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
Cerebral perfusion pressure = what?
MAP - ICP
Goal CPP?
> 60-70
Treatment for head trauma and decreased CPP?
Elevate HOB, sedate/paralyze, moderate hyperventilation (Pco2 30-35), mannitol to decrease brain edema, may need craniectomy
When does maximum brain swelling occur after trauma?
48-72h
Symptoms of elevated ICP? Signs?
Stupor, headache, n/v, stiff neck
HTN, HR lability, slow respirations
What is Cushing’s triad?
HTN, bradycardia, slow respiratory rate
What does dilated pupil after trauma indicate?
Ipsilateral temporal herniation onto 3rd cranial nerve
Symptoms of complete cord transection?
Areflexia, flaccidity, anesthesia, autonomic paralysis below the level of lesions
Signs of spinal shock?
Hypotension, normal or slow heart rate, warm extremities
Spinal shock can occur with what level of cord injury?
T5 and above (loss of sympathetic tone)
Treatment for spinal shock?
Fluids, phenylephrine (alpha-agonist)
What is anterior spinal artery syndrome?
Most commonly occurs with acutely ruptured cervical disc
Bilateral loss of motor, pain, and temperature sensation below the level of lesion (preservation of position-vibratory sensation and light touch)
What % of anterior spinal artery syndromes recover to ambulation?
10%
What is Brown-Sequard syndrome?
Hemisection of cord; most commonly due to penetrating injury
Loss of ipsilateral motor, contralateral pain and temp below level of lesion
What % of Brown-Sequard recover to ambulation?
90%
What is central cord syndrome?
Most commonly occurs with hyperflexion of C spine
Bilateral loss of motor pain and temperature sensation in upper extremities, lower extremities spared
What is cauda equina syndrome?
Pain and weakness in lower extremities due to compression of lumbar nerve roots
What tract carries pain and temp sensory neurons?
Spinothalamic tract
What tract carries motor neurons?
Corticospinal and rubrospinal tract tract
What nerve roots are generally afferent; carry sensory fibers?
Dorsal nerve roots
What nerve roots are generally efferent; carry motor neruon fibers?
Ventral nerve roots
The majority of adult brain tumors are supra or infratentorial? Children?
Adult: 2/3 supratentorial
Children: 2/3 infratentorial
What is the most common primary brain tumor? Most common subtype?
Glioma
Glioma multiforma
What is the #1 tumor with mets to the brain?
Lung
What is the most common brain tumor in children?
Medulloblastoma
What is the most common metastatic brain tumor in children?
Neuroblastoma
Where does an acoustic neuroma arise from? Symptoms?
From 8th cranial nerve
Hearing loss, unsteadiness, vertigo, nausea/vomiting
1 tumor overall of the spine?
Neurofibroma
What type of tumors are most likely benign?
Intradural tumors
What lab tests are checked with paraganglionoma?
Metanephrine in urin, MIGB for extramedullary chromatin tissue
When is intraventricular hemorrhage seen in children?
In premies secondary to rupture of the fragile vessels in germinal matrix
Risk factors for IVH in children?
ECMO, cyanotic congenital heart disease
Treatment of IVH in children?
Ventricular catheter for drainage and prevention of hydrocephalus
What is a myelomeningocele?
Neural corde defect with herniation of spinal cord and nerve roots through defect in vertebra
Where is the most common location for myelomeningocele?
Lumbar region
Where is Wernicke’s area? What is its function?
Speech comprehension
Temporal lobe
Where is Broca’s area? What is its function?
Speech motor
Posterior part of anterior lobe
What is the diagnosis for a patient with pituitary adenoma, undergoing XRT, now in shock? Treatment?
Pituitary apoplexy
Steroids
What cells act as brain macrophages?
Microglial cells
