Neurological Functions & Lesions Flashcards
lateral nucleus (hypothalamus)
hunger; stimulated by ghrelin
lesion = anorexia, failure to thrive (infants)
ventromedial nucleus (hypothalamus)
satiety; stimulated by leptin
lesion = hyperphagia
anterior nucleus (hypothalamus)
cooling, parasympathetic
posterior nucleus (hypothalamus)
heating, sympathetic
suprachiasmatic nucleus (hypothalamus)
circadian rhythm
supraoptic and paraventricular nuclei (hypothalamus)
synthesize ADH and oxytocin
preoptic nucleus (hypothalamus)
thermoregulation, sexual behavior; releases GnRH
failure of GnRH-producing neurons to migrate from olfactory pit => Kallmann syndrome
ventral posterolateral nucleus (thalamus)
vibration, pain, pressure, proprioception (conscious), light touch, temperature
input: spinothalamic and dorsal columns/medial lemniscus
ventral posteromedial nucleus (thalamus)
face sensation, taste
input: trigeminal and gustatory pathway
lateral geniculate nucleus (thalamus)
vision
input: CNII, optic chiasm, optic tract
medial geniculate nucleus (thalamus)
hearing
input: superior olive and inferior colliculus of tectum
ventral anterior and ventral lateral nuclei (thalamus)
motor
input: basal ganglia, cerebellum
limbic system
structures: hippocampus, amygdalae, mammillary bodies, anterior thalamic nuclei, cingulate gyrus
functions: feeding, fleeing, fighting, feeling, and sex
mesocortical dopaminergic pathway
ventral tegmental area => cortex
decreased activity: negative symptoms (anergia, apathy, lack of spontaneity)
mesolimbic dopaminergic pathway
ventral tegmental area => nucleus accumbens
increased activity: positive symptoms (delusions, hallucinations)
nigrotriatal dopaminergic pathway
substantia nigra => dorsal striatum
decreased activity: extrapyramidal symptoms (dystonia, akathisia, parkinsonism, tardive dyskinesia)
tuberoinfundibular dopaminergic pathway
hypothalamus => pituitary gland
decreased activity: increased prolactin (decreased libido, sexual dysfunction, galactorrhea, gynecomastia)
lateral cerebellar lesions
affect voluntary movement of extremities; propensity to fall toward injured (ipsilateral) side
medial cerebellar lesions
truncal ataxia (wide-based cerebellar gait), nystagmus, head tilting; bilateral motor deficits affecting axial and proximal limb musculature
basal ganglia structures
striatum: putamen + caudate nucleus
lentiform: putamen + globus pallidus
ACA-MCA watershed infarct
proximal upper and lower extremity weakness
PCA-MCA watershed infarct
higher-order visual dysfunction
venous sinus thrombosis
increased ICP (headache, seizures, papilledema, focal neurologic deficits)
accommodation reflex: afferent and efferent limbs
afferent: II
efferent: III
corneal reflex: afferent and efferent limb
afferent: V1 (ophthalmic nasociliary branch)
efferent: bilateral VII (temporal branch)
cough reflex: afferent and efferent limb
afferent: X
efferent: X (also phrenic and spinal nerves)
gag reflex: afferent and efferent limb
afferent: IX
efferent: X
jaw jerk reflex: afferent and efferent limb
afferent: V3 (sensory - muscle spindle from masseter)
efferent: V3 (motor - masseter)
lacrimation reflex: afferent and efferent limb
afferent: V1
efferent: VII
pupillary reflex: afferent and efferent limb
afferent: II
efferent: III
prefrontal cortex lesion
frontal lobe syndrome: disinhibition, hyperphagia, impulsivity, loss of empathy, impaired executive function, akinetic mutism
frontal eye fields lesion
eyes look toward brain lesion (away from side of hemiplegia); seen in MCA stroke
paramedian pontine reticular formation lesion
eyes look away from brain lesion (toward side of hemiplegia)
dominant parietal cortex lesion
Gerstmann syndrome: agraphia, acalculia, finger agnosia, left-right disorientation
nondominant parietal cortex lesion
hemispatial neglect syndrome: agnosia of the contralateral side of the world
basal ganglia lesion
tremor at rest, chorea, athetosis
Parkinson disease, Huntington disease
subthalamic nucleus lesion
contralateral hemiballismus
amygdala lesion
bilateral lesions = Kluver-Bucy syndrome: disinhibition (hyperphagia, hypersexuality, hyperorality)
seen in HSV-1 encephalitis
mammillary bodies lesion
bilateral lesions = Wenicke-Korsakoff syndrome
due to thiamine deficiency
hippocampus lesion
bilateral lesions = anterograde amnesia
seen in Alzheimer disease
dorsal midbrain lesion
Parinaud syndrome: paralysis of upwards gaze, pseudo-Argyll Robertson pupils, convergence-retraction nystagmus, eyelid retraction
often due to pineal gland tumors
reticular activating system lesion
reduced levels of arousal and wakefulness, coma
medial longitudinal fasciculus lesion
internuclear ophthalmoplegia (impaired adduction of ipsilateral eye, nystagmus of contralateral eye with abduction)
seen in multiple sclerosis
cerebellar hemisphere lesion
intention tremor, limb ataxia, loss of balance; ipsilateral deficits; fall toward side of lesion
cerebellar vermis lesion
truncal ataxia (wide-based gait), nystagmus, dysarthria
decorticate (flexor) posturing
upper limb flexion, lower limb extension
lesion above red nucleus (often cerebral cortex) => overactive rubrospinal and vestibulospinal tracts
decerebrate (extensor) posturing
upper and lower limb extension
lesion between red and vestibular nuclei (brainstem) => overactive vestibulospinal tract
worse prognosis than decorticate posturing
ACA stroke
area affected: motor and sensory cortices (lower limb)
contralateral paralysis and sensory loss (lower limb, urinary incontinence)
MCA stroke
area affected: motor and sensory cortices (upper limb and face), temporal lobe (Wernicke area), frontal lobe (Broca area)
contralateral paralysis and sensory loss (lower face and upper limb); aphasia (dominant hemisphere) or hemineglect (nondominant hemisphere)
lenticulostriate artery stroke
area affected: striatum, internal capsule
contralateral paralysis; absence of cortical signs (pure motor stroke)
PCA stroke
area affected: occipital lobe
contralateral hemianopia with macular sparing; alexia without agraphia (dominant hemisphere), prosopagnosia (nondominant hemisphere)
basilar artery stroke
area affected: pons, medulla, lower midbrain, corticospinal and corticobulbar tracts, ocular cranial nerve nuclei, paramedian pontine reticular formation
locked in syndrome: consciousness preserved if RAS spared; quadriplegia, loss of voluntary facial mouth, and tongue movements; loss of horizontal, but not vertical eye movements
AICA stroke
area affected: facial nerve nuclei => paralysis of face, decreased lacrimation and salivation, decreased taste from anterior 2/3 of tongue
area affected: vestibular nuclei => vomiting, vertigo, nystagmus
area affected: spinothalamic tract, spinal trigeminal nucleus => decreased pain and temperature sensation from contralateral body, ipsilateral face
area affected: sympathetic fibers => ipsilateral Horner syndrome
area affected: middle and inferior cerebellar peduncles => ipsilateral ataxia, dysmetria
area affected: inner ear => ipsilateral sensorineural deafness, vertigo
PICA stroke
lateral medullary (Wallenberg) syndrome
area affected: nucleus ambiguus (CN IX, X, XI) => dysphagia, hoarseness, decreased gag reflex, hiccups
area affected: vestibular nuclei => vomiting, vertigo, nystagmus
area affected: lateral STT, spinal trigeminal nucleus => decreased pain and temperature sensation from contralateral body, ipsilateral face
area affected: sympathetic fibers => ipsilateral Horner syndrome
area affected: inferior cerebellar peduncle => ipsilateral ataxia, dysmetria
anterior spinal artery stroke
medial medullary syndrome
area affected: corticospinal tract => contralateral paralysis (upper and lower limbs)
area affected: medial lemniscus => decreased contralateral proprioception
area affected: caudal medulla (hypoglossal nerve) => ipsilateral hypoglossal dysfunction (tongue deviates ipsilaterally)
CN V motor lesion
jaw deviates toward side of lesion (unopposed force from opposite pterygoid muscle)
CN X lesion
uvula deviates away from side of lesion (weak side collapses and uvula points away)
CN XI lesion
weakness turning head to contralateral side of lesion, shoulder droop on side of lesion
CN XII lesion
LMN lesion; tongue deviates toward side of lesion (weakened tongue muscles on affected side)
