The nature of Bell's palsy: its aetiology, and the role of Herpes simplex virus
Williamson, Ian George
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This thesis aims to investigate the nature and aetiology of Bell's palsy by studying its natural history and epidemiology in general practice, and by means of virological studies.This thesis is concerned principally with testing the first part (sentence) of this hypothesis.A new hypothesis is outlined of the aetiology of Bell's palsy which provides a framework for the investigations:-"Bell's palsy is due to a reactivation of HSV in the geniculate ganglion. During this process, neurotransmitters (opioid peptides) and interferon are produced. These cause local vaso-dilation and damage, particularly to the suprageniculate part of the facial nerve."This thesis is concerned principally with testing the first part (sentence) of this hypothesis.The virological studies set out to examine a possible role for HSV in Bell's palsy, which is contingent on the belief that HSV is normally resident or resident to some degree in the geniculate ganglia of the general population. The evidence of the DNA/DNA hybridization study suggests that HSV may be ubiquitously present in human cadaveric geni¬ culate ganglia. From these a substantial proportion might be expected to reactivate. In contrast the observed incidence of Bell's palsy in the descriptive study of 16.4 per 100,000 per year suggests that if HSV is a cause the mere occurrence of reactivation is an inadequate explanation of the disease mechanism.The epidemiological studies describe Bell's palsy in British general practice where cases are less strongly selected than in hospital studies. By means of a case-control study and match-pair analysis further inves¬ tigations are made as to the effect of different factors including various types of stress in the aetiology of Bell's palsy. The results of these studies suggest numerous aetiological agents,of particular relevance to the hypothesis are genetic factors, states of increased "stress" and opioid "sensivity", which are discussed.In conclusion the balance of evidence is compatible with the proposed hypothesis, which in the author's opinion justifies further research, especially since it carries treatment implications.