1,527 articles
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 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.
Split cord malformation type I
Split cord malformation type I (diastematomyelia, SCM type I): rare congenital dysraphism with two hemicords in separate dural sacs divided by a bony or cartilaginous spur; Pang 1992 classification, Mahapatra Ia-Id subtypes.
Split cord malformation type II
Split cord malformation type II (diplomyelia, SCM type 2): congenital spinal cord split into two hemicords within a single dural sac, separated by a fibrous septum, per Pang's 1992 classification; treated by cord detethering.
Spontaneous periodic hypothermia
Spontaneous periodic hypothermia, also called Shapiro syndrome or episodic spontaneous hypothermia, is a rare neurologic disorder of recurrent core-temperature drops below 35 °C with hyperhidrosis, without hypothalamic lesions; fewer than 1 per million prevalence, onset 6 months to 62 years.
Sporadic fatal insomnia
Sporadic fatal insomnia (sFI, sCJDMM2 thalamic subtype) is an extremely rare sporadic prion disease mimicking fatal familial insomnia without PRNP mutation, causing sleep loss, autonomic and motor signs, thalamic degeneration, and death within two to three years.
Sporadic hyperekplexia
Sporadic hyperekplexia, or startle disease, is a rare neurologic disease of excessive startle response with hyperreflexia in patients with no affected relatives and no other neurologic cause.
Sporadic infantile bilateral striatal necrosis
Sporadic infantile bilateral striatal necrosis (Sporadic IBSN, ABSN, ORPHA:225147) is a rare, non-inherited syndrome of bilateral symmetric degeneration of the caudate, putamen, and pallidum, often post-febrile, causing choreoathetosis, dystonia, and regression.
Sporadic Parkinson disease
Sporadic Parkinson disease (ICD-11 8A00.00; idiopathic PD) is Parkinson disease without apparent inheritance, the majority of cases, a multifactorial Lewy body disease driven by polygenic risk, environment, and aging.
Squamous cell carcinoma of cornea
Squamous cell carcinoma of the cornea is a rare invasive cancer of the corneal surface epithelium, the advanced end of a spectrum called ocular surface squamous neoplasia.
Squamous cell carcinoma of middle ear
Squamous cell carcinoma of middle ear (ICD-11 2C21.1), a rare keratinising carcinoma of middle ear epithelium; presents as otorrhea, otalgia, hearing loss; treated by temporal bone resection plus radiotherapy.
Staphyloma
Staphyloma: a circumscribed outpouching of the thin cornea or sclera lined by uveal tissue. Posterior staphyloma is a hallmark of pathologic myopia, classified by Curtin into ten types, with no medical treatment.
Startle epilepsy
Startle epilepsy, a rare reflex epilepsy (ICD-10 G40.5, ICD-11 8A61.40), causes tonic seizures triggered by sudden startle stimuli, mostly auditory, with falls, spastic plegia, intellectual disability, and refractory seizures.
Status epilepticus
Status epilepticus (SE), a prolonged or recurrent seizure emergency defined by ILAE 2015 (5 minutes for tonic-clonic seizures), treated with benzodiazepines then levetiracetam, fosphenytoin, or valproate, with about 20% mortality.
Status migrainosus
Status migrainosus: a debilitating migraine attack lasting more than 72 hours, an ICHD-3 complication of migraine (code 1.4.1), also called intractable migraine, treated with parenteral drugs in emergency settings.
Stellate multiform amelanotic choroidopathy
Stellate multiform amelanotic choroidopathy (SMACH), formerly serous maculopathy due to aspecific choroidopathy, is a rare choroidal disease with stellate amelanotic lesions, subretinal fluid in about 59% of cases, and stable lesion size.
Stellate non-hereditary idiopathic foveomacular retinoschisis
SNIFR (stellate non-hereditary idiopathic foveomacular retinoschisis) is a rare, usually unilateral macular schisis of the Henle fiber layer in middle-aged women, described by Ober et al. in 2014, with preserved vision and diagnosis by exclusion.
Stephen J. Ryan
Stephen J. Ryan (1940–2013) was an American retina specialist who chaired USC ophthalmology, led the Doheny Eye Institute, and defined animal models for macular degeneration and eye trauma.
Steroid-responsive encephalopathy associated with autoimmune thyroiditis
SREAT, or Hashimoto encephalopathy, is a rare steroid-responsive encephalopathy with elevated antithyroid antibodies, diagnosed after excluding other causes; seizures, confusion, and cognitive decline are common, and corticosteroids help most patients.
Stiff-person syndrome
Stiff-person syndrome (SPS), also called stiff-man syndrome or stiff person spectrum disorder (SPSD), is a rare autoimmune neurological disorder causing trunk and limb rigidity, stimulus-triggered spasms, and falls, linked to GAD65 antibodies and often misdiagnosed.
Straatsma syndrome
Straatsma syndrome: rare ophthalmologic triad of myelinated retinal nerve fibers, axial myopia, and amblyopia, usually unilateral; described by Bradley R. Straatsma et al. in 1979, with strabismus frequent and amblyopia typically refractory to treatment.
Strychnine poisoning
Strychnine poisoning, also called strychnine intoxication, is glycine-receptor blockade from Strychnos nux-vomica alkaloid, causing painful conscious muscle spasms, respiratory failure, and often death; treated with benzodiazepines and supportive care.
STXBP1-related developmental and epileptic encephalopathy
STXBP1-related developmental and epileptic encephalopathy (STXBP1-DEE, EIEE4), also called STXBP1 encephalopathy, is a rare autosomal dominant disorder caused by de novo STXBP1/Munc18-1 variants, causing early-onset refractory epilepsy, intellectual disability, movement disorders, and autism features.
Stye
Stye (hordeolum): a painful bacterial abscess of an eyelid gland, usually Staphylococcus aureus; external (Zeis/Moll glands) or internal (meibomian). Treated with warm compresses; distinct from a painless chalazion.
Subacute inflammatory demyelinating polyneuropathy
Subacute inflammatory demyelinating polyneuropathy (SIDP, ORPHA:206594) is a rare immune-mediated neuropathy intermediate between GBS and CIDP, with symmetric weakness and elevated CSF protein peaking over 4 to 8 weeks.
Subacute sclerosing panencephalitis
Subacute sclerosing panencephalitis (SSPE), formerly Dawson's disease, is a rare, fatal progressive brain disease caused by persistent defective measles virus infection, appearing 4-10 years after measles, prevented only by vaccination.