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ICD-10-CM 2027

ICD-10 code for brain maldevelopment

Q07.9

Congenital malformation of nervous system, unspecified

✓ Billable / specific

From the official ICD-10-CM alphabetic index entry “Maldevelopment › brain”. Page updated September 29, 2026.

About coding brain maldevelopment

The ICD-10-CM code for brain maldevelopment is Q07.9 (Congenital malformation of nervous system, unspecified).

Within Q07, choose Q07.9 (Congenital malformation of nervous system, unspecified) only when documentation doesn't support a more specific option: Arnold-Chiari syndrome (Q07.0) and other specified congenital malformations of nervous system (Q07.8).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 091 (Other Disorders of Nervous System with MCC, relative weight 1.7046), DRG 092 (Other Disorders of Nervous System with CC, relative weight 1.0239), DRG 093 (Other Disorders of Nervous System without CC/MCC, relative weight 0.7783), DRG 791 (Prematurity with Major Problems, relative weight 4.1075) and DRG 793 (Full Term Neonate with Major Problems, relative weight 4.2195), in MDC 01 (Diseases and Disorders of the Nervous System) and MDC 15 (Newborns and Other Neonates with Conditions Originating in the Perinatal Period), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

Common questions about brain maldevelopment ICD-10 codes

What is the ICD-10 code for brain maldevelopment?

Q07.9 — Congenital malformation of nervous system, unspecified.

Is Q07.9 billable?

Yes. Q07.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can Q07.9 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict Q07.9 as a principal diagnosis.

Is Q07.9 a CC or MCC?

No. Q07.9 is neither a CC nor an MCC under MS-DRG v44.0.