Hand function after nerve repair.

Treatment of injuries to major nerve trunks in the hand and upper extremity remains a major and challenging reconstructive problem. Such injuries may cause long-lasting disabilities in terms of lost fine sensory and motor functions. Nowadays there is no surgical repair technique that can ensure recovery of tactile discrimination in the hand of an adult patient following nerve repair while very young individuals usually regain a complete recovery of functional sensibility. Post-traumatic nerve regeneration is a complex biological process where the outcome depends on multiple biological and environmental factors such as survival of nerve cells, axonal regeneration rate, extent of axonal misdirection, type of injury, type of nerve, level of the lesion, age of the patient and compliance to training. A major problem is the cortical functional reorganization of hand representation which occurs as a result of axonal misdirection. Although protective sensibility usually occurs following nerve repair, tactile discriminative functions seldom recover - a direct result of cortical remapping. Sensory re-education programmes are routinely applied to facilitate understanding of the new sensory patterns provided by the hand. New trends in hand rehabilitation focus on modulation of central nervous processes rather than peripheral factors. Principles are being evolved to maintain the cortical hand representation by using the brain capacity for visuo-tactile and audio-tactile interaction for the initial phase following nerve injury and repair (phase 1). After the start of the re-innervation of the hand (phase 2), selective de-afferentation, such as cutaneous anaesthesia of the forearm of the injured hand, allows expansion of the nerve-injured cortical hand representation, thereby enhancing the effects of sensory relearning. Recent data support the view that training protocols specifically addressing the relearning process substantially increase the possibilities for improved functional outcome after nerve repair

Kinematic assessment of manual skill following functional hand surgery in tetraplegia

To determine whether surgical key grip reinforcement actually leads to a better movement ability we developed a procedure for the kinematic analysis of manual skill following hand surgery in tetraplegia. The functional results of surgery in 5 cases were examined by the kinematic analysis of drawing movements using an electronic pen and a digitizer under 3 conditions: with eyes open, with eyes closed, and while performing a concurrent arithmetic task. Movement velocity and dysfluency (ie, the number of velocity changes per centimeter) were measured before and at several moments after surgery during subsequent rehabilitation. Both movement velocity and dysfluency showed good stability across repeated trials and were consistently affected by visual deprivation. Movement velocity showed a 39% increment between the first and last assessment. Although grip strength increased in all patients, it was not associated with the change of movement velocity. These results suggest that other factors (eg deep sensibility, cognition, muscle coordination) play a critical role in the ability to use improved grip force for controlling drawing movements and emphasize the value of a kinematic assessment besides measuring isolated grip force in the evaluation of functional hand surgery. Copyright (C) 2000 by the American Society for Surgery of the Hand