ABSTRACT
Two siblings of Laurence-Moon-Biedl (L-M-B) syndrome with nystagmus and/or sensorineural hearing loss were reported. One sibling had a slight hearing impairment as well as gaze and rebound nystagmus. The auditory brainstem responses (ABR) showed increased latencies of wave V on both ears. The optokinetic nystagmus (OKN) was limited toward the both horizontal sides. Nystagmus was superimposed on the eye tracking movement. Ocular hypermetria was observed, with bilateral weakness of caloric responses and even a failure of visual fixation suppression. Another sibling had a left-beating spontaneous nystagmus. The latencies of wave V of ABR were prolonged in both ears. The leftward OKN was limited and bilateral saccadic pursuits observed on eye tracking test. These results suggest that cerebellar of brain-stem lesions may be involved in L-M-B syndrome.
