Neuro Flashcards
Which cells hypertrophy and scar in response to CNS injury?
Astrocytes
Which cells regulate CNS blood flow by contacting CNS capillaries?
Astrocytes
Which cells form an “immune system” within the CNS?
Microglia - phagocytose dead cells
o The microglia at the repair stage after ischemia have a high lipid content because of the extensive phagocytosis of myelin breakdown products
CN 1
Olfactory
Smell
(Sensory)
Exits via cribiform plate
CN 2
Optic
Sight
(Sensory)
Exits via optic canal
CN 3
Oculomotor
Eye movement, pupillary constriction, accomodation, eyelid opening
(Motor)
Exits via superior orbital fissure
CN 4
Trochlear
Depression and inward eye movement: superior oblique muscle
(Motor)
Exits via superior orbital fissure
CN 5
Trigeminal
Mastication, facial sensation (V1, V2, V3), sensation of anterior 2/3 of tongue, tensor tympani muscle
(Both: motor and sensory)
V1: superior orbital fissure
V2: foramen rotundum
V3: foramen ovale
CN 6
Abducens
Outward eye movements: Lacteral rectus muscle
(Motor)
Exits via superior orbital fissure
CN 7
Facial
Facial expression, taste of anterior 2/3 of tongue, lacrimation, salivation, eye lid closing (orbicularis oculi), stapedius muscle
(Both: motor and sensory)
Exits via internal acoustic meatus
CN 8
Vestibulococular
Hearing, balance
(Sensory)
Exits via internal acoustic meatus
CN 9
Glossopharyngeal
Taste and somatosensation of post 1/3 of tongue, swallowing, salivation from parotid gland, stylopharyngeus muscle
(Both: motor and sensory)
Exits via jugular foramen
CN 10
Vagus
Taste from epiglottis, soft palate elevation, talking, coughing, thoracic and abdominal viscera autonomics
(Both: motor and sensory)
Exits via jugular foramen
CN 11
Accessory
Head turning, shoulder shrugging (sternocleidomastoid and trapezius muscles)
(Motor)
Exits via jugular foramen
CN 12
Hypoglossal
Tongue movement
(Motor)
Exits via hypoglossal canal
Charcot-Marie-Tooth Disease
Mutations in connexin 32 protein leads to nonfunctional gap junctions (demyelination) → slow but progressive loss of motor and sensory activity
Epidural Bleed
Tearing of the middle meningeal artery secondary to temporal bone trauma
Localized
Lens shaped
Does not cross suture lines
Subdural bleed
Tearing of the bridging veins as they enter dural venous sinuses
Large
Crescent shaped
Crosses suture lines
Seen in alcoholics, elderly, and shaken babies
Subarachnoid bleed: caused by what and what is an important sequela to take under consideratin
Secondary to rupture of ordinary arteries and veins (berry aneurysm), fills sulci and cisterns
Bleeding between the arachnoid mater and pia mater
Berry aneurysms are associated with EDS and ADPKD
4-10 days after hemorrhage, vasospasm can occur and cause an ischemic infarct (prevent this with Nimodipine – dihydropyradine Calcium channel blocker)
What do Golgi tendon organs detect? What do muscle spindles detect?
Golgi - detect Force generated in muscle (has nothing to do with stretch) – In passive movements, golgi tendon organs are not activated
muscle spindles detect stretch
Gemistocytic astrocytes
Astrocytes turn into these in response to a pathologic process.
Lay down glial fibers.
Multiple Sclerosis
S/S
Hypersensitivity?
Autoimmune inflammation and demyelination in the CNS (destruction of oligodendrocytes)
Type IV hypersensitivity
SIN: Scanning speech, Intention tremor/Incontinence/Internuclear opthalmoplegia, Nystagmus
Relapsing and remitting course with gradual downhill progression
See plaques of demyelination in periventricular white matter
CSF findings in Multiple Sclerosis
Increased immunoglobulins with oligoclonal IgG bands and myelin basic protein
Internuclear opthalmoplagia
Seen in MS
A lesion in the medial longitudinal fasciculus of the brain stem
if right MLF is affected – when the patient looks left and the left CN6 fires to contract the lateral rectus muscle, the lack of communication to Right CN 3 (via defective MLF) will cause the right eye to lag behind due to lack of contraction of the medial rectus muscle
Central pontine myelinosis
Massive axonal demyelination in pontine white matter secondary to osmotic changes (alcoholism, electrolyte imbalance, rapid correction of hyponatremia)
Rapid onset of paralysis, dysarthria, loss of consciousness, locked in syndrome
Correcting serum Na levels too fast
“From high to low your brain will blow” Cerebral edema/herniation
“From low to high your pons with die” Central pontine myelinosis
Guillain Barre Syndrome
Autoimmune condition (likely due to molecular mimicry) that causes destruction of Schwann cells in the PNS Histo: Endoneural inflammatory infiltration with multifocal demyelination
Ascending paralysis that can affect the respiratory muscles
Associated with Campylobacter jejuni or Influenza infection
Sturge-Weber Syndrome
affects small blood vessels (port wine stain), ipsilateral leptomeningeal angioma, seizures, eoiscleral hemangioma → inc intraocular pressure leading to early onset glaucoma
Where does anterior brain blood supply come from?
Internal carotids –> MCA and ACA
Where does posterior brain blood supply come from?
Vertebral arteries –> Basilar a –> PCA
Patient presents with right arm and face paralysis and loss of sensation to the same areas. where is the infarct?
Left middle cerebral artery (MCA)
Patient presents with left leg weakness and loss of sensation, where is the infarct?
Right anterior cerebral artery (ACA)
Patient presents with visual deficits, where is the infarct?
Posterior cerebral artery (PCA)
Stroke in which artery causes “locked in syndrome?”
Basilar artery
Supplies the pons, medulla, lower midbrain, corticospinal and corticobulbar tracts
Progression of stroke histology
1) red neurons (red = dead) - 12 hours
2) Neutrophils - 1 day
3) Macrophages/microglia (days)
4) reactive gliosis and vascular proliferation (1 week) liquefactive necrosis
5) Glial scar (>2 weeks)
Midbrain nuclei
Pontine nuclei
Medulla nuclei
Spinal cord nuclei
Midbrain nuclei: CN 3 and 4
Pontine nuclei: CN 5, 6, 7, 8
Medulla nuclei: CN 9, 10, 12
Spinal cord nuclei: CN 11
Cause of subacute pancencephalitis
Persistent infection of the brain by measles virus (seen many years after the initial infection)
Destruction of grey and white matter
Progressive multifocal leukoencephalopathy
Associated with reactivation of the JC virus in white matter, usually due to immunosuppression
Progressive neurologic signs, leading to death
What are the causes of “locked in” syndrome?
Central pontine myelinosis
Basilar artery occlusion
Where are low sound frequencies heard best? High sound frequencies?
Low - apex of the cochlea (helicotrema)
High - base of the cochlea (near oval window)
Conductive hearing loss vs sensorineural hearing loss
Conductive
Rinne test is abnormal (bone>air)
Weber test localizes to the affected ear
Sensorineural
Rinne test is normal (air > bone)
Weber test localizes to the unaffected ear
Blink reflex
CN V1 in (unilateral)
CN VII out (bilateral)
Both eyes should blink
Pupillary reflex
CN II in (unilateral)
CN III out (bilateral)
Both pupils should constrict
Facial lesions (UMN vs LMN)
UMN: contralateral lower face paralysis with forehead sparing (because there is bilateral innervation to the upper face)
LMN: ipsilateral upper and lower facial paralysis
Horner Syndrome
Disruption of the sympathetic fibers of the face (any lesion above T1)
“PAM is horny”
Ptosis, anhydrosis, miosis”
What visual field defect does a pituitary adenoma cause?
Bitemporal hemianopia - due to compression of the optic chiasm, which affects the nasal fibers
Can also be caused by a craniopharyngioma in a child
Role of VEGF in eye pathology
Causes proliferation of new blood vessels that are thin and fragile (break easily)
Seen in proliferative diabetic retinopathy and in proliferative macular degeneration
Patient presents with painless progressive vision loss starting with night blindness
Retinitis pigmentosa (inherited retinal degeneration)
the rods are affected first, causing night blindness
Thalamus: VL
Input from basal ganglia and cerebellum
Output to motor cortex
Thalamus: VPL
Input from spinothalamic and medial lemniscus tracts (spinal component)
Output to somatosensory cortex (pain, temp, pressure, touch, vibration)
Thalamus: VPM
Input from spinothalamic and medial lemniscus tracts (tigeminal component)
Output to somatosensory cortex (face sensation, taste)
VPM* – Makeup goes on the face
Thalamus: MGN
Input from superior olive and inferior colliculus (auditory)
Output to auditory cortex (temporal lobe)
M = music = auditory
Thalamus: LGN
Input from optic tract (CN II)
Output to visual cortex (calcarine sulcus of the occipital lobe)
L = look = optic
Thalamus: AN
Input from Mammillothalamic Tract
Input to cingulate gyrus
Hypothalamus: supraoptic nucleus
Makes ADH
Hypothalamus: paraventricular nucleus
Makes oxytocin
*think gravida-para(ventricular) –> make breast milk when pregnant
Hypothalamus: lateral area
Drives hunger
Damage causes anorexia
Hypothalamus: Ventromedial area
Drives satiety
Damage causes obesity
Anterior hypothalamus
Cooling (A/C)
Parasympathetic
Posterior hypothalamus
Heating
Sympathetic
Hypothalamus: suprachiasmatic nucleus
Circadian rhythm
Release of melatonin from pineal gland
(you need sleep to be charismatic)
A tumor is found in the cerebellum of a 4 year old child
Medulloblastoma
Neuroectodermal tumor
Homer-wright rosettes on histology
Poor prognosis: spreads via CSF and can metastasize to the cauda equina “drop metastases”
M = metastases
A tumor is found in the 4th ventricle of a 5 year old child
Ependymoma
Arises from ependymal cells (lining of the ventricles)
Can block CSF and cause hydrocephalus
Perivascular rosettes on histology