This sagittal T1-weighted MR image demonstrates some of the features found in the skull in achondroplasia.

There was moderate enlargement of ventricles and surface CSF spaces consistent with communicating hydrocephalus. CSF flow studies demonstrated flow around the craniocervical junction. MR venography demonstrated restricted flow in the sigmoid sinuses and jugular bulbs, which probably contributed to the hydrocephalus.

Craniocervical junction constriction can give rise to problems in achondroplasia including sleep apneoa, sudden apneoas, sudden death, and myelomalacia. Surgical decompression may be helpful in selected cases.

Image contributed by: Dr Laughlin Dawes