G40.509 Epileptic seizures related to external causes, not intractable, without status epilepticus

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applicable to

• Epileptic seizures related to external causes, NOS

Applies from G40 Epilepsy and recurrent seizures

Excludes1 (never code together)

• conversion disorder with seizures (F44.5)
• convulsions NOS (R56.9)
• post traumatic seizures (R56.1)
• seizure (convulsive) NOS (R56.9)
• seizure of newborn (P90)

Excludes2 (not included here)

• hippocampal sclerosis (G93.81)
• mesial temporal sclerosis (G93.81)
• temporal sclerosis (G93.81)
• Todd's paralysis (G83.84)

Notes

• the following terms are to be considered equivalent to intractable: pharmacoresistant (pharmacologically resistant), treatment resistant, refractory (medically) and poorly controlled

Applies from G40.5 Epileptic seizures related to external causes

Applicable to

• Epileptic seizures related to alcohol
• Epileptic seizures related to drugs
• Epileptic seizures related to hormonal changes
• Epileptic seizures related to sleep deprivation
• Epileptic seizures related to stress

Use additional code

• code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)

Code also

• , if applicable, associated epilepsy and recurrent seizures (G40.-)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 201 — Seizure Disorders and Convulsions
• CMS-HCC V22: HCC 79 — Seizure Disorders and Convulsions
• RxHCC V08: HCC 164 — Epilepsy and Other Seizure Disorders, Except Intractable Epilepsy
• ESRD V24: HCC 79

MS-DRG index

Defines the logic of DRG(s) 023 in MDC 01.

Approximate ICD-9-CM (GEMs)

• 345.80 Other forms of epilepsy and recurrent seizures, without mention of intractable epilepsy (approximate)

Code annotations containing back-references to G40.509

Back-references to G40

• Code Also: E20.810 Autosomal dominant hypocalcemia ("seizure disorder (G40.-, R56.9)")
• Code First: F02 Dementia in other diseases classified elsewhere ("epilepsy and recurrent seizures (G40.-)")
• Type 2 Excludes: F44.0 Dissociative amnesia ("postictal amnesia in epilepsy (G40.-)")
• Type 2 Excludes: F44.1 Dissociative fugue ("postictal fugue in epilepsy (G40.-)")
• Code Also: F78.A1 SYNGAP1-related intellectual disability ("epilepsy and recurrent seizures (G40.-)")
• Code Also: G04.8 Other encephalitis, myelitis and encephalomyelitis ("any associated seizure (G40.-, R56.9)")
• Type 1 Excludes: G25.3 Myoclonus ("myoclonic epilepsy (G40.-)")
• Code Also: G40.5 Epileptic seizures related to external causes (", if applicable, associated epilepsy and recurrent seizures (G40.-)")
• Code Also: G43.1 Migraine with aura ("any associated seizure (G40.-, R56.9)")
• Code Also: G93.45 Developmental and epileptic encephalopathy ("epilepsy, by specific type (G40.-)")
• Code Also: I67.850 Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy ("epilepsy (G40.-)")
• Code Also: Q87.85 MED13L syndrome ("epilepsy and recurrent seizures (G40.-)")
• Use Additional: Q87.87 Hao-Fountain Syndrome ("epilepsy, by specific type (G40.-)")
• Use Additional: Q93.52 Phelan-McDermid syndrome ("epilepsy and recurrent seizures (G40.-)")
• Code Also: QA0 Neurodevelopmental disorders related to specific genetic pathogenic variants ("epilepsy, by specific type (G40.-)")
• Type 1 Excludes: R56 Convulsions, not elsewhere classified ("epileptic convulsions and seizures (G40.-)")
• Type 1 Excludes: R56.1 Post traumatic seizures ("post traumatic epilepsy (G40.-)")
• Code Also: Z15.1 Genetic susceptibility to epilepsy and neurodevelopmental disorders ("epilepsy, by specific type (G40.-)")

Diagnosis Index entries for G40.509

• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › alcohol
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › alcohol › not intractable
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › alcohol › not intractable › without status epilepticus
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › drugs
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › drugs › not intractable
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › drugs › not intractable › without status epilepticus
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › external causes
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › external causes › not intractable
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › external causes › not intractable › without status epilepticus
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › hormonal changes
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › hormonal changes › not intractable
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › hormonal changes › not intractable › without status epilepticus
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › sleep deprivation
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › sleep deprivation › not intractable
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › sleep deprivation › not intractable › without status epilepticus
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › stress
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › stress › not intractable
• Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) › related to › stress › not intractable › without status epilepticus

Nearby codes

• G40.419 Other generalized epilepsy and epileptic syndromes, intractable, without status epilepticus
• G40.42 Cyclin-Dependent Kinase-Like 5 Deficiency Disorder
• G40.5 Epileptic seizures related to external causes
• G40.50 Epileptic seizures related to external causes, not intractable
• G40.501 Epileptic seizures related to external causes, not intractable, with status epilepticus
• G40.509 Epileptic seizures related to external causes, not intractable, without status epilepticus (this code)
• G40.8 Other epilepsy and recurrent seizures
• G40.80 Other epilepsy
• G40.801 Other epilepsy, not intractable, with status epilepticus
• G40.802 Other epilepsy, not intractable, without status epilepticus
• G40.803 Other epilepsy, intractable, with status epilepticus