chapter 41: neurosurgery Flashcards
come together to form a single basilar artery, which branches into 2 posterior cerebral arteries
vertebral arteries
connect middle cerebral arteries to posterior cerebral arteries
posterior communicating arteries
branches off middle cerebral arteries and are connected to each other thru the 1 anterior communicating artery
anterior cerebral arteries
no axonal injury (temporary loss of function, foot falls asleep)
neurapraxia
disruption of axon with preservation of axon sheath, will improve
axonotmesis
disruption of axon and axon sheath (whole nerve is disrupted), may need surgery for recovery
neurotmesis
how fast does regeneration of nerves occur?
1mm/day
nerves: bare sections; allows salutatory conduction
nodes of ranvier
what controls the release of antidiuretic hormone (ADH)?
release controlled by supraoptic nucleus of hypothalamus, which descends into the posterior pituitary gland
released in response to high plasma osmolarity; ADH increases water absorption in collecting ducts
antidiuretic hormone (ADH)
increased urine output
decreased urine specific gravity
increased serum Na
increased serum osmolarity
diabetes insipidus (decreased ADH)
two situations which can cause diabetes insipidus
ETOH, head injury
tx: diabetes insipidus
DDAVP, free water
decreased urine output concentrated urine decreased serum Na decreased serum osmolarity - can occur with head injury
SIADH (increased ADH)
Tx: SIADH
fluid restriction, then diuresis
50% present with hemorrhage; are congenital
- usually in patients
arteriovenous malformation
tx: arteriovenous malformation
resection if symptomatic
- can coil embolize these prior to resection
usually occur in patients > 40; most are congenital.
- can present with bleeding, mass effect, seizures, or infarcts
cerebral aneurysms
where do cerebral aneurysms most likely occur?
occur at branch points in artery, most off middle cerebral artery
tx: cerebral aneurysm
often place coils before clipping and resecting aneursym
cause by torn bridging veins
subdural hematoma
- has crescent shape on head CT and conforms to brain
- higher mortality than epidural hematoma
subdural hematoma
tx: subdural hematoma
operate for significant neurologic degeneration of mass effect (shift > 1cm)
caused by injury to middle meningeal artery
- has lens shape on heat CT and pushes brain away
- patients classically lose consciousness, have a lucid interval, and then lose consciousness again
epidural hematoma
tx: epidural hematoma
operate for significant neurologic degeneration or mass effect (shift > 0.5 cm)
caused by cerebral aneurysms (50% middle cerebral artery) and AVMs
- symptoms: stiff neck (nuchal rigidity), severe headache, photophobia, neurologic defects
subarachnoid hemorrhage (nontraumatic)
tx: subarachnoid hemorrhage (nontraumatic)
goal is to isolate the aneurysm from systemic circulation (clipping vascular supply), maximize cerebral perfusion to overcome vasospasm, and prevent rebleeding; use hypervolemia and CCB to overcome vasospasm
when do you go to OR for subarachnoid hemorrhage?
go to OR only if neurologically intact
lobe most often affected in intracerebral hematomas
temporal lobe most often affected
management: intracerebral hematomas
those that are large and cause focal deficits should be drained
symptoms of increased ICP
stupor, headache, nausea and vomiting, stiff neck
signs of increased ICP
hypertension, HR lability, slow respirations
sign of severely elevated ICP and impending herniation
intermittent bradycardia
hypertension
bradycardia
slow respiratory rate
Cushing’s triad
tx: spinal cord injury with deficit
give high dose steroids (decreased swelling)
areflexia
flaccidity
anesthesia
autonomic paralysis below the level of the lesion
complete spinal cord transection
hypotension, normal or slow heart rate, and warm extremities (vasodilator)
- occurs with spinal cord injuries above T5 (loss of sympathetic tone)
spinal shock
tx: spinal shock
fluids initially, may need phenylephrine drip (alpha agonist)
mcc 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
anterior spinal artery syndrome
rate of peeps that recover to ambulation with anterior spinal artery syndrome
about 10% recover to ambulation
incomplete cord transection (hemisection of cord); most commonly due to penetrating injury
brown-sequard syndrome
symptoms of brown-sequard syndrome
loss of ipsilateral motor and contralateral pain/temperature below level of lesion
rate of peeps that recover to ambulation with brown-sequard syndrome
about 90% recovery to ambulation
mcc central cord syndrome
most commonly occurs with hyperflexion of the cervical spine
bilateral loss motor, pain, and temperature sensation in upper extremities; lower extremities spared
central cord syndrome
pain and weakness in lower extremities due to compression of lumbar nerve roots
cauda equina syndrome
carries pain and temperature sensory neurons
spinothalamic tract
carries motor neurons
corticospinal tract
rubrospinal tract
are generally afferent; carry sensory fibers
dorsal nerve roots
are generally efferent; carry motor neuron fibers
ventral nerve roots
headache, seizures, progressive neurologic deficit, and persistent vomiting
brain tumors
where do most brain tumors present in adults?
adults: 2/3 supratentorial
where do most brain tumors present in children?
children: 2/3 infratentorial
most common primary brain tumor in adults and overall
gliomas
most common subtype of glioma, uniformly fatal
glioma multiforme
1 metastasis to brain
lung
most common brain tumor in children
medulloblastoma
most common metastatic brain tumor in children
neuroblastoma
arises from the 8th cranial nerve at the cerebellopontine angle
acoustic neuroma
symptoms: hearing loss, unsteadiness, vertigo, nausea, and vomiting
- tx: surgery usual
acoustic neuroma
overal most are benign; #1 spine tumor overall
neurofibroma
spinal tumors: more likely benign
intradural tumors
spinal tumors: more likely malignant
extradural tumors
what do you check for with paraganglioma?
check for metanephrines in urine
what causes intraventricular hemorrhage (subependymal hemorrhage) in premature infants?
secondary to rupture of the fragile vessels in germinal matrix
risk factors for intraventricular hemorrhage in premature infants
ECMO, cyanotic congenital heart disease
- patients go on to get intraventricular hemorrhage
symptoms: bulging fontanelle, neurologic deficits, decreased BP and decreased Hct
- tx: ventricular catheter for drainage and prevention of hydrocephalus
intraventricular hemorrhage (subependymal hemorrhage)
- neural cord defect: herniation of spinal cord and nerve roots through defect in vertebra
- most commonly occurs in the lumbar region
myelomeningocele
speech comprehension, temporal lobe
Wernicke’s area
speech motor, posterior part of anterior lobe
broca’s lobe
dx/tx: pituitary adenoma, undergoing XRT, patient now in shock
dx: pituitary apoplexy
tx: steroids
cervical nerve roots innervating diaphragm
cervical nerve roots 3-5
acts as brain macrophages
microglial cells
CN1
olfactory - smell
CN2
optic - sight
CN3
oculomotor - motor to eye
CN4
trochlear - superior oblique (eye)
CN5
trigeminal: ophthalmic, maxillary, and mandibular branches
- sensory to face
- muscles of mastication
CN6
abducens
- taste to anterior 2/3 of tongue
- motor to face
CN7
facial
- taste to anterior 2/3 of tongue
- motor to face
CN8
vestibulocochlear
- hearing
CN9
glossopharyngeal
- taste to posterior 1/3 of tongue
- swallowing muscles
CN10
vagus
- many functions
CN 11
accessory
- trapezius, SCM
CN12
hypoglossal
- tongue
