Shoulder arthrodesis for the treatment of brachial plexus palsy

In 14 adult patients with brachial plexus injuries, shoulder arthrodesis was completed in a position of 30 degrees abduction, 30 degrees flexion, and 30 degrees internal rotation. Abduction was measured by the position of the arm in relation to the side of the body with the scapula in the anatomic position. Internal fixation was used in each case. Six patients had had Steindler procedures. Three patients with complete paralysis were treated by above-elbow amputation. All shoulders fused. Mean follow-up time was 32 months. All patients noted that shoulder fusion had improved the function of their extremities. Minimum shoulder motion was 60 degrees abduction and 50 degrees flexion. Three procedures failed because of continued pain that was not relieved by surgery. One patient with an elbow flexion contracture disliked the combination of shoulder and elbow flexion. Seven patients required plate removal. Only one of the three patients who had had above-elbow amputation became a good prosthetic user. Shoulder arthrodesis is a reliable procedure that improves function in adult patients with brachial plexus palsy.

Nerve regeneration through a pseudosynovial sheath in a primate model

This study investigated nerve regeneration through a pseudosynovial sheath in a primate. After resecting a 3-cm segment of the ulnar nerve at the elbow, the two ends of the divided nerve were placed at either end of the pseudosynovial tube, positioning the nerve ends such that they were separated by a 3-cm gap. Histologic evaluation at 3, 5, 7, and 9 months demonstrated evidence of nerve regeneration across this gap. Nerve fiber diameter and density assessment demonstrated a maturation of the fiber pattern with time. The overall morphologic pattern of the regenerating nerve within the pseudosheath was that of multiple small fascicles, each within its own perineurial compartment. This pattern resembled neither the proximal nor distal nerve fascicular pattern.

Peripheral nerve injection injury with purified bovine collagen--an experimental model in the rat

This study investigated the effect of purified bovine collagen (Zyderm collagen implant) on peripheral nerve tissue in rats. Zyderm was injected extrafascicularly and intrafascicularly into the sciatic nerve of adult Wistar rats. The nerves were examined by light and electron microscopy and the integrity of the blood-nerve barrier assessed by protein tracer technique. With light microscopy the precise anatomical location of the injected material could be identified. The purified bovine collagen did not appear to be neurotoxic. After extrafascicular injection, only minimal nerve fiber damage was seen. Intrafascicular injection produced a histological picture compatible with compression neuropathy and was associated with a breakdown in the blood-nerve barrier.

The nerve allograft response--an experimental model in the rat

The nerve allograft response in a rat model is presented. The Lewis rat (RTI1) served as the recipient animal while Fischer rats (RTI1) and ACI rats (RTIa) provided the donor nerve allografts. A Lewis/Lewis autograft group was used as the control group. Histological and electrophysiological measurements of nerve regeneration were assessed at five months. While good regeneration was noted in the autograft and matched allograft groups, regeneration across the unmatched allograft was poor. The degree of nerve regeneration (as measured with histological and electrophysiological values) correlated well with previous immunological studies and would support the use of this model for future investigation of the nerve allograft response in the rat.

Histologic assessment of nerve regeneration in the rat

This study reports the degree of spontaneous regeneration that will occur in the sciatic nerve of a rat 5 months after complete resection of the nerve. In 30 animals, the sciatic nerve was excised. Histological assessment at 5 months revealed evidence of regeneration for a variable distance (mean 23.7 mm +/- 6.4 mm). Histological sections were studied at 1-cm intervals along the length of the nerve. Evidence of compartmentation with "minifascicle" formation was noted. The orientation of the nerve fibers was parallel to the long axis of the nerve. This study assessing spontaneous regeneration is meant to serve as a control for other studies evaluating the effect of factors that may influence nerve regeneration in the rat model.

A primate model for chronic nerve compression

Peripheral compression neuropathy is a common clinical entity but little human nerve material has been available for study. It has been difficult to develop an experimental model of chronic nerve compression which is reliable and reproducible, making it difficult to assess the various treatment modalities currently in use to manage this problem. In a recent study using a rat model, connective tissue and nerve fiber changes associated with chronic nerve compression were described by the authors. The present study expands this same model of chronic nerve compression to the multifascicular median nerve of the cynomolgus monkey, using this model to test whether or not current surgical treatment modalities for nerve entrapment will alter the course of chronic nerve compression. Using histologic and morphometric parameters, there did not appear to be a difference between nerves treated by decompression alone or by decompression and internal neurolysis. Total number of nerve fibers remained constant, as did axon size, but a demyelinating process was demonstrated which is a significant component of chronic nerve compression. Although the small number of experimental animals (7) makes precise evaluation of the clinical modalities impossible, the authors expect that further study of the multifascicular median nerve of the cynomolgus monkey will prove to be a useful source of future experimental evidence and will help to interpret the diverse therapeutic and operative techniques currently in use.

Peripheral nerve allograft: an assessment of regeneration across pretreated nerve allografts

Regeneration across lyophilized and irradiated peripheral nerve allografts was assessed using electrical and histological parameters. Regeneration did occur across these pretreated nerve allografts and was intermediate between that regeneration which occurred across a fresh, untreated nerve allograft and that which occurred across the control autograft.

Chronic nerve compression--an experimental model in the rat

This study reports a rat model of chronic nerve compression. The sciatic nerves of adult male Sprague Dawley rats were bonded with 1-cm lengths of tubing with varying internal diameters. Histological and electrical studies as well as studies to assess the blood-nerve barrier function were carried out at one through six months. With marked compression of the sciatic nerve, profound electrical changes were noted as early as one month, and histological findings were those of degeneration and regeneration. In the rats with minimal compression, nerve conduction studies remained normal. The earliest findings were alterations in the blood-nerve barrier, followed by histological changes in the large myelinated fibers at the periphery of the fascicles and changes about the nodes of Ranvier. This model appears to be a valid one with which to study other aspects of both the pathophysiology and treatment of chronic nerve compression.

Perineurioma (localized hypertrophic neuropathy)

Three patients with localized hypertrophic neuropathy ( LHN ) had a painless, slowly progressive mononeuropathy over many years, resulting in severe focal neurologic deficit. Grossly, the affected nerves showed a fusiform enlargement. Histologically, there was loss of nerve fibers, disorganization of the fascicular pattern, and proliferation of elongated cells with whorl formation. These cells exhibited no immunoreactivity for S-100 protein, and ultrastructural features set them apart from Schwann's cells. We conclude that LHN is not a disorder caused by hyperplasia of Schwann's cells but a benign peripheral nerve tumor of perineurial cell origin. This study also suggests that perineurial and Schwann's cells may not derive from the same precursor element.

Peripheral nerve injury by chymopapain injection

Chymopapain injected into the intervertebral disc space (chemonucleolysis) has been used clinically in patients with disc disease with success. Neurosurgical complications secondary to the procedure have, however, been reported. In this study, the authors have investigated the possible neurotoxic effect of chymopapain on the peripheral nerve in rat and primate models. While the extrafascicular injection caused no nerve fiber damage, the intrafascicular injection caused dose-related nerve fiber damage in both species.

Differences in the effects of selenite and biological selenium on the chemical form and distribution of mercury after the simultaneous administration of HgCl2 and selenium to rats

The interaction was compared between inorganic (HgCl2) mercury and selenite (Na2SeO3) vs. the interaction between inorganic mercury and biological selenium (a freeze-dried preparation of liver from rats treated with selenite). Organ concentrations of selenium were always significantly lower after biological selenium than after selenite. Biological selenium affected the organ distribution of inorganic mercury differently than selenite. Furthermore, the speciation of mercury was affected by this form of selenium. A mercury-selenide compound (presumably HgSe) accounted for a greater proportion of total mercury in tissues after selenite than after a dose of biological selenium. Administration of selenomethionine had a similar effect on the speciation of mercury to that seen after biological selenium. As the forms of selenium in selenomethionine or selenium deposited in the liver are most likely nearer than selenite to selenium present in food, our results suggest that, as far as the reaction of mercury with selenide is concerned, experiments with selenite overestimate the protective effect of dietary selenium against inorganic mercury and possibly against methylmercury.

Peripheral nerve allograft: an immunological assessment of pretreatment methods

An in vivo immunological assay was used to determine quantitatively the nerve allograft response in a rat model. The nerve allograft was then pretreated with a number of pretreatment methods that have been used clinically and experimentally. Using the same immunological assay to determine quantitatively the nerve allograft response, we found that lyophilization and high doses of irradiation could modify the nerve allograft in such a way as to make it less immunogenetic to the host animal. The other methods of pretreatment did not alter the antigenicity of the allograft.

Nerve injection injuries

Nerve injection injury is preventable. There is now a reasonable basis for management of the unfortunate victims, should an accident occur. Practitioners who follow the basic steps of management will both aid their patients and also allow them to give a better account of themselves in the medicolegal setting.

Computed tomography of sphenoid sinus mucocele

The clinical presentation of sphenoid sinus mucocele is usually dependent on the degree of involvement of adjacent structures. Since extension can be in any direction, there is a wide spectrum of symptomatology and clinical diagnosis can be difficult. Five cases of sphenoid sinus mucocele, four of which were demonstrated by computed tomography (CT), are presented. CT with its multiplanar display capability, is the diagnostic procedure of choice. It not only demonstrates the extent of the lesions non-invasively, but its ability to demonstrate bony expansion and destruction as well as density and enhancement pattern, will obviate the need for tomography. It has the greatest potential for differentiating other sphenoid and parasellar lesions.

Peripheral nerve injection injury with steroid agents

The possible neurotoxic effects of five commonly used steroid agents were examined. Using histologic studies and studies of the microneural circulation, it was found the steroids can indeed cause neurotoxicity. The injection site was critical in effecting injury. Only intrafascicular injection caused damage. The damage produced varied with the agent used. Dexamethasone (Decadron) caused minimal damage, while hydrocortisone (Solu-Cortef) and triamcinolone hexacetonide (Aristospan) caused widespread axonal and myelin degeneration. Disturbance in the blood-nerve barrier correlated with the changes noted on light and electron microscopy, but is thought to be coincidentally and not causally related. In conclusion, it was shown that the intrafascicular injection of commonly used steroid agents had a direct toxic effect on peripheral nerve-fibers and caused a disruption of the blood-nerve barrier. Use of the more toxic agents in the vicinity of peripheral nerves should probably be avoided.

Massive gastroduodenal hemorrhage and perforation in acute spinal cord injury

Fatal gastrointestinal hemorrhage or perforation are important problems in the management of patients in the acute phase of spinal cord injury. This paper describes 3 patients with these conditions, and shows some of the associated hazards, especially the danger of painless penetration, perforation, and peritonitis, plus the increased morbidity of these serious problems in the presence of the neurological sequelae of spinal cord injury. Our experience shows that life-threatening hemorrhage from the gastrointestinal tract occurs in about 2.5% of patients with cord injury, and often occurs during the first few days after the accident. We believe that a high index of suspicion and an aggressive therapeutic approach are necessary to save these patients from the traditionally high mortality associated with massive upper gastrointestinal hemorrhage, especially during this critical period of acute spinal cord injury.

Laceration of the aorta complicating spinal fracture in ankylosing spondylitis

This case report concerns major vascular injury associated with fracture-dislocation of the spine after minor trauma in a patient suffering from ankylosing spondylitis. This injury resulted in laceration of the aorta with the formation of an aortic spinal subarachnoid fistula.

Intraneural ganglion: a case report with electron microscopic observations

We report a case of common peroneal mononeuropathy caused by an intraneural ganglion in a 9-year-old boy. The mass and the contiguous nerve fascicles were excised under the operating microscope. Histologically, the cyst wall was composed of layers of elongated cells merging with fascicles that exhibited changes suggestive of a pressure-ischemia effect. Electron microscopy showed that the cells forming cyst wall were myofibroblasts, similar to the cells found in ganglia arising from joints elsewhere in the body. A review of the English literature on intraneural ganglia discloses 44 additional cases, of which 86% involved the common peroneal nerve. The most common clinical feature was motor dysfunction (followed by pain, sensory loss, and the presence of a palpable mass), and a significant male predominance is noted. The pathogenesis of this nerve lesion is discussed in light of our findings.

Experimental study of fascicular nerve repair with and without epineurial closure

Microscopic fascicular repair without closure of epineurium was compared with microscopic epineurial repair in 12 rhesus monkeys. Measurements of evoked nerve action potentials, and responses to repetitive and tetanic stimulation made at one interval 3, 6, 9, or 12 months postoperatively, were compared to baseline preoperative studies. Histological evaluation included light and electron microscopic preparations and studies of distal stump myelinated fiber maturity. Electrical measures of regeneration indicated that recovery was more advanced in the limb with epineurial repair in eight animals, whereas in four there was no difference between fascicular and epineurial repair. Fascicular repair appeared not to fare as well as epineurial repair because, although neuromas developed with both, the length of the neuroma was greater with fascicular than with epineurial repair. The relatively lengthy neuroma in the nerve with fascicular repair was due to axonal disorganization and connective tissue proliferation along the length of the dissection necessary for the repair. Nonetheless, studies of myelinated fiber distribution in the distal stump showed no significant differences. Similar studies were conducted in 11 primates, where epineurial repair was matched with fascicular repair in which the epineurium was closed. Here, regeneration as measured by both electrical and histological studies was comparable. Histological study showed less disorganization at the repair site in the nerve with fascicular suture and epineurial closures than in that with epineurial suture. However, studies of distal stump myelinated fiber maturity demonstrated no significant differences. Thus, there seems to be no advantage in either resecting or closing epineurium in fascicular nerve repair.

Clinical and experimental aspects of injection injuries of peripheral nerves

Injury to peripheral nerves complicating deep intramuscular injections of antibiotic and other agents is well recognized and can result in significant permanent neurological deficit. The purpose of this paper is to review the subject of nerve injection injuries, and report on a series of recent experimental studies carried out in this laboratory designed to improve our understanding of the pathophysiology of this condition and help provide a rational basis for its treatment. A wide variety of chemotherapeutic, prophylactic, and local anaesthetic agents in common use were injected into the sciatic nerve of the adult Wistar rat. Both intrafascicular and extrafascicular injections were examined. Results revealed that the site of injection was the most crucial factor in determining the degree of nerve fiber injury. Following intrafascicular injection, the degree of injury varied significantly, depending upon the specific agent injected. The most severe injuries were associated with wide-spread axonal and myelin degeneration. Pathological alterations in the nerve were evident as early as 30 minutes following injection injury. Regeneration was a constant finding in nerve damage by injection of the various agents. The mechanism of injury appeared to be a direct toxic effect of the injected compound on neural tissue, with an associated break down of the blood-nerve barrier.