5. Cranial Neurosurgery Flashcards
What lesion can produce head tilt?
Anterior vermis, 4th nerve palsy
In MG - head tilts back
Vermicular movement of face with pontine demyelination?
Myokymia
DBS of ventral intermediate thalamic nucleus for what dx?
Parkinson
Essential tremor
Dysarthria and clumsy-hand syndrome?
Genu of internal capsule
Dilute pilocarpine constrict what type of pupil?
Addie’s pupil, but not harm dilated
Consensual light reflex > direct light reflex
Afferent pupillary defect
Most common cause of spontaneous diplopia in middle-aged
Grave’s
Parkinson with vertical gaze palsy?
Progressive supranuclear palsy
one-and-a-half syndrome - which eye movement is preserved?
Abduction of unaffected eye
Oculomotor palsy from aneurysm vs diabetic?
Diabetes: pain with pupillary sparing
Aneurysm - compress parasympathetic fibers on periphery
Ataxia, myoclonus, positive 14-3-3 protein and bilateral sharp waves on ECG?
CJD
Actual vs absence seizure?
EEG, prolactin, muscle enzyme
EEG for absence seizure
3Hz wave and spike
Diplopia of MG vs compressive lesion?
Intermittent vs progressive/constant
Which EOM if horizontal object appears slanted?
SO
Test for HTN from pheo vs essential?
Clonidine suppression test
%L hemisphere dominant in L handed individuals
> 75%
Clinical symptoms of NPH
Gait disturbances (usually first, most pronounced)
Memory loss
Urinary incontinence
Enlarged ventricles on CT but normal pressure of CSF by LP
Area involved in cortical inhibition of B&B damaged in NPH
Paracentral lobule
R/O other dx before NPH
Vascular dementia Parkinson Lewy body dementia Cervical spondylotic myelopathy Peripheral neuropathy
Pupillary reflex pathway
Optic nerve -> superior colliculus -> Edinger-Westphal nuclei -> (third cranial nerve) ciliary ganglion -> short ciliary nerves
Causes of circumoral paresthesia
Hypocalcemia
Hyperventilation
Syringobulbia
Neurotoxin fish poison
Low vs high pitch tinnitus
Low: conductive/meniere
High: sensorineural
“Transverse smile”
Myasthenic snarl with bulbar involvement in MG
Facial myokymia
MG, intrinsic brainstem glioma
What maneuver to elicit nystagmus of benign positional vertigo?
Dix-Hallpike maneuver
Lateral medulla nuclei
Inf. vestibular nuclei Solitary nucleus Inferior cerebellar peduncle Descending tract of V Spinothalamic tract
Benign positional vertigo characteristics
Position worsens or alleviates symptoms
Meniere’s disease: clinical findings
Tinnitus, bouts of vertigo, hearing loss
Can mimic acoustic neuroma
Lateral medulla infarct (wallenberg)
Vertigo, nausea/vomiting Ddysphagia Ipsilateral sensory loss of face pain/temp Ipsilateral horner Contralateral pain/temp
Ptosis from 3rd CN palsy vs horner syndrome?
Horner disappears with looking up
Causes of partial ptosis from 1st order Horner syndrome
Posterolateral hypothalamus to intermediolateral cell column (C8-T2)
Arnold-Chiari, basal skull fracture, wallenberg, demyelinating, intrapontine hemorrhage
Pharm test for 2nd or 3rd order horner syndrome?
If intact post-ganglionic fibers (1st or 2nd order) - hydroxyamphetamine would dilate pupil
Bell phenomenon
Ask to close eye and show teeth
Eye goes up and out
Nutritional causes of dementia
Wernicke-Korsakoff
Vitamin B12/Folate
Heritable disorder - migraine in early life, then TIAs and strokes, then early dementia?
CADASIL
(Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy)
Notch3 gene - affects blood vessels grow/development
How can you tell if patient may improve from shunt for NPH?
Improvement after lumbar CSF drainage
Beta waves in ICP monitoring
Most common cause of cardioembolic stroke
Afib
Arteries supply to macular vision
PCA
Acoustic schwannomas - early manifestations?
Depression of corneal reflex (CNVII compression)
What diameter of carotid vessel feels bruit?
2.5-3mm
Cushing syndrome
Moon face, acne, hirsutism, bladness, buffalo-type obesity, purple striae, muscle wasting, osteoporosis, hypertension, infection, DM
Dx with upgaze palsy
Perinaud syndrome (tumor in pineal or quadrigeminal plate)
Hydrocephalus
Hypothyroidism/MG/GBS
Recurrent meningitis with no predisposing conditions
Children: basal encephalocele
Adult: CSF fistula
Cupulolithiasis
Benign positional vertigo
What causes horizontal vertigo?
Paresis of 6th CN
Can occur with pseudotumor cerebri (susceptible to stretch forces with high ICP)
Dx with cherry red spot
Tay-sachs
Niemann Picks
Pseudo-Hurler (GM1 ganglioside)
Dx with retinitis pigmentosa
Freidrich ataxia
Refsum (polyneuropathy)
Cockayne (premature aging)
Kern-Sayre (oculocraniosomatic neuromuscular)
Cerebellar mutism
Mute in children 1-4 days after surgery in vermian lesion resection
Classification for CN7
House-Brackman
1: Normal
5: no eye closure
6: paralysis, no tone
Recurrent orofacial edema, recurrent 7th nerve palsy, lingua plicata
Melkersson-Rosenthal
Herpes zoster oticus
Ramsay-Hunt syndrome
Uveoparotid fever
7th CNS palsy in sarcoidosis
Heerfrodt
Bilateral 7th nerve palsy
Lyme
Ips CN6/7 palsy and contralateral hemiparesis
Millard-Gubler
Ips CN7 hemispasm and contralateral hemiparesis
Brissaud-Sicard
Ips CN7/8 with horizontal gaze paralysis with contralateral hemiparesis
Foville
Benign occipital lobe epilepsy in children, induced by sleep
Panayiotopoulos
diameter in mm of a 12-French suction tip?
3-French = 1mm 12-French = 4mm
Significance of frontozygomatic point?
On lateral orbital bone (~ 2.5cm from zygoma attachment, which approximates location of sylvian fissure when connected with 75% point (3/4 distance from nasion to inion)
Incision reaching zygoma > 1.5cm anterior to ear may interrupt which nerve?
Facial nerve that reaches frontalis muscle
Approach to superficial temporal artery
- trace out with doppler to determine branching pattern
- sample frontal branch by dissecting artery under microscope
3-5 cm long
Inferior frontal gyrus of dominant hemisphere
Broca
Trautman triangle
Superior petrosal sinus
Sigmoid sinus
Posterior auricular canal
Access posterior fossa dura anterior to sigmoid sinus
Following greater superficial petrosal nerve lead to which ganglion?
Geniculate ganglion
What part of the internal capsule lies ver close to the foramen of monro?
Genu
What thalamic nucleus may be damaged while opening the body of the choroidal fissure?
dorsomedial nucleus
What areas of bone may be needed to be removed to clip a low-lying basilar artery aneurysm?
Posterior clinoid
When would you approach an acomm artery aneurysm from left?
Dominant left A1, dome pointing to the right, another left-sided aneurysm
Craniotomy - why linear incision?
Increases blood supply to wound
Craniotomy - why “lazy S incision”?
prevent incision line in dura from lying directly underneath incision in skin
Craniotomy - why flap incision?
scalp blood flow is not compromised
Craniotomy - why zigzag incision?
minimize visibility of scalp alopecia
Technique for placing ventriculoatrial shunt?
- Incision at anterior border of sternomastoid muscle to identify jugular vein
- Tie off vein distally
- Small opening to pass shunt down juvular vein into right atrium (biphasic P wave)
- intraop fluoroscopy to confirm catheter is at T6 level
Technique for placing ventriculopleural shunt?
- Incision between second and third rib lateral to midclavicular plane
- insert tube after puncture of parietal pleura
What bones form the hard palate?
Maximall anteriorly
Palatine posteriorly
What veins connected at the torcula?
(Confluence of sinus) Superior sagittal Transverse sinus Straight sinus Occipital sinus
What bones form the zygomatic arch?
Anterior (Zygoma)
Posterior (Temporal - squamosal part)
What bones form the nasal septum?
Ethmoid (perpendicular plate) and vomer
What bones form the clivus?
Sphenoid and occipital bone
What nerve carries parasympathetic innervation to parotid gland?
Auriculotemporal nerve (part of mandibular nerve)
Which cerebellar peduncle carries only afferent fibers?
Middle cerebellar peduncle
Which thalamic vein join the thalamostriate vein?
None!
Thalamostriate joins the internal cerebral vein of galen
Superior orbital fissure provides communication between which 2 areas?
Orbit and middle fossa
Lamina terminalis extends upward from optic chiasm and blends into what?
Rostrum of corpus callosum
What cistern is contained in posterior incisural space?
Quadrigeminal cistern
Lateral and medial posterior choroidal arteries are branches of which circle of willis artery?
PCA
How is CSF secreted from choroid plexus enters subarachnoid space?
Ventricular foramina of Magendie and Luschka
Rate of CSF formation
0.5L per day (0.33mL per minute)
Normal diameter of supraclinoid ICA
4-5mm
Where does basal vein originate and through which cistern does it pass?
Anterior perforated substance -> crural and ambient cisterns -> quadrigeminal cistern -> internal cerebral vein
Most medial structure in cavernous sinus?
ICA
Most common side effect of mannitol
Renal failure
When do majority of perioperative MI occur
POD3 and 5
Best method to assess cerebral metabolism
PET
Why are inhalational anesthetics called “uncoupling” agents?
Decrease cerebral metabolism but increase cerebral flow through vasodilation.
When should you reconsider use of nimodipine in vasospasm?
Diminished cardiac contractility (negative inotrope)
Elective craniotomy for meningioma who is hyponatremic and hypotension - what should you consider?
Adrenal insufficiency
What types of coagulopathies are not detected by PT/PTT/INR and platelet counts?
Dysfibrinogenemia, vWF disease, Factor XIII deficiency, ASA/Plavix use
Disorders with platelet sequestration
Hypersplenism with cirrhosis
Gaucher
Sarcoidosis
Who has increased risk of GI hemorrhage with steroid use?
Preexisting ulcer disease
O2 transport is maximal in what hematocrit range?
30-32%
What on CT is predictive for success of 3rd ventriculostomy for hydrocephalus
Triventricular hydrocephalus (obstructive) from aqueductal stenosis or blockage of 3rd ventricular outflow
Morphology of cerebral aneurysms
Saccular, dissecting and fusiform. Influences surgical and endovascular treatment
Most common cause of SAH
Head trauma
Most common cause of CSF leakage
Head trauma (skull fracture doubles risk) Leaks to nose (rhinorrhea), ear (otorrhea), or orbit (mimics tears)
CSF nasal drainage vs secretion?
Glucose level (in CSF but not nasal drainage)
Double-ring “halo” sign on bed sheets or clothing
Confirm with beta-2 transferrin test
Best initial treatment for CSF leak
Bed rest and head elevation.
If persists for 3 days, lumbar drainage
Major cause of spontaneous intracranial hypotension
Spontaneous CSF leaks
Look for diffuse pachymeningeal enhancement on MIR
Areas most prone to DAI after head trauma
Corpus callosum and superior cerebellar peduncle
Microscopic hallmark of DAI
Axonal retraction balls (eosinophilic globular swellings at proximal/distal sites of disrupted axons)
Bullet wound: entrance or exit wound larger?
Entrance typically smaller
What radiologic view to fully appreciate occipital bone fracture
Towne view (mandible)
Which allele predisposes one to greater risk of Alzheimer after head injury
Apo E4
Area of intracranial facial nerve most commonly damaged by blunt trauma
Facial nerve around geniculate ganglion
Schirmer test
Distinguish facial nerve injury proximal/distal to geniculate ganglion. Assess lacrimation (proximal = dry eye; distal = not interfere)
What type of temporal bone fractures most frequently results in external manifestations (otorrhea, tympanic membrane rupture)?
Longitudinal fractures
Transverse spares middle ear, tympanic membrane and external auditory canal (fewer signs)
Why EEG ordered in lowered levels of consciousness posttrauma?
R/O subclinical status epilepticus
Range of cerebral perfusion pressure accommodated by cerebral autoregulation
60-160mmHg
Calculation for cerebral perfusion pressure?
Mean arterial pressure - intracranial pressure
CPP should be maintained above what after severe head injury?
70 mmHg
Calculating MAP?
1/3SBP+2/3DBP
At what blood flow rate does electrical activity of cerebral cortex fail?
20 mL/100g /min
Brainstem reflexes mandatory to test in brain death evaluation
Pupils, corneal, oculovestibular, oculocephalic, gag.
Response to deep central pain and apnea test
No evidence of drug or metabolic intoxication
Auditory evoked potentials in evaluating brain death, what weight is necessary for the test to be valid?
Wave I, at least on one side
Neuroprotective medications
Corticosteroids, calcium channel blockers, glutamate antagonist, Manitoba, barbiturates
Trauma patient with broken leg deteriorates after manipulation of broken leg on hospital day five. Most likely cause?
Fat emboli syndrome
Why bifrontal exposure for persistent rhinorrhea after trauma?
Fracture of anterior fossa often extends across midline
Prophylactic antibiotics for CSF leaks after traumatic brain injury?
Not recommended according to Lancet 1994 article. Encourage resistance and late attacks of meningitis
Use of hyperventilation and head injury?
No good random my studies to support for use. May decrease cerebral perfusion pressure and delivery of oxygen and glucose.
Young adult with family history of migraines present with head trauma and blindness
Trauma triggered migraine with transient cortical blindness
How can acute SDH appear ice so intense to brain in multi-trauma patient?
Hematocrit less than 23
Coagulopathy
Why EDH more common in younger adults?
Dura is thinner and more adherent to the skull in elderly
EDH in children versus adults
Children: caused by venous bleeding more
Adult: middle meningeal artery
Common drug to suppress cerebral metabolism in setting of major cerebral trauma
Barbiturates
Typical dosage of pentobarbital for suppression of cerebral metabolism and setting of major cerebral trauma
Loading dose of 10 mg/kg over 30 minutes, then 5 mg/kg per hour over three hours
Where on carotid artery is the most common location for a traumatic aneurysm?
Between proximal and distal dural rings. Pseudoaneurysms that may project medially into sphenoid sinus.
Shortcomings of GCS
Eye-opening in periorbital trauma, verbal response and intubated patient, brainstem functions or reflexes
Association between mean your skull fracture on radiograph and risk of intracranial hematoma
Increase risk by 400 fold
Early versus late posttraumatic seizure
Early: first seven days. Prophylactic phenytoin therapy to prevent early posttraumatic seizures
Late: after seven days. No proven advantage to prevent late seizures
Preferred method of intubation in patients with basal skull fracture
Orotracheal intubation. Possibility of entering cranium through cribriform plate with nasotracheal intubation.
Prerequisites for growing skull fracture
- Fracture occurs in infancy or early childhood
- Dural tear at time of fracture
- Brain injury at time of fracture with displacement up leptomeninges
- Subsequent enlargement of fracture to form cranial defect
Fall in end tital CO2 could be the only clue to what?
Air embolus
Treatment of air embolism
Lower patients head, rotate patients left side downward, aspirate from venous line in right atrium, and eventually patient while maintaining blood pressure and heart rate
Cases where hyperemia of brain occurs?
Head trauma, after carotid endarterectomy/stenting, excision of AVM
How to confirm diagnosis of DIC?
Low platelet count, prolonged PT, elevated fibrin degradation products, reduced fibrinogen levels
Treatment of cluster headaches
Oxygen, sumatriptan
Best drug for immediate control of seizures and status epilepticus
Lorazepam, better than diazepam are phenytoin
Signs and symptoms of myxedema coma
Emergency of hypothyroidism: hypotension, bradycardia, hyponatremia, hypoglycemia, hypothermia, hypoventilation
Treatment of myxedema coma
IV fluids, intubation if necessary, IV glucose
400 MG hydrocortisone IV over 24 hours, 0.5 MG levothyroxine IV followed by 0.05 levothyroxine per day
Three places a shunt maybe occluded
- Entry point (proximal occlusion)
- Valve system (valve obstruction)
- Distal and (distal catheter occlusion)
CT head, shunt series, palpation about
Patient with history of pituitary trauma presents with sudden onset headache and rapid visual failure with extra ocular nerve palsy. Most likely diagnosis
Pituitary apoplexy, can mimic SAH. Treatment is urgent steroids
Management of life-threatening cerebellar swelling from infarction
Reception up cerebellar infarction maybe needed
Ventriculostomy as temporizing measure in anticipation of surgery
Drugs used in NMS
Bromocriptine and dantrolene
Most common cerebrovascular comp patient during pregnancy
SAH
Risk of rupture parallels hemodynamic changes with blood volume change; most prone to rupture during seventh and eight months of pregnancy
Most common site of hypertensive cerebral hemorrhage?
Putamen
Addisonian crisis: signs and symptoms
Atrial insufficiency emergency: mental status changes, muscle weakness, postural hypotension, shock, hyponatremia, hyperkalemia, hypoglycemia, hyperthermia
Addisonian crisis: treatment
100 MG IV hydrocortisone immediately and then 50 MG IV Q6 hours
Central pontine myelinolysis
Rapid correction of hyponatremia causing disorder of punching white matter; insidious flaccid quadriplegia and mental status changes.
Sodium should not be corrected faster than 10 mEq per liter/24h
Neurogenic pulmonary edema
Associated with SAH, head trauma, seizure
Increased capillary permeability and lungs associated with increased sympathetic discharge.
Neurogenic pulmonary edema: treatment
Reduce ICP, maintain positive pressure ventilation, supportive care
Treatment of acute migraine attack
Compazine/prochlorperazine 10 MG IV
What potential emergency can occur intracranial late if nitrous oxide anesthesia is not discontinued prior to closure of director in surgery?
Tension pneumocephalus
Most common complication of trans oral operative route?
CSF leakage and infection
Cystic tumor of suprasellar region that arises from neuroectodermal remnants of Rathke pouch
Craniopharyngioma
Preop medications to lessen risk of patients with growth hormone secreting tumor
Somatostatin analog
Lesion with calcification in cellar area and erode through posterior clinoid
Craniopharyngioma. Erosion of posterior clinoid may also occur from chronic increase in ICP
Tumor that can erode internal acoustic meatus
Acoustic schwannoma
Tumor that can erode petrous apex
Trigeminal schwannoma
Tumor that can erode clivus
Chordoma
Tumor that can erode sellar floor
Large pituitary tumor
Tumor that can erode orbital foramen
Optic nerve glioma
Tumor that can erode jugular foramen (the bone)
Glomus jugulare
What disease may produce generalizable erosion? and hyperostosis?
Multiple myeloma, paget disease
Meningioma results in focal hyperostosis
Most common extradural neoplasm involving the clivus
Chordoma (typical, and chondroid - better prognosis)
IHC of chordoma versus chordosarcoma
Chordoma always things positive for keratin with S 100.
Chordosarcoma lacks epithelial markers but always positive for S 100
Malignant potential of chordoma
Critical location, locally aggressive nature, hybrid of recurrence, occasional tendency to metastasize
Histologically benign
Most common site of origin of chordoma
Sacrum
Second most common site of chordoma
Clivus
Prophylactic cranial irradiation may be considered for what patients
Small cell lung cancer
What lesion most commonly removed by endoscopic methods
Colloid cyst
Where are colloid cyst found?
Anterior roof of third ventricle
How do colloid cyst cause death?
Obstructive hydrocephalus
Most common in intraorbital tumor in adults
Cavernous hemangioma: benign, slow-growing vascular lesion
Painless, progressively proptotic eye
Second most common type of intracranial schwannoma
Trigeminal schwannoma
Vestibular type most common
Most common presentation of choroid plexus tumor?
Intracranial hypertension
Location of choroid plexus papilloma between adults and children
Children: left lateral ventricle
Adults: fourth ventricles
Rare benign tumors of CMS, male predominance
