Human health and medicine

Spinocerebellar ataxia type 41

Spinocerebellar ataxia type 41 (SCA41, OMIM 616410) is a rare autosomal dominant cerebellar ataxia caused by gain-of-function TRPC3 mutations, first the p.Arg762His variant, causing adult-onset ataxic gait and Purkinje cell degeneration.

Spinocerebellar ataxia type 42

Spinocerebellar ataxia type 42 (SCA42, OMIM 616795) is a rare autosomal dominant cerebellar ataxia caused by CACNA1G (Cav3.1 T-type calcium channel) missense mutations, chiefly p.Arg1715His, causing slowly progressive gait ataxia, dysarthria, and nystagmus.

Spinocerebellar ataxia type 43

Spinocerebellar ataxia type 43 (SCA43, OMIM 617018) is a rare autosomal dominant, adult-onset, slowly progressive cerebellar ataxia with axonal peripheral neuropathy, caused by heterozygous missense mutation in MME (neprilysin) at 3q25.2.

Spinocerebellar ataxia type 45

Spinocerebellar ataxia type 45 (SCA45, OMIM 617769) is a rare autosomal dominant pure cerebellar ataxia caused by missense FAT2 mutations, with late-onset gait ataxia, dysarthria, nystagmus, and cerebellar atrophy.

Spinocerebellar ataxia type 46

Spinocerebellar ataxia type 46 (SCA46, OMIM 617770) is a rare autosomal dominant, adult-onset cerebellar ataxia with sensory axonal neuropathy, linked to a PLD3 p.Leu308Pro mutation reported in a single Dutch family; the gene link is disputed.

Spinocerebellar ataxia type 48

Spinocerebellar ataxia type 48 (SCA48, OMIM 618093) is a rare autosomal dominant ataxia from heterozygous STUB1 mutations at 16p13.3, causing adult-onset gait ataxia, cognitive decline, and movement disorders; biallelic STUB1 variants cause SCAR16.

Spinocerebellar ataxia type 5

Spinocerebellar ataxia type 5 (SCA5), or Lincoln ataxia, a rare autosomal dominant pure cerebellar ataxia caused by SPTBN2 mutations encoding beta-III spectrin; mean onset 33 years, very slow progression, five reported families.

Spinocerebellar ataxia type 6

Spinocerebellar ataxia type 6 (SCA6), an autosomal dominant ataxia from CAG repeat expansion in CACNA1A (Cav2.1 calcium channel), causing late-onset, slowly progressive pure cerebellar ataxia with nystagmus; slowest-progressing common SCA.

Spinocerebellar ataxia type 7

Spinocerebellar ataxia type 7 (SCA7) is an autosomal dominant neurodegenerative disease caused by a CAG repeat expansion in the ATXN7 gene, causing progressive ataxia and blindness from cone-rod retinal dystrophy.

Spinocerebellar ataxia type 8

Spinocerebellar ataxia type 8 (SCA8), also called ATXN8OS/ATXN8 CTG expansion ataxia, is a rare autosomal dominant cerebellar ataxia on chromosome 13q21 with reduced penetrance, slow progression, and variable phenotype including tremor and parkinsonism.

Spinocerebellar ataxia with axonal neuropathy type 1

SCAN1 (OMIM 607250) is a rare autosomal recessive ataxia caused by TDP1 p.His493Arg, featuring late-childhood cerebellar ataxia, distal axonal neuropathy, cerebellar atrophy, and hypoalbuminemia, distinct from AOA1 by absent oculomotor apraxia.

Spinocerebellar ataxia with axonal neuropathy type 2

Spinocerebellar ataxia with axonal neuropathy type 2, also called AOA2 or SCAR1, is a rare autosomal recessive cerebellar ataxia caused by biallelic SETX mutations, with onset ages 3-30, sensorimotor neuropathy in 90-100%, oculomotor apraxia in about half, and elevated serum alpha-fetoprotein.

Spinocerebellar ataxia with epilepsy

Spinocerebellar ataxia with epilepsy (SCAE), now classified as myoclonic epilepsy myopathy sensory ataxia (MEMSA), is a rare autosomal recessive disorder caused by POLG mutations, causing ataxia, epilepsy, and cognitive decline.

Spinothalamic tract

The spinothalamic tract, or spinal lemniscus, is a nerve fiber bundle that conveys sensations of pain, temperature, and crude touch from the spinal cord to the thalamus.

Spiral Cone-Beam Computed Tomography

Spiral cone-beam computed tomography, also called helical cone-beam CT, unites a cone-shaped x-ray beam with continuous spiral gantry rotation and table movement, first published in 1991.

Sep 29, 2026

Spiral CT

Spiral CT, also called helical CT, is a CT mode in which the tube rotates continuously while the table moves, scanning a whole volume in 20 to 60 seconds.

Sep 29, 2026

Spiral enteroscopy

Spiral enteroscopy is a device-assisted deep enteroscopy technique in which a rotating spiral-tipped overtube pleats the small intestine over the enteroscope, allowing diagnosis and treatment of small-bowel disease.

Spiral ganglion

The spiral ganglion is a group of sensory neurons in the cochlea of the inner ear that relays sound information from hair cells to the brainstem.

Spiramycin

Spiramycin (Rovamycin) is a 16-membered macrolide antibiotic from Streptomyces ambofaciens, isolated in France in 1954. Used against gram-positive bacteria and to prevent congenital toxoplasmosis in pregnancy; not commercially available in the US.

Spirapril

Spirapril (Renormax, SCH-33844) is a non-sulfhydryl ACE inhibitor prodrug hydrolyzed to active spiraprilat; 50% oral bioavailability, dual renal-hepatic elimination, 6 mg once daily for hypertension; FDA-approved 1994, discontinued in North America.

SPIRE2 trial

SPIRE2 (Supporting Practices In Respecting Elders Phase 2) is a cluster-randomized clinical trial comparing the Medicare Annual Wellness Visit alone with a GRACE-augmented version in older adults with complex health needs.

SPIRIT II trial

SPIRIT II trial: 300-patient randomized trial (Serruys, EuroIntervention 2006) comparing the XIENCE V everolimus-eluting stent with the TAXUS paclitaxel-eluting stent in Europe and Asia Pacific; EES cut in-stent late loss at 180 days (0.11 vs 0.36 mm, p<0.0001) with favorable 5-year safety.

SPIRIT-P1 trial

SPIRIT-P1 (NCT01695239) is Eli Lilly's phase III trial of ixekizumab, an IL-17A antibody, in biologic-naive active psoriatic arthritis; 417 patients, adalimumab reference, 156-week efficacy and safety follow-up.

Spiritual Therapies

Spiritual therapies are mystical, religious, or spiritual practices performed for health benefit, including prayer, faith healing, Reiki, Therapeutic Touch, meditation, and yoga; randomized trial evidence is mixed with very low certainty.

Spirometer

Spirometer: device measuring lung air volume and flow, invented and named by John Hutchinson in 1846, who also coined vital capacity. Central to spirometry for diagnosing asthma and COPD, standardized by ATS/ERS since 1979.

Spirometry

Spirometry is a pulmonary function test measuring how much air a person can exhale and how quickly, widely used to diagnose and monitor lung diseases such as COPD.

SPIROMICS study

SPIROMICS (SubPopulations and InteRmediate Outcome Measures In COPD Study), NCT01969344, is an NHLBI-funded US prospective COPD cohort of about 2,981 participants at twelve centers, identifying COPD subpopulations and biomarkers, with SOURCE, AIR, and HF extensions.

Spironolactone

Spironolactone (Aldactone) is a steroidal mineralocorticoid receptor antagonist and potassium-sparing diuretic discovered at Searle in the 1950s, launched 1960, used for edema, hypertension, heart failure, and PCOS, with hyperkalemia and gynecomastia as key risks.

Splanchnic arteriovenous fistula

Splanchnic arteriovenous fistula (arterioportal fistula, ICD-11 DB98.73) is an abnormal artery-to-portal-vein connection in the abdominal circulation, usually traumatic or iatrogenic, causing non-cirrhotic portal hypertension and treated mainly by endovascular embolization.