LB73.21

ICD-11 MMS 2026-01

Occipitalisation of atlas

Description

A condition caused by failure of the atlas and occiput to correctly develop during the antenatal period. This condition is characterised by fusion of the atlas to the base of the occiput. This condition may present with headache, suboccipital stiffness, restricted motion, or dizziness. Confirmation is through observation of the fusion by imaging.

Index terms

  • Occipitalisation of atlas

Exclusions from above levels

  • http://id.who.int/icd/entity/733825440 – Inborn errors of metabolism

Sibling codes

  • LB73.20 – Klippel-Feil anomaly
  • LB73.22 – Atlanto-axial instability or subluxation
  • LB73.23 – Aplasia or hypoplasia of the odontoid process of axis
  • LB73.24 – Segmentation anomalies of vertebrae
  • LB73.25 – Congenital scoliosis due to congenital bony malformation
  • LB73.26 – Sacralisation of the last lumbar vertebra
  • LB73.27 – Lumbarisation of the first sacral vertebra
  • LB73.28 – Sacrum agenesis or hypoplasia
  • LB73.29 – Caudal appendage
  • LB73.2A – Congenital spondylolisthesis
  • LB73.2Y – Other specified structural developmental anomalies of spine
  • LB73.2Z – Structural developmental anomalies of spine, unspecified

Foundation entity

Occipitalisation of atlas – http://id.who.int/icd/entity/1814363019

Allowed postcoordination axes

Part of: LB73.2: Structural developmental anomalies of spine › LB73: Structural developmental anomalies of spine or bony thorax › 20: Developmental anomalies