Neurological & Special Senses Biomedical Sciences Review

Comprehensive 200 vocabulary flashcard set reviewing biomedical sciences topics across neurology, neuropathology, neuroanatomy, embryology, and special senses.

Intracerebral Hemorrhage

Hemorrhage in small arteries within the brain parenchyma, most commonly caused by systemic hypertension, amyloid angiopathy, vasculitis, or neoplasms; acutely appears hyperdense on CT scan.

Charcot-Bouchard Microaneurysm

Small aneurysms associated with chronic hypertension; commonly located in the basal ganglia, followed by the thalamus, pons, and cerebellum.

Subarachnoid Hemorrhage

Bleeding in the subarachnoid space between the arachnoid and pia mater, usually caused by a ruptured Berry aneurysm or AVM; presents with sudden-onset severe headache ("worst headache of life"), nuchal rigidity, and photophobia.

Xanthochromia

Yellowish color of cerebrospinal fluid (CSF) seen on spinal tap due to red blood cell breakdown, diagnostic for subarachnoid hemorrhage.

Vasospasm (Post-SAH)

Delayed ischemic complication occurring $3\text{--}10\text{ days}$ post-subarachnoid hemorrhage; prevented with calcium channel blockers such as Nimodipine.

Transient Ischemic Attack (TIA)

Brief, reversible episode of focal neurological deficit without acute infarction on MRI, with symptoms typically resolving in $<15\text{ minutes}$ and definitionally in $<24\text{ hours}$.

Ischemic Stroke

Acute disruption of cerebral blood flow causing tissue ischemia and liquefactive necrosis, resulting from thrombosis, embolism, or severe hypoperfusion.

Red Neurons

Histological manifestation of eosinophilic neuronal cell death accompanied by edema, occurring $12\text{--}48\text{ hours}$ following an ischemic stroke.

Ischemic Stroke tPA Window

Treatment window of $3\text{--}4.5\text{ hours}$ from symptom onset during which tissue plasminogen activator (tPA) can be administered if hemorrhage is ruled out.

Central Post-Stroke Pain Syndrome

Neuropathic pain condition resulting from thalamic lesions, initially presenting as paresthesia and evolving weeks later into allodynia and dysesthesia.

Middle Cerebral Artery (MCA) Infarct

Ischemic stroke presenting with contralateral motor and sensory loss in the face and arm, as well as aphasia if the dominant hemisphere is affected.

Anterior Cerebral Artery (ACA) Infarct

Ischemic stroke presenting with contralateral motor and sensory loss primarily affecting the lower extremity.

Posterior Cerebral Artery (PCA) Infarct

Ischemic stroke presenting with contralateral visual deficits, such as contralateral homonymous hemianopia with macular sparing.

Subdural Hematoma

Bleeding in the potential space between the dura and arachnoid layers caused by rupture of bridging veins; appears as a crescent-shaped hematoma on CT that can cross dural suture lines.

Epidural Hematoma

Bleeding between the dura mater and skull resulting from rupture of the middle meningeal artery; appears as a lentiform (biconvex) disk on CT that does not cross suture lines.

Lucid Interval

Temporary recovery of consciousness following head trauma before rapid neurological deterioration due to expanding hematoma, characteristic of epidural hematoma.

Hypoxic/Ischemic Encephalopathy (HIE)

Perinatal birth complication in full-term infants from impaired cerebral blood flow and oxygenation; diagnostic markers include umbilical cord blood $\text{pH} < 7.0$ or base deficit $\ge 12\,\text{mmol/L}$.

Spinal Arteriovenous Malformations (AVMs)

Abnormal direct connections between arteries and veins bypassing capillary beds; cervical rupture causes subarachnoid hemorrhage, back pain, and progressive neurological deficits.

Amyotrophic Lateral Sclerosis (ALS)

Progressive, fatal neurodegenerative disease affecting both UMN and LMN pathways, linked to superoxide dismutase $1$ defects, leading to death via respiratory failure.

Alzheimer’s Disease

Most common cause of dementia in the elderly, characterized pathologically by loss of acetylcholine in the basal nucleus of Meynert, hyperphosphorylated tau neurofibrillary tangles, and ApoE-4 risk allele.

Spinocerebellar Ataxia (SCA)

Group of inherited autosomal dominant neurodegenerative disorders (most common: SCA3) presenting with progressive cerebellar ataxia, altered gait, balance deficits, and ocular motor abnormalities.

Parkinson’s Disease

Movement disorder caused by loss of dopaminergic neurons in the substantia nigra; clinically presents with resting tremor, rigidity, akinesia/bradykinesia, postural instability, and shuffling gait (TRAPS).

Lewy Bodies

Intracellular alpha-synuclein inclusions found in depigmented neurons of the substantia nigra in Parkinson's disease.

Huntington’s Disease

Autosomal dominant neurodegenerative disease caused by CAG trinucleotide repeats on chromosome $4$; presents with caudate nucleus and putamen atrophy, chorea, aggression, and progressive dementia.

Guillain-Barré Syndrome

Autoimmune demyelination of the peripheral nervous system (Schwann cells) following infection (e.g., Campylobacter jejuni, CMV); presents with ascending paralysis, loss of DTRs, and endoneurial inflammatory infiltrates.

Multiple Sclerosis (MS)

Autoimmune demyelinating disease of the CNS initiated by Th1 cells reacting to myelin basic protein; diagnosed via oligoclonal IgG bands in CSF and periventricular plaques on MRI.

Acute Disseminated Encephalomyelitis (ADEM)

Immune-mediated demyelinating disease affecting brain and spinal cord white matter, commonly triggered by viral infection or vaccination in children.

Vasogenic Cerebral Edema

Most common form of cerebral edema caused by breakdown of the blood-brain barrier and osmotic fluid draw into interstitium, mediated by VEGF, glutamate, and leukotrienes.

Cytotoxic Cerebral Edema

Intracellular swelling of neurons and glia following trauma or ischemia, caused by failure of sodium-potassium pumps and cellular sodium influx.

Communicating Hydrocephalus

Hydrocephalus resulting from impaired CSF reabsorption by arachnoid granulations, frequently secondary to post-meningitis or post-hemorrhage arachnoid scarring.

Normal Pressure Hydrocephalus

Form of communicating hydrocephalus in the elderly characterized by episodically elevated CSF pressure without subarachnoid space expansion; reversible with ventricular shunting.

Non-Communicating Hydrocephalus

Hydrocephalus caused by structural blockage of CSF flow within the ventricular system (e.g., aqueductal stenosis, colloid cyst of foramen of Monro, tumors).

Hydrocephalus Triad ("Wet, Wobbly, Wacky")

Classic clinical triad of normal pressure hydrocephalus comprising urinary incontinence, gait apraxia (magnetic gait), and cognitive dysfunction.

Hepatic Encephalopathy

Reversible neuropsychiatric state in liver cirrhosis caused by portosystemic shunting and impaired hepatic clearance of ammonia ($\text{NH}_3$).

Asterixis

Flapping tremor of the hands observed during wrist extension, characteristic of hepatic encephalopathy and hyperammonemia.

Peripheral Neuropathy

Peripheral nerve dysfunction presenting with paresthesias, sensory loss, muscle weakness/atrophy, and loss of deep tendon reflexes.

Vitamin B12 Deficiency (Subacute Combined Degeneration)

Demyelination of dorsal columns, lateral corticospinal tracts, and spinocerebellar tracts; leads to ataxic gait, paresthesias, macrocytic anemia, and elevated methylmalonic acid.

Wernicke Encephalopathy

Acute, reversible manifestation of vitamin B1 (thiamine) deficiency presenting with the triad of confusion, ophthalmoplegia, and ataxia.

Korsakoff Syndrome

Chronic, irreversible neurological consequence of thiamine deficiency characterized by anterograde and retrograde amnesia, confabulation, and personality changes.

Down Syndrome (Trisomy 21)

Chromosomal abnormality ($95\%$ meiotic nondisjunction, $4\%$ Robertsonian translocation) presenting with intellectual disability, epicanthal folds, single palmar crease, and elevated serum $\beta\text{-hCG}$ during prenatal screening.

Adrenoleukodystrophy

X-linked peroxisomal genetic disorder causing accumulation of very long-chain fatty acids (VLCFA) in the brain white matter and adrenal cortex.

Phenylketonuria (PKU)

Autosomal recessive deficiency of phenylalanine hydroxylase or BH4, causing neurotoxic accumulation of phenylalanine; presents with intellectual disability, seizures, musty odor, and fair skin.

Wilson Disease

Autosomal recessive mutation in the ATP7B gene (chromosome $13$) causing impaired copper transport, low ceruloplasmin, and copper toxicity in the liver, brain, and cornea.

Kayser-Fleischer Rings

Golden-brown copper deposits in Descemet's membrane of the cornea, pathognomonic for Wilson disease.

Medulloblastoma

Most common malignant brain tumor in children; arises in the cerebellum, compresses the 4th ventricle, and features Homer-Wright rosettes on histology.

Homer-Wright Rosettes

Histological pattern composed of tumor cells surrounding a central acellular neuropil, seen in medulloblastomas and neuroblastomas.

Meningioma

Common, benign extra-axial adult tumor arising from arachnoid cells; exhibits a dural tail on imaging and whorled spindle cells with psammoma bodies on histology.

Psammoma Bodies

Concentric, laminated calcified structures seen on histological examination of meningiomas.

Neuroblastoma

Malignant neural crest-derived APUD tumor of the adrenal medulla or sympathetic chain in children $<4\text{ years}$; associated with N-myc overexpression and elevated urinary HVA/VMA.

Opsoclonus-Myoclonus Syndrome

Paraneoplastic syndrome ("dancing eyes, dancing feet") associated with pediatric neuroblastoma.

Glioblastoma Multiforme

Grade IV astrocytoma; highly malignant adult primary brain tumor featuring GFAP-positivity and pseudopalisading necrosis on histology.

Pilocytic Astrocytoma

Benign childhood brain tumor located in the cerebellum; characteristically contains Rosenthal fibers and cystic/solid components.

Oligodendroglioma

Slow-growing primary frontal lobe brain tumor; features "fried egg" appearance cells and "chicken-wire" capillaries on histology.

Vestibular Schwannoma

Benign S-100 positive tumor of Schwann cells at the cerebellopontine angle affecting CN VIII; causes sensorineural hearing loss, tinnitus, and vertigo.

Neurofibromatosis Type 1 (NF1)

Autosomal dominant disorder caused by mutation on chromosome $17$; characterized by café-au-lait spots, Lisch nodules, cutaneous neurofibromas, and optic gliomas.

Neurofibromatosis Type 2 (NF2)

Autosomal dominant disorder caused by mutation on chromosome $22$; pathognomonically characterized by bilateral vestibular schwannomas (acoustic neuromas).

Arboviruses

Mosquito-borne viral pathogens (such as Zika, West Nile, St. Louis, and California encephalitis) capable of causing central nervous system infections like meningitis and encephalitis.

Botulism

Paralytic syndrome caused by Clostridium botulinum exotoxin, which cleaves SNARE proteins to block presynaptic acetylcholine release at the neuromuscular junction; presents with descending flaccid paralysis.

Brain Abscess

Focal intracranial suppurative infection appearing as a ring-enhancing lesion on MRI; commonly caused by Viridans streptococci or Staphylococcus aureus.

Encephalitis

Inflammation of the brain parenchyma, most commonly caused by HSV-1 (sporadic form affecting temporal lobes), presenting with fever, headache, altered mental status, and focal seizures.

Leprosy (Hansen Disease)

Chronic granulomatous infection of superficial skin and peripheral nerves caused by Mycobacterium leprae.

Lepromatous Leprosy

Severe form of leprosy driven by a Th2 immune response with low cell-mediated immunity; presents with diffuse skin lesions (leonine facies) and high bacterial load.

Tuberculoid Leprosy

Milder form of leprosy driven by a Th1 immune response with high cell-mediated immunity; presents with few hypoesthetic, hairless skin plaques and low bacterial load.

Neurosyphilis

Central nervous system infection caused by Treponema pallidum during tertiary syphilis; causes tabes dorsalis, brain gummas, and Argyll Robertson pupil.

Tabes Dorsalis

Degeneration of dorsal columns and dorsal roots due to neurosyphilis; results in sensory ataxia, shooting pains, positive Romberg sign, and Charcot joints.

Argyll Robertson Pupil

Bilateral small pupils that constrict during accommodation to near objects but do not react to light; classic sign of neurosyphilis.

Poliomyelitis

Enteroviral infection caused by poliovirus that destroys anterior horn motor neurons in the spinal cord, leading to asymmetric lower motor neuron flaccid paralysis.

Prion Disease

Transmissible neurodegenerative condition caused by conformational change of normal $\text{PrP}^c$ (alpha-helical) protein into protease-resistant $\text{PrP}^{sc}$ (beta-pleated sheet) protein.

Progressive Multifocal Leukoencephalopathy (PML)

Opportunistic CNS demyelinating disease caused by reactivation of latent JC virus in oligodendrocytes of severely immunocompromised patients.

Subacute Sclerosing Panencephalitis (SSPE)

Fatal, progressive demyelinating disease occurring years after initial measles (Rubeola) infection due to persistence of a hypermutated measles virus.

Bacterial Meningitis CSF Profile

Lumbar puncture findings showing increased opening pressure, elevated polymorphonuclear neutrophils (PMNs), high protein, and decreased glucose.

Viral Meningitis CSF Profile

Lumbar puncture findings showing normal or slightly elevated pressure, elevated lymphocytes, slightly elevated protein, and normal glucose.

Tetanus

Neuromuscular disorder caused by Clostridium tetani toxin, characterized by spastic paralysis, trismus ("lockjaw"), risus sardonicus, and opisthotonos.

Tetanospasmin

Protease exotoxin produced by Clostridium tetani that cleaves SNARE proteins to block the release of inhibitory neurotransmitters (GABA and glycine) from spinal Renshaw cells.

Concussion

Mild traumatic brain injury caused by head impact leading to temporary neurological dysfunction, headache, memory loss, and possible brief loss of consciousness.

Contusion

Traumatic parenchymal brain bruise, commonly involving frontal lobes, carrying risk of local edema, swelling, and secondary hemorrhage.

Spinal Cord Transection

Complete traumatic tear of the spinal cord resulting in permanent loss of motor and sensory function below the level of injury.

Bell’s Palsy

Acute, unilateral lower motor neuron palsy of CN VII due to facial nerve swelling (frequently post-HSV reactivation), resulting in facial paralysis including the forehead.

Crocodile Tears

Complication of Bell's palsy recovery where aberrant regeneration of parasympathetic nerve fibers causes lacrimation during salivation.

Carpal Tunnel Syndrome

Entrapment neuropathy of the median nerve beneath the transverse carpal ligament, producing pain and paresthesias in the thumb, index, middle, and lateral ring fingers.

Disc Herniation

Protrusion of nucleus pulposus through the annulus fibrosus, typically posterolaterally compressing the nerve root below the level of herniation (e.g., L4/L5 herniation affects L5).

Nerve Root Entrapment (Radiculopathy)

Compression of spinal nerve roots causing dermatomal sensory loss, motor weakness, and reduced reflexes; pain improves with spine extension and worsens with flexion.

Sciatica

Radicular burning pain radiating down the buttock, posterior thigh, and leg caused by compression of L4, L5, or S1 nerve roots; elicited by positive Straight Leg Raise test.

Thoracic Outlet Syndrome (TOS)

Compression of the lower trunk of the brachial plexus (C8-T1) by a cervical rib or scalene muscle anomalies, leading to pain and paresthesias radiating to the medial hand.

Trigeminal Neuralgia

Paroxysmal, excruciating, shooting facial pain in the CN V distribution triggered by light touch or chewing, caused by vascular compression of the trigeminal root.

Conjunctivitis

Inflammation of the conjunctiva; viral presents with watery discharge and swollen preauricular nodes, bacterial with purulent discharge, and allergic with bilateral itching.

Blepharitis

Inflammation of the eyelid margins; acute bacterial forms cause pustules and shallow marginal ulcers with eyelids glued together upon waking.

Cataracts

Painless, progressive opacification of the crystalline lens resulting in decreased visual acuity and night glare.

Open-Angle Glaucoma

Optic disc neuropathy with characteristic cupping and slow, painless loss of peripheral vision due to impaired aqueous humor drainage through the trabecular meshwork.

Closed/Narrow-Angle Glaucoma

Ophthalmic emergency where the iris blocks aqueous humor flow through the pupil, causing acute, painful red eye, sudden vision loss, and halos around lights.

Keratitis

Corneal inflammation commonly caused by HSV-1, presenting with photophobia, conjunctival hyperemia, and dendritic corneal ulcers on slit-lamp examination.

Macular Degeneration

Degeneration of the macula causing loss of central vision; dry form features subretinal drusen deposits, while wet form features rapid vision loss from choroidal neovascularization.

Anterior Uveitis

Inflammation of the iris and ciliary body (iritis) associated with HLA-B27 conditions and trauma; presents with eye pain, photophobia, redness, and hypopyon.

Posterior Uveitis

Inflammation involving the choroid and retina caused by infectious agents (e.g., CMV, toxoplasmosis); presents with visual floaters and painless decreased vision.

Meniere’s Disease

Inner ear disorder caused by excess endolymph volume and pressure; presents with episodic vertigo ($1\text{--}6\text{ hours}$), fluctuating sensorineural hearing loss, and tinnitus.

Acute Otitis Media (AOM)

Infection of the middle ear space common in children $<3\text{ years}$ caused by S. pneumoniae, H. influenzae, or E. coli; presents with otalgia and a bulging, erythematous tympanic membrane.

Vestibular Neuritis

Inflammation of the vestibular nerve (branch of CN VIII) following a viral infection; presents with acute peripheral vertigo and nystagmus without hearing loss or tinnitus.

Neural Tube Formation

Embryological process occurring on Day $21$ where the neural plate invaginates to form the neural tube and neural crest cells under the influence of notochord signaling.

Sonic Hedgehog (Shh)

Ventral signaling protein secreted by the notochord during neural tube development that induces basal plate (motor) differentiation.

Alar Plate

Dorsal structural region of the embryonic neural tube influenced by Wnt signaling, giving rise to sensory neurons.