Chapter 41 - Neurosurgery Flashcards
What is neuropraxia?
No axonal injury (temporary loss of function)
What is axonotmesis?
Disruption of axon with preservation of axon sheath, will improve
What is neurotmesis?
Disruption of axon and axon sheath (whol enerve disrupted), may need surgery for recovery
What is the rate of regeneration of nerves?
1mm/d
What are the Nodes of Ranvier? What is the purpose?
Bare sections
Allow salutatory conduction
Release of ADH controlled by what?
Supraoptic nucleus of hypothalamus which descends into the posterior pituitary gland
What stimulates release of ADH?
In response to high plasma osmolarity
Leads to increased water absorption in collecting ducts
What are the manifestations of DI (low ADH)?
Increased urine output, decreased urine specific gravity, increased serum Na, increased serum osmolarity
When can DI occur?
ETOH, head trauma
Treatment for DI?
DDAVP, free water
What are the manifestations of SIADH (high ADH)?
Decreased urine output, concentrated urine, low serum Na, low serum osmolarity
When will SIADH occur?
With head injury
Treatment for SIADH?
Fluid restriction, diuresis; can give hypertonic saline if initial treatment fails
How do AV malformations present 50% of the time?
Hemorrhage
Treatment of AV malformation?
Resection if possible; can coil prior to resection
How do cerebral aneurysms present?
Bleeding, mass effect, seizures, infarcts
Where do cerebral aneurysms occur?
At branch points in artery, most in carotid or anterior circulation; most congenital
Cause of SDH?
Torn bridging veins
CT findings with SDH?
Crescent shape on head CT; conforms to brain
Cause of epidural hematoma?
Injury to middle meningeal artery?
CT findings with epidural?
Lens shape, pushes brain away
What is the cause of nontraumatic SAH?
Cerebral aneurysms and AVMs
Symptoms of SAH?
Nuchal rigidity, severe headache, photophobia, neurologic defects
Treatment for SAH?
Hypervolemia, calcium channel blockers
What lobe is most often affected by intracerebral hematoma?
Temporal lobe