Neuro and Special Senses Flashcards
Neuroepithelia in neural tube become what?
CNS neurons, ependymal cells, oligodendrocytes, astrocytes
What do neural crest cells become in the brain?
PNS neurons and Schwann cells
What does the mesoderm become in the brain?
Microglia
Risks for neural tube defects?
Maternal diabetes as well as low folic acid intake
Labs of NTD?
Elevated AFP and AChE as confirmatory
What is holoprosencephaly and risk factors?
Failure of left and right hemispheres to separate
Seen in trisomy 13 and fetal alcohol syndrome
Clinical presentation of holoprosencephaly?
Moderate form has cleft lip/palate, most severe form results in cyclopia
MRI: monoventricle and fusion of basal ganglia
Chiari I malformation
Ectopia of cerebellar tonsils
Asymptomatic; HA in adulthood
Assoc w/ syringomyelia
Chiari II malformation
Herniation of low-lying cerebellar vermis and tonsils through foramen magnum with aqueductal stenosis -> hydrocephalus
Assoc w/ LS meningomyelocele
Dandy-Walker syndrome
Agenesis of cerebellar vermis with cystic enlargement of 4th ventricle
Assoc w/ noncommunicating hydrocephalus, spina bifida
Syringomyelia
Cystic cavity (syrinx) in central canal of spinal cord AWC damaged first: cape-like loss of pain and temp (fine touch intact) Expansion into AMH (weakness); expansion into LH: Horners
Tongue sensation
-1st and 2nd branchial arches form anterior 2/3 (sensation via CN V3, taste via CN VII)
-3rd and 4th branchial arches form posterior 1/3 (sensation and taste mainly via CN IX,
extreme posterior via CN X)
Tongue motor innervation
-CN XII to hyoglossus
(retracts and depresses tongue), genioglossus (protrudes tongue), and styloglossus (draws sides of tongue upward to create a trough for swallowing)
-CN X to palatoglossus (elevates posterior tongue during swallowing)
Astrocytes
Derived from neuroectoderm. Astrocyte marker: GFAP
Physical support, repair, EC K+ buffer, removal of excess NT, part of BBB, glycogen fuel reserve buffer
Microglia
mesodermal, mononuclear origin
Phagocytic scavenger cells of CNS
multinucleated giant cells in CNS of HIV patients
fused microglia
Schwann cells
Derived from neural crest
Each Schwann cell myelinates only 1 PNS axon
Oligodendrocytes
Derived from neuroectoderm
Can myelinate many axons
“Fried egg” on histology
What is the BBB formed by?
Tight junctions between nonfenestrated capillary endothelial cells
Basement membrane
Astrocyte foot processes
Function of hypothalamus
TAN HATS
Thirst, Adeno and Neuro hypophysis (pituitary), Hunger, ANS, Temperature, Sex
Lateral area of hypothalamus
Hunger
(No lateral area: shrink laterally)
Stimulated by ghrelin,
inhibited by leptin
Ventromedial area of hypothalamus
Satiety (destruction: hyperphagia)
Stimulated by leptin
Anterior hypothalamus
Cooling, parasympathetic
A/C: anterior/cooling
Posterior hypothalamus
Heating, sympathetic
Suprachiasmatic nucleus of hypothalamus
Circadian rhythm
Supraoptic and paraventricular nuclei of hypothalamus
Synthesize ADH and oxytocin
At what stage of the sleep cycle does bruxism occur?
N2 of non-REM sleep
Delta on EEG
Thalamus
Major relay for all ascending sensory information except olfaction
Ventral Postero- Lateral nucleus of thalamus
Input from spinothalamic and dorsal columns/ medial lemniscus
Vibration, Pain, Pressure, Proprioception, Light touch, Temp
Ventral postero- Medial nucleus of thalamus
Input from trigeminal and gustatory pathway
Face sensation, taste
Lateral geniculate nucleus of thalamus
Input from CN II
Vision; goes to calcirine sulcus
(lateral = light)
Medial geniculate nucleus
Input from superior olive and inferior colliculus of tectum
Hearing; goes to auditory cortex of temporal lobe
(medial = music)
Ventral lateral nucleus
Input from basal ganglia and cerebellum
Motor; goes to motor cortex
What is the limbic system
Collection of neural structures involved in emotion, long-term memory, olfaction, behavior modulation, ANS function (the five Fs)
Mesocortical dopaminergic pathway
Decreased activity -> negative symptoms
Mesolimbic dopaminergic pathway
Increased activity: positive symptoms
Nigrostriatal dopaminergic pathway
Decreased activity: extrapyramidal sx
Tuberoinfundibular dopaminergic pathway
Decreased activity: increased prolactin and decreased libido
Lateral lesions of cerebellum
Affect voluntary movement of extremities (Limbs tend to fall toward ipsilateral side
Medial lesions of cerebellum
Involvement of Midline structures
Bilateral motor deficits
Purpose of basal ganglia
Voluntary movements and making postural adjustment
Location of ACh synthesis
Basal nucleus of Meynert
Location of dopamine synthesis
Ventral tegmentum, SNc (pars compacta)
Location of GABA synthesis
Nucleus accumbens
Location of Norepinephrine synthesis
Locus ceruleus
Location of Serotonin synthesis
Raphe nucleus
Ascending spinal tracts
Dorsal and Spinothalamic
Function of dorsal column
Pressure, vibration, fine touch, proprioception
Where does the dorsal column cross?
In the medulla
Where is the first synapse of the dorsal column nerves?
Nucleus gracilis or cuneatus (in the ipsilateral medulla)
Function of spinothalamic tract
Lateral: pain, temperature
Anterior: crude touch, pressure
Where does the spinothalamic tract cross?
anterior white commissure
Where is the first synapse of the spinothalamic tract nerves?
Ipsilateral gray matter of the spinal cord
Where is the second synapse of the dorsal and spinothalamic tracts?
VPL of the thalamus
Function of lateral corticospinal tract
Voluntary movement of contralateral limbs
Where is the first synapse of the lateral corticospinal tract?
Cell body of anterior horn (spinal cord)
Where does the lateral corticospinal tract cross?
most fibers decussate at caudal medulla (pyramidal decussation)
What spinal level does the cremasteric reflex test?
L1, L2
What spinal level does the anal wink reflex test?
S3, S4
Clinical significance of lesion in the frontal lobe
Disinhibition and deficits in concentration, orientation, judgment; reemergence of primitive reflexes
Clinical significance of lesion in the frontal eye fields
Eyes look toward lesion
Clinical significance of lesion in the paramedian pontine reticular formation
Eyes look away from lesion
Clinical significance of lesion in the medial longitudinal fasciculus
Internuclear ophthalmoplegia (can occur in MS)
Clinical significance of lesion in the dominant parietal cortex
Agraphia, acalculia, finger agnosia, left-right disorientation
(Gerstmann syndrome)
Clinical significance of lesion in the nondominant parietal cortex
Agnosia of the contralateral side of the world
Hemispatial neglect syndrome
Clinical significance of lesion in the hippocampus (bilateral)
Anterograde amnesia: inability to make new memories
Clinical significance of lesion in the basal ganglia
May result in tremor at rest, chorea, athetosis
Parkinson and Huntington
Clinical significance of lesion in the subthalamic nucleus
Contralateral hemiballismus (type of chorea)
Clinical significance of lesion in the mammillary bodies (bilateral)
Wernicke-Korsako syndrome: Confusion, Ataxia, Nystagmus, Ophthalmoplegia, memory loss (anterograde and retrograde amnesia), confabulation, personality changes
Clinical significance of lesion in the amygdala (bilateral)
Klüver-Bucy syndrome: disinhibited behavior
HSV-1 encephalitis
Clinical significance of lesion in the superior colliculus
Parinaud syndrome: paralysis of conjugate vertical gaze (rostral interstitial nucleus also involved)
(Stroke, hydrocephalus, pinealoma)
Clinical significance of lesion in the reticular activating system (midbrain)
Reduced levels of arousal and wakefulness
Clinical significance of lesion in the cerebellar hemisphere
Intention tremor, limb ataxia, loss of balance; damage to cerebellum: ipsilateral deficits; fall toward side of lesion
Clinical significance of lesion in the cerebellar vermis
Truncal ataxia, dysarthria
Time to irreversible brain damage and areas most vulnerable
5 minutes
hippocampus, neocortex, cerebellum, watershed areas
Epidural hematoma
Middle meningeal artery
2° to skull fracture
Lucid interval
CT shows biconvex (lentiform/lens), hyperdense blood collection not crossing suture lines
Subdural hematoma
Bridging veins; 2° to frontal trauma
Crescent-shaped hemorrhage that crosses suture lines
Can cause midline shift; progressive neurologic signs
Subarachnoid hemorrhage
Rapid time course; worst HA of life
Bloody or yellow spinal tap
Intraparenchymal hemorrhage
Usually due to HTN
Typically occurs in basal ganglia and internal capsule (Charcot-Bouchard microaneurysm of lenticulostriate vessels)
Middle cerebral artery lesion in a stroke will affect what areas of the brain
Motor and sensory cortices: upper limb and face Temporal lobe (Wernicke area) Frontal lobe (Broca area)
Middle cerebral artery lesion in a stroke will have what sx?
Contralateral paralysis and sensory loss—face and upper limb.
Aphasia if in dominant (usually left) hemisphere. Hemineglect if lesion affects nondominant (usually right) side
Anterior cerebral artery lesion in a stroke will affect what areas of the brain
Motor and sensory cortices—lower limb
Anterior cerebral artery lesion in a stroke will have what sx?
Contralateral paralysis and sensory loss—lower limb
Lenticulo- striate artery lesion in a stroke will affect what areas of the brain
Striatum, internal capsule
Lenticulo- striate artery lesion in a stroke will have what sx?
Contralateral paralysis and/or sensory loss—face and body. Absence of cortical signs
Anterior spinal artery lesion in a stroke will affect what areas of the brain
Lateral corticospinal tract.
Medial lemniscus.
Caudal medulla—hypoglossal nerve
Anterior spinal artery lesion in a stroke will have what sx?
Medial medullary syndrome
Contralateral paralysis—upper and lower limbs.
Decreased contralateral proprioception.
Ipsilateral hypoglossal dysfunction (tongue deviates ipsilaterally)
Posterior inferior cerebellar artery lesion in a stroke will affect what areas of the brain
Lateral medulla: Nucleus ambiguus (CN IX, X, XI) Vestibular nuclei
Lateral spinothalamic tract, spinal trigeminal nucleus
Sympathetic fibers
Inferior cerebellar peduncle
Posterior inferior cerebellar artery lesion in a stroke will have what sx?
Lateral medullary (Wallenberg) syndrome
Dysphagia, hoarseness, ↓ gag reflex
Vertigo, nystagmus, ↓ pain and temperature sensation
from contralateral body,
ipsilateral face
Ipsilateral Horner syndrome Ataxia, dysmetria
Anterior inferior cerebellar artery lesion in a stroke will affect what areas of the brain
Lateral pons: Facial nucleus Vestibular nuclei: Spinothalamic tract, spinal trigeminal nucleus Sympathetic fibers Middle and inferior cerebellar peduncles
Anterior inferior cerebellar artery lesion in a stroke will have what sx?
Lateral pontine syndrome
Paralysis of face
Vertigo, nystagmus, vomiting, decreased pain and temperature sensation
from contralateral body,
ipsilateral face
Ipsilateral Horner syndrome Ataxia, dysmetria
Basilar artery lesion in a stroke will affect what areas of the brain
Pons, medulla, lower midbrain
Corticospinal and corticobulbar tracts
Ocular cranial nerve nuclei, paramedian pontine reticular formation
Basilar artery lesion in a stroke will have what sx?
“Locked-in syndrome.”
Loss of horizontal, but not vertical, eye movements
Posterior cerebral lesion in a stroke will affect what areas of the brain
Occipital lobe
Posterior cerebral lesion in a stroke will have what sx?
Contralateral hemianopia with macular sparin
Central post-stroke pain syndrome
Neuropathic pain due to thalamic lesions
Broca aphasia
Expressive aphasia
Able to comprehend but not speak fluently
Broca area in inferior frontal gyrus of frontal lobe. Patient
appears frustrated, insight intact
Wernicke aphasia
Receptive aphasia
Able to speak fluently but not understand others
Wernicke area in superior temporal gyrus of temporal lobe
Conduction aphasia
Can be caused by damage to arCuate fasciculus.
Global aphasia
Cannot speak or understand
Arcuate fasciculus; Broca and Wernicke areas affected
Transcortical motor aphasia
Able to comprehend but not speak fluently
Affects frontal lobe around Broca area, but Broca area is spared
Transcortical sensory aphasia
Able to speak fluently but not understand others
Affects temporal lobe around Wernicke area, but Wernicke area is spared
Transcortical, mixed aphasia
Broca and Wernicke areas and arcuate fasciculus remain intact; surrounding watershed areas affected
Most common location of a berry aneurysm
bifurcations in the circle of Willis; most common is junction of ACom and ACA
Cluster HA
Unilateral; 15m-3h
Brief, repetitive
Periorbital pain w/ lacrimation and rhinorrhea
Treatment and prophylaxis for cluster HA?
Acute: sumatriptan, 100% O2 Prophylaxis: verapamil
Tension HA
Bilateral; >30m, constant
Steady pain
No photophobia or phonophobia
No aura
Migraine
Unilateral; 4-72h
Pulsating pain with
nausea, photophobia, or phonophobia; “aura”
Treatment and prophylaxis for tension HA?
Analgesics, NSAIDs, acetaminophen; amitriptyline for chronic pain
Treatment and prophylaxis for migraine HA?
Acute: NSAIDs, triptans, dihydroergotamine
Prophylaxis: lifestyle changes, β-blockers, calcium channel blockers, amitriptyline, topiramate, valproate
Akathisia
Restlessness and intense urge to move
Seen in neuroleptic use or Parkinsons
Asterixis
Extension of wrists causes “flapping” motion
Hepatic encephalopathy, Wilsons
Athetosis
Slow, snake-like, writhing movements; especially seen in the fingers
Basal ganglia lesion
Chorea
Sudden, jerky, purposeless movements
Basal ganglia lesion
Dystonia
Sustained, involuntary muscle contractions
Writer’s cramp, blepharospasm, torticollis
Essential tremor
High-frequency tremor with sustained posture
(eg, outstretched arms); worse with movement or anxious
Decreases w/ alcohol
Treat w/ non-selective β-blockers
Hemiballismus
Sudden, wild flailing of 1 arm +/− ipsilateral leg
Contralateral subthalamic nucleus lesion
Intention tremor
Slow, zigzag motion when pointing/extending toward a target
Cerebellar dysfunction
Myoclonus
Sudden, brief, uncontrolled muscle contraction
Common in metabolic abnormalities such as renal and liver failure
Resting tremor
Uncontrolled movement of distal appendages
Substansia nigra lesion
“pill rolling”
Parkinson disease sx
Tremor (pill-rolling tremor at rest)
Rigidity (cogwheel)
Akinesia (or bradykinesia) Postural instability
Shuffling gait
Parkinson disease etiology
Loss of dopaminergic neurons (ie, depigmentation) of substantia nigra pars compacta
Lewy bodies: composed of α-synuclein (intracellular eosinophilic inclusions)
Huntington disease sx
Symptoms manifest between ages 20 and 50: chorea, athetosis, aggression, depression, dementia (sometimes mistaken for substance abuse)
Huntington disease etiology
AD(CAG) repeat on chromosome 4
Atrophy of caudate and putamen with ex vacuo ventriculomegaly
↑ dopamine
↓ GABA and ACh
Neuronal death via NMDA-R binding and glutamate excitotoxicity
Alzheimer disease risk factors
Down syndrome: APP on 21
ApoE2: ↓ risk of sporadic form
ApoE4: ↑ risk of sporadic form
APP, presenilin-1: familial forms (10%) with earlier onset
Alzheimer disease histology
Widespread cortical atrophy
Narrowing of gyri and widening of sulci
Senile plaques in gray matter: extracellular β-amyloid core; may cause amyloid angiopathy
Neurofibrillary tangles
Loss of cholinergic neurons in nucleus basalis of Meynert
Frontotemporal dementia (Pick disease) sx
Early changes in personality and behavior (behavioral variant), or aphasia (primary progressive aphasia)
May have associated movement disorders
Frontotemporal dementia (Pick disease) histology
Frontotemporal lobe degeneration
Inclusions of hyperphosphorylated tau (round Pick bodies) in the cortex
Lewy body dementia histology
Intracellular Lewy bodies primarily in cortex
Vascular dementia
Due to multiple arterial infarcts and/or chronic ischemia
Step-wise decline in cognitive ability with late- onset memory impairment
Creutzfeldt-Jakob disease
Rapidly progressive (w to mo) dementia with myoclonus (“startle myoclonus”)
Periodic sharp waves on EEG
↑ 14-3-3 protein in CSF
Spongiform cortex
Idiopathic intracranial HTN (pseudotumor cerebri) cause and risk factors
Increased ICP w/ no cause
Risk factors: female gender, obesity, vitamin A excess, tetracycline, danazol
Idiopathic intracranial HTN (pseudotumor cerebri) sx?
HA, diplopia (CN VI palsy), no change in mental status. Papilledema on fundoscopy
LP: ↑ opening pressure and HA relief
Idiopathic intracranial HTN (pseudotumor cerebri) treatment
weight loss, acetazolamide, topiramate, invasive procedures for refractory cases (eg, repeat LP, CSF shunt, optic nerve sheath fenestration)
Communicating hydrocephalus
Decreased CSF absorption by arachnoid granulations
Increased ICP, papilledema, herniation
Normal pressure hydrocephalus
Affects the elderly; idiopathic
Does not result in increased subarachnoid space volume
Expansion of ventricles distorts fibers of corona radiata: triad of urinary incontinence, ataxia, and cognitive dysfunction (wet, wobbly, wacky)
Characteristic magnetic gait (feet appear stuck to floor)
Noncommunicating hydrocephalus
Structural blockage of CSF circulation within ventricular system
Ex vacuo ventriculomegaly
Appearance of increased CSF but actually decreased brain tissue
Osmotic demyelination syndrome (central pontine myelinolysis)
Acute paralysis, dysarthria, dysphagia, diplopia, LOC; “Locked in”
Massive axonal demyelination in pontine white matter
Caused by overly rapid correction of hyponatremia (Low to high; your pons will die)
Multiple sclerosis cause
Autoimmune inflammation and demyelination of CNS
Lhermitte phenomenon
Neck flexion precipitates sensation of electric shock running down spine (seen in MS and chemo)
Multiple sclerosis disease course
Most often affects women in their 20s and 30s; more common in Caucasians living farther from equator; HLA-DR2
Relapsing and remitting
MS sx
Optic neuritis (sudden loss of vision resulting in Marcus Gunn pupils), INO, hemiparesis, hemisensory symptoms, bladder/bowel dysfunction
Charcot triad of MS
Scanning speech
Intention tremor (also Incontinence and Internuclear ophthalmoplegia)
Nystagmus
MS histology and labs
Increased IgG and MBP in CSF
Oligoclonal bands
Periventricular plaques
Treatment of MS
Disease-modifying therapies (β-interferon, glatiramer, natalizumab)
Acute: IV steroids
Treatment for acute inflammatory demyelinating plyradiculopathy
(Guillain-Barre most common subtype)
plasmapheresis and IV ig
Charcot-Marie-Tooth disease cause
Also known as hereditary motor and sensory neuropathy (HMSN)
defective production of proteins involved in the structure and function of peripheral nerves or the myelin sheath
Charcot-Marie-Tooth disease sx
Foot deformities (pes cavus, hammer toe), lower extremity weakness (foot drop) and sensory deficits
Krabbe disease cause
AR lysosomal storage disease due to deficiency of galactocerebrosidase: destruction of myelin sheath; galatocerebrosidase build up in macrophages
Krabbe disease sx
Peripheral neuropathy, developmental delay, optic atrophy, globoid cells
Metachromatic leukodystrophy
AR lysosomal storage disease: arylsulfatase deficiency; build up of myelin
Progressive multifocal leukoencephalopathy
Demyelination of CNS due to destruction of oligodendrocytes
Assoc w/JC virus
Adrenoleukodystrophy
X-linked
Disrupts metabolism of very-long-chain fatty acids d/t impaired addition of coenzyme A
FA accumulates and damages adrenal glands and white matter
Sturge-Weber syndrome (encephalotrigeminal angiomatosis) cause
Congenital, noninherited, developmental anomaly of neural crest derivatives due to somatic mosaicism for an activating mutation in one copy of the GNAQ gene
Sturge-Weber syndrome (encephalotrigeminal angiomatosis) sx
- port-wine stain of the face
- ipsilateral leptomeningeal angioma: seizures/ epilepsy; intellectual disability
- episcleral hemangioma: increased IOP -> early glaucoma
Tuberous sclerosis cause
TSC1/TSC2 mutation on chromosome 16. Autosomal dominant, variable expression
Tuberous sclerosis sx
HAMARTOMAS: Hamartomas in CNS and skin Angio fibromas Mitral regurgitation Ash-leaf spots cardiac Rhabdomyoma (Tuberous sclerosis) autosomal dOminant Mental retardation (intellectual disability) renal Angiomyolipoma Seizures Shagreen patches Increased subependymal giant cell astrocytomas and ungual fibromas
Neurofibromatosis type I (von Recklinghausen disease) cause
Mutation in NF1 tumor suppressor gene on chromosome 17: codes for neuro bromin, a negative regulator of RAS
Autosomal dominant, 100% penetrance
Neurofibromatosis type I (von Recklinghausen disease) sx
Café-au-lait spots, cutaneous neurofibromas, optic gliomas, pheochromocytomas, Lisch nodules (pigmented iris hamartomas)
Neurofibromatosis type II cause
Mutation in NF2 tumor suppressor gene on chromosome 22
Autosomal dominant
Neurofibromatosis type II sx
bilateral acoustic schwannomas, juvenile cataracts, meningiomas, and ependymomas
von Hippel-Lindau disease cause
Deletion of VHL gene on chromosome 3p
Autosomal dominant
von Hippel-Lindau disease sx
HARP: Hemangioblastomas (high vascularity with hyperchromatic nuclei) in retina, brain stem, cerebellum, spine
Angiomatosis (cavernous hemangiomas in skin, mucosa, organs)
bilateral Renal cell carcinomas
Pheochromocytomas
Glioblastoma multiforme
Adult primary brain tumor grade IV astrocytoma highly malignant, cerebral hemispheres, butterfly Astrocyte origin, GFAP ⊕ "Pseudopalisading”
Oligodendroglioma
Adult primary brain tumor Rare, slow growing Frontal lobes; “Chicken-wire” capillary pattern “Fried egg” cells Often calcified
Meningioma
Adult primary brain tumor
occurs near surfaces of brain and in parasagittal region; dural attachment
may present with seizures or focal neurologic signs
Arachnoid cell origin; whorled; psammoma
Hemangioblastoma
Adult primary brain tumor
Cerebellar; assoc w/ VHL
Can produce erythropoietin: 2° polycythemia
Blood vessel origin
Schwannoma
Adult primary brain tumor
Classically at cerebellopontine angle
Localized to CN VIII in internal acoustic meatus → vestibular schwannoma
Schwann cell origin: S-100 ⊕
Pilocytic (low-grade) astrocytoma
Childhood 1° brain tumor
Well circumscribed, found in posterior fossa
Glial cell origin, GFAP ⊕ Rosenthal fibers- eosinophilic, corkscrew fibers
Medulloblastoma
Childhood 1° brain tumor
Most common malignant brain tumor in childhood
Involves cerebellum
Can compress 4th ventricle, causing noncommunicating hydrocephalus; drop metastases
Homer-Wright rosettes, small blue cells
Ependymoma
Childhood 1° brain tumor
Found in 4th ventricle; hydrocephalus
Ependymal cell origin; perivascular rosettes
Craniopharyngioma
Childhood 1° brain tumor
Most common childhood supratentorial tumor
Derived from remnants of Rathke pouch
Calcification is common
Cholesterol crystals found in “motor oil”—like fluid within tumor
Pinealoma
Childhood 1° brain tumor
Tumor of pineal gland
Parinaud syndrome (compression of tectum → vertical gaze palsy)
Precocious puberty in males
Sx of CN V motor lesion
Jaw deviates toward side of lesion due to unopposed force from the opposite pterygoid muscle
Sx of CN X lesion
Uvula deviates away from side of lesion
Weak side collapses and uvula points away
Sx of CN XI lesion
Weakness turning head to contralateral side of lesion (SCM)
Shoulder droop on side of lesion (trapezius)
Sx of CN XII lesion
LMN lesion
Tongue deviates toward side of lesion
Facial nerve LMN lesion
paralysis of upper and lower muscles of facial expression, hyperacusis, loss of taste sensation to anterior tongue
Middle ear bones name and function
Ossicles (malleus, incus, stapes); conduct and amplify sound from eardrum to inner ear
Conductive hearing loss
Abnormal Rinne (bone > air) Weber to affected ear
Sensorineural hearing loss
Normal Rinne (air > bone) Weber to unaffected ear
Noise-induced hearing loss
Damage to stereociliated cells in organ of Corti
Loss of high-frequency hearing first
Presbycusis
Aging-related sensorineural hearing loss (higher frequencies) due to destruction of hair cells at cochlear base
Cholesteatoma
Overgrowth of desquamated keratin debris within middle ear space
erode ossicles, mastoid air cells -> conductive hearing loss
Conjunctivitis
Inflammation of the conjunctiva; redeye
Hyperopia
“farsightedness”
Eye too short for refractive power of cornea and lens -> light focused behind retina
Correct with convex (converging) lenses
Myopia
“nearsightedness”
Eye too long for refractive power of cornea and lens -> light focused in front of retina
Correct with concave (diverging) lens
Astigmatism
Abnormal curvature of cornea: different refractive power at different axes
Correct with cylindrical lens
Presbyopia
Aging-related impaired accommodation
Cataract
opacification of lens
Glaucoma
Optic disc atrophy with characteristic cupping
Elevated IOP
Uveitis
Innflammation of uvea
Age-related macular degeneration
Causes distortion (metamorphopsia) and eventual loss of central vision (scotomas)
Miosis
Constriction, PSNS:
1st neuron: Edinger-Westphal nucleus to ciliary ganglion via CN III
2nd neuron: short ciliary nerves to sphincter pupillae muscles
Mydriasis
Dilation, sympathetic
Marcus Gunn pupil
Afferent pupillary defect: optic nerve damage or severe retinal injury.
Decreased bilateral pupillary constriction when light is shone in affected eye relative to unaffected eye
CN III damage: motor
ptosis, “down and out” gaze
CN III damage: PSNS
diminished or absent pupillary light reflex, “blown pupil” often with “down-and-out” gaze
CN IV damage
Eye moves upward, particularly with contralateral gaze
CN VI damage
Medially directed eye that cannot abduct
Cavernous sinus syndrome
variable ophthalmoplegia, decreased corneal sensation, Horner syndrome and occasional decreased maxillary sensation
CN VI is most susceptible to injury
Internuclear ophthalmoplegia
Lesion in medial longitudinal fasciculus: conjugate horizontal gaze palsy
When CN VI nucleus activates ipsilateral lateral rectus, contralateral CN III nucleus does not stimulate medial rectus to contract
Seen in MS
Suvorexant
Orexin (hypocretin) receptor antagonist
For insomnia
Ramelteon
Melatonin receptor agonist, binds MT1 and MT2 in suprachiasmatic nucleus
For insomnia
Drugs used in Huntington disease
Tetrabenazine and reserpine: inhibit VMAT
Haloperidol: D2 receptor antagonist
Riluzole
Treatment for ALS that modestly increases survival by decreasing glutamate excitotoxicity via an unclear mechanism
Memantine
NMDA-r antagonist
For Alzheimer
MOA of local anesthetics
Block Na+ channels by binding to specific receptors on inner portion of channel
Baclofen
Activates GABAb receptors at spinal cord level, inducing skeletal muscle relaxation.
Cyclobenzaprine
Centrally acting skeletal muscle relaxant
Structurally related to TCAs, similar anticholinergic side effects
Pentazocine
κ-opioid receptor agonist and μ-opioid receptor weak antagonist or partial agonist
Analgesia for moderate to severe pain
Butorphanol
κ-opioid receptor agonist and μ-opioid receptor partial agonist; produces analgesia
Tramadol
Very weak opioid agonist; also inhibits 5-HT and norepinephrine reuptake
Frog-like appearance of a fetus
anencephaly
What is impaired in anencephaly?
Amniotic fluid swallowing: polyhydraminos
Cerebral aquaduct stenosis
Stenosis of channel that drains CSF from 3rd into 4th ventricle; accumulates in ventricular space
Most common cause of hydrocephalus in a newborn
Cerebral aquaduct stenosis
Histology of acute neuronal injury
Red neurons; 12-24hrs
Cell body shrinkage, pyknosis, loss of Nissle bodies, eosinophilia
Axonal reaction
Increased protein synthesis, axonal sprouting, peripheral displacement of nucleus
Astrocyte injury
Gliosis; nuclei prominent and vesicular with expansion into cytoplasm
Alzheimer type II astrocyte
Gray matter cell with large nucleus and pale chromatin
Seen in longstanding hyper-ammonia: liver dz, Wilson’s, urea cycle disorder
Werdnig-Hoffman Disease
AR; Degeneration of AMH
Amyotrophic Lateral Sclerosis
Degenertive disorder with UMN (lateral corticospinal tract) and LMN (AMH)
Atrophy and b/l hand weakness - early signs
NO sensory loss
SOD mutation in familial cases (most are spontaneous)
Friedreich Ataxia
Degeneration of cerebellum and spinal cord
Loss of vibration and proprioception, LE weakness, ↓ DTRs
GAA repeat; frataxin gene regulates iron in mitochondria
Assoc w/ hypertrophic cardiomyopathy
Most common cause of meningitis in adults and elderly
S. pneumo
Infarct of pyramidal neurons in the cerebral cortex leads to what
(layer 3, 5, 6)
Laminar necrosis
Lacunar stroke
2° to hyaline arteriolosclerosis
Involved lentriculstriae vessels (from the MCA)
Pure motor stroke
Internal capsule
Pure sensory stroke
thalamus
What kind of stroke leads to liquefactive necrosis?
Ischemic
When do red neurons appear in a stroke
12-24 hours
Intracerebral hemorrhage
Into brain parenchyma; usually basal ganglia
Rupture of Charcot-Bouchard of lentriculstriae vessels
2° to HTN
Subarachnoid hemorrhage
Bleed into subarachnoid space; only cause of blood on bottom of brain
Xanthochromia on LP
Berry aneurysm, usually at branch points of ACA
Subacute Sclerosing Panencephalitis
D/t measles
Viral inclusion in neurons and oligodendrocytes
Excessive correction of hypernatremia
Cerebral edeama or herniation (from high to low, your brain will blow)
