{"code":"A81.9","type":"code","title":"Atypical virus infection of central nervous system, unspecified","codeAlso":[],"includes":["diseases of the central nervous system caused by prions"],"modern_v":"official26","codeFirst":[],"excludes1":["postpolio syndrome (G14)","sequelae of poliomyelitis (B91)","sequelae of viral encephalitis (B94.1)"],"excludes2":[],"isBillable":true,"fyEffectivity":{"fy2026":true,"fy2027":true,"billableFy2026":true,"billableFy2027":true},"sibling_codes":["A81","A81.0","A81.1","A81.2","A81.8"],"inclusionTerms":["Prion diseases of the central nervous system NOS"],"sibling_titles":{"code":"A81.8","title":"Other atypical virus infections of central nervous system","isBillable":false},"useAdditionalCode":["code, if applicable, 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-)"],"clinicalDefinition":"Atypical virus infection of central nervous system, unspecified is a billable ICD-10-CM diagnosis code (A81.9). Includes: diseases of the central nervous system caused by prions. Inclusion terms: Prion diseases of the central nervous system NOS. Excludes1 (not coded here): postpolio syndrome (G14); sequelae of poliomyelitis (B91); sequelae of viral encephalitis (B94.1). Use additional code: code, if applicable, to identify:; dementia with anxiety (F02.84, F02.A4, F02.B4, F02.","officialDefinition":"Atypical virus infection of central nervous system, unspecified is a billable ICD-10-CM diagnosis code (A81.9). Includes: diseases of the central nervous system caused by prions. Inclusion terms: Prion diseases of the central nervous system NOS. Excludes1 (not coded here): postpolio syndrome (G14); sequelae of poliomyelitis (B91); sequelae of viral encephalitis (B94.1). Use additional code: code, if applicable, 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-).","seventhCharacterInstructions":[],"workflowProtocols":[],"guidelines":{"whenToUse":[],"whenNotToUse":[],"commonBillingMistakes":[],"codeComparisons":[],"documentationChecklist":[]},"domainLandscape":{"summary":"Primary diagnostic domain and clinical landscape evaluation.","keyCategories":[],"diagnosticContinuum":"Progression continuum from acute presentation to resolution."},"children":[],"hierarchy":[],"relatedCodes":[],"relevantCPTCodes":[],"documentationTips":[],"caseStudies":[],"description":"","overview":"","noteProvenance":{"postpolio syndrome (G14)":"A81","sequelae of poliomyelitis (B91)":"A81","sequelae of viral encephalitis (B94.1)":"A81","code, if applicable, to identify:":"A81","dementia with anxiety (F02.84, F02.A4, F02.B4, F02.C4)":"A81","dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)":"A81","dementia with mood disturbance (F02.83, F02.A3, F02.B3, F02.C3)":"A81","dementia with psychotic disturbance (F02.82, F02.A2, F02.B2, F02.C2)":"A81","dementia without behavioral disturbance (F02.80, F02.A0, F02.B0, F02.C0)":"A81","mild neurocognitive disorder due to known physiological condition (F06.7-)":"A81","diseases of the central nervous system caused by prions":"A81"},"hcc":{"mapped":true,"model":"CMS-HCC V28","paymentYear":"2026","categories":[{"hcc":"127","label":"Dementia, Mild or Unspecified","family":"","suppresses":[]}],"otherModels":[{"model":"RxHCC V08","hcc":"112"}]}}