F06.7 vs G31.9
F06.7 and G31.9 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
Mild neurocognitive disorder due to known physiological condition
- Chapter 5
- Mental, Behavioral and Neurodevelopmental disorders
- Section
- F01-F09
- Mild neurocognitive impairment due to a known physiological condition
Degenerative disease of nervous system, unspecified
- Chapter 6
- Diseases of the nervous system
- Section
- G30-G32
- Atrophy, atrophic › brain (of)
- Degeneration, degenerative › brain
- Degeneration, degenerative › cerebellar NOS
- Degeneration, degenerative › nervous system
- Hemiatrophy › cerebellar
These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027