DxCodebookFY2027 · Oct 1, 2026 – Sep 30, 2027

Category · FY2027

G31 Other degenerative diseases of nervous system, not elsewhere classified

  • Header · not billable

G31 is not billable. The category heads 14 billable codes in FY2027, grouped under 5 subdivisions.

ICD-10 code by name

What is the ICD-10 code for Lewy body dementia?
Lewy body dementia ICD-10 code: G31.83 Neurocognitive disorder with Lewy bodies. Tabular List, inclusion term at G31.83: Lewy body dementia. Search ICD-10 for Lewy body dementia
What is the ICD-10 code for frontotemporal dementia?
Frontotemporal dementia ICD-10 code: G31.09 Other frontotemporal neurocognitive disorder. Alphabetic Index: Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)frontotemporal → G31.09. Search ICD-10 for frontotemporal dementia

Where it sits

  1. Chapter 6 Diseases of the nervous system (G00-G99)
  2. G30-G32 Other degenerative diseases of the nervous system (G30-G32)
  3. G31 Other degenerative diseases of nervous system, not elsewhere classified
Billable codes
14
Subdivisions
5
CC / MCC codes
2 / 0
HCC V28 codes
7
New FY2027
0
Index entries
82

Codes in G31

  1. G31.0
    Frontotemporal dementia
    Header
  2. G31.01
    Pick's disease
    Billable127
    Inclusion terms 2

    Inclusion terms

    • Primary progressive aphasia
    • Progressive isolated aphasia
  3. G31.09
    Other frontotemporal neurocognitive disorder
    Billable127
    Inclusion terms 1, Use additional code 1

    Inclusion terms

    • Frontal dementia

    Use additional code

    • code, if applicable, to identify mild neurocognitive disorders due to known physiological condition (F06.7-) F06.7
  4. G31.1
    Senile degeneration of brain, not elsewhere classified
    Billable
    Excludes1 2

    Excludes1

    • Alzheimer's disease (G30.-) G30
    • senility NOS (R41.81) R41.81
  5. G31.2
    Degeneration of nervous system due to alcohol
    Billable
    Inclusion terms 5, Code also 1

    Inclusion terms

    • Alcoholic cerebellar ataxia
    • Alcoholic cerebellar degeneration
    • Alcoholic cerebral degeneration
    • Alcoholic encephalopathy
    • Dysfunction of the autonomic nervous system due to alcohol

    Code also

    • associated alcoholism (F10.-) F10
  6. G31.8
    Other specified degenerative diseases of nervous system
    Header
  7. G31.80
    Leukodystrophy, unspecified
    Billable200
  8. G31.81
    Alpers disease
    BillableCC127
    Inclusion terms 1

    Inclusion terms

    • Grey-matter degeneration
  9. G31.82
    Leigh's disease
    BillableCC127
    Inclusion terms 1

    Inclusion terms

    • Subacute necrotizing encephalopathy
  10. G31.83
    Neurocognitive disorder with Lewy bodies
    Billable127
    Inclusion terms 2, Use additional code 1

    Inclusion terms

    • Lewy body dementia
    • Lewy body disease

    Use additional code

    • code, if applicable, to identify mild neurocognitive disorders due to known physiological condition (F06.7-) F06.7
  11. G31.84
    Mild cognitive impairment of uncertain or unknown etiology
    Billable
    Inclusion terms 2, Excludes1 11, Use additional code 8

    Inclusion terms

    • Mild cognitive disorder NOS
    • Mild neurocognitive disorder of uncertain or unknown etiology

    Excludes1

    • age related cognitive decline (R41.81) R41.81
    • altered mental status (R41.82) R41.82
    • cerebral degeneration (G31.9) G31.9
    • cerebrovascular diseases (I60-I69) I60 I69
    • change in mental status (R41.82) R41.82
    • cognitive deficits following (sequelae of) cerebral hemorrhage or infarction (I69.01-, I69.11-, I69.21-, I69.31-, I69.81-, I69.91-) I69.01 I69.11 I69.21 I69.31 I69.81 I69.91
    • cognitive impairment due to intracranial or head injury (S06.-) S06
    • dementia (F01.-, F02.-, F03.-) F01 F02 F03
    • mild neurocognitive disorder due to a known physiological condition (F06.7-) F06.7
    • neurologic neglect syndrome (R41.4) R41.4
    • personality change, nonpsychotic (F68.8) F68.8

    Use additional code

    • code to identify presence of:
    • alcohol abuse and dependence (F10.-) F10
    • exposure to environmental tobacco smoke (Z77.22) Z77.22
    • history of tobacco dependence (Z87.891) Z87.891
    • hypertension (I10-I1A) I10 I1A
    • occupational exposure to environmental tobacco smoke (Z57.31) Z57.31
    • tobacco dependence (F17.-) F17
    • tobacco use (Z72.0) Z72.0
  12. G31.85
    Corticobasal degeneration
    Billable
  13. G31.86
    Alexander disease
    Billable127
  14. G31.87
    Primary progressive apraxia of speech
    Billable
  15. G31.89
    Other specified degenerative diseases of nervous system
    Billable
  16. G31.9
    Degenerative disease of nervous system, unspecified
    Billable

CC/MCC: as a secondary diagnosis, unless the principal diagnosis is on the code’s PDX exclusion list (MS-DRG v44 Appendix C; list on the code card).

Sources of each column.

Instructions

At G31

Excludes2

  • Reye's syndrome (G93.7) G93.7

Use additional code

Notes that also apply

Chapter 6 instructions (Excludes2 8): printed on the chapter 6 page.

Index entries

  • Leukodystrophy → G31.80
  • Alpers' disease → G31.81
  • Leigh's disease → G31.82
  • Lewy body(ies) (disease) → G31.83
  • Seitelberger's syndrome (infantile neuraxonal dystrophy) → G31.89
  • Aphasia (amnestic) (global) (nominal) (semantic) (syntactic)primary progressive → G31.01 [F02.80]
  • Aphasia (amnestic) (global) (nominal) (semantic) (syntactic)progressive isolated → G31.01 [F02.80]
  • Disease, diseasedPick's → G31.01 [F02.80]
  • Pick'scerebral atrophy → G31.01 [F02.80]
  • Pick'sdisease or syndrome (brain) → G31.01 [F02.80]
  • Atrophy, atrophic (of)sclerosis, lobar (of brain) → G31.09 [F02.80]
  • Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)frontal (lobe) → G31.09 [F02.80]
  • Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)frontotemporal → G31.09 [F02.80]
  • Degeneration, degenerativemotor centers, senile → G31.1
  • Encephalopathy (acute)alcoholic → G31.2
  • Degeneration, degenerativegrey matter (brain) (Alpers') → G31.81
  • Encephalopathy (acute)necrotizing, subacute (Leigh) → G31.82
  • Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)Lewy body → G31.83 [F02.80]
  • Disease, diseasedLewy body (dementia) → G31.83 [F02.80]
  • Disorder (of)mild neurocognitive → G31.84
  • Impaired, impairment (function)cognitive, mild, of uncertain or unknown etiology → G31.84
  • Impaired, impairment (function)mild cognitive → G31.84
  • Degeneration, degenerativecorticobasal → G31.85
  • Disease, diseasedAlexander → G31.86
  • Apraxia (classic) (ideational) (ideokinetic) (ideomotor) (motor) (verbal)primary progressive, of speech → G31.87
  • Degeneration, degenerativecortical (cerebellar) (parenchymatous) → G31.89
  • Degeneration, degenerativespinal (cord) → G31.89
  • Dystrophy, dystrophiainfantile neuraxonal → G31.89
  • SyndromeSeitelberger's → G31.89
  • Atrophy, atrophic (of)brain (cortex) (progressive) → G31.9
  • Degeneration, degenerativebrain (cortical) (progressive) → G31.9
  • Degeneration, degenerativecerebellar NOS → G31.9
  • Degeneration, degenerativenervous system → G31.9
  • Hemiatrophycerebellar → G31.9
  • Aphasia (amnestic) (global) (nominal) (semantic) (syntactic)primary progressivewith behavioral disturbance → G31.01 [F02.81-]
  • Aphasia (amnestic) (global) (nominal) (semantic) (syntactic)progressive isolatedwith behavioral disturbance → G31.01 [F02.81-]
  • Atrophy, atrophic (of)brain (cortex) (progressive)frontotemporal circumscribed → G31.01 [F02.80]
  • Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)in (due to)Pick's → G31.01 [F02.80]
  • Disease, diseasedPick'swith behavioral disturbance → G31.01 [F02.81-]
  • Disease, diseasedPick'sbrain → G31.01 [F02.80]

42 more, longer entries are not listed; the search box finds them by word.

NCHS Alphabetic Index. Index first, then the Tabular List.

Hierarchy