Congenital ocular motor apraxia: imaging findings.

PURPOSE To determine the frequency of cerebellar and cerebral abnormalities on brain imaging studies in children with congenital ocular motor apraxia. METHODS Brain imaging studies were performed in 19 children with typical congenital ocular motor apraxia who were in the care of a visual impairment program at a children's hospital. Independent clinical review categorized the subjects as having partial (n = 10) or expanded (n = 9) congenital ocular motor apraxia on the basis of extent of associated speech or neurodevelopmental problems. Fifteen CT studies and 13 MR examinations of the brain performed in these children were reviewed independently by two pediatric neuroradiologists. Radiologic findings were agreed on by consensus. RESULTS Cerebellar abnormalities were found in 12 of 19 cases. The cerebellar vermis was small in 10 children. A small cerebellar vermis was the only abnormality in five of 10 children with partial congenital ocular motor apraxia and in two of nine children with expanded congenital ocular motor apraxia. Among seven children with a small vermis examined with high-resolution MR imaging, the inferior portion of the vermis was preferentially involved in each case. Of these seven subjects, none of four with partial congenital ocular motor apraxia but two of three with expanded congenital ocular motor apraxia had an abnormality of the superior portion of the vermis. Miscellaneous supratentorial lesions affecting both gray and white matter were found in six subjects. Five of the 19 children had normal imaging findings. CONCLUSION Inferior vermian hypoplasia is the most common abnormality in children with congenital ocular motor apraxia.