clearance of bacteria led to acute otitis media. * If antibiotic therapy is not effective, intratemporal, or intracranial complications can develop. This patient has developed mastoiditis, which is an intratemporal complication of acute otitis media. * Opacification of mastoid air cells, as seen on CT of the head, is suggestive of mastoiditis. The infection spreads into the meninges, which further causes meningitis. * When the diagnosis of otitis media is established, the goal of treatment is to control pain and to target the infectious process with antibiotics.

Answer 74

**1. Pain with lumbar spine hyperextension** ## Footnote * This young gymnast with a potential diagnosis of hypermobile joints presents with back pain associated with training. The history is typical for lumbosacral spondylolisthesis. * In highly functioning, the physical examination of patients with low-moderate grades of spondylolisthesis is unlikely to reveal any significant findings. Lumbar spine hyperextension is often the only positive provocative sign present on examination. * Pain on back hyperextension is the most common finding followed by hamstring contractures and, in severe cases, L5 nerve root signs. * Although in high-grade lumbosacral spondylolisthesis, the L5 nerve root can be affected, the numbness would be expected in the first web space, not over the lateral aspect of the foot. Hamstring tightness is more often associated with lumbosacral spondylolisthesis. Waddle gait can be associated with high- grade cases with significant compression of the L5 nerve root. In this scenario, the patient can practice gymnastics and is limited mainly by activity-related back pain. She would be unlikely to perform with advanced L5 nerve root weakness.

Answer 75

**3. Aseptic meningitis** ## Footnote * During resection of an epidermoid tumor, keratin may leak into the surrounding tissue and cause aseptic meningitis. * Aseptic meningitis symptoms after resection of an epidermoid tumor can be reduced with the use of corticosteroids during the postoperative period. * Removal of keratin debris decreases the incidence of aseptic meningitis. * Bacterial meningitis is rare on the second postoperative day and will usually have a pathogen identified on gram staining.

Answer 76

**3. Oral prednisone** ## Footnote * This patient has delayed-onset facial nerve palsy, which is common in temporal bone fractures. * Delayed facial nerve palsy occurs in approximately 76% of patients who experience traumatic facial nerve palsy. * These patients generally have a good prognosis. One study found that 100% of their 820 patients with delayed onset facial weakness returned to House–Brackmann grade 2 function or better. * High-dose steroids are the treatment of choice for acute facial palsy. CSF rhinorrhea suggests trauma to the skull base and may indicate the need for prophylactic antibiotics, although this is somewhat controversial.