Medical terms, defined.

Peripheral vascular disease (PVD), most often peripheral artery disease (PAD), is atherosclerotic narrowing of arteries supplying the limbs (usually the lower extremities). It classically presents with intermittent claudication, which is...

Alcoholic neuropathy is a chronic, symmetric, distal sensorimotor (length-dependent) axonal polyneuropathy caused by long-term heavy ethanol use, via direct neurotoxicity and associated nutritional deficiencies (especially thiamine/B1, a...

Alcoholic ketoacidosis (AKA) is a high anion gap metabolic acidosis seen in chronic alcohol users after binge drinking with poor oral intake and vomiting. Starvation plus ethanol metabolism raises the NADH/NAD+ ratio, which favors β-hydr...

Alcoholic cerebellar degeneration is a chronic, progressive loss of cerebellar neurons (especially Purkinje cells of the anterior superior vermis) in long-term alcohol users, causing a wide-based gait ataxia with relative sparing of the...

Drug-induced hemolytic anemia is RBC destruction triggered by a medication, through immune-mediated mechanisms (Coombs-positive) or non-immune oxidative stress (e.g., G6PD deficiency). Classic immune examples: penicillin/cephalosporins (...

Autoimmune pancreatitis (AIP) is a fibroinflammatory pancreatic disease that classically presents with obstructive jaundice and a "sausage-shaped" diffusely enlarged pancreas, mimicking pancreatic adenocarcinoma. Type 1 AIP is the pancre...

Alcoholic cirrhosis is the end-stage of alcohol-related liver disease, characterized by diffuse fibrosis and conversion of normal hepatic architecture into regenerative nodules, typically micronodular (Laennec cirrhosis). It follows year...

Drug-induced parkinsonism (DIP) is a secondary parkinsonism caused by dopamine D2 receptor blockade (or dopamine depletion) in the nigrostriatal pathway, most commonly from antipsychotics, metoclopramide, and prochlorperazine. It present...

Drug-induced thrombocytopenia (DITP) is a fall in platelet count (<150,000/µL) caused by drug-dependent antibodies (e.g., quinine, vancomycin, TMP-SMX, carbamazepine, GP IIb/IIIa inhibitors), by direct marrow suppression (chemotherapy, l...

Peripheral nerve injury is damage to nerves outside the CNS, classified by Seddon (neurapraxia, axonotmesis, neurotmesis) or Sunderland (grades I–V). Prognosis depends on integrity of the endoneurium and connective tissue layers. Walleri...

Autoimmune thyroiditis most commonly means Hashimoto thyroiditis, a T-cell–mediated autoimmune destruction of the thyroid with anti-TPO and anti-thyroglobulin antibodies. It is the most common cause of hypothyroidism in iodine-sufficient...

The autonomic nervous system (ANS) is the involuntary division of the peripheral nervous system that regulates visceral functions (heart rate, BP, digestion, pupil size, glandular secretion, etc.) to maintain homeostasis. It has two main...

Drug-induced hepatitis (drug-induced liver injury, DILI) is hepatocellular injury caused by medications, herbals, or supplements, presenting with elevated AST/ALT (hepatocellular), ALP (cholestatic), or mixed patterns. It can be intrinsi...

Autoimmune polyglandular syndromes (APS) are disorders in which autoimmune destruction affects multiple endocrine glands (plus non-endocrine tissues). APS-1 (APECED) is caused by AIRE mutation and presents in childhood with chronic mucoc...

Autoimmune encephalitis is a group of non-infectious inflammatory brain disorders caused by antibodies against neuronal surface/synaptic antigens (e.g., NMDA receptor) or intracellular antigens. It presents with subacute (<3 months) psyc...

Compensated heart failure is a state of chronic cardiac dysfunction (reduced CO or elevated filling pressures) in which neurohormonal and structural compensatory mechanisms (Frank-Starling, SNS, RAAS, hypertrophy/remodeling) maintain ade...

Fungal pneumonia is lung infection caused by inhaled fungal spores (endemic dimorphic fungi: Histoplasma, Coccidioides, Blastomyces; or opportunistic: Aspergillus, Cryptococcus, Pneumocystis jirovecii, Mucorales). Endemic mycoses occur i...

Chronic graft rejection is a slow, progressive loss of graft function occurring months to years after transplantation, driven by both cell-mediated (CD4+ T-cell/delayed-type hypersensitivity) and humoral (donor-specific antibody) mechani...

Acute sinusitis is inflammation of the paranasal sinus mucosa lasting <4 weeks, most often viral (rhinovirus) and self-limited; only ~0.5–2% become bacterial. Suspect bacterial infection with symptoms >10 days without improvement, severe...

Hyperacute graft rejection occurs within minutes to hours (typically during or immediately after surgical anastomosis) due to preformed recipient antibodies against donor antigens (ABO or HLA). It is a type II hypersensitivity reaction c...

Benign prostatic hyperplasia (BPH) is nonmalignant hyperplasia of stromal and glandular cells in the periurethral (transition) zone of the prostate. It causes lower urinary tract symptoms (LUTS) in older men: hesitancy, weak stream, inco...

Chronic otitis media (COM) is persistent middle ear inflammation/infection (>3 months) typically with tympanic membrane perforation and recurrent or persistent otorrhea (chronic suppurative otitis media, CSOM), or chronic effusion withou...

Acute graft rejection is T-cell–mediated destruction of an allograft occurring days to weeks (typically within the first 6 months) after transplantation, due to recipient recognition of donor MHC (HLA) antigens. It presents with graft dy...

Malignant (necrotizing) otitis externa is an invasive infection of the external auditory canal that spreads to the skull base (temporal bone osteomyelitis), classically caused by Pseudomonas aeruginosa in elderly diabetic or immunocompro...

Chronic rhinosinusitis (CRS) is inflammation of the paranasal sinuses and nasal mucosa lasting ≥12 weeks, with ≥2 of: nasal obstruction/congestion, mucopurulent drainage (anterior/posterior), facial pain/pressure/fullness, or decreased s...

Ischemic bowel disease is injury to the intestine from inadequate blood flow. It includes acute mesenteric ischemia (embolic, thrombotic, nonocclusive, or venous), chronic mesenteric ischemia ("intestinal angina"), and ischemic colitis....

Acute liver failure (ALF) is the rapid onset (<26 weeks) of severe hepatic injury with coagulopathy (INR ≥1.5) and hepatic encephalopathy in a patient with no preexisting cirrhosis. Most common causes in the US are acetaminophen toxicity...

Tricuspid stenosis (TS) is narrowing of the tricuspid valve orifice that obstructs right atrial emptying into the right ventricle. It is rare and most often caused by rheumatic heart disease (almost always with concurrent mitral valve di...

Hepatic (cavernous) hemangioma is the most common benign liver tumor, composed of vascular channels lined by endothelial cells. It is usually asymptomatic and found incidentally, is more common in women, and should NOT be biopsied becaus...

Renal colic is acute, severe, colicky flank pain caused by obstruction of the ureter (most often by a kidney stone), leading to ureteral spasm and distension of the collecting system. Pain radiates from the flank to the groin and is acco...

Hepatic abscess is a localized, pus-filled collection in the liver, most commonly pyogenic (polymicrobial, biliary or portal seeding; E. coli, Klebsiella, anaerobes) or amebic (Entamoeba histolytica). Classic presentation is fever, RUQ p...

A pansystolic (holosystolic) murmur begins with S1 and continues through all of systole to S2, because blood flows continuously from a high-pressure chamber to a low-pressure one throughout systole. The three classic causes are mitral re...

Adrenal carcinoma (adrenocortical carcinoma, ACC) is a rare, aggressive malignancy of the adrenal cortex, often presenting as a large (>6 cm) unilateral mass with hormone excess (Cushing syndrome ± virilization most common) or mass effec...

Thyroid eye disease (TED; Graves orbitopathy/ophthalmopathy) is an autoimmune inflammatory disorder of orbital fat and extraocular muscles, most often associated with Graves disease. Autoantibodies against the TSH receptor and IGF-1R on...

Adrenal hyperplasia (usually congenital adrenal hyperplasia, CAH) is a group of autosomal recessive enzyme defects in cortisol synthesis. Low cortisol removes negative feedback, so ACTH rises, causing adrenal hyperplasia and buildup of p...

Tarsal tunnel syndrome is a compression neuropathy of the posterior tibial nerve (or its branches) as it passes through the tarsal tunnel behind and below the medial malleolus beneath the flexor retinaculum. It causes burning pain, pares...

Subfalcine (cingulate) herniation is the most common type of brain herniation, in which the cingulate gyrus is displaced under the free edge of the falx cerebri toward the opposite side due to unilateral mass effect. It can compress the...

Cubital tunnel syndrome is compression or entrapment of the ulnar nerve at the elbow, most commonly in the cubital tunnel posterior to the medial epicondyle. It is the second most common upper extremity compression neuropathy after carpa...

A cardiac murmur is an abnormal sound heard during auscultation, caused by turbulent blood flow producing audible vibrations, either through valves, across septal defects, or through narrowed or dilated vessels. Murmurs are classified by...

Erb-Duchenne palsy (Erb's palsy) is an upper brachial plexus injury involving C5-C6 roots (upper trunk), classically from lateral traction on the neck during shoulder dystocia at birth or from trauma. It produces the "waiter's tip" postu...

MG most commonly = Myasthenia Gravis, an autoimmune neuromuscular junction disorder caused by antibodies against postsynaptic nicotinic acetylcholine receptors (AChR). It presents with fatigable muscle weakness (ptosis, diplopia, dysphag...

Cerebral herniation is displacement of brain tissue across rigid intracranial barriers (falx cerebri, tentorium cerebelli, foramen magnum) due to raised intracranial pressure (ICP) or mass effect. It compresses brain parenchyma, vessels,...

Tonsillar herniation is downward displacement of the cerebellar tonsils through the foramen magnum, compressing the medulla. It causes cardiorespiratory failure (Cushing triad: hypertension, bradycardia, irregular respirations) and is a...

ALS (Amyotrophic Lateral Sclerosis, Lou Gehrig disease) is a progressive neurodegenerative disease causing combined upper and lower motor neuron degeneration, with sparing of sensory function, extraocular muscles, and bowel/bladder (Onuf...

Radial nerve palsy is dysfunction of the radial nerve (C5–T1, posterior cord of brachial plexus) causing wrist drop and loss of extension of the wrist, fingers (MCP), and thumb. Classic causes are midshaft humeral fracture (spiral groove...

MS most commonly means multiple sclerosis, a chronic immune-mediated demyelinating disease of the CNS. It typically affects young women (20-40 years) and causes relapsing-remitting neurologic deficits disseminated in time and space, such...

Ulnar claw (main en griffe) is a hand deformity from ulnar nerve injury: hyperextension of the MCP joints and flexion of the IP joints of the 4th and 5th digits. It results from paralysis of the ulnar-innervated medial lumbricals, so the...

Hand of benediction is a classic posture in which the index and middle fingers stay extended while the ring and little fingers stay flexed when the patient tries to make a fist. It indicates a proximal median nerve lesion (e.g., at the e...

Ulnar nerve palsy is dysfunction of the ulnar nerve (C8–T1, medial cord of brachial plexus), most commonly from compression at the elbow (cubital tunnel/medial epicondyle) or wrist (Guyon canal). It causes sensory loss over the medial 1....

Common peroneal (fibular) nerve palsy is the most common lower-limb mononeuropathy, usually from compression at the fibular neck. It causes foot drop (loss of dorsiflexion and eversion) with a high-stepping (steppage) gait and sensory lo...