Neuro - Surgery

Question 1

What is anterior cord syndrome?

Answer 1

Due to spinal cord infarction, which can be a complication of thoracic aortic aneurysm repair.
Anterior spinal artery supplies motor and sensory tracts involved in pain/temperature sensation.
Presentation: bilateral flaccid paralysis and loss of pain/temp sensation below level of injury; flaccid paralysis is due to shock; upper motor neuron signs (spasticity and hyper-reflexia) subsequently develops over days to weeks; bowel and bladder dysfunction (eg urinary retention)
vibration and proprioception are preserved b/c dorsal column is not affected

Question 2

What is a transtentorial (uncal) herniation?

Answer 2

Compression of the contralateral crus cerebri against tentorial edge - ipsilateral hemiparesis
Compression of ipsilateral oculomotor nerve by herniated uncus - loss of CN3, PNS innervation (mydriasis, ptosis, down and out gaze of ipsilateral pupil)
Compression of ipsilateral posterior cerebral artery (i.e., ischemia of visual cortex) - contralateral homonymous hemianopsia
Compression of reticular formation - altered level of consciousness; coma

Question 3

What is Cushing’s reflex?

Answer 3

HTN, bradycardia, respiratory depression - indicates elevated intracranial pressure

Question 4

What is Cauda Equina syndrome?

Answer 4

Most common following a large, anterior lumbosacral disc herniation.
Presentation: severe back pain radiating into one or both legs, loss of LE motor strength, sensation, and reflexes in affected dermatomes; saddle anesthesia* (S2-S4), bladder (urinary straining) and rectal sphincter paralysis (S3-S5), loss of ankle reflex (S1-S2), hyporeflexia/areflexia; asymmetric motor weakness
Positive straight leg raise test (Lasegue)
Dx: MRI of lumbosacral spine
Tx: surgical decompression

Question 5

What is central cord syndrome?

Answer 5

Typically occurs w/ hyperextension injuries in elderly pts with pre-existing degenerative changes in cervical spine
Presentation: weakness more pronounced in upper extremities than lower; occasional selective loss of pain and temperature sensation in the arms due to damage to STT

Question 6

What is brown-sequard syndrome?

Answer 6

Hemisection of the cord, most often due to penetrating injury
Loss of pain, temperature, and light touch on contralateral side
Weakness, loss of motor function and vibration, position/proprioception, and deep touch sensation on ipsilateral side

Question 7

What is cervical myelopathy?

Answer 7

Epidemiology: age>55, degenerative cervical spine/discs–>canal stenosis–> cord compression and interruption of blood supply–>cervical spondylotic myelopathy; most common cause is spondylosis, a degenerative spine disease that can narrow the cervical spinal canal and compress the spinal cord
Presentation: gait dysfunction - usually first, extremity weakness and numbness;
LMN (damage to spine nerve roots/PNS) signs at the level of the lesion (arms) - weakness/muscle atrophy, hyporeflexia;
UMN (CNS) signs below level of lesion (legs) - Babinski, hyperreflexia, decreased proprioception/vibration/pain sensation
Lhermitte sign = electric shock-like sensation down spine w/ forward flexion of the neck
Dx: MRI of cervical spine, CT myelogram
Tx: nonsurgical - immobilization, surgical decompression

Question 8

What is a spinal epidural abscess?

Answer 8

Epidemiology: s. aureus (65%), inoculating sources (distant infection -eg cellulitis, jt/bone; spinal procedure - eg epidural catheter; injection drug use)
Presentation: classic triad: FEVER, focal/severe back PAIN, NEURO findings (eg motor weakness/sensory change, bowel/bladder dysfunction, paralysis)
Progression due to worsening spinal cord compression: focal back pain–>nerve root pain (eg shooting, electric shock sensation)–>motor weakness, sensory changes, bowel/bladder dysregulation –> paralysis
Dx: increased ESR, blood and aspirate cultures, MRI* of the spine
Tx: broad spectrum antibiotics (eg vanc + ceftriaxone), aspiration/surgical decompression

Question 9

What is an epidural hematoma?

Answer 9

Most common in children/adolescents
Pathogenesis: trauma to sphenoid bone with tearing of middle meningeal artery, bleeding between dura mater and skull
Presentation: brief loss of consciousness followed by lucid interval
Hematoma expansion leads to increased intracranial pressure (impaired consciousness, headache, nausea/vomiting), uncal herniation (ipsilateral CN 3 palsy and hemiparesis)
Dx: head CT - biconvex (lens-shaped) hyperdensity that does not cross suture lines
Tx: urgent surgical evacuation for symptomatic patients

Question 10

What is a subdural hematoma?

Answer 10

Occurs secondary to tearing of the bridging veins w/ subsequent slow bleeding into the subdural space following traumatic head injury
Symptoms of headache and confusion occur gradually (over 1-2 days) compared to those of epidural hematoma

Question 11

What is the femoral nerve?

Answer 11

Innervates muscles of the anterior compartment of thigh (quad femoris, sartorius, pectineus), responsible for knee extension and hip flexion
Provides sensation to anterior thigh (via anterior cutaneous branches of the femoral nerve) and medial leg (via the saphenous branch)
Injury: decreased patellar reflex, as reflex involves quads
Vulnerable to injury from pelvic fracture, hip dislocation, or hematoma (eg iliacus), can suffer iatrogenic injury during prolonged maintenance of dorsal lithotomy position (eg hip/pelvic surgery, childbirth) or vascular procedures involving the femoral artery or vein

Question 12

What is malignant hyperthermia?

Answer 12

Epidemiology: AD genetic mutation alters control of intracellular calcium (excessive Ca release), triggered by volatile anesthetics (eg halothane), succinylcholine, excessive heat
Presentation: masseter muscle/generalized rigidity, sinus tachycardia, hypercarbia resistant to increased minute ventilation, rhabdomyolysis, hyperkalemia, hyperthermia (late manifestation), myoglobinuria
Tx: respiratory/ventilatory support, immediate cessation of causative anesthetic, dantrolene

Question 13

What is anterior shoulder dislocation?

Answer 13

Most common dislocation. Typically caused by blow to an externally rotated and abducted arm.
Presentation: flattening of the deltoid prominence, protrusion of the acromion, anterior axillary fullness; axillary nerve is most injured in anterior shoulder dislocations (it innervates teres minor and deltoid - weak shoulder abduction; also provides sensory innervation to skin overlying lateral shoulder)

Question 14

What is syringomyelia?

Answer 14

A disorder caused by disruption of cerebrospinal fluid drainage from central canal, leading to formation of fluid filled cavity (syrinx) that compresses surrounding tissue
Commonly seen in pts with Arnold-Chiari type 1 malformations (extension of cerebellar tonsils into foramen magnum), can also occur due to meningitis, inflammatory disorders, tumors, and trauma
Presentation: loss of pain and temperature sensation (STT) in dermatomes corresponding to level of spinal cord involvement; may affect motor fibers in ventral horns (flaccid paralysis); touch, vibration, and proprioception are preserved
Development of central pain, incontinence, and lower extremity manifestations over time
Dx: MRI
Tx: surgical intervention (eg shunt placement)

Question 15

What are interventions for lowering intracranial pressure?

Answer 15

Head elevation - increases venous outflow from the brain
Sedation - decreases metabolic demand and control of HTN
IV mannitol - extraction of free water from normal brain tissue -> osmotic diuresis
Hyperventilation - CO2 washout –> cerebral vasoconstriction [as levels of paCO2 rise, so does blood flow]
Removal of CSF - reduction of CSF volume/pressure

Question 16

What is epidural spinal cord compression?

Answer 16

Causes: spinal injury (eg motor vehicle crash), malignancy (eg mets from breast, lung, prostate, myeloma)
Presentation: gradually worsening, severe local back pain; pain worse in the recumbent position/at night; early signs - symmetric lower extremity weakness, hypoactive/absent deep-tendon reflexes; late signs - bilateral Babinski reflex, decreased rectal sphincter tone, bladder dysfunction, paraparesis/paraplegia with increased deep-tendon reflexes/hyperreflexia, sensory loss
Mgmt: emergency MRI, IV glucocorticoids (decrease vasogenic edema caused by obstructed epidural venous plexus; help alleviate pain, and may restore neurologic function), radiation-oncology and neurosurgery consultations

Question 17

What is autonomic dysreflexia?

Answer 17

A complication of spinal cord injury occurring above T6. Loss of modulatory activity below the lesion.
Noxious stimuli (eg urinary retention, constipation, pressure ulcers) can precipitate an unregulated sympathetic response, leading to vasoconstriction and severe hypertension.
Above the lesion, a compensatory parasympathetic response causes diaphoresis, flushing, bradycardia, and nasal congestion; vasodilation occurs but cannot overcome the sympathetic drive to normalize systemic pressure
Severe disease can result in intracranial hemorrhage or progressive bradycardia w/ cardiac arrest
Mgmt: close monitoring of blood pressure, placing pt in upright position to encourage orthostatic blood pressure reduction; tight-fitting clothes should be removed; pt should be evaluated for urinary retention, fecal impaction, or pressure sores
Short duration antihypertensives (eg nitrates, hydralazine) may be indicated for blood pressure control

Question 18

What is central cord syndrome?

Answer 18

An incomplete acute spinal cord injury; Common after whip-lash injuries (hyperextension injury to neck) in older adults with underlying cervical spondylosis
Presentation: primarily upper extremity manifestations - weakness due to damage to alpha motor neuron cell bodies in anterior horn of spine; pain, temp, and sensory loss in dermatomes at and surrounding level of injury due to damage to posterior grey column; reflex loss (eg tricep reflex) at level of injury due to damage to fibers as they cross from dorsal to ventral horn
Lateral spinal tracts to sacrum (eg bowel, bladder) and limbs are spared due to central location of lesion
Dx: cervical myelogram (shows persistent cord compression)
XR often normal but may show cervical spondylosis
Tx: glucocorticoids and/or surgery

Question 19

What is acute spinal cord injury?

Answer 19

Neurogenic shock due to traumatic spinal cord injury
Loss of spinal cord function (eg areflexia, anesthesia, paralysis, distended bladder) below level of lesion.
Initial period (several min) of massive SNS stimulation (leading to hypertension and tachycardia) due to release of NE from adrenals. Quickly followed by SNS loss due to injury to descending spinal tracts carrying signals from brainstem to preganglionic sympathetic neurons in lateral horn of spinal cord at levels T1-L2–>unopposed PNS stimulation (carried by intact vagus nerve) leading to hypotension and hypothermia from peripheral vasodilation and bradycardia
Neurogenic shock lasts 1-5w before improving

Question 20

What is management of cervical spine trauma?

Answer 20

Prehospital: spinal immobilization (eg backboard, rigid cervical collar, lateral head supports); careful helmet removal (eg motorcycle helmet); airway oxygenation
ED: orotracheal intubation preferred unless significant facial trauma present; rapid sequence intubation added for unconscious pts who are breathing but need ventilatory support; in-line cervical stabilization suggested unless it interferes with intubation; CT of entire cervical spine; monitoring for neurogenic shock from spinal cord injury

Question 21

What is the glasgow coma scale (GCS)?

Answer 21

It estimates the severity of the patient’s neurologic injury for triage; used to predict the prognosis of coma and other medical conditions, such as bacterial meningitis, traumatic brain injury, and subarachnoid hemorrhage; not used to diagnose coma in a pt
Assesses pt’s ability to open his/her eyes, motor response, and verbal response

Question 22

What is conus medullaris syndrome?

Answer 22

Sudden onset severe back pain
Perianal hypo/anesthesia
Symmetric motor weakness 
Hyperreflexia
Early onset bowel and bladder dysfunction

Question 23

Atlantoaxial instability

Answer 23

Pt w/ down syndrome are at increased risk of atlantoaxial instability.
When symptomatic, it can present w/ upper motor neuron findings (spasticity, hyperreflexia, and + Babinski), urinary/fecal incontinence, gait changes, or weakness due to compression of the psinal cord.
Dx: lateral XR of the cervical spine in flexion, extension, and a neutral position
Open mouth XR an also be helpful in visualizing the odontoid
Tx: surgical fusion of C1 to C2

Question 24

What is tethered cord syndrome?

Answer 24

It can cause weakness, decreased sensation, urinary incontinence, and hyporeflexia.
B/c the spinal cord is affected below T12/L1 upper motor neuron findings are not seen.
Tethered cord syndrome is commonly associated w/ spina bifida.