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Episodic generalized hypotonia

MedGen UID:
Concept ID:
Anatomical Abnormality
Synonym: Episodic generalised hypotonia
HPO: HP:0006852


The occurrence of repeated episodes of generalized muscular hypotonia. [from HPO]

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVEpisodic generalized hypotonia

Conditions with this feature

Cerebellar ataxia-areflexia-pes cavus-optic atrophy-sensorineural hearing loss syndrome
MedGen UID:
Concept ID:
Disease or Syndrome
ATP1A3-related neurologic disorders represent a clinical continuum in which at least three distinct phenotypes have been delineated: rapid-onset dystonia-parkinsonism (RDP); alternating hemiplegia of childhood (ACH); and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS). However, some affected individuals have intermediate phenotypes or only a few features that do not fit well into one of these major phenotypes. RDP has been characterized by: abrupt onset of dystonia over days to weeks with parkinsonism (primarily bradykinesia and postural instability); common bulbar involvement; and absence or minimal response to an adequate trial of L-dopa therapy, with few exceptions. Often fever, physiologic stress, or alcoholic binges trigger the onset of symptoms. After their initial appearance, symptoms often stabilize with little improvement; occasionally second episodes occur with abrupt worsening of symptoms. Rarely, affected individuals have reported a more gradual onset of symptoms over weeks to months. Anxiety, depression, and seizures have been reported. Age of onset ranges from four to 55 years, although a childhood variation of RDP with onset between ages nine and 14 months has been reported. AHC is a complex neurodevelopmental syndrome most frequently manifesting in infancy or early childhood with paroxysmal episodic neurologic dysfunction including alternating hemiparesis or dystonia, quadriparesis, seizure-like episodes, and oculomotor abnormalities. Episodes can last for minutes, hours, days, or even weeks. Remission of symptoms occurs with sleep and immediately after awakening. Over time, persistent neurologic deficits including oculomotor apraxia, ataxia, choreoathetosis, dystonia, parkinsonism, and cognitive and behavioral dysfunction develop in the majority of those affected; more than 50% develop epilepsy in addition to their episodic movement disorder phenotype. CAPOS (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss) syndrome is characterized by episodes of ataxic encephalopathy and/or weakness during and after a febrile illness. Onset is between ages six months and four years. Some acute symptoms resolve; progression of sensory losses and severity vary.
Episodic ataxia type 6
MedGen UID:
Concept ID:
Disease or Syndrome
An exceedingly rare form of hereditary episodic ataxia with varying degrees of ataxia and associated findings including slurred speech, headache, confusion and hemiplegia.

Professional guidelines


Olpin SE, Murphy E, Kirk RJ, Taylor RW, Quinlivan R
J Clin Pathol 2015 Jun;68(6):410-7. Epub 2015 Apr 15 doi: 10.1136/jclinpath-2014-202808. PMID: 25878327
Adli M, Pilhatsch M, Bauer M, Köberle U, Ricken R, Janssen G, Ulrich S, Bschor T
Pharmacopsychiatry 2008 Nov;41(6):252-7. Epub 2008 Dec 9 doi: 10.1055/s-0028-1083819. PMID: 19067263

Recent clinical studies

Clinical prediction guides

Schultz-Rogers L, Ferrer A, Dsouza NR, Zimmermann MT, Smith BE, Klee EW, Dhamija R
Cold Spring Harb Mol Case Stud 2019 Dec;5(6) Epub 2019 Dec 13 doi: 10.1101/mcs.a004309. PMID: 31604776Free PMC Article

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