Epileptic spasms
West syndrome | |
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Specialty | Neurology |
West syndrome is an epileptic encephalopathy, a severe childhood epilepsy syndrome arising during infancy,[1] often as a complication of various other medical conditions.[2] It is clinically defined by the occurrence of the characteristic infantile spasms in association with characteristic EEG pattern findings (hypsarrhythmia), and cognitive delay or deterioration.[1][2] The peak age of onset is 4-6 months of age, with 90% of cases presenting during the first year of life. The spasms are usually resistant to conventional antiepileptic pharmacotherapy. They may persist beyond infancy, or, rarely, commence only later in childhood. Many individuals with West syndrome go on to develoop other forms of epilepsy later in life, and persisting neurodevelopmental deficits are common;[1] notably, up to about a third of children are diagnosed with autism.[3] Pharmacotherapy consists of either adrenocorticotropic hormone (ACTH) or glucocorticoids (prednisone), or vigabatrin. Ketogenic diet may be effective as second-line therapy for treatment-resistant cases. Neurosurgery may be indicated in certain cases.[1]
The term infantile spasms is used to designate the characteristic seizures seen in West syndrome. Infantile spasms may however also occur outside of West syndrome (that is, in the absence of hyperarrhythmia and cognitive regression) - notably in association with severe brain disorders (e.g. lissencephaly).[1] When such seizures are present in later life, they are designated epileptic spasms. Nevertheless, revised terminology of the International League Against Epilepsy recommends that the distinction be abandoned and that both infantile and epileptic seizures be referred to as epileptic spasms.[2]
West syndrome/infantile spasms are commonly classified as symptomatic when a potential cause cause be identified, and as cryptogenic if otherwise (though these designations are used inconsistently).[1] A specific cause can be identified in ~70-75%. Any condition that may cause cerebral insult may give rise to West syndrome. Causes range from genetic disorders, infections, congenital malformations, malnutrition, to brain trauma. The most commonly identified common cause is tuberous sclerosis complex. Cryptogenic cases entail a more favourable prognosis overall.[2]
West syndrome is named for the English physician William James West who was first to describe the condition in an article in The Lancet in 1841[4] based on observations of the condition in his son.[5]
Signs and symptoms
Epileptic spasms
Epileptic spasms are a seizure type characteristic for the first year of life. The spasms are typically resistent to conventional pharmacotherapy. There are many episodes per day.[1] Episodes may take place after waking or feeding,[2] or less often before falling asleep.[6] Episode duration,[1][2] intensity, and muscle groups affected are variable.[2] Mild spasms may involve mere nodding,[6] muscle twitching or eye movements, whereas powerful spasms may result in the infant's body violently bending over (the so-called "salaam" or "jackknife" movements). Individual spasms typically last only seconds, but episodes may last over 20 minutes.[2] An episode is typically followed by exhaustion.[1]
The spasms present as episodes of brisk neck flexions-extensions and upper limp abductions-adductions,[1] lower limb extension, and trunk musculature contractions,[2] accompanied by upward deviation of the eyes.[1] Most often, there is both flexion and extension, but either movement type may occur alone.[6] Unilateral brain lesions often (but not always) result in asymmetric spasms; unilateral spasms may progress to generalised spasms.[1]
When spontaneous remissions occurs, it is typically gradual. Remission by the age of 3 is 50%, rising to 90% by the age of 5.[1]
Developmental
The onset of epileptic spasms is often associated with developmental regression: autistic withdrawal, and loss of social smiling and of visual attention.[1] A majority of individuals with West syndrome exhibit regression of psychomotor skills.[2] However, developmental delay is noted in up to 70% of persons with West syndrome already before the onset of spasms.[1]
Causes
Based on aetiology, cases of West syndrome are commonly classified as either symptomatic or cryptogenic - although these terms have not been used consistently. Symptomatic cases are most often defined as those in which a clear cause can be identified, though some investigators also use the designation in cases in which there was previous clinical or imaging evidence of brain lesions and/or abnormal development was noted prior to the onset of the syndrome. Cryptogenic cases are thus contrastingly defined as those in which no specific cause can be identified, or where no such lesions or abnormalities were noted prior to syndrome onset.[1]
- Brain malformations
- Microcephaly[citation needed]
- Hemimegalencephaly[2]
- Cortical dysplasia[2]
- Cerebral atrophy[citation needed]
- Lissencephaly (may be of heritable aetiology)[1]
- Cerebrovascular malformations[citation needed]
- Genetic disorders
- Phakomatoses (e.g. tuberous sclerosis)[2]
- Aicardi syndrome[citation needed]
- lncontinentia pigmenti[2]
- Foix–Chavany–Marie syndrome[citation needed]
- Down syndrome (trisomy 21)[2]
- Patau syndrome (trisomy 13)[citation needed]
- Sturge–Weber syndrome[2]
- Maple syrup urine disease[2]
- Phenylketonuria[2]
- Biotinidase deficiency[2]
- Ohtahara syndrome[2]
- PEHO syndrome[1]
- Leukodystrophy[1]
- Mitochondrial diseases[1][2]
- Mutations of the ARX gene, or CDKL5 gene[2][1]
- Chromosomal deletions (e.g. affecting MAGI2 gene that mediates glutamate receptor functioning)[1]
- Infectious[2]
- Congential infections (e.g. cytomegalovirus)[citation needed]
- Bacterial meningitis[citation needed]
- Metabolic
- Periventricular leukomalacia
- Cerebrovascular accidents[citation needed]
- Traumatic brain injury[2]
- Hypoxic-ischaemic encephalopathy[1] (e.g. perinatal asphyxia)[citation needed]
Down syndrome
West syndrome appears in 1% to 5% of infants with Down syndrome. West syndrome in those with Down syndrome is milder, more responsive to treatment (due to unknown reasons), and less likely to evolve into Lennox-Gastaut syndrome or other forms of epilepsy.[citation needed] A child with Down syndrome presenting with seizures that are difficult to control should be assessed for autistic spectrum disorder.[7][verification needed]
Genetic
Mutations in several genes have been associated with West syndrome. These include the Aristaless related homeobox (ARX) and cyclin dependent kinase like 5 (CDKL5) genes.[8] The ARX gene in particular seems to be responsible for at least some of the X linked cases.[9] Variants in the KCNT1 gene can also in rare cases result in West syndrome.[10]
Diagnosis
Infantile spasms continue to be often misdiagnosed as non-epileptic, non-pathological movements such as infantile colic, startle response, or Moro reflex.[1]
Treatment
Pharmacotherapy
There is limited evidence as to which pharmacotherapy approach is optimal.[11][1] Hormones therapy with either adrenocorticotrophic hormone (ACTH) or oral prednisone is the standard of care (with the two treatments apparently producing equivalent outcomes). ACTH therapy is cost-prehibitive in the US.[11] ACTH therapy produces improvement in spasms within days whereas neurodevelopmental improvements take weeks. ACTH therapy is associated with increased risk of infections (which account for the majority of deaths).[1] Therapy with vigabatrin is also commonly undertaken (though long-term use is associated with a risk of visual field loss);[11] vigabatrin is considered the treatment of choice for infantile spasms associated with tuberous sclerosis complex, and is also favoured in those with serious brain lesions or malformations.[6]
Neurosurgery
Prompt neurosurgery may be indicated in treatment-resistent cases with a demonstrated localised epileptic focus. Some 60% of persons having undergone neurosurgery are subsequently seizure-free. Small epileptic foci augur a favourable outcome, however, in most cases, resection of extensive multilobar cortical dysplasias is called for, resulting in limited cognitive improvement.[1]
Ketogenic diet
There is some evidence for the use of the ketogenic diet in cases which have failed to respond to pharmacotherapy.[1]
Prognosis
Prognosis of infantile spasms and West syndrome depends predominately upon aetiology, and less so on treatment. Unfavourable prognostic factors include: symptomatic aetiology, early onset (prior to 3 months), presence of other seizure types prior to onset of infantile spasms, poor treatment response, EEG asymmetry, absence of typical hypsarrhythmia, and (prolongued) developmental regression.[1] Premature mortality rates range from 5% to 31%, and depend upon the underlying aetiology of the infantile spasms.[6]
Whereas some 80% of all individuals West syndrome will exhibit residual neurodevelopmental impairment, the figure falls to only a third for cryptogenic cases.[1] Brisk initiation of therapy appears to be associated with more favourable neurodevelopmental outcomes - especially in cryptogenic cases.[6]
Seizures
In about one quarter to one third of children with West syndrome, seizures will subside completely with time; such resolution is more common among those with cryptogenic West syndrome. In another third, the characteristic epilepstic spasms of West syndrome will persist in later life. Finally, a third will develop experience a deterioration with the appearance of additional recalcitrant seizure types - often evolving into Lennox–Gastaut syndrome.[2] About 50% of cases will exhibit other types of epilepsy later in life.[1]
Autism
From 10% to 35% of children with infantile spasms are eventually recognised as autistic. Autism may arise more frequently in those with bilateral temporal lobe epileptic foci. The aetiology of infantile spasms-associated autism may be idiopathic, or an additional comorbidity that itself better explains the autism may be identified. It is believed that early aggressive treatment of infantile spasms can often prevent the later development of autistic features, or lessen their severity.[3]
Epidemiology
Incidence is around 1:3200 to 1:3500 of live births. Statistically, boys are more likely to be affected than girls at a ratio of around 3:2.[12]
See also
References
- ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae Shorvon, S. D.; Guerrini, Renzo; Cook, Mark; Lhatoo, Samden D., eds. (2013). Oxford Textbook of Epilepsy and Epileptic Seizures. Oxford Textbooks in Clinical Neurology. Oxford, United Kingdom: Oxford University Press. pp. 63, 140, 177–179. ISBN 978-0-19-965904-3. OCLC 806014746.
- ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa "West Syndrome - Symptoms, Causes, Treatment | NORD". rarediseases.org. Retrieved 2024-09-28.
- ^ a b Coleman, Mary; Gillberg, Christopher; Gillberg, Christopher (2012). "17. Prevention, Reversible Autism, and Medical Therapies". The Autisms (4th ed.). New York: Oxford University Press. pp. 315–316. ISBN 978-0-19-973212-8. OCLC 711828867.
- ^ West, W. J. (1841). "On a Peculiar Form of Infantile Convulsions". The Lancet. 35 (911): 724–725. doi:10.1016/S0140-6736(00)40184-4.
- ^ "West's syndrome". Whonamedit? A dictionary of medical eponyms. Ole Daniel Enersen.
- ^ a b c d e f "Infantile Spasms". MSD Manual Professional Edition. Retrieved 2024-09-29.
- ^ Goldberg-Stern et al., 2001 & Eisermann et al. 2003 in: American Journal of Medical Genetics part C, 2006, S. 163: Neurobehavioral disorders in children, adolescents and young adults with down syndrome
- ^ Bahi-Buisson N, Bienvenu T (2012) CDKL5-related disorders: from clinical description to molecular genetics. Mol Syndromol 2(3-5):137-152
- ^ Sherr EH (2003) The ARX story (epilepsy, mental retardation, autism, and cerebral malformations): one gene leads to many phenotypes. Curr Opin Pediatr 15(6):567-571
- ^ Gertler, T.; Bearden, D.; Bhattacharjee, A.; Carvill, G.; Adam, M. P.; Mirzaa, G. M.; Pagon, R. A.; Wallace, S. E.; Bean LJH; Gripp, K. W.; Amemiya, A. (1993). "KCNT1-Related Epilepsy". KCNT1-Related Epilepsy - GeneReviews® - NCBI Bookshelf. University of Washington, Seattle. PMID 30234941.
- ^ a b c Wilmshurst JM, Ibekwe RC, O'Callaghan FJK (January 2017). "Epileptic spasms - 175 years on: Trying to teach an old dog new tricks" (PDF). Seizure. 44: 81–86. doi:10.1016/j.seizure.2016.11.021. PMID 27989601. S2CID 4977080.
- ^ Johnston, Michael V.; Adams, Harold P.; Fatemi, Ali (2016-08-18). Neurobiology of Disease. Oxford University Press. ISBN 9780190219086.
External links
- Much of this article is translated from the German Wikipedia article