1,527 articles
Apraxia of speech
Apraxia of speech (AOS), also called verbal apraxia, is a motor speech disorder impairing planning of speech movements, caused by stroke, injury, or neurodegeneration, and distinguished from aphasia and dysarthria by absent weakness and language deficits.
Arachnoiditis
Arachnoiditis: chronic inflammation of the spinal arachnoid mater causing pain and neurological deficits; also called chronic adhesive arachnoiditis or spinal adhesive arachnoidopathy; causes include spinal surgery, myelography dye, trauma, and infections like tuberculosis; no cure, symptom-based treatment.
Argyll Robertson pupil
The Argyll Robertson pupil, also called the Argyll Robertson phenomenon, is a small, irregular pupil that constricts to near targets but not to light, classically a sign of neurosyphilis.
Arnold-Chiari malformation type I
Arnold-Chiari malformation type I, commonly called Chiari I malformation, is a congenital brain disorder in which the cerebellar tonsils herniate into the upper spinal canal, often causing headaches.
Arnold-Chiari malformation type II
Arnold-Chiari malformation type II (Chiari II, CM II) is a congenital hindbrain herniation of the cerebellar vermis, brainstem, and fourth ventricle, found only with myelomeningocele, usually with hydrocephalus, and a leading cause of death under age 2.
Arthrogryposis-oculomotor limitation-electroretinal anomalies syndrome
Arthrogryposis-oculomotor limitation-electroretinal anomalies syndrome, also called distal arthrogryposis type 5 (DA5, OMIM 108145), is a rare PIEZO2-related disorder with congenital limb contractures, ptosis, ophthalmoplegia, strabismus, and abnormal electroretinogram, with normal intelligence.
Asterixis
Asterixis (flapping tremor, liver flap) is negative myoclonus: brief lapses of posture from sudden muscle relaxation, first described by Adams and Foley in 1949, seen mainly in toxic-metabolic encephalopathies such as hepatic encephalopathy.
Astroblastoma
Astroblastoma, MN1-altered: rare circumscribed glial brain tumor of children and young adults, cerebral hemispheres, perivascular pseudorosettes, MN1 fusions, defined in WHO CNS5 2021.
Astrocytoma grade 3
Astrocytoma grade 3 (astrocytoma, IDH-mutant, CNS WHO grade 3; formerly anaplastic astrocytoma) is an infiltrative IDH-mutant brain tumor without 1p/19q codeletion, treated with radiotherapy plus adjuvant temozolomide, median survival about 8 years.
Ataxia-hypogonadism-choroidal dystrophy syndrome
Ataxia-hypogonadism-choroidal dystrophy syndrome, or Boucher-Neuhäuser syndrome (BNS), is a rare autosomal recessive PNPLA6-related neurodegenerative disorder combining cerebellar ataxia, chorioretinal dystrophy, and hypogonadotropic hypogonadism, with onset from 1 to 40 years.
Ataxia-intellectual disability-oculomotor apraxia-cerebellar cysts syndrome
Ataxia-intellectual disability-oculomotor apraxia-cerebellar cysts syndrome, or Poretti-Boltshauser syndrome (ORPHA:370022, OMIM 615960), is a rare autosomal recessive LAMA1-related disorder with nonprogressive cerebellar ataxia, intellectual disability, ocular motor apraxia, high myopia, and cerebellar dysplasia with cysts on MRI.
Ataxia-oculomotor apraxia type 1
Ataxia-oculomotor apraxia type 1 (AOA1, EAOH) is a rare autosomal recessive cerebellar ataxia caused by APTX mutations, with childhood-onset ataxia, oculomotor apraxia, neuropathy, hypoalbuminemia, and hypercholesterolemia.
Ataxia-oculomotor apraxia type 4
Ataxia-oculomotor apraxia type 4 (AOA4), PNKP-related ataxia, is a rare autosomal recessive cerebellar ataxia with dystonia, oculomotor apraxia, and polyneuropathy beginning around age 4, causing wheelchair dependence by the third decade.
Ataxia-telangiectasia
Ataxia-telangiectasia (A-T, Louis-Bar syndrome) is a rare autosomal recessive multisystem disorder caused by biallelic ATM gene variants, marked by progressive cerebellar ataxia, telangiectasia, immunodeficiency, radiosensitivity, and cancer predisposition.
Ataxia-telangiectasia variant
Ataxia-telangiectasia variant is a rare genetic movement disorder caused by ATM gene mutations, resembling ataxia-telangiectasia but with adult onset, slower progression, and an extended lifespan.
Ataxia-telangiectasia-like disorder
Ataxia-telangiectasia-like disorder (ATLD, OMIM 604391): rare autosomal recessive chromosomal instability syndrome with progressive cerebellar ataxia, oculomotor apraxia, and radiosensitivity but no telangiectasia; ATLD1 from MRE11A mutations, ATLD2 from PCNA mutations.
Ataxic cerebral palsy
Ataxic cerebral palsy (ICD-11 8D22, ICD-10 G80.4) is the least common CP subtype, dominated by cerebellar signs: ataxia, hypotonia, dysmetria, dysarthria, nystagmus; about 3.8% of cases, often genetic origin.
Ataxic disorders
Ataxic disorders (ICD-11 8A03) are conditions causing loss of coordination from cerebellar, sensory, or vestibular damage, spanning hereditary ataxias such as Friedreich ataxia and over 40 spinocerebellar ataxias, acquired causes like stroke and alcohol, and sporadic idiopathic forms.
Ataxic gait
Ataxic gait (staggering gait; ICD-10 R26.0, ICD-11 MB44.0) is an unsteady, wide-based, highly variable walking pattern from cerebellar, sensory, vestibular, or functional causes, rated by SARA and related scales.
Athabaskan brainstem dysgenesis syndrome
Athabaskan brainstem dysgenesis syndrome (ABDS, formerly Navajo brainstem syndrome) is a rare autosomal recessive HOXA1 disorder of Navajo and Apache children causing horizontal gaze palsy, deafness, central hypoventilation, and developmental delay.
Athetosis
Athetosis: slow, sinuous, writhing involuntary movements of the distal limbs, first described by Hammond in 1871, caused by basal ganglia injury, common in dyskinetic cerebral palsy, now often classified within the dystonia spectrum.
Atkin-Flaitz syndrome
Atkin-Flaitz syndrome (X-linked intellectual disability, Atkin type; OMIM 300431) is a very rare X-linked dominant disorder with intellectual disability, macrocephaly, short stature, distinctive facies, seizures, and macroorchidism, described in one family in 1985.
Atopic keratoconjunctivitis
Atopic keratoconjunctivitis, first described by Hogan in 1953, is a chronic bilateral inflammation of the conjunctiva and cornea in people with atopic dermatitis, and can threaten vision.
Atrophia bulbi
Atrophia bulbi (eyeball atrophy, ICD-11 9C22.0) is atrophy of intraocular structures with low eye pressure from end-stage ocular disease; with shrinkage and disorganization it becomes phthisis bulbi (9C22.1).
Attention deficit hyperactivity disorder predominantly inattentive
ADHD predominantly inattentive presentation (ADHD-I, formerly ADD) is the DSM-5 ADHD form meeting inattention criteria without hyperactivity-impulsivity; six symptoms required up to age 16, five for adults, with childhood onset before age 12.
Atypical juvenile parkinsonism
Atypical juvenile parkinsonism (ORPHA:391411) is a rare autosomal recessive, complex young-onset Parkinson disease with pyramidal signs, eye movement abnormalities, intellectual disability, ataxia, epilepsy, and psychiatric features, linked to ATP13A2, PLA2G6, FBXO7, DNAJC6, SPG11, SPG15, and SYNJ1.
Atypical papilloma of choroid plexus
Atypical papilloma of choroid plexus (atypical choroid plexus papilloma, aCPP), WHO grade II, ICD-O 9390/1, is a rare intermediate choroid plexus tumor defined by ≥2 mitoses per 10 high-power fields, with higher recurrence risk than grade I papilloma.
Atypical Rett syndrome
Atypical (variant) Rett syndrome: rare genetic neurological disorder requiring regression plus 2 of 4 main and 5 of 11 Rett criteria; linked to MECP2, CDKL5, FOXG1; milder or more severe than classic Rett.
Atypical teratoid rhabdoid tumor
Atypical teratoid rhabdoid tumor (ATRT, AT/RT) is a rare grade 4 embryonal brain or spinal cord cancer of infants and young children, driven by SMARCB1 or SMARCA4 loss, with TYR, SHH, and MYC molecular subgroups.
Audiogenic epilepsy
Audiogenic epilepsy (ORPHA:166415, ICD-11 8A61.40) is a rare reflex epilepsy in which acoustic stimuli, from sudden noises to specific music or voices, trigger seizures; inferior colliculus-driven in rodent models, extremely rare as simple sound-triggered seizures in humans.