There are at least three well-known forms of pathological change in the motor apparatus of the forearm (independent of the ordinary paralytic or spastic conditions due to nerve lesions) that may give rise to contractions of the fingers. These are—the ischæmic paralysis of Volckmann, inflammatory processes in the muscular sheaths, and gummatous formations, or more rarely other tumour growths in the muscles.
(a) The affection described by Volckmann as muscular paralysis of ischæmic origin is now seldom met with. It is a result of prolonged immobilisation of forearm fractures by any form of apparatus that intercepts the free circulation of blood through the muscles and nerves of the part. When the splint is removed the hand is found painful, dusky, and swollen, and the fingers are bent like claws, any attempt to extend them causing great pain. Volckmann believed that the nerves in these cases have preserved their power of conduction, but that the muscular fibres are structurally injured and have lost their excitability. The lesion, however, is seldom of a permanent character, and the function may generally be restored by systematic active and passive movements, with massage, and if necessary the use of a galvanic current. Its existence is a reproach to surgery, since a careful observation of the hand and fingers during the use of splints will always give due warning of the danger.
(b) Diffuse inflammation of the inter-muscular planes and perimysial connective tissue may occur as a result of poisoned wounds, and other injuries, and may lead to a like deformity in the fingers. In a case under my own charge it was caused by a sting in the forearm by an adder. The injury was followed by the usual pain and swelling, accompanied by a painful contraction of the fingers, which lasted for nearly three months, but was ultimately relieved by the measures recommended for the ischæmic paralysis. Wounds implicating the flexors may occasionally lead to permanent contraction—either as a result of actual loss of substance, or in young subjects from interference with the development of the muscle (as in the case already mentioned). Under these circumstances the operation of tendon lengthening may be required if the endeavours to secure gradual extension are unsuccessful. König describes a case of flexion of the hand and fingers in a newly-born child, caused by a tearing of the flexors at the moment of disengagement of the arm in the course of delivery.
(c) Gummatous formations in the forearm flexors, causing painful contraction of the finger, are comparatively rare. A very interesting case of the kind is reported by Dr. A. G. Barrs in the Medical Chronicle for May 1891. The muscle affected was evidently the flexor profundus in its ulnar portion; and the finger contraction which bore a superficial resemblance to Dupuytren’s disease, was complicated by other symptoms indicating a concomitant affection of a portion of the cord.
CONTRACTION OF THE FINGERS DEPENDENT UPON A TENDO-VAGINITIS OF THE BURSAL SHEATH OF THE FLEXOR TENDONS.
The following notes of an example of this somewhat rare condition under my observation may be of interest:
The patient, a girl, aged twenty, attended St. Thomas’s Hospital for a swelling of the front of the right wrist, with contraction of the fingers and complete loss of use of the hand. She stated that the contraction appeared six days before without apparent cause. On examination a large swelling was found, extending upwards for about an inch and a half above the anterior annular ligament, and distally along the ulnar side of the palm as far as the root of the little finger. The phalangeal joints of all the fingers were flexed, and any attempt to straighten them caused considerable pain, while the movements of the little finger were accompanied by a peculiar coarse grating, that could be felt along the whole length of the theca and in the palm, ceasing, however, at the level of the carpus. The thumb was flexed and adducted, and the movements of flexion and extension were painful, apparently because they led to disturbance of the enlarged bursal sheath of the finger flexors. The affection was evidently a tendo-vaginitis involving the carpal bursal sheath of the finger flexors and the palmar extension which brings this into communication with the digital bursal sheath of the little finger. The crepitation indicated that the intra-vaginal portion of the tendon was roughened by inflammatory deposits, and it is possible that these irregularities may lay the foundation for a subsequent trigger finger. The case was successfully treated by immobilisation of all the joints of the wrists and fingers in plaster of Paris, followed by passive movement as soon as the acute stage was passed.
A tendo-vaginitis of the extensors over the back of the hand may induce considerable functional impairment of the fingers, with more or less contraction at the metacarpo-phalangeal joints. Such a condition has been described by Vogt as an occasional result of gonorrhœa, and Verneuil has met it as a manifestation of syphilis. The majority of examples, however, occur without any ascertainable constitutional cause.