Elevation of the petrous bone caused by hyperplasia of the occipital bone presenting as hemifacial spasm: diagnostic values of magnetic resonance imaging and three-dimensional computed tomographic images in a bone anomaly.
 A case of elevation of the petrous bone due to hyperplasia of the occipital bone presenting as hemifacial spasm is reported.
 A 44-year-old man sought treatment for twitching of the buccal muscles on the right side that progressed rapidly in severity within 2 weeks of the onset.
 The anatomical details of the petrous and occipital bones were delineated clearly by computed tomographic scans of a bone window level.
 Details of the brain stem were shown by magnetic resonance images.
 The bone anomaly was displayed more realistically by three-dimensional computed tomographic reconstructions.
 The faithful representation of structures with these radiological studies should be mandatory, to prepare the surgical planning of such a complicated bone anomaly.
