ICD-10-CM Book 2026 Edition

Chapters  /  Chapter 17  /  Q00-Q07

Congenital malformations of the nervous system (Q00-Q07)

Q00 Anencephaly and similar malformations
Q00.0 Anencephaly
Acephaly
Acrania
Amyelencephaly
Hemianencephaly
Hemicephaly
Q00.1 Craniorachischisis
Q00.2 Iniencephaly
Q01 Encephalocele
Includes Arnold-Chiari syndrome, type III
encephalocystocele
encephalomyelocele
hydroencephalocele
hydromeningocele, cranial
meningocele, cerebral
meningoencephalocele
Excludes1 Meckel-Gruber syndrome (Q61.9)
Q01.0 Frontal encephalocele
Q01.1 Nasofrontal encephalocele
Q01.2 Occipital encephalocele
Q01.8 Encephalocele of other sites
Q01.9 Encephalocele, unspecified
Q02 Microcephaly
Includes hydromicrocephaly
micrencephalon
CodeFirst , if applicable, congenital Zika virus disease
Excludes1 Meckel-Gruber syndrome (Q61.9)
Q03 Congenital hydrocephalus
Includes hydrocephalus in newborn
Excludes1 Arnold-Chiari syndrome, type II (Q07.0-)
acquired hydrocephalus (G91.-)
hydrocephalus due to congenital toxoplasmosis (P37.1)
hydrocephalus with spina bifida (Q05.0-Q05.4)
Q03.0 Malformations of aqueduct of Sylvius
Anomaly of aqueduct of Sylvius
Obstruction of aqueduct of Sylvius, congenital
Stenosis of aqueduct of Sylvius
Q03.1 Atresia of foramina of Magendie and Luschka
Dandy-Walker syndrome
Q03.8 Other congenital hydrocephalus
Q03.9 Congenital hydrocephalus, unspecified
Q04 Other congenital malformations of brain
Excludes1 cyclopia (Q87.0)
macrocephaly (Q75.3)
Q04.0 Congenital malformations of corpus callosum
Agenesis of corpus callosum
Q04.1 Arhinencephaly
Q04.2 Holoprosencephaly
Q04.3 Other reduction deformities of brain
Absence of part of brain
Agenesis of part of brain
Agyria
Aplasia of part of brain
Hydranencephaly
Hypoplasia of part of brain
Lissencephaly
Microgyria
Pachygyria
Excludes1 congenital malformations of corpus callosum (Q04.0)
Q04.4 Septo-optic dysplasia of brain
Q04.5 Megalencephaly
Q04.6 Congenital cerebral cysts
Porencephaly
Schizencephaly
Excludes1 acquired porencephalic cyst (G93.0)
Q04.8 Other specified congenital malformations of brain
Arnold-Chiari syndrome, type IV
Macrogyria
Q04.9 Congenital malformation of brain, unspecified
Congenital anomaly NOS of brain
Congenital deformity NOS of brain
Congenital disease or lesion NOS of brain
Multiple anomalies NOS of brain, congenital
Q05 Spina bifida
Includes hydromeningocele (spinal)
meningocele (spinal)
meningomyelocele
myelocele
myelomeningocele
rachischisis
spina bifida (aperta)(cystica)
syringomyelocele
UseAdditionalCode code for any associated paraplegia (paraparesis) (G82.2-)
Excludes1 Arnold-Chiari syndrome, type II (Q07.0-)
spina bifida occulta (Q76.0)
Q05.0 Cervical spina bifida with hydrocephalus
Q05.1 Thoracic spina bifida with hydrocephalus
Dorsal spina bifida with hydrocephalus
Thoracolumbar spina bifida with hydrocephalus
Q05.2 Lumbar spina bifida with hydrocephalus
Lumbosacral spina bifida with hydrocephalus
Q05.3 Sacral spina bifida with hydrocephalus
Q05.4 Unspecified spina bifida with hydrocephalus
Q05.5 Cervical spina bifida without hydrocephalus
Q05.6 Thoracic spina bifida without hydrocephalus
Dorsal spina bifida NOS
Thoracolumbar spina bifida NOS
Q05.7 Lumbar spina bifida without hydrocephalus
Lumbosacral spina bifida NOS
Q05.8 Sacral spina bifida without hydrocephalus
Q05.9 Spina bifida, unspecified
Q06 Other congenital malformations of spinal cord
Q06.0 Amyelia
Q06.1 Hypoplasia and dysplasia of spinal cord
Atelomyelia
Myelatelia
Myelodysplasia of spinal cord
Q06.2 Diastematomyelia
Q06.3 Other congenital cauda equina malformations
Q06.4 Hydromyelia
Hydrorachis
Q06.8 Other specified congenital malformations of spinal cord
Q06.9 Congenital malformation of spinal cord, unspecified
Congenital anomaly NOS of spinal cord
Congenital deformity NOS of spinal cord
Congenital disease or lesion NOS of spinal cord
Q07 Other congenital malformations of nervous system
Excludes2 congenital central alveolar hypoventilation syndrome (G47.35)
familial dysautonomia [Riley-Day] (G90.1)
neurofibromatosis (nonmalignant) (Q85.0-)
Q07.0 Arnold-Chiari syndrome
Arnold-Chiari syndrome, type II
Excludes1 Arnold-Chiari syndrome, type III (Q01.-)
Arnold-Chiari syndrome, type IV (Q04.8)
Q07.00 Arnold-Chiari syndrome without spina bifida or hydrocephalus
Q07.01 Arnold-Chiari syndrome with spina bifida
Q07.02 Arnold-Chiari syndrome with hydrocephalus
Q07.03 Arnold-Chiari syndrome with spina bifida and hydrocephalus
Q07.8 Other specified congenital malformations of nervous system
Agenesis of nerve
Displacement of brachial plexus
Jaw-winking syndrome
Marcus Gunn's syndrome
Q07.9 Congenital malformation of nervous system, unspecified
Congenital anomaly NOS of nervous system
Congenital deformity NOS of nervous system
Congenital disease or lesion NOS of nervous system