Program Operations Manual System (POMS)
TN 45 (08-21)
DI 23022.496 SCN8A-related Epilepsy with Encephalopathy
COMPASSIONATE ALLOWANCES INFORMATION
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SCN8A-RELATED EPILEPSY WITH ENCEPHALOPATHY
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ALTERNATE NAMES
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Early Infantile Epileptic Encephalopathy 13; EIEE13; SCN8A Encephalopathy
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DESCRIPTION
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SCN8A-related Epilepsy with Encephalopathy is a rare autosomal-dominant genetic disorder affecting infants, characterized by
recurrent seizures of multiple types, along with intellectual disability. These seizures
are described as refractory, meaning that they generally do not respond to or improve
with treatment.
While the condition is often evident at birth, some affected infants will exhibit
apparently normal development until the onset of seizures, at which point the child
will begin to regress from both physical and cognitive standpoints. The severity of
intellectual impairment associated with SCN8A-related epilepsy encephalopathy varies
from mild to severe.
As the name indicates, the condition is caused by a mutation on the SCN8A gene. The
relationship between the genetic anomaly and its distinct effects on intellectual
and physical development are poorly understood; some research indicates that these
symptoms are more closely correlated with the brain damage resulting from the seizures,
rather than the mutation itself.
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DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM/ICD-10-CM
CODING
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Diagnostic testing:
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Molecular genetic testing is required to confirm mutation on the SCN8A gene.
Physical findings: Common symptoms include:
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Seizures of multiple types (absence, tonic-clonic, convulsive);
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Intellectual disability including autistic features;
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ICD-9: 345.81
ICD-10: G40.803
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PROGRESSION
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Affected infants will begin exhibiting symptoms between birth and 18 months of age,
with median onset at 4 months. Treatment is supportive; people with SCN8A-related
epilepsy with encephalopathy can survive to adulthood with appropriate care.
In about 10% of identified cases, the infant dies without any obvious cause, a phenomenon
known as sudden unexpected death in epilepsy (SUDEP).
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TREATMENT
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SCN8A-related epilepsy with encephalopathy typically does not respond to traditional
anticonvulsive medication. Antiepileptic drugs that block sodium channels (e.g., phenytoin,
valproate, carbamazepine) have shown promise in some studies.
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SUGGESTED PROGRAMMATIC ASSESSMENT*
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Suggested MER for Evaluation:
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Clinical history and examination that describes the diagnostic features of the impairment;
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Genetic testing confirming mutation of the SCN8A gene; and
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Imaging reports such as CT scan or MRI scan.
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Suggested Listings for Evaluation:
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DETERMINATION
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LISTING
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REMARKS
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Meets
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111.02
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Equals
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* Adjudicators may, at their discretion, use the Medical Evidence of Record or the
listings suggested to evaluate the claim. However, the decision to allow or deny the
claim rests with the adjudicator.
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