Nervous and sensory conditions

Self-limited neonatal epilepsy

Self-limited neonatal epilepsy (SeLNE), formerly benign familial neonatal seizures, is a KCNQ2/KCNQ3 genetic epilepsy with focal seizures starting days 2-7 of life, remitting by 6 months.

Self-limited neonatal/infantile epilepsy

Self-limited neonatal/infantile epilepsy (SeLFNIE, ORPHA:140927) is a rare autosomal dominant genetic epilepsy with brief focal seizure clusters from the first days to six months, mainly due to SCN2A or KCNQ2 variants, resolving without sequelae.

Sensation disturbance

Sensation disturbance (感覚障害), ICD-11 code MB40, is a symptom category covering lost, reduced, exaggerated, or abnormally perceived sensation, from anesthesia and analgesia to allodynia and dysesthesia, most often caused by sensory neuropathy.

Sensory ataxic neuropathy-dysarthria-ophthalmoparesis syndrome

SANDO (sensory ataxic neuropathy-dysarthria-ophthalmoparesis syndrome, ORPHA:70595) is a rare adult-onset autosomal recessive mitochondrial disease caused by POLG mutations, featuring ataxic neuropathy, dysarthria, and ophthalmoparesis; valproic acid is contraindicated.

Sensory processing disorder

Sensory processing disorder (SPD), also called sensory integration dysfunction, is a proposed condition of atypical sensory modulation not recognized in DSM-5 or ICD-11; the AAP advises against diagnosing it, and sensory symptoms are instead features of autism and ADHD.

Separation of retinal layers

Separation of retinal layers (ICD-10 H35.7; ICD-11 9B78.6) covers retinal detachment, retinoschisis, bacillary layer detachment, foveoschisis, and pigment epithelial detachment, distinguished by OCT layer-level findings.

Sequelae of leprosy

Sequelae of leprosy (ICD-11 1G82): lasting nerve damage, deformities, eye injury, and stigma persisting after Hansen disease treatment, driven mainly by leprosy reactions affecting 40–50% of patients.

Sequelae of viral encephalitis

Sequelae of viral encephalitis, also called late effects of viral encephalitis (ICD-10 B94.1, ICD-11 1G84), are persistent neurological, cognitive, and psychiatric deficits after viral brain infection, affecting up to 50% of survivors.

Serotonin syndrome

Serotonin syndrome, or serotonin toxicity, is a potentially life-threatening drug-induced toxidrome from excess CNS serotonin, marked by neuromuscular excitation, autonomic hyperactivity, and altered mental status; severe cases usually involve MAOI plus SSRI combinations, diagnosed clinically via Hunter criteria and treated with supportive care and cyproheptadine.

Serous conjunctivitis, except viral

Serous conjunctivitis, except viral (ICD-10-CM H10.23; ICD-11 9A60.6) is a diagnostic classification for acute conjunctivitis with clear, watery discharge not attributed to a virus, coded by laterality subcodes H10.231-H10.239.

Serous detachment of retinal pigment epithelium

Serous detachment of retinal pigment epithelium (serous PED; ICD-10 H35.729, ICD-11 9B78.60) is serous fluid separating the RPE from Bruch membrane, seen mainly in neovascular AMD and central serous chorioretinopathy, diagnosed by OCT, with no proven treatment and RPE tear as the key complication.

Serpiginous choroiditis

Serpiginous choroiditis, also called geographic or helicoid peripapillary choroidopathy, is a rare chronic bilateral posterior uveitis of the choroid, RPE, and choriocapillaris, distinguished from tubercular multifocal serpiginoid choroiditis by imaging and TB testing.

Severe early-childhood-onset retinal dystrophy

Severe early-childhood-onset retinal dystrophy (SECORD), also called early-onset severe retinal dystrophy (EOSRD), is an inherited retinal dystrophy with night blindness, nystagmus, and progressive vision loss beginning before age 5.

Severe intellectual disability and progressive spastic paraplegia

Severe intellectual disability and progressive spastic paraplegia, now called AP-4 deficiency syndrome, is a rare autosomal recessive hereditary spastic paraplegia causing developmental delay, severe intellectual disability, and progressive spasticity.

Severe vision impairment

Severe vision impairment, WHO category 2 (ICD-10 H54.1/H54.6, ICD-11 9D90.3), is distance acuity in the better eye worse than 6/60 but 3/60 or better, between moderate impairment and blindness.

Severe X-linked mitochondrial encephalomyopathy

Severe X-linked mitochondrial encephalomyopathy, or COXPD6 (OMIM 300816), is an ultra-rare X-linked recessive AIFM1-related mitochondrial encephalomyopathy with neonatal or infantile onset, hypotonia, psychomotor impairment, and combined respiratory chain deficiency.

Sexual headache

Sexual headache, or primary headache associated with sexual activity (PHASA, coital cephalalgia), is an ICHD-3 primary headache disorder triggered only by sexual activity, typically dull then explosive at orgasm, more common in males, and diagnosed only after excluding subarachnoid hemorrhage, RCVS, and dissection.

Short stature-brachydactyly-obesity-global developmental delay syndrome

Short stature-brachydactyly-obesity-global developmental delay syndrome, also called SBIDDS (OMIM 617157), is an ultra-rare autosomal recessive PRMT7-related neurodevelopmental disorder with short stature, brachydactyly, intellectual disability, seizures, delayed-onset obesity, and a recognizable facial gestalt.

Short stature-optic atrophy-Pelger-Huët anomaly syndrome

SOPH syndrome (short stature-optic atrophy-Pelger-Huët anomaly syndrome), also called Kleinwuchs-Optikusatrophie-Pelger-Huët-Anomalie-Syndrom, is a rare autosomal recessive NBAS-related disorder with severe postnatal growth failure, optic atrophy, neutrophil nuclear anomaly, and normal intelligence.

Short stature-skeletal dysplasia-retinal degeneration-intellectual disability-sensorineural hearing loss syndrome

Liberfarb syndrome (LIBF) is an extremely rare autosomal recessive disorder caused by variants in the PISD gene, combining short stature, skeletal deformities, retinal degeneration, intellectual disability, and hearing loss.

Short-term insomnia

Short-term (acute) insomnia, ICD-11 7A01, is sleep-initiation or maintenance difficulty under 3 months despite adequate sleep opportunity, with daytime impairment; usually stress-precipitated, treated first with CBT-I.

Simple febrile seizures

Simple febrile seizures are brief (<15 min), generalized, non-recurrent seizures with fever in children 6-60 months, also called typical febrile convulsions. They affect 2-5% of children, need no EEG or imaging, and carry an excellent prognosis with about one-third recurrence risk.

Single unprovoked seizure

A single unprovoked seizure is a seizure with no structural or metabolic cause, affecting about 150,000 US adults each year and carrying a 43% risk of recurrence by 2 years.

Sjögren-Larsson syndrome

Sjögren-Larsson syndrome (SLS, OMIM #270200): autosomal recessive neurocutaneous disorder from ALDH3A2/FALDH deficiency, causing congenital ichthyosis, spastic diplegia, intellectual disability, and diagnostic retinal glistening white dots; distinct from Sjögren's disease.

Skew deviation

Skew deviation, also called ocular tilt reaction component, is an acquired vertical eye misalignment from disrupted utriculo-ocular vestibular pathways, usually brainstem or cerebellar stroke or demyelination, mimicking fourth nerve palsy.

Sleep deprivation

Sleep deprivation: getting less sleep than needed (acute total, partial, or chronic restriction). Adults need 7+ hours; impairment rivals alcohol intoxication; linked to cardiometabolic disease and dementia risk.

Sleep disorder

Sleep disorder: any of more than 100 conditions disturbing normal sleep, including insomnia, sleep apnea, restless legs syndrome, narcolepsy, circadian rhythm disorders, and parasomnias; diagnosed by history and polysomnography, treated with CBT-I, CPAP, or medication.