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Dysarthria
Dysarthria is a motor speech disorder from weak or poorly coordinated speech muscles, causing slurred speech. Types include flaccid, spastic, ataxic, hypokinetic, hyperkinetic, and mixed; common after stroke and Parkinson's disease.
Dysautonomia
Dysautonomia, also called autonomic dysfunction or autonomic neuropathy, is an umbrella term for disorders of the autonomic nervous system, covering POTS, pure autonomic failure, familial dysautonomia, and secondary forms from diabetes or Parkinson disease.
Dysbetalipoproteinemia
Dysbetalipoproteinemia (type III hyperlipoproteinemia, broad-beta disease, remnant removal disease) is a rare APOE-related combined hyperlipidemia with IDL remnant accumulation, 1/10,000 prevalence, and premature atherosclerosis risk.
Dyscalculia
Dyscalculia, also known as mathematics disorder, is a learning disorder marked by severe difficulty with arithmetic and processing numbers, affecting roughly 3 to 7% of people.
Dyschromatosis symmetrica hereditaria
Dyschromatosis symmetrica hereditaria (reticulate acropigmentation of Dohi, OMIM 127400) is a rare autosomal dominant pigmentary genodermatosis caused by ADAR1 mutations, producing mixed hyper- and hypopigmented macules on the dorsal extremities, mainly in East Asian populations.
Dyschromatosis universalis hereditaria
Dyschromatosis universalis hereditaria (DUH), OMIM 127500, is a rare hereditary genodermatosis with mottled hyper- and hypopigmented macules from infancy; genes ABCB6, SASH1, KITLG; no curative treatment.
Dysembryoplastic neuroepithelial tumor
Dysembryoplastic neuroepithelial tumor (DNET/DNT), a benign WHO grade I glioneuronal brain tumor first described in 1988, typically causing drug-resistant focal epilepsy in children and young adults, mostly in the temporal lobe.
Dysentery
Dysentery is bloody, mucoid diarrhea from intestinal invasion, mainly bacillary (Shigella) or amoebic (Entamoeba histolytica). Key facts: fecal leukocyte counts, Shigella mortality OR 3.9, antibiotic and amoebicide treatment, dysentery as a poor Shigella marker.
Dysesthesia
Dysesthesia, an unpleasant abnormal sensation defined by the IASP, distinct from paresthesia; includes allodynia and hyperalgesia, occurs in neuropathic pain, skin and neurological disorders, with causes, diagnosis, and treatments.
Dysferlin-related limb-girdle muscular dystrophy R2
Dysferlin-related limb-girdle muscular dystrophy R2 (LGMDR2, formerly LGMD2B) is an autosomal recessive dystrophy caused by DYSF mutations, with proximal weakness from the late teens, very high CK, and possible cardiac involvement.
Dysgeusia
Dysgeusia is a taste disorder in which taste is distorted, so a foul, salty, rancid, or metallic taste persists in the mouth; it is distinct from ageusia, the complete loss of taste.
Dysgraphia
Dysgraphia, also called disorder of written expression, is a neurological learning disorder causing writing difficulty despite adequate instruction. Estimated 5-20% prevalence; treated with remedial education, occupational therapy, and accommodations.
Dyshidrosis
Dyshidrosis (dyshidrotic eczema, pompholyx): recurrent itchy 1–2 mm tapioca-like vesicles on palms, finger sides, and soles, clearing in 2–3 weeks; cause unknown, linked to atopy, nickel/cobalt allergy, and hyperhidrosis.
Dyskinesia
Dyskinesia: involuntary abnormal movements, chiefly tardive dyskinesia from dopamine receptor blocking agents (24–32% with older antipsychotics) and levodopa-induced dyskinesia in Parkinson's disease; treated with VMAT2 inhibitors valbenazine and deutetrabenazine.
Dyskinetic cerebral palsy
Dyskinetic cerebral palsy (athetoid, dystonic CP; ICD-11 8D21): CP subtype with involuntary movements and dystonia from basal ganglia/thalamus injury; 6-15% of CP cases, second most common after spastic CP.
Dyslexia
Dyslexia is a neurodevelopmental learning disability affecting word reading and spelling, first named by Rudolf Berlin in the 1880s; prevalence estimates range from 5 to 17.5 percent, with phonological processing deficits as the leading marker.
Dyslexia or alexia
Dyslexia or alexia (ICD-11 MB4B.0) is the acquired loss, usually in adulthood after stroke or brain injury, of previously fluent reading and comprehension, distinct from developmental dyslexia; syndromes include pure, surface, phonological, and deep dyslexia.
Dyslipidemia
Dyslipidemia: abnormal blood lipid levels (high cholesterol, high triglycerides, high Lp(a), or low HDL-C), also called hyperlipidemia. Causes are genetic or secondary; treatment is lifestyle plus statins, guided by 2026 ACC/AHA PREVENT-based risk thresholds and LDL-C goals.
Dysmenorrhea
Dysmenorrhea, or painful menstrual periods, affects 50–90% of young women. Primary dysmenorrhea (about 90% of cases) stems from uterine prostaglandins; secondary forms arise from endometriosis, adenomyosis, or other pelvic pathology. NSAIDs and hormonal contraceptives are first-line treatments.
Dysmenorrhoea
Dysmenorrhoea, or dysmenorrhea, is painful menstruation, classified as primary (no pelvic pathology) or secondary (caused by conditions such as endometriosis). Prostaglandin-driven uterine hypercontractility causes the pain; NSAIDs and combined oral contraceptives are first-line treatments.
Dysosteosclerosis
Dysosteosclerosis (DSS, DOS; OMIM 224300) is an ultrarare genetic bone dysplasia with progressive osteosclerosis and platyspondyly, an osteoclast-poor osteopetrosis-like disorder linked to SLC29A3, TNFRSF11A, TCIRG1, LRRK1, and CSF1R, with fewer than 30 reported cases.
Dyspareunia
Dyspareunia is recurrent pain with vaginal intercourse, superficial (introital) or deep, affecting up to 3 of 4 women at some point; causes include vulvodynia, endometriosis, and menopausal atrophy.
Dysphagia
Dysphagia, difficulty swallowing, is classified as oropharyngeal or esophageal. Prevalence 10–20%; linked to stroke pneumonia risk (RR 3.17); assessed by VFSS, FEES, endoscopy, and manometry.
Dysphagia lusoria
Dysphagia lusoria (Bayford syndrome) is difficulty swallowing from esophageal compression by an aberrant right subclavian artery, a congenital aortic arch anomaly in 0.5-2.5% of people, mostly asymptomatic.
Dysphagia screening
Dysphagia screening is a rapid bedside pass/fail procedure, standard in acute stroke care, that identifies patients at risk of swallowing difficulty before any oral intake.
Dysphonia
Dysphonia (hoarseness): altered voice quality, pitch, loudness, or effort impairing communication; affects about one-third of people. Causes include laryngitis, reflux, lesions, and laryngeal dystonia; voice therapy is first-line.
Dysphoria
Dysphoria (Greek dysphoria, 'hard to bear') is a mood of generalized discontent, agitation and unease, not a standalone diagnosis. It appears across PMDD, gender dysphoria, mixed bipolar states, and epilepsy, measured with scales such as the UGDS, IDDI, and DRSP.
Dysplasia
Dysplasia: abnormal cells in a tissue or organ, not cancer but sometimes precancerous; graded mild, moderate, or severe. Also means birth-related developmental disorders of skin, brain, cartilage, or bone.
Dysplastic cortical hyperostosis
Dysplastic cortical hyperostosis (ORPHA:646139), also called Kozlowski-Tsuruta type, is an extremely rare autosomal recessive bone dysplasia causing lethal neonatal dwarfism with hydrops and generalized cortical thickening of the skeleton; molecular basis unknown.
Dyspnoea
Dyspnoea (dyspnea, breathlessness, shortness of breath) is the subjective experience of breathing discomfort, distinct from tachypnea or hyperventilation. Common in cardiopulmonary disease, coded ICD-11 MD11.5, measured by MRC, Borg, D-12, and MDP scales.