8,704 articles
Sublingual varices
Sublingual varices, also called caviar tongue or lingual varicosities, are benign dilated tortuous veins under the tongue, affecting roughly 23–35% of adults, increasing with age, and associated with hypertension, smoking, and cardiovascular disease.
Subluxation of tooth
Subluxation of tooth (ICD-11 NA0D.11): a traumatic dental injury to periodontal tissues causing abnormal tooth loosening without displacement, with gingival sulcus bleeding; managed conservatively with soft diet and radiographs.
Submucosal cleft palate
Submucosal cleft palate (SMCP, ORPHA:155878) is a congenital cleft palate variant with midline soft palate muscle diastasis under intact mucosa, diagnosed by Calnan's triad of bifid uvula, zona pellucida, and hard palate notch; occult forms lack the triad.
Subsequent myocardial infarction
Subsequent myocardial infarction (ICD-11 BA42; ICD-10 I22) is a heart attack occurring within 28 days of a previous one, clinically called re-infarction; diagnosed by recurrent ST elevation, new Q waves, or a >20% troponin rise.
Subtrochanteric fracture of femur
Subtrochanteric fracture of femur: break of the femoral shaft from the lesser trochanter to 5 cm distal, 7–34% of femur fractures, bimodal by age, treated mainly with intramedullary nailing; linked to bisphosphonate-related atypical fractures.
Succinic semialdehyde dehydrogenase deficiency
Succinic semialdehyde dehydrogenase deficiency (SSADHD, 4-hydroxybutyric aciduria, gamma-hydroxybutyric aciduria), ALDH5A1 autosomal recessive GABA metabolism disorder causing intellectual disability, hypotonia, ataxia, epilepsy; prevalence about 1/500,000.
Sudan virus disease
Sudan virus disease (SVD), also called Sudan ebolavirus disease, is a severe hemorrhagic fever caused by Orthoebolavirus sudanense, first identified in Sudan in 1976, with repeated Uganda outbreaks, 41-70% case fatality, and no licensed vaccine or treatment.
Sudden arrhythmic death syndrome
Sudden arrhythmic death syndrome (SADS), also called autopsy-negative sudden unexplained death, is sudden cardiac death with a structurally normal heart and negative toxicology; family screening yields about 12% and molecular autopsy about 11%.
Sudden cardiac death in hypertrophic cardiomyopathy
Sudden cardiac death in hypertrophic cardiomyopathy is the leading cause of death in HCM; risk scores such as HCM Risk-SCD estimate five-year risk to guide implantable cardioverter-defibrillator decisions.
Sudden idiopathic hearing loss
Sudden idiopathic hearing loss (SIHL, ICD-11 AB55; also idiopathic sudden sensorineural hearing loss, 突聋) is unexplained inner-ear hearing loss developing within 72 hours, usually unilateral, treated urgently with corticosteroids.
Sudden infant death-dysgenesis of the testes syndrome
Sudden infant death-dysgenesis of the testes syndrome (SIDDT), also called TSPYL1-related syndrome, is a lethal autosomal recessive disorder of infants with testicular dysgenesis in 46,XY males, staccato cry, autonomic dysfunction, and death before 12 months from cardiorespiratory arrest; described mainly in Old Order Amish families.
Sudden sensorineural hearing loss
Sudden sensorineural hearing loss (SSNHL, sudden deafness): rapid ≥30 dB inner-ear hearing loss over 3 frequencies within 3 days, usually unilateral, 90% idiopathic, an ENT emergency treated with corticosteroids.
Sudden unexpected death in epilepsy
SUDEP (sudden unexpected death in epilepsy) is a sudden, non-traumatic, non-drowning death in epilepsy excluding status epilepticus. Key facts: 1.2/1,000 patient-years in adults, GTCS frequency as dominant risk factor, respiratory-cardiac arrest mechanism.
Suicide by electrocution
Suicide by electrocution, a rare method of suicide caused by electric current, about 0.2% of UK suicides (222 of 102,163, 2005-2021), one quarter of electrocution deaths in autopsy series, with cardiac arrhythmia as the fatal mechanism.
Sulfasalazine
Sulfasalazine, also spelled sulphasalazine and sold as Azulfidine, is a DMARD drug used for rheumatoid arthritis, ulcerative colitis, and Crohn's disease, first synthesized in Sweden in the late 1930s.
Sulfinpyrazone
Sulfinpyrazone (Anturane) is an oral uricosuric drug, a phenylbutazone analog that lowers serum urate in chronic gout by blocking uric acid reabsorption in the kidney.
Sun tanning
Sun tanning is UV-induced skin darkening from increased melanin triggered by DNA damage; a tan signals skin injury, provides only SPF 2-4, and sunbed tanning raises melanoma risk (IARC group 1 carcinogen).
Sunburn
Sunburn, also called erythema solare, is acute UV-induced skin inflammation causing redness, pain, and blisters; UVB (280–320 nm) is the main cause, healing in 3–5 days, and it raises skin cancer risk.
Sunburn erythema
Sunburn erythema (ICD-11 EJ40.0), also called solar erythema, is UV-induced skin redness peaking 12–24 hours after exposure; 35.1% of U.S. adults sunburn yearly, raising skin cancer risk.
SUNCT syndrome
SUNCT syndrome (short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing) is a rare trigeminal autonomic cephalalgia causing brief, severe one-sided eye-area pain with eye redness and tearing; treated with lamotrigine.
Superficial bacterial folliculitis
Superficial bacterial folliculitis, also called Bockhart impetigo, is a Staphylococcus aureus infection of the hair follicle opening causing pustules; treated with topical mupirocin, clindamycin, or benzoyl peroxide, distinct from deep boils.
Superficial epidermolytic ichthyosis
Superficial epidermolytic ichthyosis (SEI, ichthyosis bullosa of Siemens, OMIM 146800) is a rare autosomal dominant keratinopathic ichthyosis caused by KRT2 mutations, with superficial blisters at birth and milder features than epidermolytic ichthyosis.
Superficial fibromatoses
Superficial fibromatoses: benign, slow-growing fibroblastic tumors of fascia or aponeurosis, including Dupuytren contracture, Ledderhose disease, Peyronie disease, knuckle pads, pachydermodactyly, and infantile digital fibromatosis; genetically distinct from deep fibromatoses.
Superficial frostbite
Superficial frostbite (frostnip, first or second degree frostbite, ICD-11 NE40) is skin-limited freezing injury with blistering but no significant tissue necrosis, treated mainly with rapid rewarming.
Superficial ovarian endometriosis
Superficial ovarian endometriosis (ICD-11 GA10.B4), also called ovarian endometriosis NOS, is endometriosis on the ovarian cortex with typical or subtle superficial lesions, distinct from cystic ovarian endometrioma; diagnosed mainly by laparoscopy.
Superficial siderosis
Superficial siderosis, also called superficial hemosiderosis of the CNS, is a rare neurologic disease from chronic subarachnoid bleeding causing hemosiderin deposition, with progressive hearing loss, ataxia, and pyramidal signs.
Superficial thrombophlebitis
Superficial thrombophlebitis, or superficial venous thrombosis (SVT), is clotting with inflammation in a vein just under the skin, usually varicose leg veins; it differs from DVT but coexists with it in 6 to 40% of cases.
Superficial thrombophlebitis in pregnancy
Superficial thrombophlebitis (superficial vein thrombosis, SVT) in pregnancy: inflamed, clotted superficial vein affecting about 0.1% of pregnancies, with roughly two-fold raised VTE risk, usually managed with LMWH.
Superficial vein thrombosis
Superficial vein thrombosis (SVT, superficial thrombophlebitis) is clotting in veins just under the skin, usually leg saphenous veins. About 20-25% have concomitant DVT or PE; fondaparinux or rivaroxaban for 45 days treats higher-risk cases.
Superior vena cava syndrome
Superior vena cava syndrome (SVCS, SVC obstruction): symptoms from blockage of the superior vena cava, ~70% malignant (lung cancer) and ~30% device-related; treated with stenting, radiotherapy, chemotherapy, or anticoagulation.