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Background: Late-onset Tay-Sachs disease (LOTS) is an adult-onset, autosomal recessive, progressive variant of GM2 gangliosidosis, characterized by involvement of the cerebellum and anterior horn cells., Objective: To determine the range of visual and ocular motor abnormalities in LOTS, as a prelude to evaluating the effectiveness of novel therapies., Methods: Fourteen patients with biochemically confirmed LOTS (8 men; age range 24 to 53 years; disease duration 5 to 30 years) and 10 age-matched control subjects were studied. Snellen visual acuity, contrast sensitivity, color vision, stereopsis, and visual fields were measured, and optic fundi were photographed. Horizontal and vertical eye movements (search coil) were recorded, and saccades, pursuit, vestibulo-ocular reflex (VOR), vergence, and optokinetic (OK) responses were measured., Results: All patients showed normal visual functions and optic fundi. The main eye movement abnormality concerned saccades, which were "multistep," consisting of a series of small saccades and larger movements that showed transient decelerations. Larger saccades ended earlier and more abruptly (greater peak deceleration) in LOTS patients than in control subjects; these changes can be attributed to premature termination of the saccadic pulse. Smooth-pursuit and slow-phase OK gains were reduced, but VOR, vergence, and gaze holding were normal., Conclusions: Patients with late-onset Tay-Sachs disease (LOTS) show characteristic abnormalities of saccades but normal afferent visual systems. Hypometria, transient decelerations, and premature termination of saccades suggest disruption of a "latch circuit" that normally inhibits pontine omnipause neurons, permitting burst neurons to discharge until the eye movement is completed. These measurable abnormalities of saccades provide a means to evaluate the effects of novel treatments for LOTS.

Many children who roller skate sustain injuries. To determine the type and severity of these mishaps, the medical records of 76 children less than 16 years of age with roller skating injuries presenting to two pediatric emergency departments were reviewed. Seventy-five percent were girls, and 25% were boys. The upper extremity was the most common body part injured (74%) (P less than 0.0001). Lower extremity injuries occurred in 12%, head and face injuries in 10%, and chest injuries in 4%. The most common type of injury was a fracture (69%), with the wrist and forearm being most frequently fractured (53%). Hospitalization and long-term sequelae were infrequent. Younger children (less than or equal to 9) had an increased frequency of fracture injury (P less than 0.02). This is most likely because maturation of lower and upper extremity speed, strength, agility, coordination, balance, and reaction time and morphologically stronger bones combine to afford relative protection to the older child. Physicians and parents need to be aware of a child's skill level before the child is encouraged to roller skate. Measures which may decrease the likelihood of injury include protective gear, instruction in roller skating technique, learning to skate in an uncongested area on level, familiar terrain, and learning to fall properly.