Bilateral diaphragmatic paralysis: clinical spectrum, prognosis, and diagnostic approach.

In a retrospective review of the clinical course of five patients with nontrauma-related bilateral diaphragmatic paralysis, we found that the diagnosis is generally delayed (median delay: two years) in the presence of moderate to severe respiratory insufficiencies. Orthopnea out of proportion to the underlying cardiopulmonary status and thoracoabdominal paradoxus in the supine position are the clues to the diagnosis. Pulmonary function tests showed a typical restrictive ventilatory defect, and arterial blood gas showed chronic respiratory acidosis. Failure to recognize the diaphragmatic impairment led to cardiopulmonary decompensations such as cor pulmonale and acute respiratory failure. However, with the institution of appropriate therapy, adverse effects resolved and all five patients are alive and continue to lead independent lives. We conclude that nontrauma-related bilateral diaphragmatic paralysis is an underrecognized and underdiagnosed condition. The results also indicate that early diagnosis and treatment can minimize morbidity and mortality, and that excellent long-term, good-quality survival can be expected.

Median and radial sensory latencies to digit I: normal values and usefulness in carpal tunnel syndrome.

Median and radial sensory latencies were recorded from digit I at a distance of 10cm in 78 neurologically healthy people aged 20 to 79 years. The mean median latency was 2.5 +/- 0.3ms, and mean radial latency was 2.4 +/- 0.2ms. Both were measured to the negative peak. Twenty individuals with carpal tunnel syndrome determined by traditional electrodiagnostic techniques had at least 1ms longer latency in median nerve than the median latency for the healthy control group. This technique is useful in diagnosis of carpal tunnel syndrome.

Some functional effects of suppressing bioelectric activity in fetal mouse spinal cord-dorsal root ganglion explants.

Organotypic explants of fetal mouse spinal cord-dorsal root ganglia were grown for 3 weeks in the presence of 10 mM magnesium ion, which effectively eliminated all recordable bioelectric activity throughout the culturing period. When tested in minimal essential medium, the chronically silenced explants had significantly fewer points from which spontaneous neuronal activity could be recorded. In addition, fewer points could be found that showed dorsal root ganglion-evoked responses, resulting from a greater tendency for the spinal cord activity to be restricted to the vicinity of the dorsally entering DRG fibers. These findings, therefore, support the hypothesis that spontaneous bioelectric activity is required for functional as well as structural maturation of neural networks.

Selectivity of the uptake of glutamate and GABA in two morphologically distinct insect neuromuscular synapses.

The common inhibitor (CI) and slow excitor tibiae (SETi) innervated slow muscles 135cd of the locust Schistocerca gregaria were incubated under high-affinity uptake conditions either in [3H]GABA or in [3H]glutamate. [3H]GABA is accumulated in the glia of the nerve endings of the CI as well as the SETi; however, it is accumulated only in the terminal axons of the CI, not in the terminal axons of the SETi. The grain densities above the glia and above the CI terminal axons are approximately 2 grains/micron2. After incubation in [3H]glutamate the grain densities above the CI terminal axons and the SETi terminal axons are approximately 4 grains/micron2; the grain densities above the glia of both types of nerve endings are approximately 17 grains/micron2. The relatively high labeling (3 grains/micron2) of the muscles after incubation in the presence of glutamate is ascribed to the high metabolic requirements of slow muscles. The conclusion is drawn that a high-affinity uptake system for GABA is present in the CI terminal axons and in the glia of both the CI and SETi nerve endings. However, while the glutamate uptake in the CI and SETi nerve endings of the slow 135cd is comparable to the high-affinity uptake of glutamate in the fast excitor tibiae (FETi) nerve endings of the fast retractor unguis muscle, a high-affinity uptake of glutamate was only demonstrated in the glia of both types of nerve endings. A high-affinity uptake in the terminal axons of the CI and SETi may be masked by an extensively low-affinity uptake of glutamate by the muscles.