Two different modes of cutaneous sensory reinnervation are thought to be engaged following nerve injury: regenerative growth of the injured nerve and 'collateral sprouting' of neighboring intact nerves. Although both processes are well known from experimental preparations, there is little unequivocal documentation of collateral sprouting in human skin. We report here on 5 patients in whom at least partial recovery of sensation in the hand following traumatic or surgical nerve section was apparently based on collateral sprouting from nerves that had not themselves been injured. Two types of evidence are brought. In three of the cases a totally anesthetic region of skin at a distance from the site of injury was shown to recover sensitivity long before regenerating nerve fibers could have arrived, given the known rates of fiber outgrowth. In the remaining two cases, nerve blocks using local anesthetics were used to establish that the reinnervated skin was served by a nerve other than the injured one. Thus, collateral sprouting appears to contribute to cutaneous sensory recovery in man as well as in animals.
The long flexor tendons of the second, third and fourth toes of 94 chickens were cut and sutured. After operation the birds were divided into three groups. To reduce peritendinous adhesions, an aqueous solution of beta-aminopropionitrile (BAPN) was added to a solution of enriched native collagen (ECS) and applied to the cut tendons of one group; untreated controls and controls treated with collagen solution alone comprised the other groups. Chickens from each group were killed one, two, three, four and five weeks after operation. The results were evaluated both biomechanically and biochemically. It was found that the collagen solution alone had the same effect as the treatment with BAPN. It is suggested that the exogenous collagen present at the site of injury binds the collagenase inhibitor released by tendon cells, thus providing enough active collagenase to control the formation of fibrous adhesions. The inefficiency of BAPN in these experiments might have been due to either inadequate dosage or wrong timing, or both.
In order to improve gliding function of damaged flexor tendons in chickens, we topically applied enriched collagen solution (ECS) to the tendon sheaths of severed tendons. Previous studies using the same experimental model showed improvement of gliding function in the damaged tendons biomechanically and increased collagenolytic activity in the area of the damage after application of ECS. In the present study we evaluated the influence of ECS on peritendinous adhesion formation and on the healing process of the tendons histologically. We found that topically applied ECS reduced adhesion formation, mostly during the first week, without adversely affecting tendon healing or scar maturation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.