Bilateral deficit is larger for step than for ramp isometric contractions.

The force produced by a muscle group during a maximum effort bilateral task has been reported to be less than that produced during a maximum effort unilateral task. It was hypothesized that if decreased activation of primarily fast motor units is responsible for this bilateral deficit, 1) the bilateral deficit would be larger in step than in ramp isometric contractions and 2) the rate of torque generation in step contractions would be slower in bilateral than in unilateral tasks. Twelve healthy male subjects performed unilateral and bilateral isometric knee joint extension tasks in which maximum torque was generated under ramp and step conditions. The maximum torques produced in the bilateral tasks were 17.0 and 24.6% less than those produced in the unilateral tasks during the ramp and step conditions, respectively (both P < 0.001). The bilateral torque deficit for the step condition was significantly greater than that for the ramp condition (P = 0.012). The rate of torque generation in the step condition was 19.7% slower in the bilateral than in the unilateral task (P = 0.010). Thus the results from these torque measurements support the notion that decreased activation of primarily fast motor units may be responsible for the bilateral deficit.

Cerebellar astrocytomas in elderly patients with very long preoperative histories: report of three cases.

Three patients, ages 69, 67, and 74 years, respectively, underwent surgical removal of cystic cerebellar astrocytomas. All three had past histories pointing to the existence of a cerebellar lesion for many decades prior to surgery: Patient 1 had had nystagmus on lateral gaze on the side of the tumor since early childhood; Patient 2 had had sensorineural hearing loss on the side of her neoplasm for 38 years preceding the operation; and Patient 3 was diagnosed as having a brain tumor 51 years before the operation. (He has been blind because of pressure hydrocephalus for half a century, but otherwise managed to live a productive farming and family life until he sustained a head injury in a car accident, which forced him to undergo removal of his cerebellar tumor.) The neoplasms in all three instances were found by histological examination to be low-grade astrocytomas. These cases indicate that low-grade cerebellar astrocytomas, which are well known for their characteristically long postoperative courses, may at times manifest a slow growth potential with an exceptionally long preoperative course.