Neurology Formative Flashcards
what are the 2 divisions of the corticospinal tract?
lateral - motor control of limbs and digits - decussates in pyramids ventral - motor control of trunk and posture - decussates segmentally
function of corticobulbar tract?
type of descending pyramidal tract
controls muscles of face, head, neck (contains UMNs of CNs)
how can a central/peripheral lesion affecting corticobulbar tract be differentiated?
central = forehead sparing
- corticobulbar tract gives bilateral innervation to CN nuclei apart from CNs 12 and lower 7 (which innervates forehead)
what are the 2 non-pyramidal descending tracts?
rubrospinal
reticulospinal
origin and function of rubrospinal tract?
originates in red nucleus of midbrain
excites flexor muscles of upper limb and inhibits extensor muscles
(doesn’t innervate lower limb)
origin and function of reticulospinal tract?
originates in pons/medulla
excites flexors
what is decorticate rigidity?
posture caused by damage to nerves between brain and spinal cord
flexed plantars, internally rotated legs, flexed arms and wrists
adducted arms
what is decerebrate rigidity?
posture caused by midbrain lesion flexed plantars extended and pronated arms flexed wrists adducted arms
what are the 2 divisions of the dorsal column and what does each carry?
cuneate fasciculus = from arm
gracile fasciculus = from leg
neurones in dorsal column pathway?
1st = site of excitation > dorsal root ganglion 2nd = dorsal root ganglion > spinal cord > thalamus 3rd = thalamus > post central gyrus
neurones in spinothalamic tract pathway?
1st = site of excitation > dorsal root ganglion 2nd = decussates and ascends spinal cord to thalamus 3rd = thalamus > post central gyrus
what causes central cord syndrome?
damage to medial fibres in spinal cord
usually due to hyperflexion or extension in an already stenotic neck
common in elderly
can be due to syringomyelia (fluid filled cavity in spine) in younger people
features of central cord syndrome?
loss of spinothalamic sensation in cape distribution
mainly upper limb signs
- distal weakness, tingling/numbness
normal lower limbs and dorsal column sensation
what is anterior cord syndrome?
compression of anterior spinal artery causing anterior cord ischaemia
features of anterior cord syndrome?
dorsal column intact
complete motor paralysis and loss of spinothalamic sensation below lesion level
features of brown sequard syndrome?
ipsilateral dorsal column and corticospinal dysfunction
contralateral spinothalamic dysfunction
common cause of brown sequard syndrome?
stab wound to back
where is the circle of willis found?
subarachnoid space
where are dural venous sinuses found?
between periosteal and meningeal dural layers
main cause of extradural haemorrhage?
rupture of middle meningeal artery due to head trauma
common in younger people and boxers
presentation of extradural haemorrhage?
punched on side of head, lost consciousness but was fine straight after but then unconscious 4 hours after
“lucid interval”
imaging findings of extradural haemorrhage?
hyperdense biconvex lens appearance
cause of chronic subdural haemorrhage?
rupture of cerebral bridging veins
common in elderly after a fall (low impact trauma)
presentation of chronic subdural haemorrhage?
progressive headache and confusion weeks after a fall
imaging findings in chronic subdural haemorrhage?
hypodense crescent shaped appearence
cause of subarachnoid haemorrhage?
rupture of berry aneurysm in circle of willis due or severe head injury
presentation of subarachnoid haemorrhage?
severe thunderclap headache
meningeal irritation
loss of consciousness
imaging findings in subarachnoid haemorrhage?
hyperdense signal in subarachnoid space
where does blood accumulate if each vessel ruptures?
- bridging cerebral vein
- posterior communicating artery
- middle meningeal
bridging = subdural
posterior communicating = subarachnoid
middle meningeal = extradural
general features of cerebral herniation?
extensor response
UMN signs
cushings triad
unreactive pupils
what is cushings triad?
hypertension
bradycardia
irregular breathing
what type of herniation is most associated with unreactive, blown pupul?
uncal herniation
inner aspect of temporal lobe herniates, compressing CN III
what is Hoffman’s sign?
where flicking/tapping of the middle finger produces twitching/flexing of the index finger to thumb
sign of UMN lesion
Babinski reflex?
where stimulation of the sole of the foot causes upward flexion of the big toe
indicates UMN lesion
anterior circulation in brain?
internal carotid via carotid canal > ophthalmic (to eyes) > middle cerebral and anterior cerebral arteries
- anterior communicating artery between anterior cerebral arteries
posterior circulation in brain?
posterior inferior cerebellar artery, anterior inferior cerebellar artery and superior cerebellar artery supply cerebellum
pontine artery branches off basillar artery
posterior communicating artery forms edges of circle of willis
features of total anterior circulation stroke?
all 3 of
- higher cerebral dysfunction
- homonymous visual field defect
- contralateral motor and/or sensory deficit of at least 2 areas (face/arm/leg)
partial anterior circulation stroke?
2 of:
- higher cerebral dysfunction
- homonymous visual field defect
- motor and/or sensory deficit in at least 2 areas (face/arm/leg)
features of posterior circulation stroke?
cerebellar dysfunction
isolated homonymous visual field defect
cranial nerve dysfunction
features of lacunar stroke?
pure motor or pure sensory stroke
common in longstanding cerebrovascular disease and risk factors (Smoking etc)
site and function of broca’s area?
inferior frontal gyrus
formulating language
- expressive dysphasia if damaged
site and function of wernickes area?
superior temporal gyrus
language comprehension
- receptive/Wernicke’s dysphasia if damaged
function of parietal lobes?
writing
calculations
dressing self
where is the auditory complex?
superior temporal gyrus
3 main features of cerebellar dysfunction?
nystagmus
dysarthria
intention tremor
classic history of cerebellum tumour?
children
progressive headache
wide based ataxia
difficulty speaking
a lesion where cause left superior quadrantanopia?
right temporal lobe
what is gerstmann syndrome?
specific symptoms caused by dominant parietal lobe lesion
- inability to write
- inability to do mathematics
- inability to distinguish own from another person’s fingers
- inability to distinguish left from right side of body
which types of hydrocephalus is most common in children and what usually causes this?
non-communicating
aqueduct stenosis
how does non-communicating hydrocephalus present in children?
large head
retracted eyes
sunsetting of eyes
impaired upward gaze
