G31Other degenerative diseases of nervous system, not elsewhere classified

G31 is the ICD-10-CM diagnosis code for other degenerative diseases of nervous system, not elsewhere classified. It belongs to block G30-G32 (other degenerative diseases of the nervous system) and chapter 6 (diseases of the nervous system). It is a header code, so it can't be reported by itself; one of its 5 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: G31.0 (dementia), G31.1 (classified), G31.2 (alcohol), G31.8 (system) and G31.9 (unspecified).

The conditions in its Excludes2 note aren't part of G31, but may be coded alongside it if the patient has both: Reye's syndrome (G93.7).

Use an additional code, if applicable, for codes G31.0-G31.83, G31.85-G31.9, 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) and 1 more.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.