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B94.1 ICD-10-CM Code: Sequelae of viral encephalitis

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
1 code-first instruction

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 091 — OTHER DISORDERS OF NERVOUS SYSTEM WITH MCC (MDC 01)
  • MS-DRG 092 — OTHER DISORDERS OF NERVOUS SYSTEM WITH CC (MDC 01)
  • MS-DRG 093 — OTHER DISORDERS OF NERVOUS SYSTEM WITHOUT CC/MCC (MDC 01)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for B94.1 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 B94.1 itself; “inherited from” names the category or block whose note applies here.

Code First

Underlying conditions that must be sequenced before this code.

  • condition resulting from (sequela) the infectious or parasitic disease

Source: inherited from B90-B94

Coder workflow for B94.1

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

Choose the right path

  1. Is the underlying (etiologic) condition the Code First note names documented?
    Yes → Sequence the underlying condition first, then B94.1.
    No → Continue; do not add an underlying condition the record does not document.

Consider B94.1. 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).
The underlying (etiologic) condition
Named in the Code First note; sequenced before this code when documented (Guidelines I.A.13).

Official instructions as workflow

  • Code First — sequencing check(1 note)

    Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before B94.1. Do not add an underlying condition the record does not document.

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

Coding decision scenarios

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

Documentation: The underlying condition the Code First note names is documented alongside this condition.

Coding question: How are the two sequenced?

Path: Review the Code First note.

Reason: The underlying condition is sequenced first and the manifestation follows (Guidelines I.A.13).

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.

Code Overview

Sequelae of viral encephalitis is a billable ICD-10-CM diagnosis code (B94.1).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

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.

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 B94.1 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 12 Excludes1 notes across 2 chapters: A80 — Acute poliomyelitis, A80-A89 — Viral and prion infections of the central nervous system (A80-A89), A81 — Atypical virus infections of central nervous system, A82 — Rabies, A83 — Mosquito-borne viral encephalitis, A84 — Tick-borne viral encephalitis, A85 — Other viral encephalitis, not elsewhere classified, A86 — Unspecified viral encephalitis, A87 — Viral meningitis, A88 — Other viral infections of central nervous system, not elsewhere classified, A89 — Unspecified viral infection of central nervous system, Z86.1 — Personal history of infectious and parasitic diseases (via B94.-).

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):INF011 — Sequela of specified infectious disease conditions (default); NVS022 — Sequela of specified nervous system conditions.

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 categories (Sequela of specified infectious disease conditions, Sequela of specified nervous system conditions).

B90.0 — Sequelae of central nervous system tuberculosis, B90.1 — Sequelae of genitourinary tuberculosis, B90.2 — Sequelae of tuberculosis of bones and joints, B90.8 — Sequelae of tuberculosis of other organs, B90.9 — Sequelae of respiratory and unspecified tuberculosis, B91 — Sequelae of poliomyelitis, B92 — Sequelae of leprosy, B94.0 — Sequelae of trachoma, B94.2 — Sequelae of viral hepatitis, B94.8 — Sequelae of other specified infectious and parasitic diseases, B94.9 — Sequelae of unspecified infectious and parasitic disease, G09 — Sequelae of inflammatory diseases of central nervous system, G65.0 — Sequelae of Guillain-Barré syndrome, G65.1 — Sequelae of other inflammatory polyneuropathy, G65.2 — Sequelae of toxic polyneuropathy

Same Index main term, other category

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

B90.0 — Sequelae of central nervous system tuberculosis (tuberculosis, central nervous system), B90.1 — Sequelae of genitourinary tuberculosis (tuberculosis, genitourinary), B90.2 — Sequelae of tuberculosis of bones and joints (tuberculosis, bones and joints), B90.8 — Sequelae of tuberculosis of other organs (tuberculosis, specified organs NEC), B90.9 — Sequelae of respiratory and unspecified tuberculosis (tuberculosis), B91 — Sequelae of poliomyelitis (poliomyelitis), B92 — Sequelae of leprosy (leprosy), E64.0 — Sequelae of protein-calorie malnutrition (protein-energy malnutrition), E64.1 — Sequelae of vitamin A deficiency (vitamin deficiency NEC, A), E64.2 — Sequelae of vitamin C deficiency (vitamin deficiency NEC, C), E64.3 — Sequelae of rickets (rickets), E64.8 — Sequelae of other nutritional deficiencies (niacin deficiency), E64.9 — Sequelae of unspecified nutritional deficiency (nutritional deficiency), E68 — Sequelae of hyperalimentation (hyperalimentation), G09 — Sequelae of inflammatory diseases of central nervous system (meningitis, bacterial), I69.00 — Unspecified sequelae of nontraumatic subarachnoid hemorrhage (hemorrhage, subarachnoid), I69.020 — Aphasia following nontraumatic subarachnoid hemorrhage (hemorrhage, subarachnoid, aphasia), I69.021 — Dysphasia following nontraumatic subarachnoid hemorrhage (hemorrhage, subarachnoid, dysphasia), I69.022 — Dysarthria following nontraumatic subarachnoid hemorrhage (hemorrhage, subarachnoid, dysarthria), I69.023 — Fluency disorder following nontraumatic subarachnoid hemorrhage (hemorrhage, subarachnoid, fluency disorder), +92 more

Contextual Map

Every relationship of B94.1 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 B94.1 with these 8 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes (12)

Clinical classification (CCSR)

MS-DRG Grouper

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

  • Sequelae (of), encephalitis or encephalomyelitis (conditions in G04), viral[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Sequelae (of), viral, encephalitis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

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

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "B94.1 — Sequelae of viral encephalitis." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/b94.1-sequelae-of-viral-encephalitis

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Sequelae of viral encephalitis

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to B94.1 in its code family, with their registry titles.

View all codes in the B94 family