There are many controversies that afflict the definition of polyneuritis. The most urgent question involves the minimum requirements for the diagnosis. The patient who is suddenly and conspicuously paralyzed in all extremities, who has lost sensation in the distal portions of the limbs and in whom tendon reflexes cannot be obtained does not test diagnostic acumen. But there is confusion at the other extreme. Diagnostic criteria of minimal polyneuritis appear to vary from writer to writer, and some persons disciplined in neurology doubt whether all who seem to speak authoritatively know what polyneuritis is. In fact, neurologists are themselves doubtful in borderline cases. A tendency to include pain in the leg under the heading of polyneuritis might contribute to a therapeutic fashion.
Another controversial point is the nutritional deficiency hypothesis, which is at present rather overworked. No one has advanced any convincing figures to show that the incidence of the