Congenital malformations of the nervous system (Q00-Q07)

Q00-Q07 codes in the ICD-10-CM classify congenital malformations of the nervous system, covering a range of structural brain, spinal cord, and nerve defects present at birth.

This chapter includes codes for specific conditions like anencephaly (Q00.0), also known by synonyms such as congenital brain aplasia and acrania, which involve absence of major portions of the brain and skull. The encephalocele group (Q01) refers to brain tissue herniations through skull defects, with types like frontal, nasofrontal (frontoethmoidal), and occipital encephaloceles. Microcephaly (Q02) encompasses various congenital small head conditions often linked to intellectual disability and developmental delay. Congenital hydrocephalus (Q03) codes address abnormal cerebrospinal fluid buildup, including subclasses involving the aqueduct of Sylvius and the foramina of Magendie and Luschka (Dandy-Walker syndrome). Spina bifida (Q05) codes detail defects in spinal closure, differentiated by location and presence of hydrocephalus. Other categories cover malformations of corpus callosum, brain reduction deformities, and Arnold-Chiari syndrome (Q07), a condition involving hindbrain herniation often associated with hydrocephalus or spina bifida. Unspecific or other congenital nervous system anomalies are grouped under unspecified codes to capture broad or rare defects. This ICD chapter aids precise documentation of congenital nervous system anomalies, such as hypoplasia, dysplasia, and cystic malformations.