A case study of occipital outgrowth: a rare suboccipital abnormality.

PURPOSE: To describe the clinical and radiological characteristics of uncommon upper cervical spine abnormality in children.

METHODS: Clinical and diagnostic characteristics of three patients aged 6-12 years with a similar uncommon type of occipital anomaly are described. The patients were admitted in 2007, 2009, and 2014, respectively.

RESULTS: All patients were clinically and radiologically examined. In each case the massive, additional unilateral outgrowth of the occipital bone (os occipitale) was visualized. The signs and symptoms included torticollis, acute brain ischemia, and limited head motion. Two of the three patients underwent surgical treatment: an occipital-cervical fusion was performed in the first patient, and the outgrowth was removed in the second patient. After 1 year of follow-up the results were estimated as good for both patients, with better functional outcome for the second patient. The parents of the third patient did not consent for the surgical treatment.

CONCLUSIONS: The unique features of this abnormality distinguish it from previous descriptions of the manifestation of pro-atlas, atlas, or atlanto-occipital synostosis. The presented abnormality had different manifestation of various severity in each case, from torticollis to acute vascular disorder.

STUDY DESIGN: Clinical case series.

LEVEL OF EVIDENCE: IV.