Rare Epilepsies & ICD Codes

ICD Code Search Tool | What are ICD Codes | Why ICD Codes Matter |
Rare Epilepsies & Neurodevelopmental Disorders with ICD Recognition |
Developmental & Epileptic Encephalopathies (DEEs) | Disorders Without Specific Codes |
ICD-9, ICD-10 &ICD-11: What’s the Difference? | Why the U.S. Still Uses ICD-10 |
Why ICD-11 Matters for Rare Epilepsies | Who Decides Which Codes Are Added? |
Looking Ahead | Additional Resources

ICD Code Search Tool

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To promote the utilization of codes, REN is tracking rare epilepsies with codes and maintaining a list here. If you are aware of missing codes, please contact: info@rareepilepsynetwork.org

What Are ICD Codes?

ICD (International Classification of Diseases) codes are standardized medical codes used around
the world to classify diseases and health conditions. These codes are used in:

medical records
insurance and billing
research studies
public health reporting
healthcare planning
clinical trials

For rare epilepsy and neurodevelopmental disorder communities, ICD codes help make disorders “visible” within healthcare systems.

ICD codes help to:

Track incidence, prevalence, comorbidity, and mortality
Assess DEEs' impact on healthcare systems
Optimize patient-specific care strategies
Enhance healthcare provider communication
Potentially reduce diagnosis time
Target populations for precision therapies
Support care management and health initiatives
Select patients for clinical trial enrollment

Why ICD Codes Matter

Without a specific ICD code, rare disorders can be difficult to:

identify in healthcare systems
count accurately
study through research
track outcomes and healthcare utilization
recruit for clinical trials
justify specialized care and services
prioritize in policy and public health efforts

In modern healthcare systems, disorders that cannot be coded are often difficult to count, study, track, reimburse, or prioritize.

Rare Epilepsies & Neurodevelopmental Disorders with ICD Recognition

Rare Epilepsies with ICD Codes

Some rare epilepsies and neurodevelopmental disorders now have disease-specific ICD codes, while others are grouped into broader categories based on shared biology or genetic mechanisms such as ion channel, glutamate receptor, developmental, or epileptic encephalopathy disorders.

The FY2026 ICD-10-CM update introduced new “QA0” codes for genetic neurodevelopmental disorders - an important milestone that begins recognizing some conditions by their underlying genetic cause rather than only clinical symptoms. These updates reflect the growing role of genetics and precision medicine in neurology and rare disease care.

Developmental & Epileptic Encephalopathies
(DEEs)

There is not yet one single ICD category that captures all Developmental and Epileptic
Encephalopathies (DEEs).

Instead, DEEs are currently represented through a combination of:

epilepsy syndrome codes
epileptic encephalopathy codes
syndrome-specific codes
newer QA0 genetic neurodevelopmental codes

Common ICD-10-CM categories used for DEEs include:

G40.4 — Other generalized epilepsy and epileptic syndromes
G40.42 — Epileptic encephalopathy, intractable
G40.8 — Other epilepsy and recurrent seizures

Disorders Without Specific Codes

Patients become difficult to identify at scale.
Hospitals, insurers, researchers, and public health systems often rely on ICD codes to find patient populations. Without a distinct code, it becomes very hard to accurately identify how many people have a condition or where they are receiving care.
The true burden of disease is underestimated.
If individuals are scattered across nonspecific categories, healthcare utilization, mortality, costs, hospitalizations, comorbidities, and outcomes cannot be reliably measured.
Research and clinical trial recruitment become harder.
Researchers frequently use coded datasets and electronic medical records to identifyeligible patients. Lack of coding specificity can slow natural history studies, observational research, and trial readiness.
Health systems and policymakers may not “see” the disorder.
Many policy, reimbursement, and public health decisions are data-driven. Disorders
without distinct coding may appear smaller, less prevalent, or less burdensome than they truly are.
Insurance and reimbursement challenges can arise.
Precise coding can help justify specialized testing, therapies, multidisciplinary care,
durable medical equipment, and other services.
Rare disease ecosystems increasingly depend on data infrastructure.
Precision medicine, AI-enabled research, outcomes tracking, registries, and real-world
evidence all rely heavily on structured diagnostic coding.

Many rare epilepsies still do not have individualized ICD codes.Historically, these disorders
were often grouped under broad categories such as:

“other epilepsy”
“developmental delay”
“metabolic disorder”
“chromosomal abnormality”

While this does not prevent progress, it can limit visibility within:

healthcare systems
research databases
epidemiology
reimbursement systems
public health reporting

The newer QA0 codes represent important progress toward better recognition of genetically defined rare epilepsies.

ICD-9, ICD-10 & ICD-11: What’s the Difference?

ICD-9, ICD-10, and ICD-11 are different generations of the International Classification of
Diseases system.

Each version expanded and modernized disease classification to reflect advances in:

medicine
genomics
digital health systems
precision medicine

ICD-9

Older system with fewer and less specific codes.

ICD-10

Much more detailed system currently used in the United States for healthcare and billing.

ICD-11

Newest World Health Organization system with major advances for:

rare disease classification
genomic medicine
precision neurology
digital interoperability

Why the U.S. Still Uses ICD-10

Although the World Health Organization released ICD-11 in 2022, the United States still
primarily uses ICD-10-CM.

Transitioning to ICD-11 is extremely complex and requires updating:

insurance systems
hospital billing infrastructure
electronic medical records
regulatory systems
reimbursement systems nationwide

The U.S. transition from ICD-9 to ICD-10 took more than 20 years and was not completed until 2015. Federal agencies including the CDC and CMS are actively studying ICD-11, but there is currently no official nationwide implementation timeline.

Why ICD-11 Matters for Rare Epilepsies

ICD-11 is especially important for rare disease communities because it:

greatly expands rare disease representation
better supports genomic medicine
improves precision medicine classification
allows more detailed phenotyping
improves interoperability between health systems
is better designed for modern research and data systems

Who Decides Which Codes Are Added?

In the United States, new ICD-10-CM diagnosis codes are reviewed by the ICD-10 Coordination and Maintenance (C&M) Committee.

The committee is jointly overseen by:

the Centers for Disease Control and Prevention (CDC)
the Centers for Medicare & Medicaid Services (CMS)

The committee continues to actively review proposals for new rare disease and
neurodevelopmental disorder codes through public meetings and stakeholder input.

Looking Ahead

The growing recognition of rare epilepsies within ICD systems represents more than
administrative coding changes. It is an important step toward:

better visibility
improved care coordination
stronger research infrastructure
enhanced clinical trial readiness
more accurate epidemiology
and ultimately better outcomes for individuals and families living with rare epilepsies and neurodevelopmental disorders
and future regulatory and reimbursement pathways