ICD-10-CM Tabular Index · Chapter 6 · FY 2026 G40–G47
Episodic and paroxysmal disorders (G40-G47) ICD-10-CM
The G40–G47 section covers episodic and paroxysmal disorders with 307 ICD-10-CM diagnosis codes, of which 205 are billable in fiscal year 2026. The section is organized into the 6 code ranges listed below.
✓ Built from the official CMS FY 2026 datasetEffective Oct 1, 2025 – Sep 30, 2026
The info icon previews the code ranges inside each row and its instructional notations from the official Tabular List.
About the G40–G47 Code Range
ICD-10 codes G40-G47 cover a spectrum of episodic and paroxysmal disorders primarily related to epilepsy, migraine, headache syndromes, transient cerebral ischemic attacks, vascular brain syndromes, and sleep disorders. These codes specify conditions such as different types of epileptic seizures, syndromes like Lennox-Gastaut and Dravet, various migraines, and specific sleep disturbances.
This range starts with G40, detailing epileptic disorders including focal, generalized, symptomatic, and idiopathic epilepsy, with distinctions for intractability and presence of status epilepticus. Synonyms like Motor function seizures, Rolandic epilepsy, and Temporal lobe epilepsy correspond to specific codes, assisting coders in precise classification. Migraines (G43) are broken down by aura presence, chronicity, and variants such as menstrual and hemiplegic migraine, with terms like status migrainosus and atypical absence seizure helping clarify coding choices. Headache syndromes (G44) include cluster headaches, tension-type headaches, and post-traumatic types, with syndromes like hemicrania continua highlighted. Transient cerebral ischemic attacks and related syndromes (G45) cover conditions like vertebrobasilar artery syndrome and amaurosis fugax, critical for coding transient brain ischemia. Vascular syndromes of the brain (G46) address stroke syndromes affecting specific cerebral arteries and lacunar syndromes. Finally, sleep disorders (G47) include insomnia, hypersomnia, circadian rhythm disorders, sleep apnea, narcolepsy with or without cataplexy, parasomnias, and sleep-related movement disorders, incorporating recognized synonym phrases such as Kleine-Levin syndrome and sleep bruxism, guiding accurate coding for sleep medicine.
Questions About This Page
How many codes are in the G40-G47 range?
The G40-G47 range contains 307 ICD-10-CM diagnosis codes in FY 2026. 205 of them are billable, and the rest are category headers that organize the section.
What conditions does G40-G47 cover?
The range covers episodic and paroxysmal disorders. The code ranges listed above break it into groups of related conditions, and each one links to its own page with the full code list.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
the following terms are to be considered equivalent to intractable: pharmacoresistant (pharmacologically resistant), treatment resistant, refractory (medically) and poorly controlled
The “use additional code” indicates that a secondary code could be used to further specify the patient’s condition. This note is not mandatory and is only used if enough information is available to assign an additional code.
code for adverse effect, if applicable, to identify drug T36T50
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
the following terms are to be considered equivalent to intractable: pharmacoresistant (pharmacologically resistant), treatment resistant, refractory (medically) and poorly controlled
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
