1,527 articles
Subarachnoid hemorrhage
Subarachnoid hemorrhage (SAH), bleeding into the subarachnoid space around the brain, usually from a ruptured cerebral aneurysm; presents as thunderclap headache, diagnosed by CT, treated by clipping or coiling.
Subcortical band heterotopia
Subcortical band heterotopia (SBH, double cortex syndrome, subcortical laminar heterotopia): a neuronal migration disorder forming a gray-matter band beneath the cortex, mainly in females, caused by DCX or PAFAH1B1 mutations and part of the lissencephaly spectrum.
Subdural hematoma
Subdural hematoma: bleeding between the dura mater and brain surface, usually from torn bridging veins after head injury. Acute forms are surgical emergencies; chronic forms affect older adults, and middle meningeal artery embolization now reduces recurrence after drainage.
Subependymal giant cell astrocytoma
Subependymal giant cell astrocytoma (SEGA), a benign slow-growing grade 1 brain tumor of the ventricle walls, occurring almost exclusively in tuberous sclerosis complex; treated by surgery or everolimus.
Subependymoma
Subependymoma: rare WHO grade 1 ependymal tumor of the brain or spinal cord, mainly in adults around age 50, arising in the fourth and lateral ventricles, with excellent prognosis after surgical resection.
Subepithelial mucinous corneal dystrophy
Subepithelial mucinous corneal dystrophy (SMCD) is a rare autosomal dominant corneal disorder, first described in 1993, causing painful recurrent erosions in childhood and progressive corneal clouding in adulthood.
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 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.
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 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.
Susac syndrome
Susac syndrome is a rare autoimmune disease that blocks small vessels in the brain, retina, and inner ear, causing encephalopathy, vision loss, and hearing loss.
Sydenham chorea
Sydenham's chorea (chorea minor, St. Vitus dance, rheumatic chorea): post-streptococcal autoimmune movement disorder, major manifestation of acute rheumatic fever, mainly in children 8-9 years, treated with antibiotics, symptomatic drugs, and immunotherapy.
Symbolic dysfunctions
Symbolic dysfunctions (ICD-11 MB4B, 表象機能の障害) is a WHO ICD-11 category grouping acquired losses of reading, calculation, writing, naming, and recognition (alexia, acalculia, agraphia, anomia, agnosia), excluding developmental learning disorder.
Sympathetic ophthalmia
Sympathetic ophthalmia, also called sympathetic uveitis, is a rare bilateral granulomatous panuveitis triggered by trauma or surgery to one eye, driven by T-cell autoimmunity to exposed ocular antigens, with onset from 5 days to 66 years and corticosteroid plus immunomodulator treatment.
Syncope or collapse
Syncope, also known as fainting or collapse, is a brief loss of consciousness from reduced blood flow to the brain, resolving quickly without treatment and affecting one-third to one-half of people.
Synergistic divergence
Synergistic divergence is a rare congenital ocular motility disorder in which the affected eye abducts further on attempted adduction, often classified as type 4 Duane syndrome.
SYNGAP1-related developmental and epileptic encephalopathy
SYNGAP1-related developmental and epileptic encephalopathy (SYNGAP1-DEE), also called SYNGAP1-related intellectual disability, is a rare genetic disorder causing developmental delay, epilepsy, and autism, usually with seizures beginning around age 2.
Synthetic cathinone intoxication
Synthetic cathinone intoxication (ICD-11 6C47.3), also called bath salts toxicity, is acute poisoning by khat-derived amphetamine-like stimulants, causing a sympathomimetic toxidrome of agitation, tachycardia, hyperthermia, and seizures, treated supportively with benzodiazepines and cooling.
Synucleinopathy
Synucleinopathy: group of neurodegenerative diseases, including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy, defined by aggregated alpha-synuclein inclusions in neurons or glia, prion-like spread, and seed amplification assay diagnosis.
Syringobulbia
Syringobulbia (ICD-11 8D66.2) is a fluid-filled cavity (syrinx) within the brain stem, usually the medulla, closely associated with syringomyelia; caused by Chiari I malformation, tumors, or inflammation; treated by posterior fossa decompression.
Syringomyelia
Syringomyelia, also called syringohydromyelia, is a spinal cord disorder in which a CSF-filled syrinx forms, usually with Chiari I malformation, trauma, or arachnoiditis; treated by foramen magnum decompression or shunting.
Tarsal kink syndrome
Tarsal kink syndrome (ORPHA:99170), a rare congenital eyelid disorder: a horizontal kink in the upper tarsal plate causing upper lid entropion, blepharospasm, absent eyelid crease, and risk of corneal ulceration, treated surgically.
Telecanthus
Telecanthus, also called dystopia canthorum or pseudohypertelorism, is an increased distance between the inner eyelid corners (medial canthi) with normal pupil spacing, usually from genetic syndromes or facial trauma, treated surgically.
Temple-Baraitser syndrome
Temple-Baraitser syndrome (TBS, OMIM 611816, ORPHA 420561) is a rare KCNH1 gain-of-function channelopathy with severe intellectual disability, epilepsy, and absent or hypoplastic thumb and great-toe nails; allelic to Zimmermann-Laband syndrome, unrelated to Temple syndrome.
Temporal lobe epilepsy
Temporal lobe epilepsy (TLE), the most common focal epilepsy, involves seizures starting in the temporal lobes; mesial TLE with hippocampal sclerosis causes déjà vu auras and is often treated with surgery or laser ablation.
Tension headache
Tension-type headache (TTH), also called tension headache or muscle contraction headache, is the most common primary headache disorder: bilateral, pressing, mild-to-moderate pain lasting 30 minutes to 7 days, treated with simple analgesics and prevented with acupuncture or amitriptyline.
Thallium poisoning
Thallium poisoning, illness from the tasteless, odorless heavy metal Tl that mimics potassium; causes gastroenteritis, painful neuropathy, and alopecia; treated with Prussian blue, FDA-approved 2003.
The Diving Bell and the Butterfly
The Diving Bell and the Butterfly (Le Scaphandre et le Papillon), Jean-Dominique Bauby's 1997 memoir dictated by blinking his left eye with locked-in syndrome, and Julian Schnabel's 2007 Cannes Best Director film adaptation.
The Man Who Mistook His Wife for a Hat
The Man Who Mistook His Wife for a Hat, Oliver Sacks's 1985 book of neurological case histories including Dr. P.'s visual agnosia; million-selling best-seller adapted into a Michael Nyman opera and credited with reviving narrative medicine.