G31.86 Alexander disease

Billable ICD-10-CM code, FY2026.

Applies from G31 Other degenerative diseases of nervous system, not elsewhere classified

Excludes2 (not included here)

• Reye's syndrome (G93.7)

Use additional code

• code, if applicable, for codes G31.0-G31.83, G31.85-G31.9, to identify:
• dementia with anxiety (F02.84, F02.A4, F02.B4, F02.C4)
• dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)
• dementia with mood disturbance (F02.83, F02.A3, F02.B3, F02.C3)
• dementia with psychotic disturbance (F02.82, F02.A2, F02.B2, F02.C2)
• dementia without behavioral disturbance (F02.80, F02.A0, F02.B0, F02.C0)
• mild neurocognitive disorder due to known physiological condition (F06.7-)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 127 — Dementia, Mild or Unspecified
• RxHCC V08: HCC 112 — Dementia, Except Alzheimer's Disease
• ESRD V24: HCC 52

MS-DRG index

Defines the logic of DRG(s) 056-057 in MDC 01.

Diagnosis Index entries for G31.86

• Disease, diseased › Alexander

Nearby codes

• G31.81 Alpers disease
• G31.82 Leigh's disease
• G31.83 Neurocognitive disorder with Lewy bodies
• G31.84 Mild cognitive impairment of uncertain or unknown etiology
• G31.85 Corticobasal degeneration
• G31.86 Alexander disease (this code)
• G31.87 Primary progressive apraxia of speech
• G31.89 Other specified degenerative diseases of nervous system
• G31.9 Degenerative disease of nervous system, unspecified