Vascular system of the brain Flashcards
Regulation of cerebral perfusion
Relies on tight autoregulation
Cerebral perfusion primarily driven by PCO2 (steady up to 90mmHg)
Also PO2 modulates perfusion in severe hypoxia
- Hypoxemia cerebral perfusion pressure ONLY when PO2 <50 mmHg (normally at 100)
Therapuetic hyperventilation (reduced PCO2) helps decrease ICP in cases of acute cerebral edema (stroke, trauma) via decreasing cerebral perfusion.
MCA
ANTERIOR CIRCULATION
Lesion: Motor cortex --upper limb and face Sensory cortex -- upper limb and face Temporal lobe-- Wernicke's area Frontal lobe -- Broca's
Symptoms: Contralateral paralysis (upper limb and face) Contralateral LOS (upper limb and face) Aphasia if in dominant hemisphere. Hemineglect if in nondominant hemisphere.
ACA
ANTERIOR CIRCULATION "anterior cerebral artery" Lesion: Motor cortex-lower limb Sensory cortex- lower limb
Symptoms:
Contralateral paralysis–lower limb
Contralateral LOS–lower limb
Lateral striate artery
ANTERIOR CIRCULATION
Lesion:
Striatum, internal capsule
Symptoms:
Contralateral hemiparesis/hemiplegia
This is common location of lacunar infarcts, 2/2 malignant HTN.
ASA and what syndrome?
POSTERIOR CIRCULATION
“anterior spinal artery”
Lesion:
Lateral corticospinal tract
Medial lemniscus
Caudal medulla (CN12 hypoglossal nerve)
Symptoms: Contralateral hemiparesis-lower limbs contralateral proprioception decreased Ipsilateral hypoglossal dysfunction (tongue deviates ipsilaterally)
Stroke commonly bilateral
Medial medullary syndrome: caused by infarct of PARAMEDIAN branches of ASA and vertebral arteries.
(vs. lateral medullary of PICA)
PICA and what syndrome?
POSTERIOR CIRCULATION
“Posterior inferior CEREBELLAR”
Lesion: lateral medulla; vestibular nuclei, lateral spinothalamic tract, spinal trigeminal nucleus, nucleus ambiguus, sympathetic fibers, interior cerebellar peduncle.
Symptoms: vomiting, vertigo, nystagmus
Decreased pain and temp sensation to limbs/faces
Dysphagia and hoarseness, decreased gag reflex
Ipsilateral Horner’s syndrome, ataxia, dysmetria
Lateral medullary (wallenberg’s) syndrome:
Nucleus ambiguus effects are specific to PICA lesions
(vs. medial medullary of ASA)
“Don’t pick a horse (hoarseness) that can’t eat (dysphagia).”
AICA and what syndrome?
POSTERIOR CIRCULATION
“Anterior inferior CEREBELLAR”
Lesion: lateral pons--cranial nerve nuclei: vestibular nuclei, facial nucleus spinal trigeminal nucleus, cochlear nuclei sympathetic fibers \+ Middle and inferior cerebellar peduncles
Symptoms:
Vomiting, vertigo, nystagmus,
PARALYSIS of face, decreased lacrimation, salivation, decreased taste from anterior 2/3 of tongue,
decreased corneal reflex
Face–decreased pain and temp sensation
Ipsilateral decreased hearing
Ipsilateral Horner’s syndrome, ataxia and dysmetria
Lateral Pontine syndrome:
Facial nucleus effects are specific to AICA lesions
“Facial droop means AICA’s pooped”
PCA
POSTERIOR CIRCULATION
“Posterior cerebral artery”
Lesion: occipital cortex, visual cortex
Symptoms:
Contralateral hemianopsia with macular sparing.
AComm
Communicating arteries
Common site of saccular (berry) aneurysm - impingement on cranial nerves
Symptoms: visual field defects
Lesions are typically aneurysms, not strokes.
PComm
Communicating arteries
Common site of saccular (berry) aneurysm
Symptoms: CN3 palsy; eye is down and out with ptosis and pupil dilation
Lesions are typically aneurysms, not strokes.
Aneurysms
In general, abnormal dilation of artery due to weakening of vessel wall
Berry aneurysm: at the bifurcation of the circle of Willis.
Most common site at the anterior communicating artery.
Can also cause bitemporal hemianopia via compression of optic chiasm.
Associated with ADPKD, Ehler-Danlos, and Marfans.
Other factors: advanced age, HTN, smoking, race
Charcot-Bouchard microaneurysm
Associated with chronic HTN, affects small vessels (in basal ganglia, thalamus)
Epidural hematoma
Rupture of middle meningeal, 2/2 fracture of temporal bone
Lucid period.
Rapid expasion under sstemid arterial pressure -> transtentorial herniation, CN 2 palsy.
CT shows viconvex(lentiform)
Can cross flax and tentorium
Subdural hematom
Rupture of bridging veins
Slow venous bleeding.
Seen in elderly, alcoholic, blunt trauma, shaken baby (predisposing factors: brain atrophy, shaking, whiplash).
Crescent shaped that crosses suture line
Midline shift
Cannot cross falx, tentorium
Subarachnoid hemorrhage
Rupture of an aneurys
Rapid time course.
Worse HA of my life
Bloody or yellow spinal tap
2-3 days afterwards, vasospasm due to blood breakdown
(not visible on CT, treat with NIMODIPINE) and rebleed (visible on CT)
