CNS pathophys Flashcards
spina bifida
failure of closure of caudal end of neural tube
related to folic acid deficiency in early pregnancy
compare anencephaly, failure of closure of rostral end, which is perinatal lethal
hydrocephalus
excess accumulation of CSF
- communicating: CSF can leave ventricular system, accumulate in subarachnoid space
- noncommunicating/obstructive: blockage within ventricular system
- high pressure: typical
- normal pressure: in older individuals; triad: gait, urinary incontinence, mental decline
- ex vacuo: fills space where brain tissue has been lost
upper motor neuron signs
- muscle weakness
- spasticity resulting from damage to descending motor pathways
- indicate lesion above anterior horn cell (i.e. CNS)
excessive involuntary motor activity i.e.
- little wasting
- increased tone/spasticity
- brisk reflexes/hyperreflexia
- primitive reflexes/Babinski
lower motor neuron signs
- muscle weakness
- flaccidity
- physio: lower motor neurons prevent excessive muscle movement
- indicate PNS lesion
lack of voluntary motor activity i.e.
- wasting
- low to normal tone/flaccidity
- hypo or areflexia
- fasciculations - low threshold for motor neuron irritation
spasticity
- increased tonic stretch reflexes, flexor muscle activity
- velocity-dependent increase in resistance to passive movement
- loss of inhibitory descending input
d/t:
- TBI
- stroke
- MS
- CP
- spinal cord injury
decerebrate rigidity
hands flexed, arm extended
decorticate rigidity
arms flexed
CN III damage appearance
down and out gaze
ptosis
± edinger-westphal nucleus involvement: mydriasis (dilated pupil)
- ipsilateral
CN III sensitivity to vascular disease
oculomotor (lateral portion) more sensitive than parasympathetic/pupillary (medial)
more likely to cause down/out gaze and ptosis
CN III sensitivity to compression
parasympathetic/pupillary (medial) more sensitive than oculomotor
more likely to cause mydriasis
damage to pupillary light reflex
CN II optic n. lesion:
- no pupillary light reflex when shined in that eye
CN III lesion:
- lesioned side never constricts
- other eye always constricts (doesn’t matter which eye light is shined in)
CN IV damage
elevated eye (up and out)
worse with aDduction (medial)
*ipsilateral (unless it affects only the nucleus, which is unlikely b/c it’s so small)
CN VI damage
inability to aBduct
CN V damage
any or all, depending on lesion
to a division or to the nerve:
- loss of fine touch and pain
to nerve:
- jaw deviates toward lesioned side
to ascending pathways
- contralateral
to nuclei:
- only specific fx of that nucleus
CN VII damage versus corticobulbar damage
- facial weakness
- upper face: test eyebrow raising
- lower face: test smiling
corticobulbar:
- lower face only
- contralateral
CN VII:
- upper and lower face
- contralateral
- ± loss of taste (anterior 2/3 of tongue)
unilateral deafness
- damage at or before cochlear nuclei of CN VIII
- note that even if damage to central auditory pathway is unilateral, deafness will be bilateral
dysphagia
difficulty swallowing
CN X damage
CN XII damage
tongue:
- deviates toward lesioned side
- atrophy
- fasciculations
BBB in MS
immune cells have components that break down BBB
tight junction abnormalities
down regulation of laminin in BM
BBB in trauma
bradykinin –> IL6 –> BBB opening
mx of neurotropic pathogens crossing BBB
- transcellular
- paracellular: binds to BMECs, taken up by receptor mediated endocytosis
- Trojan horse
encephalitis
inflammation of brain tissue
possible sequela of meningitis
altered mental status
PE and vitals meningitis
(not all will be present but should check)
systemic:
- fever
- bp, hr: signs of septic shock
skin:
- rash (meningococcal meningitis)
neuro:
- nuchal rigidity - chin to chest
- mental status - cerebral dysfunction
- neuro damage (advanced): hearing loss, vision loss, cranial neuropathies
CV:
- signs of septic shock
sx meningitis
triad (~41%)
- fever
- HA
- nuchal rigidity
2+ (~95%)
- fever
- HA
- nuchal rigidity
- AMS
others:
- photophobia
- phonophobia
acute is most common, presents within hours or days
chronic evolving over weeks may also occur