The clinical and neuroradiological findings, and long-term intellectual prognosis in 10 patients (4 boys and 6 girls) with congenital ocular motor apraxia (COMA) are reviewed by researchers at Tottori University, Yonago, Japan. Age at first examination was 4 months to 5 years, and follow-up ranged from 4 to 37 years (mean 17.3 years). COMA was diagnosed by impaired voluntary, saccadic eye movements, and head thrusting movements in the horizontal direction. A representative patient, a boy examined at the age of 7 months and sitting had head thrust movements. He looked at objects obliquely, with eyes deviated laterally. He walked late at 22 months, but speech developed normally. At 5 years of age, he was examined because of persistent unsteady gait and abnormal eye movements. Apart from the tandem ataxia, impaired eye movements, and a left external strabismus, the remainder of the neurologic exam was normal. Brain CT showed dilatation of the fourth ventricle and hypoplasia of the cerebellar vermis. At follow-up at age 7 years, tandem gait had improved, but titubation of the head and signs of OMA, including head thrust and excessive blinking at visual tracking, persisted. At 37 years old, he is an independent, working adult.

Typical oculomotor findings of COMA (locking-up during manual spinning and impaired optikokinetic nystagmus) were elicited in all patients, excessive blinking in 5, strabismus (7), and oblique lateral glance in 8. Atypical signs, including rotatory or jerky nystagmus and limitation in upward gaze, were present in 4 patients, and were often accompanied by intellectual disabilities. Delay in walking occurred in all patients, 4 at 2 years of age and 6 walked later. Ataxia was common in the later-walking group, and was complicated by speech problems and intellectual retardation. Neuroimaging revealed dilatation of the fourth ventricle in 8, hypoplasia of the cerebellar vermis in 6, and ‘molar-tooth’ sign at the midbrain in 3. None had a family history of COMA, but 3 had family members with mental retardation. [1]

COMMENT. First described by Cogan DG in 1952, congenital ocular motor apraxia (COMA) is a paresis of conjugate purposive gaze, with retained random movements, and compensatory jerking movements of the head. Optokinetic nystagmus is abnormal, with absence of the fast, refixation phase. The patient is unable to follow a fast moving object but can follow a slow moving object horizontally to either side. Jerking of the head redirects the eyes into the desired position. Repetitive blinking helps in correcting fixation. MRI is normal or may reveal agenesis of the corpus callosum, hypoplasia of the cerebellar vermis, and brainstem dysgenesis. In addition to congenital cases, the syndrome may be a sign of brain tumor, Gaucher’s disease, ataxia-telangiectasia, and Joubert syndrome. Joubert syndrome and COMA are allelic for the NPHP1 gene for juvenile nephronophthisis [2]. The congenital type, originally described as benign, is now known to be associated often with gait ataxia, speech apraxia, behavioral and learning disabilities, and intellectual delay. The present series of COMA cases demonstrates a correlation between delay in walking ability and subsequent gait ataxia, speech problems, and intellectual retardation. Structural abnormalities of the cerebellum and brainstem are demonstrated in more than half the cases.