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ICD-10-CM tabular list

A80-A89Viral and prion infections of the central nervous system

ICD-10-CM codes A80-A89 cover viral and prion infections of the central nervous system, within certain infectious and parasitic diseases. The block holds 60 codes across 10 categories, of which 48 are billable and 12 are header codes that cannot be submitted on a claim.

Excludes1 — never code together

These conditions cannot occur together. Billing both on the same encounter is a denial.

  • postpolio syndrome (G14)
  • sequelae of poliomyelitis (B91)
  • sequelae of viral encephalitis (B94.1)

Risk adjustment in A80-A89

0 codes in this block map to a CMS-HCC, which means the diagnosis carries a risk-adjustment payment when it is documented and coded. Under-coding here is money left on the table; over-coding here is what audits are for.

  • HCC 127 Dementia, Mild or Unspecified

What else to watch in A80-A89

  • 48 codes are named in Medicare coverage policies. An LCD or NCD lists them as supporting medical necessity, or explicitly as not supporting it. Which applies depends on the MAC for your state.

Categories in A80-A89

ICD-10-CMFY2026-Apr· effective April 1, 2026