Body computerized tomography and the thymus.

Preoperative body computerized tomography (CT) should be of value in depicting the size, extent, and location(s) of the thymus in myasthenic patients undergoing thymectomy. To date, we have been unable to visualize the thymus in three patients with myasthenia gravis using body CT. However, in two nonmyasthenic patients, large thymomas were clearly delineated. Although application of this technique currently appears limited by the size, location, and density of the thymus and the resolution of the scanners, we feel that CT of the mediastinum is an indicated procedure in the evaluation of the patient before thymectomy, especially in those myasthenic patients with a high risk of thymoma.

Behavioral and neurological parameters of the nerve compression block.

The nerve-compression block has been used to investigate movement control in the absence of kinesthetic information. Implicit is the assumption that tactile and kinesthetic sensation are eliminated 5 to 10 min. prior to motor function. Motor fibers in the ulnar and median nerves of the upper preferred limb were tested at systematic intervals throughout the duration of the block application. When kinesthetic cut-off was assigned, Ss performed three tapping trials with vision and audition eliminated. Progressive reduction in nerve-conduction parameters (motor nerve conduction velocity and amplitude of the muscle action potential) occurred across and below the block, with significant decrements occurring as early as 15 min. Results indicated that motor impairment was a confounding factor in the use of the nerve block technique.

The continuing saga of the nerve compression block technique.

In response to Bairstow and Laszlo (1976) the present paper points out the inconsistencies of their arguments relative to Laszlo's previous work and that of Kelso, Stelmach, and Wanamaker (1974). Data are presented indicating that the nerve compression block, as a tool, fails to meet the stringent requirements necessary for examining motor performance in the absence of kinesthetic information. Some possibilities for the discrepancy between Laszlo's performance data and those from Kelso et al. are discussed. These hinge on the availability of sensory information rather than any artifact in the Kelso et al. nerve conduction procedures as Bairstow and Laszlo (1976) suggest.

L-dopa-carbidopa: combined therapy for the treatment of Parkinson's disease.

It is now generally acknowledged that L-Dopa is the therapy of choice for Parkinson's Disease. However, L-Dopa has some short comings: It requires large daily dosage, the therapeutic benefits are achieved only after a delayed onset of 1-2 months, and it has a number of side effects both central and peripheral. In the last few years there has been an intense search for agents that are less toxic, more efficient and more rapidly acting that L-Dopa. The ideal agent has not yet been found. However, a combination therapy with L-Dopa and dopa decarboxylase inhibitors has shown promise. The decarboxylase inhibitors used have a large molecule which does not cross the blood brain barrier. Thus when L-Dopa and the decarboxylase inhibitor are given togehher, peripheral production of dopamine from L-Dopa is inhibited, therefore, rendering L-Dopa more readily and rapidly available for brain metabolism. In the present paper we present the results of the treatment of 50 patients on combined therapy using L-Dopa combined with Carbidopa.

Thrombocytopenia associated with long-term levodopa therapy.

A 63-year-old man had severe thrombocytopenia after long-term levodopa therapy. Serologic studies and clinical features indicate that the thrombocytopenia was due to an autoimmune process, presumably similar to that induced by the chemically similar drug methyldopa. Direct allergy to levodopa was ruled out by controlled challenge of the patient receiving levodopa. Combined levodopa-prednisone therapy was then instituted, with good clinical response and no recurrence of thrombocytopenia.