Carpal ganglion as a cause of paralysis of the deep branch of the ulnar nerve.

During the last forty years a few neurologists and surgeons have come to recognise various paralyses of the hand which develop spontaneously and seem to be local in origin. Various more or less plausible explanations have been offered but the only fairly constant etiological factor has been some sort of occupation which, if pursued for a sufficient length of time, somehow resulted in damage to the ulnar or median nerve. In this field of work the pioneer was J. Ramsay Hunt (1908, 1909, 1911, 1914). The paralyses fall into three groups : those affecting 1) the median nerve in the palm; 2) the whole of the motor distribution of the ulnar nerve, excepting palmaris brevis, the branch of which runs with the sensory division of the nerve ; and 3) the motor division of the ulnar distal to the branches supplying the hypothenar muscles. This paper is concerned with the last group, the condition now usually referred to as traumatic neuritis of the deep palmar branch of the ulnar nerve, and its purpose is to show that this type of paralysis may be caused by a well localised and easily remediable mechanical compression. The cause of a similar affection of the median nerve was finally established by Woltman (1941) and Zachary (1945) ; the nerve is compressed by some means or other in the carpal tunnel. It was not unreasonable to suppose that some similar mechanism might explain traumatic neuritis of the deep branch of the ulnar nerve, and of the five cases that I have seen, four were due to compression of the nerve by a small ganglion emerging from the palmar aspect of a carpal joint. One case will be described in detail and the others are summarised in Table I , which includes all the published cases that I have been able to trace.