R27.0 ICD-10-CM Code: Ataxia, unspecified

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for R27.0 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 R27.0 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for R27.0

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

Before you code R27.0

1. Check whether an established diagnosis that explains this sign or symptom is documented. If one is, review whether the documented diagnosis changes the coding pathway: a symptom that is integral to a confirmed diagnosis is not reported separately, while one not routinely associated with it may be. Signs and symptoms are reported when no definitive diagnosis is established (Guidelines I.B.4, I.B.5, I.B.6, I.C.18.b).

   Guide: Symptom code vs confirmed diagnosis →

2. Unspecified does not mean incorrect. When the record gives no greater specificity, R27.0 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

   ReviewR27.8

   See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

3. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with R27.0. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Is an established diagnosis that explains this sign or symptom documented?
   Yes → Review whether the documented diagnosis changes the coding pathway: a symptom integral to it is not reported separately.
   No → Continue — the sign or symptom code stands when no definitive diagnosis is established.
2. Does the record document the detail a more specific sibling code needs?
   Yes → Review the specific siblings in this subcategory.
   No → Continue — R27.0 is appropriate when the documentation goes no further.

   ReviewR27.8

3. Does the documentation support a condition named in R27.0’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

   ReviewI69, R26.0, G11, R42

Consider R27.0. Then confirm the code is valid for the date of service in the Verify section.

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).

Any detail beyond this code’s title

What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

• Excludes1 — check before selecting R27.0(4 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with R27.0: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareI69, R26.0, G11, R42

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

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.

• Ataxia, ataxy, ataxic
• Lack of, coordination, ataxia

Don’t confuse R27.0 with…

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

The codes most likely to be picked instead of R27.0 — 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.

• I69— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of ataxia following cerebrovascular disease moves the case to I69; the two are not reported together unless documented as unrelated.

  Full comparison: R27.0 vs I69 →

• R26.0— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of ataxic gait moves the case to R26.0; the two are not reported together unless documented as unrelated.

  Full comparison: R27.0 vs R26.0 →

• G11— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of hereditary ataxia moves the case to G11; the two are not reported together unless documented as unrelated.

  Full comparison: R27.0 vs G11 →

• R42— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of vertigo NOS moves the case to R42; the two are not reported together unless documented as unrelated.

  Full comparison: R27.0 vs R42 →

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

• No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

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 R27.0 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 2 Excludes1 notes across 2 chapters: F82 — Specific developmental disorder of motor function (via R27.-), R26 — Abnormalities of gait and mobility.

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: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 3 MS-DRGs: DRG 091 (MDC 01), DRG 092 (MDC 01), DRG 093 (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):SYM010 — Nervous system signs and symptoms (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 category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Nervous system signs and symptoms).

R25.1 — Tremor, unspecified, R25.3 — Fasciculation, R25.8 — Other abnormal involuntary movements, R25.9 — Unspecified abnormal involuntary movements, R26.0 — Ataxic gait, R26.1 — Paralytic gait, R26.2 — Difficulty in walking, not elsewhere classified, R26.81 — Unsteadiness on feet, R26.89 — Other abnormalities of gait and mobility, R26.9 — Unspecified abnormalities of gait and mobility, R27.8 — Other lack of coordination, R27.9 — Unspecified lack of coordination, R29.0 — Tetany, R29.1 — Meningismus, R29.2 — Abnormal reflex, R29.5 — Transient paralysis, R29.810 — Facial weakness, R29.818 — Other symptoms and signs involving the nervous system, R29.90 — Unspecified symptoms and signs involving the nervous system, R40.2110 — Coma scale, eyes open, never, unspecified time, +138 more

Same Index main term, other category

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

I69.393 — Ataxia following cerebral infarction (following, cerebrovascular disease, cerebral infarction), I69.893 — Ataxia following other cerebrovascular disease (following, cerebrovascular disease, specified disease NEC), I69.993 — Ataxia following unspecified cerebrovascular disease (following, cerebrovascular disease), K90.0 — Celiac disease (gluten, with celiac disease), M26.36 — Insufficient interocclusal distance of fully erupted teeth (ridge) (adequate, intermaxillary vertical dimension of fully erupted teeth), M26.57 — Lack of posterior occlusal support (posterior occlusal support), M35.9 — Systemic involvement of connective tissue, unspecified (gluten), N97.0 — Female infertility associated with anovulation (ovulation), P92.6 — Failure to thrive in newborn (development, failure to thrive, newborn), R26.0 — Ataxic gait (gait), R41.9 — Unspecified symptoms and signs involving cognitive functions and awareness (awareness), R53.83 — Other fatigue (energy), R62.50 — Unspecified lack of expected normal physiological development in childhood (development), R62.51 — Failure to thrive (child) (development, failure to thrive), R62.52 — Short stature (child) (growth), R62.59 — Other lack of expected normal physiological development in childhood (development, specified type NEC), R62.7 — Adult failure to thrive (development, failure to thrive, adult), R63.0 — Anorexia (appetite), T73.1 — Deprivation of water (water), T74.02 — Child neglect or abandonment, confirmed (care, of infant, confirmed), +43 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Thyroid Stimulating Hormone (TSH)

Contextual Map

Every relationship of R27.0 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 R27.0 with these 3 related codes in Claim Check

Hierarchy

• R00-R99 — Chapter 18: Symptoms, Signs and Abnormal Clinical and Laboratory Findings, Not Elsewhere Classified (R00-R99) (R00-R99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• R25-R29 — Symptoms and signs involving the nervous and musculoskeletal systems[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Excludes1

• I69 — Sequelae of cerebrovascular disease[Excludes1]: “ataxia following cerebrovascular disease (I69. with final characters -93)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes1 notes

• F82 — Specific developmental disorder of motor function[Excludes1](via R27.-): “lack of coordination (R27.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• R26 — Abnormalities of gait and mobility[Excludes1]: “ataxia NOS (R27.0)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• SYM010 — Nervous system signs and symptoms[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• DRG 091 — OTHER DISORDERS OF NERVOUS SYSTEM WITH MCC[MS-DRG]: “OTHER DISORDERS OF NERVOUS SYSTEM WITH MCC (MDC 01)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 092 — OTHER DISORDERS OF NERVOUS SYSTEM WITH CC[MS-DRG]: “OTHER DISORDERS OF NERVOUS SYSTEM WITH CC (MDC 01)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 093 — OTHER DISORDERS OF NERVOUS SYSTEM WITHOUT CC/MCC[MS-DRG]: “OTHER DISORDERS OF NERVOUS SYSTEM WITHOUT CC/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

• Ataxia, ataxy, ataxic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Lack of, coordination, ataxia[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

• R27 — Other lack of coordination[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• R27.8 — Other lack of coordination[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• R27.9 — Unspecified lack of coordination[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

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

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 R27.0 in its code family, with their registry titles.

• R27 — Other lack of coordination
• R27.8 — Other lack of coordination
• R27.9 — Unspecified lack of coordination

View all codes in the R27 family