Human health and medicine

Subperiosteal Dental Implantation

Subperiosteal dental implantation: custom metal frameworks placed on the jawbone surface beneath the periosteum (Dahl, 1943). Revived via CAD/CAM 3D printing for severe jaw atrophy; ~97.8% short-term survival, soft-tissue exposure the main complication.

Subretinal injection

Subretinal injection is a surgical procedure delivering fluid, cell suspensions, or viral vectors between the retina and retinal pigment epithelium, used mainly for retinal gene therapy.

Subscapularis muscle

Subscapularis (musculus subscapularis): largest rotator cuff muscle, filling the scapula's subscapular fossa, inserting on the humerus' lesser tubercle; the cuff's only internal rotator, innervated by upper and lower subscapular nerves (C5-C6), prone to underdiagnosed tears.

Subscapularis repair

Subscapularis repair is a surgical technique that reattaches a torn subscapularis tendon to its footprint on the lesser tuberosity of the humerus, performed arthroscopically or open, usually with suture anchors.

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.

Substance abuse

Substance abuse, now diagnosed as substance use disorder under DSM-5, is compulsive use of alcohol or drugs despite harm. Covers neurobiology, 40-60% genetic risk, US prevalence, overdose trends, NPS monitoring, and treatments.

Substance abuse detection

Substance abuse detection, also called drug abuse screening, is the set of clinical methods for identifying drug or alcohol misuse through questionnaires, laboratory testing, and electronic health record analysis.

Substance dependence

Substance dependence, also called physical dependence, is a state in which the body needs a drug to function, marked by tolerance and withdrawal; distinct from addiction (substance use disorder), treatable with tapering and FDA-approved medications.

Substance intoxication

Substance intoxication, also called getting high, is a reversible syndrome of disturbed consciousness, perception, and behavior after recent use of alcohol or another psychoactive substance.

Substance P

Substance P (SP) is an 11-amino acid tachykinin neuropeptide, discovered 1931 by von Euler and Gaddum, sequenced 1971, signaling mainly through the NK1 receptor; its antagonists treat chemotherapy-induced nausea.

Substance use & misuse

Substance Use & Misuse (Subst Use Misuse) is a peer-reviewed Taylor & Francis journal on drugs, alcohol, nicotine, and eating disorders; founded 1996, continuing the International Journal of the Addictions (1966–1995), ISSN 1082-6084, indexed in MEDLINE.

Substance use disorder

Substance use disorder (SUD), also called drug addiction, is a DSM-5-TR diagnosis of impaired control over alcohol or drug use, mild to severe by criteria count; 44.6 million US cases in 2025, 11% treated.

Substantia gelatinosa of Rolando

Substantia gelatinosa of Rolando (SGR), or substantia gelatinosa, is the translucent lamina II of the spinal dorsal horn, described by Rolando in 1824, that receives C and Aδ fiber input and modulates nociception via gate control circuitry.

Substantia nigra

The substantia nigra, Latin for "black substance", is a nucleus of the midbrain that supplies dopamine to the basal ganglia and helps modulate motor movement and reward.

Substitution therapy

Substitution therapy is medical treatment that supplies a substance the body lacks, such as a hormone, enzyme, or clotting factor, or replaces an addictive drug.

Substrate ablation

Substrate ablation is a catheter-based strategy for ventricular tachycardia that modifies the scar and border-zone tissue sustaining reentry, developed for VT that is unmappable, noninducible, or hemodynamically intolerable.

Substrate reduction therapy

Substrate reduction therapy is an oral treatment for lysosomal storage disorders that partially inhibits synthesis of the accumulating substrate, an alternative to enzyme replacement therapy.

Subtotal gastrectomy

Subtotal gastrectomy is an operation removing the distal 70% to 80% of the stomach, typically for distal gastric cancer, leaving a remnant reconnected by Billroth or Roux-en-Y reconstruction.

Subtotal thyroidectomy

Subtotal thyroidectomy is an operation removing most of both thyroid lobes with the isthmus, leaving a small remnant, used to treat hyperthyroidism and goiter, though guidelines now favor total thyroidectomy.

Subtraction osteotomy

Subtraction osteotomy, also called closing wedge osteotomy, is a bone-cutting procedure that removes a wedge of bone so the segments close together, realigning and shortening it.

Subtraction Technique

Subtraction Technique: medical imaging method combining two registered images so unchanged structures cancel, showing only differences like contrast-filled vessels. MeSH D013382, established 1973; spans photographic subtraction (1935), digital subtraction angiography (1980), dual-energy and temporal subtraction.

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.

Suburban Population

Suburban population: inhabitants of peripheral or adjacent areas of a city or town (MeSH D013383, introduced 1980). No official US Census suburban category; 43% of Americans self-identify as suburban; suburban counties grew faster than urban since 2000.

Suburethral Slings

Suburethral slings are surgical treatments for female stress urinary incontinence, spanning the traditional pubovaginal fascial sling, the 1995 tension-free vaginal tape and other midurethral polypropylene mesh slings (retropubic or transobturator), and single-incision slings, with cure rates above 80% at five years.

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.

Succinobucol

Succinobucol (AGI-1067), a monosuccinate ester of probucol developed by AtheroGenics, is an antioxidant anti-inflammatory drug candidate for atherosclerosis that reached Phase 3 (ARISE) without approval.

Sucralfate

Sucralfate is a locally acting aluminum sucrose octasulfate antiulcer drug that forms an ulcer-adherent barrier against acid, pepsin, and bile salts; used for duodenal ulcer treatment and maintenance, with renal and drug-interaction cautions.

Suction

Suction in medicine removes secretions, gas, or fluid from hollow organs and cavities using a tube and negative pressure, for airway clearance, drainage, and wound therapy.

Sudafed

Sudafed is a Kenvue brand of decongestants whose original products contain pseudoephedrine, sold behind US pharmacy counters under the Combat Methamphetamine Epidemic Act of 2005; Sudafed PE contains phenylephrine, judged ineffective orally by FDA advisers in 2023.