Congenital ocular motor apraxia: Clinical and neuroradiological findings, and long-term intellectual prognosis

Abstract

The severity of intellectual sequelae and prognosis varies in patients with congenital ocular motor apraxia (COMA). Here, we explored this phenomenon with regard to the accompanying oculomotor signs and gross motor development, as well as the subtentorial structure defects. Ten patients diagnosed with COMA (M:F = 4:6, 4–37 years old) were reviewed. Four individuals who gained the ability to walk at 2 years or earlier showed normal intellect and social skills. Those who walked later often showed accompanying intellectual (5/6) and speech (6/6) disabilities. In this latter group, atypical oculomotor signs for COMA (presence of nystagmus, mild limitation of vertical gaze, slower head thrust, and marked improvement of lateral saccade during early childhood) were often noted (4/6). Minor anomalies of fingers and toes were also common in this group. Neuroimaging was conduced in nine patients (pneumoencepharography 1; computed tomography: 8, magnetic resonance imaging: 2). Dilatation of the fourth ventricle, mainly at the level of the midbrain or upper pons ( n = 7), and hypoplastic cerebellar vermis ( n = 6) were commonly observed in both the early- and late-walking groups. ‘Molar tooth’ signs ( n = 3) were exclusively noted in the late-walking group, and often accompanied by atypical oculomotor signs (3/3) and intellectual disabilities (2/3). Vermian hypoplasia and dilatation of the fourth ventricle at the upper brainstem level in COMA patients, with or without intellectual disabilities, suggested that the cardinal lesion for OMA may exist in these areas. The presence of a subset of ‘atypical’ COMA patients may suggest that COMA with subtle infratentorial abnormality represents a heterogeneous disease category, showing similar oculomotor disturbance. This review indicated that clinical and neuroradiological inspection might be valuable for prediction of long-term intellectual prognosis in COMA patients.