G31.82 ICD-10-CM Code: Leigh's disease

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for G31.82 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on G31.82 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for G31.82

MedCoder structured workflow — derived from this code’s own official record

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

The conditions the Use Additional Code note names

Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

• Excludes2 — not part of G31.82(1 note)

  Coding workflow: The conditions named in this note are not included in G31.82. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  CompareG93.7

  See the official tabular notes · Guidelines I.A.12.b

• Use Additional Code — after identifying G31.82(7 notes)

  Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with G31.82 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

  ReviewF02.84, F02.A4, F02.B4, F02.C4, F02.81, F02.A1

  See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (2)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Encephalopathy (acute), necrotizing, subacute (Leigh)
• Leigh's disease

Don’t confuse G31.82 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of G31.82 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• G31.80— Specificity relationship (Review)

  Overlapping diagnoses in the same category.

  Overlapping codes in the same category — the documentation decides which is the more specific fit.

  What moves you there: A record that documents no more than “Leukodystrophy, unspecified” takes G31.80; specificity in the record moves it back here.

  Full comparison: G31.82 vs G31.80 →

• G93.7— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of Reye's syndrome adds G93.7; it is not part of this code and both may be reported when both are documented.

  Full comparison: G31.82 vs G93.7 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name G31.82 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 3 Excludes1 notes across 2 chapters: E74.4 — Disorders of pyruvate metabolism and gluconeogenesis, E88.4 — Mitochondrial metabolism disorders, G71.3 — Mitochondrial myopathy, not elsewhere classified.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 26 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 056 (MDC 01), DRG 057 (MDC 01).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):NVS006 — Other nervous system disorders (often hereditary or degenerative) (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

E75.11 — Mucolipidosis IV, E75.19 — Other gangliosidosis, E75.4 — Neuronal ceroid lipofuscinosis, F84.2 — Rett's syndrome, G30.0 — Alzheimer's disease with early onset, G30.1 — Alzheimer's disease with late onset, G30.8 — Other Alzheimer's disease, G30.9 — Alzheimer's disease, unspecified, G31.01 — Pick's disease, G31.09 — Other frontotemporal neurocognitive disorder, G31.1 — Senile degeneration of brain, not elsewhere classified, G31.2 — Degeneration of nervous system due to alcohol, G31.80 — Leukodystrophy, unspecified, G31.81 — Alpers disease, G31.84 — Mild cognitive impairment of uncertain or unknown etiology, G31.85 — Corticobasal degeneration, G31.86 — Alexander disease, G31.87 — Primary progressive apraxia of speech, G31.89 — Other specified degenerative diseases of nervous system, G31.9 — Degenerative disease of nervous system, unspecified, +5 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Dementia, Mild or Unspecified) for risk-adjusted payment.

F03.A2 — Unspecified dementia, mild, with psychotic disturbance, F03.A3 — Unspecified dementia, mild, with mood disturbance, F03.A4 — Unspecified dementia, mild, with anxiety, G30.0 — Alzheimer's disease with early onset, G30.1 — Alzheimer's disease with late onset, G30.8 — Other Alzheimer's disease, G30.9 — Alzheimer's disease, unspecified, G31.01 — Pick's disease, G31.09 — Other frontotemporal neurocognitive disorder, G31.81 — Alpers disease, G31.83 — Neurocognitive disorder with Lewy bodies, G31.86 — Alexander disease, G91.0 — Communicating hydrocephalus, G91.1 — Obstructive hydrocephalus, G91.2 — (Idiopathic) normal pressure hydrocephalus, G91.3 — Post-traumatic hydrocephalus, unspecified, G91.4 — Hydrocephalus in diseases classified elsewhere, G91.8 — Other hydrocephalus, G91.9 — Hydrocephalus, unspecified, G93.7 — Reye's syndrome, +44 more

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Dementia, Severe, Dementia, Moderate

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Other nervous system disorders (often hereditary or degenerative)).

G25.79 — Other drug induced movement disorders, G25.81 — Restless legs syndrome, G25.82 — Stiff-man syndrome, G25.83 — Benign shuddering attacks, G25.89 — Other specified extrapyramidal and movement disorders, G25.9 — Extrapyramidal and movement disorder, unspecified, G26 — Extrapyramidal and movement disorders in diseases classified elsewhere, G31.2 — Degeneration of nervous system due to alcohol, G31.80 — Leukodystrophy, unspecified, G31.81 — Alpers disease, G31.84 — Mild cognitive impairment of uncertain or unknown etiology, G31.85 — Corticobasal degeneration, G31.86 — Alexander disease, G31.87 — Primary progressive apraxia of speech, G31.89 — Other specified degenerative diseases of nervous system, G31.9 — Degenerative disease of nervous system, unspecified, G32.0 — Subacute combined degeneration of spinal cord in diseases classified elsewhere, G32.81 — Cerebellar ataxia in diseases classified elsewhere, G32.89 — Other specified degenerative disorders of nervous system in diseases classified elsewhere, G90.01 — Carotid sinus syncope, +83 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Encephalopathy”; these codes share that main term but sit in a different category of the Tabular List.

E51.2 — Wernicke's encephalopathy (Wernicke's), E52 — Niacin deficiency [pellagra] (pellagrous), E53.9 — Vitamin B deficiency, unspecified (vitamin B deficiency NEC), E56.9 — Vitamin deficiency, unspecified (in, lack of vitamin), F07.81 — Postconcussional syndrome (traumatic), G04.02 — Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis (in, vaccination), G04.30 — Acute necrotizing hemorrhagic encephalopathy, unspecified (acute necrotizing hemorrhagic), G04.31 — Postinfectious acute necrotizing hemorrhagic encephalopathy (acute necrotizing hemorrhagic, postinfectious), G04.32 — Postimmunization acute necrotizing hemorrhagic encephalopathy (acute necrotizing hemorrhagic, postimmunization), G04.39 — Other acute necrotizing hemorrhagic encephalopathy (acute necrotizing hemorrhagic, specified NEC), G32.89 — Other specified degenerative disorders of nervous system in diseases classified elsewhere (degenerative, in specified disease NEC), G37.0 — Diffuse sclerosis of central nervous system (centrolobar progressive), G37.1 — Central demyelination of corpus callosum (demyelinating callosal), G92.8 — Other toxic encephalopathy (due to, drugs), G92.9 — Unspecified toxic encephalopathy (toxic), G93.40 — Encephalopathy, unspecified, G93.41 — Metabolic encephalopathy (septic), G93.45 — Developmental and epileptic encephalopathy (early infantile epileptic), G93.49 — Other encephalopathy (specified NEC), G93.89 — Other specified disorders of brain (postradiation), +20 more

Contextual Map

Every relationship of G31.82 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run G31.82 with these 3 related codes in Claim Check

Hierarchy

• G00-G99 — Chapter 6: Diseases of the Nervous System (G00-G99) (G00-G99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Excludes1 notes

• E74.4 — Disorders of pyruvate metabolism and gluconeogenesis[Excludes1]: “Leigh's syndrome (G31.82)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• E88.4 — Mitochondrial metabolism disorders[Excludes1]: “Leigh's encephalopathy (G31.82)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• G71.3 — Mitochondrial myopathy, not elsewhere classified[Excludes1]: “Leigh's encephalopathy (G31.82)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• NVS006 — Other nervous system disorders (often hereditary or degenerative)[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

Risk adjustment (CMS-HCC)

• HCC 127 — Dementia, Mild or Unspecified [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 056 — DEGENERATIVE NERVOUS SYSTEM DISORDERS WITH MCC[MS-DRG]: “DEGENERATIVE NERVOUS SYSTEM DISORDERS WITH MCC (MDC 01)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 057 — DEGENERATIVE NERVOUS SYSTEM DISORDERS WITHOUT MCC[MS-DRG]: “DEGENERATIVE NERVOUS SYSTEM DISORDERS WITHOUT MCC (MDC 01)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 01 — Diseases and Disorders of the Nervous System[MDC crossing]: “Diseases and Disorders of the Nervous System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 8,892 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Encephalopathy (acute), necrotizing, subacute (Leigh)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Leigh's disease[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (16)

• G31 — Other degenerative diseases of nervous system, not elsewhere classified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G31.0 — Frontotemporal dementia[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G31.01 — Pick's disease[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G31.09 — Other frontotemporal neurocognitive disorder[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G31.1 — Senile degeneration of brain, not elsewhere classified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G31.2 — Degeneration of nervous system due to alcohol[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G31.8 — Other specified degenerative diseases of nervous system[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G31.80 — Leukodystrophy, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 8 more

Change history

• FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Risk adjustment Official source data

2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to G31.82 in its code family, with their registry titles.

• G31.1 — Senile degeneration of brain, not elsewhere classified
• G31.2 — Degeneration of nervous system due to alcohol
• G31.8 — Other specified degenerative diseases of nervous system
• G31.80 — Leukodystrophy, unspecified
• G31.81 — Alpers 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
• G31.87 — Primary progressive apraxia of speech

View all codes in the G31 family