1. ICD-10-CM Codes
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2. G00-G99 Diseases of the nervous system
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3. G40-G47 Episodic and paroxysmal disorders
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4. G40- Epilepsy and recurrent seizures
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5. 2021 ICD-10-CM Diagnosis Code G40

2021 ICD-10-CM Diagnosis Code G40

Epilepsy and recurrent seizures

2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code

• G40 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail.
• The 2021 edition of ICD-10-CM G40 became effective on October 1, 2020.
• This is the American ICD-10-CM version of G40 - other international versions of ICD-10 G40 may differ.

• A brain disorder characterized by episodes of abnormally increased neuronal discharge resulting in transient episodes of sensory or motor neurological dysfunction, or psychic dysfunction. These episodes may or may not be associated with loss of consciousness or convulsions.
• A disorder characterized by recurrent episodes of paroxysmal brain dysfunction due to a sudden, disorderly, and excessive neuronal discharge. Epilepsy classification systems are generally based upon: (1) clinical features of the seizure episodes (e.g., motor seizure), (2) etiology (e.g., post-traumatic), (3) anatomic site of seizure origin (e.g., frontal lobe seizure), (4) tendency to spread to other structures in the brain, and (5) temporal patterns (e.g., nocturnal epilepsy). (from Adams et al., Principles of Neurology, 6th ed, p313)
• A disorder characterized by recurrent seizures
• A group of disorders marked by problems in the normal functioning of the brain. These problems can produce seizures, unusual body movements, a loss of consciousness or changes in consciousness, as well as mental problems or problems with the senses.
• Brain disorder characterized by recurring excessive neuronal discharge, exhibited by transient episodes of motor, sensory, or psychic dysfunction, with or without unconsciousness or convulsive movements.
• 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. Epilepsy has many possible causes, including illness, brain injury and abnormal brain development. In many cases, the cause is unknown.doctors use brain scans and other tests to diagnose epilepsy. It is important to start treatment right away. There is no cure for epilepsy, but medicines can control seizures for most people. When medicines are not working well, surgery or implanted devices such as vagus nerve stimulators may help. Special diets can help some children with epilepsy.

• 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
• 2017 (effective 10/1/2016): No change
• 2018 (effective 10/1/2017): No change
• 2019 (effective 10/1/2018): No change
• 2020 (effective 10/1/2019): No change
• 2021 (effective 10/1/2020): No change

• Code Also: G04.8
  , G43.1
  , G40.5
  , I67.850
  ICD-10-CM Diagnosis Code G04.8

  Other encephalitis, myelitis and encephalomyelitis

  2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code

  Code Also

  • any associated seizure (G40.-, R56.9)
  ICD-10-CM Diagnosis Code G43.1

  Migraine with aura

  2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code

  Applicable To

  • Basilar migraine
  • Classical migraine
  • Migraine equivalents
  • Migraine preceded or accompanied by transient focal neurological phenomena
  • Migraine triggered seizures
  • Migraine with acute-onset aura
  • Migraine with aura without headache (migraine equivalents)
  • Migraine with prolonged aura
  • Migraine with typical aura
  • Retinal migraine

  Code Also

  • any associated seizure (G40.-, R56.9)

  Type 1 Excludes

  • persistent migraine aura (G43.5-, G43.6-)
  ICD-10-CM Diagnosis Code G40.5

  Epileptic seizures related to external causes

  2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code

  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

  Code Also

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

  Use Additional

  • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  ICD-10-CM Diagnosis Code I67.850

  Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy

  2019 - New Code 2020 2021 Billable/Specific Code

  Applicable To

  • CADASIL

  Code Also

  • any associated diagnoses, such as:
  • epilepsy (G40.-)
  • stroke (I63.-)
  • vascular dementia (F01.-)
• Code First: F02
  ICD-10-CM Diagnosis Code F02

  Dementia in other diseases classified elsewhere

  2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code

  Code First

  • the underlying physiological condition, such as:
  • Alzheimer's (G30.-)
  • cerebral lipidosis (E75.4)
  • Creutzfeldt-Jakob disease (A81.0-)
  • dementia with Lewy bodies (G31.83)
  • dementia with Parkinsonism (G31.83)
  • epilepsy and recurrent seizures (G40.-)
  • frontotemporal dementia (G31.09)
  • hepatolenticular degeneration (E83.0)
  • human immunodeficiency virus [HIV] disease (B20)
  • Huntington's disease (G10)
  • hypercalcemia (E83.52)
  • hypothyroidism, acquired (E00-E03.-)
  • intoxications (T36-T65)
  • Jakob-Creutzfeldt disease (A81.0-)
  • multiple sclerosis (G35)
  • neurosyphilis (A52.17)
  • niacin deficiency [pellagra] (E52)
  • Parkinson's disease (G20)
  • Pick's disease (G31.01)
  • polyarteritis nodosa (M30.0)
  • prion disease (A81.9)
  • systemic lupus erythematosus (M32.-)
  • traumatic brain injury (S06.-)
  • trypanosomiasis (B56.-, B57.-)
  • vitamin B deficiency (E53.8)

  Includes

  • Major neurocognitive disorder in other diseases classified elsewhere

  Type 2 Excludes

  • dementia in alcohol and psychoactive substance disorders (F10-F19, with .17, .27, .97)
  • vascular dementia (F01.5-)
• Type 1 Excludes: R56
  , R56.1
  , G25.3
  ICD-10-CM Diagnosis Code R56

  Convulsions, not elsewhere classified

  2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code

  Type 1 Excludes

  • dissociative convulsions and seizures (F44.5)
  • epileptic convulsions and seizures (G40.-)
  • newborn convulsions and seizures (P90)
  ICD-10-CM Diagnosis Code R56.1

  Post traumatic seizures

  2016 2017 2018 2019 2020 2021 Billable/Specific Code

  Type 1 Excludes

  • post traumatic epilepsy (G40.-)
  ICD-10-CM Diagnosis Code G25.3

  Myoclonus

  2016 2017 2018 2019 2020 2021 Billable/Specific Code

  Applicable To

  • Drug-induced myoclonus
  • Palatal myoclonus

  Type 1 Excludes

  • facial myokymia (G51.4)
  • myoclonic epilepsy (G40.-)

  Use Additional

  • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
• Type 2 Excludes: F44.0
  , F44.1
  ICD-10-CM Diagnosis Code F44.0

  Dissociative amnesia

  2016 2017 2018 2019 2020 2021 Billable/Specific Code

  Type 1 Excludes

  • amnesia NOS (R41.3)
  • anterograde amnesia (R41.1)
  • dissociative amnesia with dissociative fugue (F44.1)
  • retrograde amnesia (R41.2)

  Type 2 Excludes

  • alcohol-or other psychoactive substance-induced amnestic disorder (F10, F13, F19 with .26, .96)
  • amnestic disorder due to known physiological condition (F04)
  • postictal amnesia in epilepsy (G40.-)
  ICD-10-CM Diagnosis Code F44.1

  Dissociative fugue

  2016 2017 2018 2019 2020 2021 Billable/Specific Code

  Applicable To

  • Dissociative amnesia with dissociative fugue

  Type 2 Excludes

  • postictal fugue in epilepsy (G40.-)

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.