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Prognosis, or the forecast of the likely course of a disease, is often dependent on phenotype and timely intervention. Below, you can find more information about predicted prognosis for epilepsy, development and seizure freedom, the impact of variants and SUDEP risk.

Understanding the Possibilities with SCN8A

Dr. Christelle Achkar from Boston Children’s Hospital gives a short overview of the future outlook for those diagnosed with SCN8A, discussing the variability in prognosis depending on the specific phenotype. Explore further details below to access comprehensive resources and support tailored to SCN8A families and clinicians.

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Prognosis for Epilepsy & Development

The table below outlines the likely change over time, for both seizures and development, over time for each phenotype.

There was no consensus about the expectations for seizures in Severe DEE over time. There was a mix of expectations ranging from some respondents expecting that seizures would improve over time while others thought they were likely to worsen. In contrast, there was consensus that seizures would either have modest or significant improvement over time in Mild/Moderate DEE, SeL(F)IE and NDD with Generalized Epilepsy.

There was consensus that development in Severe DEE was not likely to improve. In contrast, there was consensus that development would have limited change or modest improvement over time in Mild/Moderate DEE, SeL(F)IE, NDD with or without epilepsy.

Likelihood of seizure freedom by phenotype

There was moderate consensus that Severe DEE was rarely likely to achieve seizure freedom, Mild/Moderate might achieve seizure freedom some of the time and NDD with Generalized Epilepsy is likely to achieve seizure freedom some or most of the time. The SE(L)Fie phenotype, while not listed in the table, almost always achieve seizure freedom.

* For the purposes of this consensus, we define seizure freedom as going 6 months or longer without having a seizure. 

A recent paper by Dr. Kyung Mi Chung in Dr. Hammer’s lab identified statistically significant correlations between genotypes and phenotypes for individual SCN8A variants with GOF properties. The results suggest that individual GOF variants 

(1) are predictive of clinical severity for individuals carrying those variants and 

(2) may underlie distinct clinical phenotypes of SCN8A disease, thus helping to explain the wide SCN8A-related epilepsy disease spectrum. 

These results also suggest that clinical features present at initial diagnosis are predictive of clinical severity outcomes. This work suggests that more informed and tailored treatment plans may serve to improve prognosis for patients with SCN8A GOF variants.

Risk factors for SUDEP are recognized as uncontrolled or frequent seizures, frequent generalized convulsive seizures, early age of seizure onset, many years of living with epilepsy, lack of treatment for seizures, reliance of three or more ASMs, and multiple ASM changes in the last year.

Both clinicians and caregivers agreed that severe risk for SUDEP is present in Severe DEE, as defined by the estimated presence of multiple risk factors including uncontrolled/frequent seizures and frequent generalized convulsive seizures. Clinicians and caregivers felt that SUDEP risks were unlikely to improve or resolve, highlighting the need for better understanding of SUDEP across all phenotypes and strategies to reduce the risk. For more information and additional resources on SUDEP, please visit Partners Against Mortality in Epilepsy.

The authors concluded there is a need for investigation into the risk and causes of SUDEP as well as potential strategies to reduce the high rate of premature deaths in the SCN8A population. 

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IMPORTANT: While this consensus data provides new and valuable insights about best practices in the diagnosis and treatment of SCN8A, this is not medical advice. It can inform clinicians and caregivers alike in developing optimal treatment plans for each individual.