Neurology Flashcards
What induces the ectoderm to differentiate into neuroectoderm and neural plate?
Notochord
What gives rise to the neural plate?
Neuroectoderm and neural crest cells
What is the fate of notochord?
nucleus pulpous of the intervertebral disc
What are neural crest derivatives?
Sensory ganglia of cranial and spinal nerves Neurolemmal sheath of PNS Meninges Retinal pigment cells Cells of adrenal medulla
Failure of neuronal migration resulting in a “smooth brain” that lacks sulci and gyri
Lissencephaly
Congenital failure of the cerebellar vermis to develop causing massively dilated 4th ventricle, absent cerebellum, hydrocephalus
Dandy-Walker Malformation
Differentiate Chiari I malformation from Chiari II malformation
Chiari I - ectopia of cerebellar TONSILS into foramen magnum –> headaches, cerebellar s/sx, associated with syringomyelia
Chiari II - ectopia of TONSILS and VERMIS into foramen magnum with aqueductal stenosis–> non-communicating hydrocephalus, associated with lumbosacral myelomeningocele
Chiari I = 1 structure
Chiari II = 2 structures
Cystic cavity (syrinx) within central canal of spinal cord. What is this condition usually associated with?
Syringomyelia and is usually associated with Chiari I malformation
What part of the spinal cord is damaged first in syringomyelia?
Fibers crossing in anterior white commissure (spinothalamic tract) causing “cape-like (C5-T4)” bilateral, symmetrical loss of pain and temperature sensation in upper extremities. Fine touch is preserved
What pharyngeal arch does the tongue develop from?
Anterior 2/3 = 1st and 2nd pharyngeal arch
Posterior 1/3 = 3rd and 4th pharyngeal arch
What are the sensory innervations of the tongue?
Anterior 2/3
Sensation - V3
Taste - VII
Posterior 1/3
Sensation - IX
extreme posterior - X
What are the motor innervations of the tongue?
X - palatoglossus –> elevates posterior tongue during deglutition
XII:
Hyoglossus –> retracts and depresses tongue
Genioglossus –> protrudes tongue
Styloglossus –> draws sides of tongue upward to create a trough for swallowing
This is the most common glial cell type in CNS, neuroectodermal. Provides physical support, repair, extracellular K buffer, removal of excess neurotransmitter, component of BBB, glycogen fuel reserve, and reactive in response to neuronal injury
Astrocytes
These are phagocytic scavenger cells of CNS, mesodermal in origin. Activation of these cells release inflammatory mediators
Microglia
What are multinucleated giant cells seen in HIV-associated dementia?
fused microglia
These are ciliated simple columnar glial cells that line the ventricles and central canal of spinal cord
Ependymal cells
Specialized ependymal cells that produce CSF
Choroid plexus
What are characteristics of chromatolysis?
Round cellular swelling
displacement of nucleus to periphery
dispersion of Nissl substance throughout the cytoplasm
This is disintegration of the axon and myelin sheath distal to the site of axonal injury with microglial cells (macrophages) removing the debris
Wallerian-Degeneration
Neurotransmitter location of synthesis
ACh - basal nucleus of Maynert Dopamine - ventral tegmentum, substantia nigra GABA - nucleus accumbens NE - locus ceruleus (pons) 5HT - Raphe nucluei (pons, medulla)
Where is chemoreceptor trigger zone located?
area postrema in 4th ventricle
Chemoreceptor trigger zone and adjacent vomiting center receive input from which receptors?
M1 H1 D2 5-HT3 NK-1 (Neurokinin)
Classify antiemetics based on receptors
5HT3, D2, NK-1 antagonists treat chemotherapy induced vomiting
H1 and M1 antagonists treat motion sickness, H1 antagonists for hyperemesis gravidarum
Hypothalamic nucleus that is responsible for hunger. Stimulated by ghrelin and inhibited by leptin
Lateral nucleus
Hypothalamic nucleus responsible for satiety. Stimulated by Leptin and inhibited by ghrelin
Ventro-medial nucleus
Hypothalamic nucleus for cooling and parasympathetic
Anterior nucleus
A/C = anterior cooling
Hypothalamic nucleus for heating and sympathetic
Posterior nucleus
Hot Pot
Hypothalamic nucleus for circadian rhythm,
Suprachiasmatic nucleus (SCN)
SCN - Sun Sensing Nucleus
Hypothalamic nucleus that synthesizes ADH and oxytocin
Supraoptic and Paraventricular nucleus
SAD POX = Supraoptic - ADH, Paraventricular - Oxytocin
Hypothalamic nucleus for thermoregulations sexual behavior, and releases GnRH
Preoptic nucleus
Failure of GnRH-producing neurons to migrate from olfactory pit
Kallmann Syndrome
Where is the main location of CSF return via arachnoid granulations?
Superior sagittal sinus
What connects lateral ventricles to 3rd ventricle?
What connects 3rd to 4th ventricle?
What connects 4th ventricle to subarachnoid space?
foramina of Monro
Cerebral aqueduct of Sylvius
Foramen of Luschka = Lateral
Foramen of Megendie = Medial
Where are the crania nerves in relation to the brain stem?
4 CNs are above the [ons (I, II, III, IV)
4 CNs exit the pons
4 CNs are in medulla
4CN nuclei are medial
Where are the cranial nerve nuclei located?
in the tegmentum portion of the brain stem Midbrain: III, IV Pons: V, VI, VII, VIII Medulla: IX, X, XII Spinal cord: XI
Dampening of noises under the innervation of trigeminal nerve is brought about by what muscle?
tensor tympani
What provides teste sensation to the anterior 2/3 of the tongue?
Facial nerve (chorda tympani)
What are the muscles of mastication that is innervated by trigneminal nerve?
Close: temporalis, masseter, medial pterygoig
Open: Lateral pterygoid
It takes more muscle to keep your mouth shut
At what level does the spinal cord end for adults?
L1-L2
site for lumbar puncture is at what spinal level?
L3-L5
What are the 9 structures that the needle must pass through in lumbar puncture?
- Skin
- fascia and fat
- Supraspinous ligament
- Interspinous ligament
- ligamtum flavum
- Epidural space (epidural needle ends here)
- dura mater
- Pia mater
- Subarachnoid space
Reemergence of primitive reflexes is brought about by damage to what part of the brain?
Frontal lobe
Differentiate frontal eye field lesions from paramedian pontine reticular formation lesions
Frontal eye field lesion = eyes look toward brain lesion (away from hemiplegia)
Paramedian pontine reticular formation = eyes look away from brain lesion. Look toward hemiplegia
Differentiate dominant and non dominant parietal cortex lesions
Dominant parietal lesion = Gerstmann syndrome: agraphia, acalculia, finger agnosia, left-right disorientation
Nondominant = agnosia of the contralateral side of the world (Hemispatial neglect syndrome)
Wernicke-korsakoff syndrome will affect which part of the brain?
Bilateral Mamillary bodies
Damage to bilateral amygdala brought about by HSV-1 encephalitis causing disinhibited behavior (hyperplasia, hypersexuality, hyperorality)
Kluver-Bucy syndrome
Differentiate damages from cerebellar hemispheres from cerebella vermis
Cerebellar hemispheres - intention tremors, limb ataxia, loss of balance (fall toward side of lesion)
Vermis - truncal ataxia, nystagmus
Damage to the red nucleus in the midbrain will cause:
decorticate - lesion above red nucleus
decerebrate - lesion at or below red nucleus
What is a lacunar stroke?
secondary to hyaline arteriolosclerosis most commonly affects lenticulostriate vessels
What is the most commonly ruptured blood vessel involved in epidural hematoma?
Middle meningeal artery
Describe cranial CT of epidural hematoma
biconvex (lentiform), hyper dense blood collection, does not cross suture lines
Rupture of bridging veins will bring about what type of intracranial hemorrhage?
Subdural hemorrhage
Bridging veins are located between dura and arachnoid.
Associated with trauma, cerebral atrophy, elderly, alcoholism
CT findings in subdural hemorrhage
Crescent shaped hemorrhage (hyperdense = acute, hypodense = chronic), cross suture lines, uncal herniation
This type of intracranial hemorrhage is most commonly d/t rupture of berry/saccular aneurysm. It is associated with Ehlers-Danlos syndrome and ADPKD. Patients will complain of the worst headache of their life
Subarachnoid hemorrhage
Hypertensive hemorrhages (Charcot-Bouchard micro aneurysm) that often occurs in the basal ganglia
Intraparenchymal hemorrhage
Stroke of MCA vs ACA
MCA - motor and sensory cortices of upper limbs and face
ACA - motor and sensory cortices of lower limbs
*Look at the homunculus
Stroke from which blood vessel will give PURE MOTOR STROKE usually d/t hyaline arteriosclerosis
Lenticulostriate artery
What are Lewy bodies seen in Parkinson’s disease?
a-synuclein (intracellular eosinophilic inclusions)
What is the chromosomal defect in Huntington Disease?
Autosomal dominant trinucleotide repeat (CAG) resulting in expansion of huntingtin (HTT) gene on chromosome 4 –> loss of ACh and GABA in the caudate lobe
Further repeat usually occurs during spermatogenesis
What symptoms would you expect in someone with Huntington disease?
AGGRESSION, chorea, athetosis, depression, dementia
This is the most common cause of dementia in the elderly. Down syndrome patients have an increased risk of developing this disease
Alzheimer’s disease
How is Down syndrome a predisposition in developing Alzheimers?
Amyloid precursor protein (APP) is located on chromosome 21
What are the proteins associated with Alzheimer disease
ApoE-2 : decreases risk of sporadic form
ApoE-4 : increases risk of sporadic form
APP, presenilin-1, presenelin-2: familial form with earlier onset
What are neurofibrillary tangles?
intracellular hyperphosphorylated tau protein
This is formerly called Pick disease where in there is frontotemporal lobe degeneration and inclusions of hyperphosphorylated tau or ubiquinated TDP-43
Frontotemporal dementia
Autoimmun demyelination of CNS presenting with acute optic neuritis, brainstem/cerebella symptoms, affects medial longitudinal fasciculus
Multiple sclerosis
Cranial CT scan of multiple sclerosis will show:
periventricular plaques (areas of oligodendrocyte loss and reactive gliosis)
Massive axonal demyelination in the pontine white matter
Osmotic demyelination syndrome (Central Pontine Demyelination)
What causes osmotic demyelination syndrome?
d/t rapid osmotic changes.
A patient in the ER suddenly develops paralysis, dysarthria, dysphagia, diplopia, loss of consciousness
A 35-year-old man presents to the emergency department with difficulty walking. His symptoms began approximately 1 week ago and has progressively worsened. He has noticed some lightheadedness upon standing up from a seated position and some bilateral numbness over lower extremities. Physical examination is notable for 4/5 muscle strength and decreased sensation to light touch and pinprick in the bilateral lower extremity and absent patellar and ankle reflexes. A lumbar puncture is performed, which demonstrates a cell count of 1/uL, protein is 135 mg/dL, and glucose is 65 mg/dL. He is admitted to the neurology floor for frequent negative inspiratory pressure and vital capacity measures and intravenous immunoglobulin.
Guillain-Barre syndrome
- Autoimmune condition that destroys Schwann cells.
- Symmetric ascending muscle weakness/paralysis.
- Likely d/t molecular mimicry and triggered by stress
- associated with campylobacter jejuni
- Increased CSF protein with normal cell count
What is the most common hereditary peripheral neuropathy?
Charcot-Marie-Tooth disease
What is the most common acute peripheral neuropathy?
Guillain-Barre syndrome
A 3-year-old boy presents to his pediatrician for multiple hyperpigmented lesions on his skin. Family history is significant for a genetic disorder in which his father to have similar skin lesions that are much larger. Medical history is otherwise unremarkable. On physical exam, there are 7 café au lait macules about 6 mm in size throughout the body along with axillary freckling.
Neurofibromatosis type I (von Recklinghausen disease)
- AD, 100% penetrance
- mutation in NF1 tumor supressor gene on chromosome 17 (17 letters in von Recklinghausen)
A 23-year-old man presents to the emergency department for worsening hearing loss and headaches. Medical history is otherwise noncontributory. Family history is notable for his mother having a meningioma and progressive hearing loss. Physical examination is notable for papilledema and bilateral sensorineural hearing loss. An MRI brain with and without contrast demonstrates bilateral enhancing lesions by the internal acoustic meatus and an extra-axial mass arising from the dura.
Neurofibromatosis type II
- AD, mutation in NF2 (tumor supressor, merlin, on chromosome 22)
- bilateral vestibular schwannomas, juvenile cataracts, meningiomas, ependymomas
A 33-year-old man presents to the emergency department after noticing blood in his urine. Medical history is notable for a recently diagnosed left eye retinal hemangioblastoma, for which ophthalmology is following. Family history is notable for his father having some sort of brain and pancreatic cancer. A CT abdomen demonstrates a left-sided renal mass with areas of necrosis and calcifications.
von Hippel-Lindau disease
- AD. Deletion of VHL gene on chromosome 3 which normally ubiquinates hypoxia-inducible factor Ia
- Hemangioblastomas, angiomatosis, bilateral renal cell CA, pheochromocytoma
Most common malignant tumor in adults. Derived from glial cells with histopathologic feature of pseudopalisading pleomorphic cells
Glioblastoma
This is the most common benign brain tumor in adults and expresses estrogen receptors with round mass attached to the dura. Arachnoid cell in origin with spindle cells concentrically arranged in a whorled pattern and psammoma bodies
Meningioma
