2026 ICD-10-CM Diagnosis Code G40.919Epilepsy, unspecified, intractable, without status epilepticus

ICD-10-CM Codes›G00–G99›G40-G47›G40

ICD-10-CM G40.919
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G40.919 is a billable ICD-10-CM diagnosis code for epilepsy, unspecified, intractable, without status epilepticus. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 100 through 101. Coders also document this condition as atrophy of cerebellar vermis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Epilepsy; convulsions.

Code Identity

ICD-10-CM Code
G40.919
Billable Status
Yes — Valid for Submission
Code Describes
Epilepsy, unspecified, intractable, without status epilepticus
Short Description
Epilepsy, unsp, intractable, without status epilepticus
Parent Code
G40.91
Epilepsy, unspecified, intractable

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG40-G47Episodic and paroxysmal disorders
CategoryG40Epilepsy and recurrent seizures
This CodeG40.919Epilepsy, unspecified, intractable, without status epilepticus

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Atrophy of cerebellar vermis
  • Diffuse atrophy of cerebellum
  • Diffuse atrophy of cerebrum
  • Diffuse cerebral and cerebellar atrophy, intractable seizures, progressive microcephaly syndrome
  • Global brain atrophy
  • Hereditary cerebellar atrophy
  • Polyhydramnios, megalencephaly, symptomatic epilepsy syndrome
  • Primary hypomagnesemia, refractory seizures, intellectual disability syndrome

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Disorder(of)
      • seizure
        • intractable
    • Epilepsy, epileptic, epilepsia(attack) (cerebral) (convulsion) (fit) (seizure)
      • intractable
    • Epilepsy, epileptic, epilepsia(attack) (cerebral) (convulsion) (fit) (seizure)
      • intractable
        • without status epilepticus
    • Seizure(s)
      • intractable

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS009
Epilepsy; convulsions
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Epilepsy

Epilepsy is a brain disorder that causes people to have recurring seizures. The seizures happen when clusters of nerve cells, or neurons, in the brain send out the wrong signals. People may have strange sensations and emotions or behave strangely. They may have violent muscle spasms or lose consciousness.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert G40.919 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
345.91 Epilepsy NOS w intr epil
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About G40.919Overview

Is G40.919 (Epilepsy, unspecified, intractable) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report epilepsy, unspecified, intractable, without status epilepticus on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does G40.919 group to?

When epilepsy, unspecified, intractable, without status epilepticus is the principal diagnosis on an inpatient stay, it groups to MS-DRG 100, 101, with relative weights from 0.9026 to 1.9368 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of G40.919?

Under the General Equivalence Mappings, epilepsy, unspecified, intractable, without status epilepticus converts to ICD-9-CM 345.91 (epilepsy NOS w intr epil). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.