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
common bacteria meningitis
- most common: strep pneumoniae
- gram + diplococci
- 2nd: meningococcal meningitis (Neisseria meningitidis)
- faster onset, ~13% mortality
- gram – diplococci
- pregnant patients, >50 y/o, immunodeficient: listeria monocytogenes
- gram + rods
<1 y/o
- group B strep (from delivery)
- unvaxx: strep pneumonia, H. flu
post-neurosurgery:
- direct spread into meninges
- staph aureus
- pseudomonas aeruginosa
meningococcal meningitis
sx:
- fever
- N + V
- HA
- loss of ability to concentrate
- severe myalgias
- bacteremia
- septic shock
- DIC
- – petechia + purpura
- rapid onset: hours
Pg:
- Neisseria meningitidis
- gram – diplococci
Tx:
- ceftriaxone
waterhouse-friderichsen syndrome
- bilateral adrenal hemorrhage
- often d/t DIC from meningococcemia
- acute adrenal insufficiency
- worsening hypotension (in addition to the septic shock)
listeria meningitis
- demo:
- pregnant
- > 50 y/o
- immunodeficient (lympho)
Pg:
- listeria monocytogenes
- gram + rods
sx:
- seizures
- focal neuro deficits
- rhombencephalitis (hindbrain)
- – ataxia
- – cranial nerve palsies
- – nystagmus
tx meningitis
- empiric abx
- try to do an LP quickly to get cultures, but do not delay abx for LP or results
abx:
- ceftriaxone: neisseria (meningococcal)
- vancomycin: strep pneumoniae
- narrow down as Pg data and sensitivity screening returns
special populations
- ampicillin to cover listeria in pregnant, >50, i.c.
- cefepime to cover pseudomonas post-neurosurgery (and vancomycin for staph aureus)
also:
- dexamethasone
- – initiate prior to abx to prevent worsening damage from inflammatory response killing Pg
- – only continue if strep pneumoniae once results return (empirically no benefit or harm in others)
viral meningitis sx
- slower onset
- less likely septic
- otherwise similar to bacterial
viral meningitis common Pg
- HSV 1 or 2
- oral and genital lesions
- more likely to cause encephalitis
- HIV
- direct or opportunistic
- enteroviruses, esp coxsackie
- arbovirus, esp West Nile
viral meningitis common Pg
- HSV 1 or 2
- oral and genital lesions
- more likely to cause encephalitis
- HIV
- direct or opportunistic
- enteroviruses, esp coxsackie
- arbovirus, esp West Nile
when to order imaging prior to LP
always:
- hx of malignancy
- immunosuppression
- focal neurological findings
all patients ideally but do not delay tx in rapidly progressing cases
why:
- space occupying lesions/hydrocephalis –> increased ICP –> risk of brain herniation
LP findings meningitis
opening pressure
- tends to be higher in bacterial or fungal infection vs viral
± discoloration, cloudiness, blood
- more likely in fungal, bacterial
elevated WBC
- neutrophil predominant in bacterial
- lymphocyte predominant in viral and fungal
CSF protein and glucose
- bacterial: higher protein, lower glucose vs viral
gram stain or culture
PCR
Ag
common Pg chronic meningitis
TB
fungal
- cryptococcal and coccidioidal predominant in LA
cryptococcal meningitis
Pg:
- cryptococcus neoformans
- bird droppings, inhalation
demo:
- immunosuppressed
- AIDS w/ CD4 <100
sx:
- gradual 1-2 wk
- fever
- HA
- malaise
- later stage: AMS, neuropathies, vision loss, hearing loss
- ~25% stiff neck, photophobia
dx:
- HIV risk fx, AIDS signs e.g. thrus, seborrheic dermatitis, low WBC, oral hairy leukoplakia
- serum and CSF cryptococcal Ag
- very high opening pressures on LP
- high lymphocytes CSF
- elevated protein CSF, normal to low glucose
- hx used India ink stain of CSF - not taken up by cryptococci –> “white halo”
tx:
- amphotericin B initial
- maintenance fluconazole for 3+ mo if HIV+; 1+ year if not i.c. (rare)
- wait 4 wk or until normal ICP b/f starting HIV treatment if applicable (this is exception to rule of starting w/in 2 wk of dx) - minimize further swelling from immune reconstitution
- shunt or serial LP may be needed if ICP high enough
IRIS
- immune reconstitution inflammatory syndrome
- occurs when treating HIV w/ active cryptococcal meningitis
- immune reconstitution –> increased Pg attack, inflammation, ICP –> worsening damage
- wait at least 4 wk or until normal ICP (sooner of) to start ARV if +cryptococcal meningitis
- steroids have been shown to not help with this
coccidioidal meningitis
Pg:
- coccidioides immitis
- dimorphic fungus
- endemic to SW
sx:
- subacute
- persistent HA
- weeks to months
demo:
- mildly i.c. (e.g. diabetes)
- immunocompetent
- from endemic region e.g. Central Valley
- migrant workers
dx:
- lymphocytic CSF
- elevated protein, low glucose CSF
- anti-cocci Abs CSF
- culture CSF
tx:
- fluconazole *for life
- ventriculoperitoneal shunt often needed as hydrocephalus is common
TB meningitis
- subacute
- lymphocytic CSF
- elevated protein, low glucose CSF
- culture or TB PCR CSF
- hydrocephalus common
tx:
- rifampin, isoniazid, pyrazinamide, ethambutol
- dexamethasone in early course
coma - anatomic basis
- bilateral lesions of reticular activating system
- midbrain and rostral pontine tegmentum
glasgow coma score
Eye opening
- 4- spontaneous
- 3- to voice
- 2- to pain
- 1- none
Verbal response
- 5- normal conversation
- 4- disoriented conversation
- 3- incoherent words
- 2- sounds only
- 1- none
Motor response
- 6- normal
- 5- localizes to pain
- 4- withdraws to pain
- 3- flexion response to pain (decorticate posturing)
- 2- extension response to pain (decerebrate)
- 1- none
comatose <8
locked in syndrome
conscious, awake, eye movement and involuntary only
- typically only vertical eye movement but depends on specific region of damage
damage to all descending corticobulbar and corticospinal tracts, most often in ventral pons
epidural hematoma
EDH
superficial to both dural layers
can cross midline
etiology:
- usually trauma
- arterial bleed - rapid accumulation
tx:
- surgical emergency
often:
- associated fracture
- clotted and unclotted blood
subdural hematoma
deep to both dural layers
etiology:
- slow venous bleeding (bridging veins)
tx:
- elective (usually) surgical evacuation
CT:
- acute: very bright density
- subacute to chronic: can be isodense with brain
- crescent-shaped
- reflects with dural reflection
- cannot cross midline
- can be along tentorium
subarachnoid hemorrhage
SAH
d/t:
- ruptured aneurysm
- trauma
- ~20% multiple aneurysms
sx:
- acute headache
types of cerebral edema
vasogenic
- BBB abnormality –> more fluid
- brain tumor, abscess, trauma
cytotoxic
- failure of Na-K ATPase usually d/t ischemia
- hypoxia, infarcts
SOL
space occupying lesion
e. g.,
- tumor
- infection
- vascular
- traumatic
- toxic e.g. Pb
morbidity and mortality d/t
- cerebral edema –> compression, herniation
- disruption of vital neural pathways
single dilated pupil exam finding
contralateral compression of CN III
usually SOL
CN III compression associated w/ concern for which artery
posterior cerebral artery
proximity means issue w/ PCA e.g. aneurysm can often have CN III compression as first clinical sign, or that something affecting CN III is also likely to affect PCA e.g. SOL/edema/herniation
cerebellar tonsillar herniation
–> ischemia of CV centers of medulla oblongata –> death
vulnerable site in SOL
middle cerebral artery infarct
- language
- spatial attention
- somatosensory and motor cortex - except lower limbs
- auditory cortex
lenticulostriate arteries (MCA) infarct
- striatum and lentiform nucleus
- internal capsule
sx:
- contralateral weakness
- sensory loss of face/body
- possible cognitive deficits
- depends on specific site
- – basal ganglia: parkinsonian
- – thalamus: sensory
- – internal capsule: motor only
one of most common sites of clinical stroke d/t small size relative to significant fx
anterior cerebral artery infarct
- sensory and motor - lower limbs
- some prefrontal cognition
posterior cerebral artery infarct
visual cortex
thalamus (sensory)
TIA
<24 h self-resolution
No evidence of injury on MRI
CT or MRI sensitivity in stroke
CT faster and better detects acute hemorrhage
MRI no contrast better for ischemic stroke - but not widely used
% of patients w/ decreased mobility following stroke
> 50% (age >65)
lateral cerebellar hemisphere lesions
ipsilateral limb dysmetria
falling toward side of lesion
± slurred speech
± swallowing difficulty
vermis cerebellar lesions
postural issues
trunk instability
symmetric gait instability
usually (–) limb ataxia
floculonodular lobe lesions
vertigo
nyastygmus
general sx of cerebellar dysfunction
dizziness/vertigo n+v loss of balance veering falls shaky hands, head clumsiness slurred speech double vision difficulty concentrating
nystagmus
hypsometric saccades (eye movements)
dysarthria
scanning speech (broken w/ pauses, variable force - overall difficulty modulating speech)
tremor - rural, intention
dysdiadochokinesis - słów, irregular, clumsy mvmnt
dysmetria - varied speed, force, direction of movement, initially overshoot target
gait ataxia - wide, veering, unable to tandem
dysmetria
feature of cerebellar dysfunction clumsy, unsteady movment movements varied in force and direction overshooting target finger to nose or heel to shin test - pt fully extends arm to reach target
SARA
scale for assessment and rating of ataxia
fx:
- gait
- stance
- sitting balance
- speech disturbance
- finger chase
- finger to nose
- rapid alternating movements
- heel to shin
causes of hereditary cerebellar ataxia
numerous
autosomal dom
- spinocerebellar
- episodic
auto rec
- freidreich’s
- telangiectasia
x linked
mitochondrial
causes of acquired cerebellar ataxia
Vascular Infectious/Inflammatory Toxic/Traumatic Autoimmune Metabolic Idiopathic/Iatrogenic Neoplastic/paraneoplastic
autosomal dom hereditary ataxias
+ fam hx
10-40 y/o onset
chronic, progressive
autosomal rec hereditary ataxias
0-20 y/o onset
± FHx
+ non-cerebellar sx
chronic, progressive
machado joseph disease
autosomal dom hereditary ataxia spinocerebellar SCA3 CAG repeat expansion in ATXN3 gene childhood-adulthood onset
sx:
- ataxia
- dystonia
- Parkinsonism
- upper/lower motor neuropathy
- cognitive impairment
freidrich’s ataxia
autosomal rec hereditary ataxia
onset age 5-15
GAA repeat expansion in FXN gene (frataxin - iron storage protein in mitochondria)
sx: - ataxia - muscle weakness - areflexia - scoliosis * cardiomyopathy ~10% diabetes - club foot and hammer toes - intellectual decline
ataxia telangiectasia
autosomal rec hereditary ataxia
onset <10 y/o usually toddlers
ATM protein - DNA repair
sx: - ataxia - oculomotor apraxia - (eventual) dysphagia - slurred speach - motor delay - mild DM - respiratory infections - hair graying - vitiligo - telangiectasias (spider veins) ~25% lymphoma, leukemia
hyperacute ataxia
minutes
usually stroke (cerebellar)
focal and often unilateral
acute ataxia
days
post-infectious
MS (cerebellum b//c involved in 50-80% of cases)
subacute ataxia
weeks to months
neoplastic and paraneoplastic
chronic ataxia
toxic/metabolic
- alcohol
- meds
- vitamin deficiencies
hereditary
neurodegenerative
- multiple system atrophy (MSA)
arteries implicated in cerebellar stoke
3 main arteries of cerebellum are:
- SCA (superior cerebellar a)
- AICA (anterior inferior cerebellar a)
- PICA (posterior inferior cerebellar a)
superior vermian atrophy
chronic acquired ataxia
alcohol use disorder
gait imbalance
usually (–) significant limb ataxia
Wernike’s encephalopathy
triad:
- ataxia
- confusion
- ophthalmoloplegia
chronic acquired ataxia
thiamine deficiency
often associated w/ alcohol use disorder
MSA
multiple system atrophy
chronic neurodegenerative ataxia
sporadic, progressive
usually ~ 50 y/o onset
sx:
- cerebellar ataxia
- dysautonomia (orthostatic, urinary incontinence, ED)
- Parkinsonism
imaging:
- “hot cross bun” sign on MRI
PD
parkinson’s
degeneration of dopamine-producing neurons in basal ganglia –> loss of excitatory effect of dopamine on direct and indirect pathways –> decreased voluntary movement
sx:
- resting tremor
- rigidity
- akinesia
- bradykinesia
- postural instabiliity
- shuffling gait
huntington’s disease clinical features
degeneration of D2-containing output neurons of striatum
loss of indirect pathways inhibiting action –> excess involuntary movement
atrophy of striatum
protein misfolding –> deposits
sx:
- chorea - quick, repeated, involuntary, dance-like movement
- athetosis - slow, writhing movements
- dementia
subthalamic nucleus (STN) infarct
normal fx:
- STN drives GPi output neurons
- loss of STN –> loss of inhibitory output –> excess involuntary movement
sx
- hemiballismus
- sudden unilateral flinging of extremities
Huntington’s disease genetics
autosomal dominant
CAG trinucleotide expansion
coding region
Fragile X syndrome genetics
X-linked
CGG trinucleotide expansion
5’ UTR
premutation 55-200
full mutation >200
maternal premutation >100 –> 100% incidence of child w/ full mutation
excessive repeats >200 result in transcriptional repression of the gene d/t hypermethylation
Myotonic dystrophy genetics
autosomal dominant
CTG trinucleotide expansion
3’ UTR
Friedreich Ataxia genetics
autosomal recessive
GAA trinucleotide expansion
intron
fragile X clinical features
> 90% cognitive dysfunction, mean IQ 30-45
children:
- ADHD
- autistic features
- hyper extendable joints
- mitral prolapse
adults:
- macroorchidism
- long face
- large ears
- prominent jaw
fragile X premutation clinical features
may be asymptomatic
female
- premature ovarian failure
male
- late-onset tremor ataxia dementia syndrome
guidelines for genetic testing
don’t test kids for adult onset diseases unless it changes current treatment course (i.e. they would not receive equal treatment benefits if treatment is delayed until adulthood)
myotonic dystrophy clinical features
- myotonia (impaired muscle relaxation/spasm)
- muscular dystrophy
- cataracts
- hypogonadism
- frontal balding
possible severe neonatal form if dramatic CTG repeat expansion from mother
frontotemporal dementia/ALS genetics
4-nucleotide repeat expansion
CCTG
intron
PD tremor
pill-rolling tremor
relatively slow
resting tremor - improves with movement (vs cerebellar tremors/essential tremor that get worse with movement)
cogwheel rigidity
characteristic feature of PD
generalized stiffness
rather than normal gradual/flowing movements of extremities, sort of clicks from one position to the next like a robot in need of oil…
also results in expressionless face, stooped posture
motor/premotor cortex lesion
contralateral
paralysis
UMN signs (hyperreflexia, etc)
frontal eye field (FEF) lesion
pt looks toward lesioned side
primary somatosensory cortex lesion
contralateral
loss of sensation
often accompanies motor/premotor cortex lesion b/c of proximity
visual cortex lesion
contralateral
hemianopia (vision loss in half of one or both eyes)
also on ddx for hemianopia: stroke
broca’s area lesion
problem with language generation/word finding
non-fluent speech, difficulty saying what they want to –> frustration
wernicke’s area lesion
problem with language understanding/interpretation
fluent, nonsensical speech
conduction aphasia
damage to arcurate fasiculus (connects Broca’s to wernicke’s area)
fluent speech
comprehends but abnormally - speech production does not match comprehension
For example:
Clinician: Now, I want you to say some words after me. Say ‘boy’.
Aphasic: Boy.
Clinician: Home.
Aphasic: Home.
Clinician: Seventy-nine.
Aphasic: Ninety-seven. No … sevinty-sine … siventy-nice…
Clinician: Let’s try another one. Say ‘refrigerator’.
Aphasic: Frigilator … no? how about … frerigilator … no frigaliterlater
global aphasia
damage to both Broca’s area and wernicke’s area
no normal speech production or comprehension
hemispatial neglect
lesion to area involved in spatial attention
essentially ignore half of their perceptive field, e.g. only drawing half of a house or ignoring any input on left side of their visual field
basal nucleus of meynert lesion
cell bodies of ACh producing neurons in brain
anatomically inferior to anterior commissure
loss –> mental decline
seen in AD, huntington’s
amygdala damage
- fearless, but placid, behavior
- hypersexuality
- overeating
- inspecting objects by smelling or tasting them
hippocampal lesions
- anterograde amnesia
= no new memories
mammillary body damage
affects memory
types of circumscribed gliomas
astrocytic:
- pilocytic astrocytoma (grade I)
- pleomorphic xanthoastrocytoma (grade II)
types of diffuse gliomas
astrocytic:
- diffuse astrocytoma (grade II)
- anaplastic astrocytoma (grade III)
- glioblastoma (grade IV)
oligodendroglial:
- oligodendroglioma and oligoastrocytoma (grade II)
- anapestic oligodendroglioma and OA (grade III)
WHO grade II glioma
- no-low mitotic activity
- no microvascular proliferation
- no necrosis
- no CDKN2A/B homozygous deletions
who grade III glioma
- significant mitotic activity
- no microvascular proliferation
- no necrosis
- no CDKN2A/B homozygous deletions
who grade IV glioma
highest grade
- significant mitotic activity 1+ of: - microvascular proliferation - necrosis - CDKN2A/B homozygous deletions
IDH
commonly mutated in astroocytoma and glioblastoma
1p19q
commonly mutated in oligodenroglioma
medulloblastoma
- most common malignant pediatric CNS neoplasm
- malignant embryonal tumor
- cerebellum
- > 70% in <16y/o
- M>F
- 60% 10 yr survival
atypical teratoid rhabdoid tumor (AT/RT)
- children <2yr
- highly aggressive
- any location in CNS
- IN11 loss
pilocytic astrocytoma
- grade 1
- most common childhood glioma
- 10% cerebral, 85% cerebellar
- MRI: enhancing, cystic, often calcified
- most common in NF1, sporadic BRAF
pediatric high grade gliomas
- diffuse midline = H3 K27
- diffuse hemispheric = H3 G34
- diffuse pediatric type high grade = H3-WT, IDH-WT
- infant-type hemispheric
diffuse intrinsic pontine glioma
- pediatric
- uniform poor prognosis
- subset of infiltrating astrocytoma
- preoperative biopsy now more common d/t clinical trials
conductive hearing loss
d/t:
- occlusive ear wax
- perforated ear drum
- cholesteatoma - skin cyst of middle ear secretes lytic enzymes that can erode bone
- otitis media or externa
- otosclerosis - fusion of stapes to bone of inner ear
dx:
- weber test: clearer in affected ear
- rinne test: poor air conduction
cholesteatoma
skin cyst of middle ear secretes lytic enzymes that can erode bone
sx:
- conductive hearing loss
- ear drainage, often foul-smelling
- sensation of ear fullness
otosclerosis
fusion of stapes to bone of inner ear
sx:
- progressive conductive hearing loss
- hearing loss starts with lower frequencies
perforated ear drum
sx:
- conductive hearing loss
- usually identifiable trigger
- sudden extremely loud sounds
sensorineural hearing loss
d/t:
- noise exposure - high frequencies lost first
- age - presbycusis - high frequencies usually lost first
- vestibular schwannoma / acoustic neuroma
- ototoxic meds
- meniere’s disease - excess endolymph
dx:
- weber test: clearer in unaffected ear
- rinne test: long air conduction (if present) compared to bone, less than other side
vestibular schwannoma
aka acoustic neuroma
sx:
- one sided sensorineural hearing loss
- sensation of ear fullness
- tinnitus
- dizziness
ototoxic medications
some chemo
some abx
heavy metals
meniere’s disease
excess endolymph
sx:
- one sided sensorineural hearing loss, can progress to both sides
- vertigo
- tinnitus
- ear fullness
- generally intense episodes lasting ~20 minutes to an hour
benign paroxysmal positional vertigo (BPPV)
strong recurrent bouts of vertigo when head moves certain way
–> nystagmus driven by posterior semicircular canal VOR circuit
sx:
- sudden, severe vertigo
- dizziness
- balance problems
- n&v
PPRF lesion
paramedian pontine reticular formation
oculomotor
can’t make voluntary eye movements of either eye toward affected side
do move involuntarily w/ VOR
FEF lesion
frontal eye field (cortex)
oculomotor
always looks toward lesioned side
abducens nerve lesion
can’t aBduct eye on affected side
abducens nerve = CN6
abducens nucleus lesion
part of PPRF
can’t make ANY eye movements of either eye toward the affected side
i.e. no voluntary or VOR
nystagmus
rapid, repeated eye movements
physiologic: if eye rotates too far in one direction, it springs to center
pathologic: this happens too often/repeatedly; slow phase generally is the underlying disorder
- horizontal
- vertical
- gaze evoked (eye drift)
directionality (L/R) defined by direction of fast phase (spring back)
horizontal nystagmus
vestibular end organ damage
beat toward intact side
vertical nystagmus
central vestibular processing
gaze evoked nystagmus
outward beat
difficulty holding eye in eccentric position
“drift”
d/t:
- damage to brainstem nuclei
- damage to vestibulocerebellum
- some meds
- muscle weakness
gaze evoked nystagmus in abducting eye
e. g.:
- pt looks right
- right eye moves right (aBducts)
- left eye does not move right (aDduct) as it should
- brain tries to move left eye repeatedly but it doesn’t
- signal keeps being sent through abducens nucleus, to both eyes
- keeps bringing right eye back to center (left beating nystagmus)
indicative of MLF damage
(medial longitudinal fasciculus)
tonsillar herniation
cerebellar tonsils herniate through foramen magnum
compresses brainstem
subfalcine herniation
deep to falx (dura)
causes a midline shift (not the only potential cause)
uncal herniation
thru tentorium cerebelli
external herniation
thru skull defect
saccular aneurysms
of arteries in circle of willis
subarachnoid hemorrhage at base of brain
deep grey matter / basal ganglia hemorrhage
htn-related vascular disease
lacunar infarct
basal ganglia
htn-related vascular disease
lesions w/ mass effect
tumor
bleed
abscess
lesions w/ no mass gain/loss
demyelination
lesions w/ loss of tissue
infarct
degeneration / atrophy
retina and choroid infections
blood-borne organisms
may be an early clue to disseminated infectious disease
retinal detachment
d/t trauma, degeneration, idiopathic
hole in retina –> full detachment
epithelial edema (cornea)
sx:
- colored haloes around lights
d/t:
- high IOP
distortion and ghost images
corneal refractive errors, irregular shape
age related macular degeneration
AMD
causes central scotoma
d/t (usually):
- neovascular tissue growth from choriocapillaris into sub-retinal space
parkinson’s disease demo
2nd most common NDD after AD 1% >60 ~90% dx >50 <40 very rare but certain genetic forms of early onset PD do exist M>F 1.5-2x
environmental + genetic
PD etiology
progressive NDD
loss of DA neurons in SN
- sx appear at 40-60% depletion
dysfunction of DA SN target projections
alpha-syn aggregates
- in axons and cell bodies
- as Lewy bodies (extraneuronal) - aggregates surrounding eosinophilic core
PD dx
clinical dx, ancillary testing in atypical cases
dx:
- bradykinesia
AND
- resting tremor OR rigidity
advanced:
- dementia
- psychosis
- postural imbalance/gait instability
- dysphagia
other sx:
- fatigue
- apathy
- pain
- dysautonomia
- dyskinesias
prodromal:
- urogenital dysfx
- constipation
- hypO-osmia (smell)
- hypO-tension
- ED
- anxiety
- depression
- subtle motor impairment
- sleep disorders e.g. REM sleep behavior disorder
dravet syx
rare pet genetic epilepsy syx refractory epilepsy neurodevelopmental problems begins in infancy drug resistant
tx:
- 2+ ASMs based on efficacy, sfx, tolerability, and access
LGS
Lennox gastaut syx
mostly d/t identifiable cause e.g. genetics, malformations, infection, injury …
sz:
- tonic
- atonic
- prolonged absence
- generalized convulsions
often
- learning difficulties
- behavioral problems
onset
- age 1-8 usually, as late as adolescence
tx
- often refractory
- 2+ ASMs
NCSE
non-convulsive status epilepticus
persistent mental status change +EEG change (–)motor signs
GCSE
generalized convulsive status epilepticus
≥5 min continuous seizures or
≥2 discrete seizures w/ incomplete recovery
first line tx:
IV lorazepam
if persistent
barbiturate (fosphenytoin, VPA, or phenobarbital)
refractory
midazolam or propofol
super refractory >24 h
high morbidity
tx pentobarbital coma (medically-induced coma)
factors contributing to drug-resistant epilepsy
~20-30% of cases
proposed mx:
- P-gp efflux transporter overexpression
- target alterations - less sensitive
- network - seizure-induced structural brain alterations e.g. synaptic reorganization, axonal sprouting, etc.
- intrinsic severity - increased disease severity = lower drug sensitivity (bigger difference to stabilizing threshold)
malignant hyperthermia
life-treating hyper metabolic state triggers: - potent volatile inhalational anesthetics - succinylcholine - in susceptible ps
