Neurology Flashcards
Diencephalon gives rise:
Thalamus.
Hypothalamus
Third ventricle
Metencephalon gives rise:
Pons
Cerebellum
Upper part of
fourth ventricle
Telencephalon
Cerebral hemispheres.
Basal ganglia
Lateral ventricles
Normal AFP present in which neural tube defect?
Spina bifida occulta
Holoprosencephaly
Failure of the embryonic forebrain (prosencephalon) to separate into 2 cerebral hemispheres;
during weeks 5- 6
F - fused basal ganglia and ventricles E - Eye (cyclopia) T - trisomy 13 A - alcohol syndrome (fetal) L - lip/palate (cleft)
Lissencephaly
Failure of neuronal migration resulting in a “smooth brain” that lacks sulci and gyro.
May be associated with microcephaly, ventriculomegaly.
Silky
Chiari I malformation
Ectopia of cerebellar tonsils inferior to foramen magnum.
Associated with spinal cavitations (eg, syringomyelia).
Chiari II malformation
Herniation of cerebellar vermis and tonsils through foramen magnum with aqueductal stenosis -> noncommunicating hydrocephalus.
associated with lumbosacral myelomeningocele
Dandy-Walker malformation
Agenesis of cerebellar vermis leads to cystic enlargement of 4th ventricle
Associated with noncommunicating hydrocephalus, spina bifida.
Syringomyelia most common location:
cervical > thoracic» lumbar.
Tongue motor innervation
CN XII:
hyoglossus (retracts and depresses tongue)
genioglossus (protrudes tongue)
styloglossus (draws sides of the tongue upward to create a trough for swallowing).
Motor innervation is via CN X to palatoglossus (elevates posterior tongue during swallowing).
Astrocytes
B - blood-brain barrier
R - repair
a
S - support (physical)
K - K+ buffer i N - neurotransmitter removal G - glycogen fuel reserve G - gliosis (reactive) G - GFAP (astrocyte marker)
Endoneurium
thin, supportive connective tissue that ensheaths and supports individual myelinated nerve fibers.
Perineurium
(blood-nerve Permeability barrier)- surrounds a fascicle of nerve fibers. Must be rejoined in microsurgery for limb reattachment.
Epineurium
dense connective tissue that surrounds entire nerve (fascicles and blood vessels).
Chromatolysis
Characterized by:
• Round cellular swelling
• Displacement of the nucleus to the periphery
• Dispersion of Nissl substance throughout the cytoplasm
Blood-brain barrier
Formed by 3 structures:
Prevents circulating blood substances (eg, bacteria, drugs) from reaching the CSF/ CNS.
Formed by 3 structures:
• Tight junctions between nonfenestrated capillary endothelial cells
• Basement membrane
• Astrocyte foot processes
antagonists used to treat chemotherapy-induced vomiting:
NK-1 antagonists
D2 antagonists
5-HT3 antagonists
all are input to CTZ.
antagonists used to treat motion sickness and hyperemesis gravidarum:
H1 and M1 antagonists
all are input to CTZ.
H1 antagonists treat hyperemesis gravidarum.
circadian rhythm is driven by:
SCN -> norepinephrine release -> pineal gland -> melatonin.
SCN is regulated by the environment (eg, light).
The circadian rhythm controls the nocturnal release of: Prolactin M - melatonin A - ACTH N - norepinephrine
Non-REM sleep - Stage N1
EEG WAVEFORM AND NOTES
(5%) Light sleep.
Theta
Non-REM sleep - Stage N2
EEG WAVEFORM AND NOTES
(45%) Deeper sleep; when bruxism - “twoth” (tooth grinding) occurs.
SeKond - Sleep spindles and K complexes
Non-REM sleep - Stage N3
EEG WAVEFORM AND NOTES
Deepest non-REM sleep. Slow-wave sleep - Delta (lowest frequency, highest amplitude)
sleepwalking, night terrors, and bedwetting occur (wee and flee in N3).
REM sleep - Notes, timing
Loss of motor tone and inc brain O2 use, variable pulse/BP, inc ACh.
REM is when dreaming, nightmares and penile/clitoral tumescence occur; it may serve memory processing function.
Extraocular movements due to the activity of PPRF.
Occurs every 90 minutes, and duration inc through the night.
REM, REM-latency, N3 in depression vs elderly
Changes in elderly: dec REM sleep time, inc REM latency.
Changes in depression: inc REM sleep time, dec REM latency.
Dec N3 in both.
Sleep physiology: NE dec____
N3
Sleep physiology: GABA rec agonist dec____
REM
N3
Preoptic nucleus
Thermoregulation, sexual behavior.
Releases GnRH.
Failure of GnRH- producing neurons to migrate from the olfactory pit - Kallmann syndrome.
INPUT Medial geniculate nucleus
Superior olive and inferior colliculus of the tectum
INPUT to Ventral lateral nucleus
Cerebellum, basal ganglia
Senses motor, goes to Motor cortex.
The limbic system consists of:
H - hippocampus
A - amygdalae
M - mammillary bodies
A - anterior thalamic nuclei
C - cingulate gyrus
E - entorhinal cortex
The limbic system is responsible for:
Feeding, Fleeing, Fighting, Feeling, and Fucking.
Mesocortical pathway:
Dec activity -> “negative” symptoms (eg, anergia, apathy, lack of spontaneity).
Antipsychotic drugs have limited effect.
Mesolimbic pathway:
Inc activity -> “positive” symptoms (eg, delusions, hallucinations).
1° therapeutic target of antipsychotic drugs
Nigrostriatal pathway:
Dec activity - >extrapyramidal symptoms (eg, dystonia, akathisia, parkinsonism, tardive dyskinesia).
Significantly affected by movement disorders and antipsychotic drugs.
Tuberoinfundibular pathway:
Dec activity -> Inc prolactin -> dec libido, sexual dysfunction, galactorrhea, gynecomastia (in men).
CPP is directly proportional to Pco2 until____
Pco2 >90mm Ilg.
Hypoxemia increases CPP only if _____
Po2 < 50 mm Hg.
If CPP = 0?
If CPP = 0, there is no cerebral perfusion -> brain death.
CPP = MAP - ICP.
Therapeutic hyperventilation
-> dec Pco2 -> vasoconstriction -> dec cerebral blood flow -> dec intracranial pressure (ICP).
May be used to treat acute cerebral edema (eg, 2° to stroke)
Cranial nerve nuclei in the spinal cord
Spinal cord-nucleus of CN XI
Middle cranial fossa foramina:
Standing Room Only, Suckers!
Superior orbital fissure
Foramen Rotundum
Foramen Ovale
Foramen spinosum
Posterior cranial fossa foramina:
Includes Jazz, Hip-hop Mofo!
Internal auditory meatus
Jugular foramen
Hypoglossal canal
Foramen magnum
Superior orbital fissure
CN 3,4,6, V1
Foramen Rotundum
CN V2
Foramen Ovale
CN V3
Foramen spinosum
Middle meningeal artery
Internal auditory meatus
CN 7,8
Jugular foramen
CN 9,10,11
jugular vein
Hypoglossal canal
CN 12
Foramen magnum
Brain stem
Spinal root of CN XI
Vertebral arteries
Nucleus Tractus Solitarius
FUNCTION & CRANIAL NERVES
Nucleus - nine
Tractus - ten
Solitarius - seven
Visceral Sensory information (eg, taste, baroreceptors, gut distention)
Nucleus aMbiguus
FUNCTION & CRANIAL NERVES
Motor innervation of pharynx, larynx, upper esophagus (eg, swallowing, palate elevation)
IX, X, XI (cranial portion)
Dorsal motor nucleus
Sends autonomic (parasympathetic) fibers to heart, lungs, upper GI
CN X
Pupillary REFLEX
Gag REFLEX
Pupillary: II -> III
Gag: IX -> X
Mastication muscles
3 muscles close jaw: Masseter, teMporalis, Medial pterygoid.
1 opens: Lateral pterygoid.
All are innervated by trigeminal nerve (V3).
Dorsal column pathway
Sensory nerve ending — (Dorsal columns)—> Nuc Gracilis/Cuneatus —(Decussates in medulla, ascends as medial lemniscus)—>VPL -> sensory cortex
Spinothalamic tract pathway
Sensory nerve ending -> ipsilateral gray matter of SC —(Decussates in SC as anterior white commissure) ->VPL -> sensory cortex
Lateral corticospinal tract pathway
UMN in primary motor cortex— (through posterior limb of internal capsule, most fibers decussate at caudal medulla)—>anterior horn of SC —(LMN)—>NMJ -> muscle
Spinothalamic tract - function (anterior vs lateral)
Anterior - crude touch and pressure (touching and pressing what’s in front)
Lateral - pain + temperature (slap from the side hurts and burns)
Common brain lesions - Frontal lobe
Disinhibition and deficits in concentration, orientation, judgment; (JOC)
may have reemergence of primitive reflexes.
Common brain lesions - Frontal eye fields
Destructive lesion such as an MCA stroke:
eyes look toward the side of the lesion (or at the hemiplegia).
Irritative lesion such as seizures: eyes look at the shaking arm and leg.
Both lesion and symptom are on the same side.
Common brain lesions - Paramedian pontine reticular formation
Eyes look toward side of hemiplegia.
ipsilateral gaze palsy (inability to look toward side of lesion).
esion and symptom are not on the same side.
Common brain lesions - Dominant parietal
cortex
Gerstmann syndrome: Gerstmann CSF
G - agraphia
C - acalculia
S - sides (left-right disorientation)
F - finger agnosia
Common brain lesions - Nondominant parietal
cortex
Agnosia of the contralateral side of the world.
Hemispatial neglect syndrome.
Common brain lesions - Hippocampus
bilateral
Anterograde amnesia-inability to make new memories.
Common brain lesions - Amygdala (bilateral)
Kluver-Bucy syndrome-disinhibited behavior encephalitis.
(eg, hyperphagia, hypersexuality, hyperorality).
HSV-1 encephalitis.
Common brain lesions - Dorsal midbrain
Parinaud syndrome - vertical gaze palsy, pupillary light-near dissociation, lid retraction, convergence-retraction nystagmus.
Stroke, hydrocephalus, pinealoma.
lenticulostriate artery stroke
Pure motor stroke. Common location of lacunar infarcts.
Contralateral para lysis. Absence of cortical signs (eg, neglect, aphasia, visual fi eld loss).
Anterior spinal artery stroke
Lateral corticospinal tract.
Medial lemniscus.
Caudal medulla - hypoglossal nerve.
Medial medullary syndrome caused by infarct of paramedian branches of ASA and/or vertebral arteries.
PICA and AICA both present with:
C - cerebellar peduncles - ipsilateral ataxia, dysmetria
T - trigeminal nucleus (spinal) - pain and temperature sensation from the ipsilateral face
S - Spinothalamic tract - pain and temperature from the contralateral body
S’ - Sympathetic fibers - ipsilateral Horner syndrome.
V - Vestibular nuclei - Vomiting, vertigo, nystagmus
Labyrinthine artery
lpsilateral sensorineural deafness, vertigo. - part of AICA stroke
Central poststroke
pain syndrome
Neuropathic pain due to thalamic lesions.
Initial paresthesias followed in weeks to months by allodynia (ord inari ly painless stimuli cause pain) and dysesthesia on the contralateral side.
Occurs in 10% of stroke patients.
Headaches Tx - Cluster
Acute: sumatriptan, 100% O2
Prophylaxis: verapamil
Headaches Tx - Acute Migraine
D - dihydroergotamine
e
N - NSAIDs
T - triptans
Headaches Tx - Tension
Acute: analgesics, NSAIDs, acetaminophen
Prophylaxis: TCA’s (eg, amitriptyline), behavioral therapy
Headaches Tx - Prophylaxis Migraine
Lifestyle changes (eg, sleep, exercise, diet),
B - beta-blockers
A - amitriptyline
B - botulinum toxin injections
T - topiramate
V - valproate
Akathisia
Rest lessness and intense urge to move (nigrostriatal pathway)
Athetosis
Slow, snake-like, writhing movements; especially seen in the fingers (Huntington)
Chorea
Sudden, jerky, purposeless movements
Dystonia vs. Myoclonus
Dystonia - Sustained, involuntary muscle contractions (tx - botulinum toxin)
Myoclonus - Sudden, brief, uncontrolled muscle contraction (common in metabolic abnormalities)
Essential tremor vs Resting tremor
Essential tremor - worsened with movement or when anxious
Resting tremor - tremor alleviated by intentional movement
Hemiballismus is a _____ lesion
Contralateral lesion.
Restless legs syndrome
Worse at rest/nighttime, ReIieved by movement
Associated with iron deficiency, CKD.
Parkinson disease
Tremor (pill-rolling tremor at rest) Rigidity (cogwheel) Akinesia (or bradykinesia) Postural instability Shuffling gait
Lewy bodies: composed of a-synuclein (intracellular eosinophilic inclusions)
Huntington disease
Atrophy of caudate and putamen with ex vacuo ventriculomegaly.
death via NMDA-R binding and glutamate excitotoxicity.
Alzheimer disease
Widespread cortical atrophy - especially hippocampus
Associated with the following altered proteins:
• ApoE-2: dec risk of sporadic form
• ApoE-4: inc risk of sporadic form
• APP, presenilin-1, presenilin-2: familial forms (10%) with earlier onset.
Frontotemporal
dementia
Formerly known as Pick disease - Frontotemporal lobe degeneration
P - personality and behavior early changes (behavioral variant)
A - aphasia (primary progressive aphasia)
P - parkinsonism (may have associated movement disorders)
I - Inclusions of hyperphosphorylated tau (round Pick bodies ) or ubiquitinated TDP-43.
Lewy body dementia
Visual hallucinations (“haLewycinations”), dementia with fluctuating cognition/ alertness, REM sleep behavior disorder, and parkinsonism.
Called Lewy body dementia if cognitive and motor symptom onset < I year apart, otherwise considered dementia 2° to Parkinson disease
Alzheimer disease - Senile plaques
Senile plaques in the gray matter:
extracellular beta-amyloid core
may cause amyloid angiopathy -> intracranial hemorrhage;
A-beta(amyloid-beta) synthesized by cleaving amyloid precursor protein (APP).
Alzheimer disease -Neurofibrillary tangles
Neurofibrillary tangles: intracellular, hyperphosphorylated tau protein = insoluble cytoskeletal elements; number of tangles corre lates with the degree of dementia.
Vascular dementia
2nd most common cause of dementia in elderly.
Result of multiple arterial infarcts and/or chronic ischemia -> stepwise decline.
Creutzfeldt-Jakob
disease
Rapidly progressive (weeks to months) dementia with myoclonus (“startle myoclonus”) and ataxia. Commonly see periodic sharp waves on EEC and inc 14-3-3 protein in CSF.
Idiopathic intracranial
hypertension risk factors
female TOAD
T - Tetracyclines
O - Obesity
A - vitamin A excess
D - Danazol
Idiopathic intracranial
hypertension Treatment:
Treatment: weight loss, acetazolamide, invasive procedures for refractory cases (eg, CSF shunt
placement, optic nerve sheath fenestration surgery for visual loss).
Multiple sclerosis presentation
Hot - exacerbate with increased body temperature
O - optic neuritis L - Lhermitte phenomenon (shock-like sensation along cervical spine on neck flexion) y M - Marcus Gunn pupil P - Pyramidal tract demyelination i C -cerebellar/BS syndromes S - Spinal cord syndromes
Multiple sclerosis Tx
Stop relapses and halt/slow progression with disease-modifying therapies (eg, beta-interferon, glatiramer, natalizumab).
Treat acute flares with IV steroids.
Multiple sclerosis Symptomatic treatment
Symptomatic treatment for:
neurogenic bladder (catheterization, muscarinic antagonists)
spasticity (baclofen, GABA-b receptor agonists)
pain (TCAs, anticonvulsants).
Acute inflammatory demyelinating polyradiculopathy - Pathogenesis:
Demyelination of motor fibers, sensory fibers, peripheral nerves (including CN III-XII).
Likely facilitated by molecular mimicry and triggered by inoculations or stress.
Campylobacter jejuni, viruses [eg, Zika])
Acute disseminated (postinfectious) encephalomyelitis
Multifocal inflammation and demyelination after infection or vaccination. Presents with rapidly
progressive multifocal neurologic symptoms, altered mental status.
Charcot-Marie-Tooth
disease
related to the defective production of proteins involved in the structure and function of peripheral nerves or the myelin sheath.
Most common type, CMT1A, is caused by PMP22 gene duplication.
autosomal dominant and associated with:
- foot deformities (eg, pes cavus, hammer toe)
- lower extremity weakness (eg, foot drop)
- sensory deficits.
Progressive multifocal
leukoencephalopathy
destruction of oligodendrocytes (2° to reactivation of latent JC virus infection).
Seen in 2- 4% of patients with AIDS.
parietal and occipital areas; visual symptoms are common. risk associated with natalizumab.
Sturge-Weber syndrome
M - Mosaicism (somatic)
R - Retardation
S - Sporadic U - Unilateral G - GNAQ gene G - Glaucoma E - Epilepsy S - Stain (port-wine) T - Tram track calcifications
Tuberous sclerosis
A - Ash-leaf spots S - Shagreen patches H - Heart rhabdomyoma L - Lung Hamartomas E - Epilepsy A - Angiomyolipoma (renal) F - Facial Angiofibromas
M - Mitral regurgitation
D - Dominant
Neurofibromatosis type I - presentation and pathophysiology
C - Cafe-au-lait spots
A - Axillary freckling
F - Fibromas
E - Eye (Lisch nodules-pigmented iris hamartomas)
S - Scoliosis
P - Pheochromocytomas
O - Optic
T - Tumors
neurofibromin, a negative RAS regulator
Neurofibromatosis type II
Bilateral vestibular schwannomas, juvenile cataracts, meningiomas, ependymomas.
von Hippel-Lindau disease
H - Hemangioblastomas -in retina, brain stem, cerebellum, spine.
A - Angiomatosis;
R - Renal cell carcinomas;
P - Pheochromocytomas.
Adult primary brain tumors
S - Schwannoma
H - Hemangioblastoma
O - Oligodendroglioma
P - Pituitary adenoma
G - Glioblastoma multiforme
M - Meningioma
Schwannoma
Resection or stereotactic radiosurgery.
Schwann cell origin S-100(+)
Biphasic.
Dense, hypercellular areas containing spindle cells alternating with hypocellular, myxoid areas.
Hemangioblastoma
Blood vessel origin. Closely arranged, thin-walled capillaries with minimal intervening parenchyma.
Oligodendroglioma
Oligodendrocyte origin. “Fried egg” cells round nuclei with clear cytoplasm.
“Chicken-wire” capillary pattern.
Frontal lobes- often calcified.
Pituitary adenoma
Maybe nonfunctioning (silent) or hyper functioning (hormone-producing).
Glioblastoma multiforme
Can cross corpus callosum (“buttery glioma”).
Astrocyte origin (stage IV) - GFAP (+)· “Pseudopalisading” pleomorphic tumor cells rn border central areas of necrosis, hemorrhage, and/or microvascular proliferation.
Meningioma
Spindle cells concentrically arranged in a whorled pattern
psammoma bodies (laminated calcifications).
Childhood primary brain tumors
C - Craniopharyngioma
P - Pilocytic astrocytoma
P - Pinealoma
M - Medulloblastoma
E - Ependymoma
Medulloblastoma
Commonly involves the cerebellum.
Can compress 4th ventricle, causing noncommunicating hydrocephalus- headaches, papilledema.
Can send “drop metastases” to the spinal cord.
Form of primitive neuroectodermal tumor (PNET).
Homer-Wright rosettes, small blue cells
Ependymoma
Most commonly found in the 4th ventricle. It can cause hydrocephalus. Poor prognosis.
perivascular pseudorosettes. Rod-shaped blepharoplasts (basal ciliary bodies} found near the nucleus.
Pinealoma
Can cause Parinaud syndrome (compression of tectum -inc vertical gaze palsy);
obstructive hydrocephalus (compression of the cerebral aqueduct);
precocious puberty in males (hCG production).
Pilocytic astrocytoma
Low-grade astrocytoma
Astrocyte origin, GFAP(+).
Rosenthal fibers-eosinophilic, corkscrew fibers.
Cystic + solid (gross).
Craniopharyngioma
Derived from remnants of Rathke pouch (ectoderm}.
Calcification is common.
Cholesterol crystals found in “motor oil”-like fluid within tumor.
Spinal cord lesions - Spinal muscular atrophy
Congenital degeneration of anterior horns of the spinal cord.
LMN lesions only, symmetric weakness.
SMA type 1 is called Werdnig-Hoffmann disease.
Spinal cord lesions - Amyotrophic lateral sclerosis
Combined UMN (corticobulbar/corticospinal) and
LMN (medullary and spinal cord) degeneration.
No sensory or bowel/bladder deficits.
It can be caused by a defect in superoxide dismutase 1.
Spinal cord lesions - Complete occlusion of anterior spinal artery
Spares dorsal columns and Lissauer tract; midthoracic ASA territory is a watershed area, as the artery
of Adamkiewicz supplies ASA below T8. Can be caused by aortic aneurysm repair.
UMN - below the lesion
LMN - at the level of lesion
spinothalamic tract - pain and temperature sensation below the lesion
Spinal cord lesions -Tabes dorsalis
Caused by 3° syphilis. Results from degeneration/ demyelination of dorsal columns and roots.
Romberg sign a nd absent DTRs.
Associated with Charcot joints, shooting pain, Argyll Robertson pupils.
Spinal cord lesions -Syringomyelia
Syrinx expands and damages anterior white commissure of spinothalamic track
Spinal cord lesions - Vitamin B12 deficiency
Subacute combined degeneration (SCD)demyelination of Spinocerebellar tracts, lateral Corticospinal tracts, and Dorsal columns.
Spinal cord lesions - Cauda equina syndrome
Compression of spinal roots L2 and below, often due to intervertebral disc herniation or tumor. Radicular pain, absent knee and ankle reflexes, loss of bladder and anal sphincter control, saddle anesthesia.
Poliomyelitis
Signs of LMN lesion: asymmetric weakness, hypotonia, flaccid paralysis, fasciculations, hyporeflexia, muscle atrophy.
Respiratory muscle involvement leads to respiratory failure.
Signs of infection: malaise, headache, fever, nausea, etc.
The virus recovered from stool or throat.
Brown-Sequard syndrome - at the level of the lesion?
lpsilateral loss of all sensation at the level of the lesion
lpsilateral LMN signs (eg, flaccid paralysis) at the level of the lesion
Brown-Sequard syndrome - below the level of the lesion?
Ipsilateral UMN signs - due to corticospinal tract damage
lpsilateral loss of proprioception, vibration, light (2-point discrimination) touch, and tactile sense - due to dorsal column damage.
Contralateral loss of pain, temperature, and crude (non-discriminative) touch - due to spinothalamic tract damage.
Brown-Sequard syndrome with ipsilateral Horner syndrome?
If lesion occurs above T1 - damage of the oculosympathetic pathway.
Friedreich ataxia
Autosomal recessive trinucleotide repeat disorder (GAA) on chromosome 9
the gene that encodes frataxin (iron-binding protein).
impairment in mitochondrial functioning.
Degeneration of lateral corticospinal tract (spastic paralysis), spinocerebellar tract (ataxia), dorsal columns (dec. vibratory sense, proprioception), and dorsal root ganglia (loss of DTRs)
pes cavus, hammer toes, diabetes mellitus, hypertrophic cardiomyopathy (cause of death).
Presents in childhood with kyphoscoliosis.
CN V motor lesion
Jaw deviates toward side of lesion
CN X lesion
Uvula deviates away from side of lesion
CN XI lesion
Weakness turning head to contralateral side of the lesion (SCM). Shoulder droop on side of lesion (trapezius).
The left SCM contracts to help turn the head to the right.
CN XII lesion
LMN lesion. Tongue deviates toward the side of the lesion.
Bell palsy
HSV reactivation
Lyme disease, herpes zoster (Ramsay I lunt syndrome),
S - sarcoidosis
T - tumors (eg, parotid gland)
D - diabetes mellitus.
Facial nerve - Upper motor neuron lesion vs Lower motor neuron lesion
Lower motor neuron lesion -Ipsilateral, Upper and lower muscles of facial expression, and the forehead is involved. Other symptoms.
Upper motor neuron lesion - Contalateral, Lower muscles of facial expression, forehead is not involved.
Acute inflammatory demyelinating polyradiculopathy - Tx
Respiratory support is critical until recovery.
Disease-modifying treatment: plasmapheresis or IV immunoglobulins.
No role for steroids.
Acute inflammatory demyelinating polyradiculopathy - Presentation / Lab values:
ascending muscle weakness/paralysis and depressed/absent DTRs
May see autonomic dysregulation.
CSF protein with normal cell count (albuminocytologic dissociation).
