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Peripheral nerve injuries:

  • Neuropraxis: (no physical damage, interruption of conduction of impulse) focal demyelination, improves.
  • Axonotmesis = (disruption of axon, preservation of myelin sheath) loss of axon continuity (nerve and sheath intact).
  • Neurotmesis = (disruption of axon and myelin sheath) loss of nerve continuity, surgery required for nerve recovery.
  • Regeneration 1 mm/day.
  • Sensory recovery first.




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 (low ADH)= high urine output, low urine Specific Gravity, high serum Na, high serum osmolarity
  • Tx for Acute DI: aqueous pitressin
  • Tx for Chronic Nefrogenic DI: desmopressin
  • May also see SIADH with CHI = oliguric, high urine osmolarity, low serum osmo/Na



Arterio-Venus Malformations

Cerebral Aneurysms

MC Age

<30 yo

> 40 yo

Ethiology

Congenital

Most congenital

Initial Presentation

50% present w hemorrhage

Bleeding, mass effect, seizures, infarcts

Signs/Symptoms:

Sudden headache, and loss of consciousness

Site

Branch points in artery, most in carotid or anterior circulation

Tx:

Resection if possible for both: symptomatic and asymptomatic AVMs

Can coil embolize this prior resection

Often place coils before clipping and resecting the aneurysm, if elective resection




Most adult brain tumors are malignant

Spinal cord tumors are 60% benign (extradural likely malignant/met)

Acoustic neuroma: CN8 at the cerebello-pontine angle (CPA)

13% of patients with head injury have a spinal injury


Subdural hematoma:

  • 50% mortality
  • Most common from tearing of venous plexus (bridging veins)
  • Crescent shape
  • Conforms to brain


Epidural hematoma:

  • Lucid interval
  • 10% mortality
  • Middle meningeal artery
  • Lens shape
  • Goes into brain




Cerebral perfusion pressure:

  • CPP = MAP – ICP
  • Want to keep ~70




Cushing's triad with increase ICP:

  • HTN
  • Bradycardia
  • Kussmaul respirations (slow, irregular)

Glasgow Coma Scale

GCS
  • GCS 14 or less: Head CT
  • GCS 10 or less: Intubation indicated
  • GCS 8 or less: ICP monitor indicated
  • GCS 5: ~ 50% mortality


Spinal Cord Injury:

  • Cord injury above T5 can cause spinal shock
  • Tx 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
  • Lost 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




Initial treatment of spinal shock

  • Central neurogenic hypotension (CNH) is treated by:
  • Ameliorating vagal tone
  • Ensuring adequate ventricular filling
  • And increasing vascular resistance.




In spinal cord lesions rostral to T1, cardiac vagal influences dominate, and bradycardia is prominent.


Hypotension (< 90 mm Hg systolic, or mean arterial pressure < 70 mm Hg) should first be treated with atropine to increase HR and prevent sudden death.


Skull fx: to OR if open fx or if depressed (to ~ thickness of skull or more)

Pages in category "Neurosurgery"

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