G99.8 — Other specified disorders of nervous system in diseases classified elsewhere
Is G99.8 billable?
Yes, but G99.8 is an unspecified code. G99.8 is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, G99.8 is an unspecified or catch-all code. Payers apply additional scrutiny to unspecified codes and many deny them when the medical record supports a more specific option, so check the documentation before selecting G99.8 — the more specific alternatives are listed below.
G99.8 at a glance
| Code | G99.8 |
|---|---|
| Description | Other specified disorders of nervous system in diseases classified elsewhere |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
What Medicare edits apply to G99.8?
The Medicare Code Editor screens inpatient claims before they are grouped. These edits name G99.8 directly.
This code describes a manifestation of an underlying disease. The underlying condition must be sequenced before it, so it can never be the principal or first-listed diagnosis.
Which MS-DRGs does G99.8 group to?
G99.8 sits in MDC 01 and helps define the logic of 3 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 070Other Cerebrovascular Disorders with MCCmedical
- 071Other Cerebrovascular Disorders with CCmedical
- 072Other Cerebrovascular Disorders without CC/MCCmedical
How is G99.8 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to G99.8. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Neuroavitaminosis
- Paralysis, paralytic › uremic (complete) (incomplete)
- Degeneration, degenerative › nervous system › amyloid
Excludes1 — never code together
The conditions below can never be reported together with G99.8 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Code first
The underlying condition below must be sequenced before G99.8. G99.8 describes a manifestation and cannot be the principal or first-listed diagnosis.
Excludes2 — not included here — inherited from Chapter 6
The conditions below are not part of G99.8, but a patient may have both at the same time. When documentation supports it, G99.8 and the excluded code may both be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
How long has G99.8 existed?
G99.8 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.
Which codes are confused with G99.8?
ICD-10-CM declares these codes mutually exclusive with G99.8 — exactly one of each pair can be correct for a given encounter.