Types Of Peripheral Nerve Injuries Research Articles

The neurone and its response to peripheral, nerve compression

In all types of peripheral nerve injury, it is important to realize that the lesion affects one extended cell, the neurone, which extends from the central nervous system down to the target tissue in the extremity. Compression of a peripheral nerve can disturb the intraneural transport (axonal transport) of a large variety of substances. This may be followed by morphological and biochemical changes in the nerve cell body. These central changes may effect the axon as a whole and confer on the nerve all increased susceptibility to trauma. Studies concerning the reaction of neurones to compression, relevant when discussing the double crush syndrome, are reviewed.

Transganglionic degeneration of capsaicin-sensitive C-fiber primary afferent terminals

Local treatment of rat peripheral nerves with capsaicin induces permanent impairment of afferent C-fiber functions and changes in the response properties of spinal dorsal horn neurons. In this study a new experimental approach, the “capsaicin gap” technique, has been utilized in an attempt to unravel pathomorphological alterations which commence in the domain of primary sensory neurons as a consequence of perineural treatment with capsaicin. The technique relies on the facts that peripheral nerves in the spinal dorsal horn are represented in a strict somatotopic manner, and on the observation that in the adult rat systemic injection of appropriate doses of capsaicin results in a selective degeneration of primary afferent fibers within Rexed's laminae I and II of the spinal cord. We have assumed that, if treatment of a peripheral nerve with capsaicin results in an irreversible destruction of primary afferent terminals related to that nerve, then the corresponding spinal projection areas will be free of degeneration following a subsequent systemic injection of capsaicin. The topographical distribution of degenerating axon terminals, induced by a systemic injection of capsaicin, was studied within the lumbar spinal cord of rats whose sciatic nerves had been treated with capsaicin or its vehicle one to three months previously. In the dorsal horn ipsilateral to the vehicle-treated nerve, axon terminal degeneration was found in the entire mediolateral extent of Rexed's laminae I and II. In contrast, in the dorsal horn ipsilateral to the capsaicin-treated nerve, virtually no degeneration was observed in areas which correspond to the projection territories of sciatic afferents. It is concluded that the central terminals of capsaicin-sensitive sciatic afferents underwent transganglionic degeneration as a result of prior perineural treatment with capsaicin, and a subsequent systemic injection of this neurotoxin therefore failed to cause axon terminal degeneration in somatotopic areas served by the treated nerve. Comparative quantitative morphometric analysis of cell populations of dorsal root ganglia related to capsaicin- or vehicle-treated nerves disclosed (1) a marked reduction in the proportion of small-sized neurons, (2) a fall of about 80% in the percentage of neurons which undergo degeneration after the systemic injection of capsaicin, (3) a marked decrease in the total number of neurons in ganglia ipsilateral to the capsaicin-treated nerves. Quantitative electron microscopic studies on saphenous nerves treated perineurally with capsaicin revealed a 32% reduction in the number of unmyelinated axons as compared with the controls, whereas the number of myelinated fibers was unchanged. The results demonstrate that unmyelinated primary afferent terminals may undergo transganglionic degeneration associated with, and probably resulting from, ganglionic cell degeneration. The “capsaicin gap” technique may be of considerable potential for evaluating transganglionic degenerative changes of unmyelinated primary afferents following various types of peripheral nerve injuries.

Transient and prolonged conduction block in different types of peripheral nerve injury : Y. Inouye, K. Kawai, M. Itoh, T. Manzai and N. Abematsu (Nagoya, Japan)

Transient and prolonged conduction block in different types of peripheral nerve injury : Y. Inouye, K. Kawai, M. Itoh, T. Manzai and N. Abematsu (Nagoya, Japan)

Median Nerve Injuries Associated with Supracondylar Fractures of the Humerus in Children

If not specifically examined for median nerve function, partial injury associated with supracondylar fracture of the humerus in children will go unrecognized. These injuries occur in as high as 5% of supracondylar fractures of the humerus in children. The 6 patients reported here as well as many cases described in the orthopedic literature present evidence that special exercises and supportive care are important as soon as the fracture is healed. Functional return may be seen as long as 4 to 5 months following supracondylar fracture, and exploration should be delayed at least that long in this type of peripheral nerve injury.

Sciatic nerve injury in infants. Recognition and prevention of impairment resulting from intragluteal injections.

Serious sciatic nerve injury can result from injections of commonly used antibiotics and other agents into the buttock, especially in young infants. Such injection injury occurs in the hands of those experienced in the care of infants and children. Twelve cases are reported; in most of these a paralytic drop foot resulting from nerve injury has been misdiagnosed as a congenital lesion or the result of unrecognized poliomyelitis. Demonstration of sensory loss and the absence of sweating over the distribution of sciatic nerve branches is the most valuable clue to the diagnosis. Surgical exploration of the buttock in the three most recent cases revealed marked scarring in and about the sciatic nerve. Recovery has been poor in this important, preventable, type of peripheral nerve injury which probably occurs more commonly than is usually supposed. The midanterior thigh is the preferred site for all intramuscular injections in infants and young children.