2026 ICD-10-CM Diagnosis Code G40.109Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, not intractable, without status epilepticus

ICD-10-CM Codes›G00–G99›G40-G47›G40

ICD-10-CM G40.109
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G40.109 is a billable ICD-10-CM diagnosis code for localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, not 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Epilepsy; convulsions.

Code Identity

ICD-10-CM Code
G40.109
Billable Status
Yes — Valid for Submission
Code Describes
Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, not intractable, without status epilepticus
Short Description
Local-rel symptc epi w simp prt seiz,not ntrct, w/o stat epi
Parent Code
G40.10
Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, not intractable

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG40-G47Episodic and paroxysmal disorders
CategoryG40Epilepsy and recurrent seizures
This CodeG40.109Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, not intractable, without status epilepticus

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Amygdalo-hippocampal temporal lobe epilepsy
  • Anterior frontopolar frontal lobe epilepsy
  • Atonic epileptic seizure
  • Benign focal seizure of adolescence
  • Benign infantile focal epilepsy with midline spikes and waves during sleep
  • Benign occipital lobe epilepsy
  • Cingulate frontal lobe epilepsy
  • Clonic epileptic seizure
  • Dorsolateral frontal lobe epilepsy
  • Epilepsy of infancy with migrating focal seizures
  • Epileptic spasms
  • Familial focal epilepsy with variable foci
  • Familial sleep-related hypermotor epilepsy
  • Focal epilepsy, intellectual disability, cerebro-cerebellar malformation syndrome
  • Focal onset atonic epileptic seizure
  • Focal onset automatism epileptic seizure
  • Focal onset autonomic epileptic seizure
  • Focal onset aware atonic epileptic seizure
  • Focal onset aware automatism epileptic seizure
  • Focal onset aware autonomic epileptic seizure
  • Focal onset aware behavior arrest epileptic seizure
  • Focal onset aware clonic epileptic seizure
  • Focal onset aware cognitive epileptic seizure
  • Focal onset aware emotional epileptic seizure
  • Focal onset aware epileptic seizure
  • Focal onset aware hyperkinetic epileptic seizure
  • Focal onset aware motor onset epileptic seizure
  • Focal onset aware motor onset Jacksonian epileptic seizure
  • Focal onset aware myoclonic epileptic seizure
  • Focal onset aware nonmotor onset epileptic seizure
  • Focal onset aware sensory epileptic seizure
  • Focal onset aware tonic epileptic seizure
  • Focal onset behavior arrest epileptic seizure
  • Focal onset clonic epileptic seizure
  • Focal onset cognitive epileptic seizure
  • Focal onset cognitive epileptic seizure with illusions
  • Focal onset cognitive epileptic seizure with memory impairment
  • Focal onset emotional epileptic seizure
  • Focal onset epileptic seizure
  • Focal onset epileptic spasms
  • Focal onset hyperkinetic epileptic seizure
  • Focal onset motor onset epileptic seizure
  • Focal onset motor onset versive epileptic seizure
  • Focal onset myoclonic epileptic seizure
  • Focal onset nonmotor onset epileptic seizure
  • Focal onset sensory epileptic seizure
  • Focal onset sensory epileptic seizure with gustatory symptoms
  • Focal onset somatosensory epileptic seizure
  • Focal onset tonic epileptic seizure
  • Frontal lobe epilepsy
  • Mesial temporal lobe epilepsy
  • Mesial temporal lobe epilepsy with hippocampal sclerosis
  • Mesiobasal limbic temporal lobe epilepsy
  • Myoclonic epileptic seizure
  • Occipital lobe epilepsy
  • Opercular frontal lobe epilepsy
  • Orbitofrontal frontal lobe epilepsy
  • Primary motor cortex frontal lobe epilepsy
  • Self-limited familial infantile epilepsy
  • Self-limited infantile epilepsy
  • Sleep-related hypermotor epilepsy
  • Supplementary motor cortex frontal lobe epilepsy
  • Tonic epileptic seizure

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures NOS

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.

    • Epilepsy, epileptic, epilepsia(attack) (cerebral) (convulsion) (fit) (seizure)
      • localization-related (focal) (partial)
        • symptomatic
          • with simple partial seizures
    • Epilepsy, epileptic, epilepsia(attack) (cerebral) (convulsion) (fit) (seizure)
      • localization-related (focal) (partial)
        • symptomatic
          • with simple partial seizures
            • not intractable
    • Epilepsy, epileptic, epilepsia(attack) (cerebral) (convulsion) (fit) (seizure)
      • localization-related (focal) (partial)
        • symptomatic
          • with simple partial seizures
            • not intractable
              • without status epilepticus
    • Epilepsy, epileptic, epilepsia(attack) (cerebral) (convulsion) (fit) (seizure)
      • syndromes
        • localization-related (focal) (partial)
          • symptomatic
            • with simple partial seizures
    • Epilepsy, epileptic, epilepsia(attack) (cerebral) (convulsion) (fit) (seizure)
      • syndromes
        • localization-related (focal) (partial)
          • symptomatic
            • with simple partial seizures
              • not intractable
    • Epilepsy, epileptic, epilepsia(attack) (cerebral) (convulsion) (fit) (seizure)
      • syndromes
        • localization-related (focal) (partial)
          • symptomatic
            • with simple partial seizures
              • not intractable
                • without status epilepticus
    • Kozhevnikof's epilepsy
    • Kozhevnikof's epilepsy
      • not intractable
    • Kozhevnikof's epilepsy
      • not intractable
        • without status epilepticus

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 G40.109 to ICD-9-CMHistory

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

ICD-9-CM
345.50 Part epil w/o intr epil
Approximate The match is approximate rather than exact.
ICD-9-CM
345.70 Epil par cont w/o int ep
Approximate The match is approximate rather than exact.
ICD-9-CM
345.80 Epilep NEC w/o 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 G40.109Overview

Is G40.109 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, not intractable, without status epilepticus on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does G40.109 group to?

When localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, not 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 G40.109?

Under the General Equivalence Mappings, localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, not intractable, without status epilepticus converts to ICD-9-CM 345.50 (part epil w/o intr epil), 345.70 (epil par cont w/o int ep), and 345.80 (epilep NEC w/o 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.