Motor nerves to voluntary muscle terminate in motor end plates applied to the muscle fibers. Between these two is a membrane with different electric potentials on each side of it. When a motor impulse arrives at the end plate, acetylcholine is released. As a result of this the electric potential difference across the membrane disappears (“depolarization”) and an electrical wave spreads from it throughout the muscle, causing it to contract. Curare blocks the action of the acetylcholine on the end plate, competing with it for a place on the end plate molecules, and so is called a “competitive blocker”. Gallamine (Flaxedil) acts in the same way. Scoline, on the other hand, causes depolarization of the end plate membrane (hence the description “depolarizing” group of relaxants) and this does not produce, as one might expect, a sustained tetanic contraction of the muscle, but renders it unexcitable so that nerve impulses produce no effect. Thus, we have our two groups of relaxants – the competitive blockers like curare, and the depolarizers like scoline (suxamethonium).
Tetanus may be mild, moderate, severe, or inevitably fatal. Our clinical experience suggests it may be classified as severe (or, maybe, inevitably fatal) when a tetanic spasm stops respiration. Ten patients with severe tetanus were treated by the total paralysis regime (T.P.R.), consisting of tracheostomy, curarization, and intermittent positiveor positive/negative-pressure respiration. Two of the patients were saved by T.P.R. and therefore only limited effectiveness can be claimed for the regime. In inevitably fatal cases survival can be prolonged by T.P.R. so that further effects of tetanus toxin emerge. Of these, the most important appears to be direct damage to the myocardium.
Six cases of Ebstein's malformation are reported. The notable clinical features seen in four patients were gross enlargement of the
heart, venous congestion and marked hepatosplenomegaly. There was complete heart block in one patient and auricular fibrillation in the remaining three. The unusual pathologic features in the four cases that came to necropsy were the large pericardial effusions associated with the cardiomegaly, the absence of an atrial septal defect or patent foramen ovale, the gross enlargement of liver with cirrhotic changes and the large spleen. Histologic examination of heart muscle revealed certain unusual features which are described.
The above survey based on a study of single stool specimens from 569 patients, drawn from a hospital population belonging to different ethnic groups and having different cultural backgrounds, failed to indicate an association between intestinal helminth infection and eosinophilic lung. The higher prevalence of eosinophilic lung in Indians than in the other ethnic groups, as reported previously, cannot be explained on a basis of differences in the prevalence of the intestinal helminths, Ascaris lumbricoides, hookworm, Trichuris trichiura and Strongyloides stercoralis.