Abstract
Poliomyelitis occurring within 30 days after tonsillectomy is predominantly bulbar 1 . When compared with the incidence of the bulbar form in patients who have not had the operation within the same period of time, the difference is greater than can be explained on the basis of pure chance and indicates a causal relationship between operation and bulbar localization. This is particularly true of children, as shown by the two examples from the literature given in Table I.
In human bulbar poliomyelitis, including the post—tonsillectomy cases, the muscles of deglutition and phonation, supplied by the X cranial nerve and the nucleus ambiguus. are practically always involved, the facial muscles (X.VII) in about half, and those supplied by the Y and XII nerves in lesser numbers 4 . The nuclei of supply in all these are in the pons or medulla. Post—tonsillectomy bulbar poliomyelitis occurs almost exclusively during epidemics of the disease, and the onset of symptoms according to Aycock's 1 compilation nearly always occurs 6-24 days after operation, with the peak at 14-16 days. These figures agree closely with the incubation period of poliomyelitis in general, suggesting that virus may be introduced at the time of operation. Only rare cases have been reported in which the onset was less than 4 days after operation. Previous attempts 5 , 6 , 7 to reproduce experimentally the sequence of bulbar paralysis after tonsillectomy have nearly always failed, paralysis when produced usually having been spinal in type. In most of these studies, notably that of von Magnus and Melnick 7 exposure of the throat to the virus has been made after rather than before operation. Unpublished observations in our laboratory have shown that in order consistently to produce infection in divided nerve it is necessary to apply virus to the central cut end before it is sealed off by blood.
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