Neurosurgery

• Peripheral Nerve Injuries
  •     Neuropraxia = focal demyelination, improves
  • Axonotmesis = loss of axon continuity (nerve and sheath intact). Regeneration 1 mm/day
  • Neurotmesis = loss of nerve continuity, surgery required for nerve recovery
• ADH produced when high osmolarity is sensed at supraoptic nucleus of hypothalamus; causes increase free H2O absorption at the distal tubules and collecting ducts. Alcohol, and head injury, inhibit ADH release = Diabetes Insipidus. DI = high urine output, low urine specific gravity, high serum osmolarity, Na. May also see SIADH with closed head injury = oliguric, high urine osmolarity, low serum osmo, Na
• AVM's: congenital, bleed age 20-50; aneurysms younger (age 40-60), are associated with HTN
• Most adult brain tumors are malignant; spinal cord tumors are 60% benign (extradural likely malignant/metastatic)
• Acoustic neuroma: CN8, at the cerebello-pontine angle (cpa)
• 13% of patients with head injury have a spinal injury
• Subdural hematoma: crescent shape, conforms to brain; 50% mortality
• Epidural hematoma: lens shape, goes into brain, 10% mortality; middle meningeal artery; 'lucid interval'
• Cerebral perfusion pressure = CPP = MAP - ICP, want to keep ~ 70
• Cushing's triad with high ICP: HTN, bradycardia, Kussmaul respirations (slow, irregular)
• GCS Motor 6 commands, 5 localizes, 4 w/drawl to pain, 3 flexion pain (decorticate), 2 extension pain, 1 flaccid. Verbal 5 oriented, 4 confused, 3 inappropriate, 2 incomprehensible, 1 none. Eye opening 4 spontaneous, 3 to command, 2 to pain, 1 none
• GCS 8 or less: ICP monitor indicated; 10 or less intubation indicated; GCS 5=50% mortality
• Cord  injury above T5 can cause spinal shock; Rx with fluids, may need alpha agonist. Recognize by hypotension with bradycardia, warm perfused extremities (vasodilated)
• Anterior Spinal Artery Syndrome: lose bilateral motor, pain and temp; keep position sense, light touch
• Brown Sequard: Spinal cord transected 1/2 way; lose ipsilateral motor, contralateral pain and temp
• Central Cord Syndrome: bilateral loss of upper extremity motor, pain, temp; legs relatively spared. Usually due to hyperextended c-spine injury
• Skull fx: to OR if open fx or if depressed (to ~ thickness of skull or more)

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