Multifocal acquired demyelinating sensory and motor neuropathy: the Lewis-Sumner syndrome

We report 11 patients with multifocal acquired demyelinating sensory and motor (MADSAM) neuropathy, defined clinically by a multifocal pattern of motor and sensory loss, with nerve conduction studies showing conduction block and other features of demyelination. The clinical, laboratory, and histological features of these patients were contrasted with those of 16 patients with multifocal motor neuropathy (MMN). Eighty-two percent of MADSAM neuropathy patients had elevated protein concentrations in the cerebrospinal fluid, compared with 9% of the MMN patients (P < 0.001). No MADSAM neuropathy patient had elevated anti-GM1 antibody titers, compared with 56% of MMN patients (P < 0.01). In contrast to the subtle abnormalities described for MMN, MADSAM neuropathy patients had prominent demyelination on sensory nerve biopsies. Response to intravenous immunoglobulin treatment was similar in both groups (P = 1.0). Multifocal motor neuropathy patients typically do not respond to prednisone, but 3 of 6 MADSAM neuropathy patients improved with prednisone. MADSAM neuropathy more closely resembles chronic inflammatory demyelinating polyneuropathy and probably represents an asymmetrical variant. Given their different clinical patterns and responses to treatment, it is important to distinguish between MADSAM neuropathy and MMN.

Glue-sniffing neuropathy

Although industrial exposure to n-hexane is known to cause neuropathy, it is less well recognized that inhalation of n-hexane present in the vapors of some commercial contact cements is also neurotoxic to peripheral nerves. A young man with a long history of addictive glue-sniffing developed severe distal symmetrical polyneuropathy several months after switching to a cement containing n-hexane and gradually improved several months after switching to another cement containing no n-hexane. Fascicular biopsy of radial cutaneous nerve showed striking segmental distention of axons by neurofilamentous masses with secondary thinning of myelin sheath, paranodal myelin retraction, and widening velocities were correspondingly slow. We conclude that n-hexane used as a solvent in some contact cements may be neurotoxic when inhaled to excess and, further, that the neuropathy has characteristic electrophysiological and pathological features.

Chronic demyelinating neuropathy associated with benign IgM paraproteinaemia

Twelve cases of chronic sensorimotor neuropathy associated with benign IgM paraproteinaemia are described. The onset was in the sixth or seventh decades and 9 cases were male. Tremor and ataxia were common features. The ESR was raised in 6 cases and the CSF protein content elevated in 10. There was severe reduction of motor nerve conduction velocity. Sera from all cases contained monoclonal IgM antibodies strongly reactive with human peripheral myelin, made up by the paraprotein. Histological studies on nerve biopsies taken from 8 cases all demonstrated a demyelinating neuropathy. Eight biopsies were examined by immunofluorescence. Monoclonal IgM was present on the myelin sheaths of surviving myelinated nerve fibres. The findings suggested that the neuropathy was of autoimmune origin and caused directly by the antimyelin antibody.

A study of nerve regeneration across synthetic (Maxon) and biologic (collagen) nerve conduits for nerve gaps up to 5 cm in the primate

In a primate model, nerve regeneration was evaluated across 2- and 5-cm nerve gaps using a synthetic nerve conduit (glycolide trimethylene carbonate, Maxon) and a biologic conduit (collagen). Two types of conduits from glycolide trimethylene carbonate (Maxon) were evaluated. The first was fashioned into a tube from a single flat piece of Maxon mesh. The second was prefabricated in a crimped form. The other material evaluated was a biologic collagen tube. At 14 months, excellent regeneration was noted across the 2-cm nerve gap through both the collagen and Maxon conduits. At 5 cm, the regeneration, as determined by morphometric analysis, was significantly better across the Maxon prefabricated, crimped conduit, although regeneration at this longer gap in all experimental groups was significantly less than across the shorter nerve gap. At the longer gap, there was no statistical difference between the groups by electrophysiologic assessment.

Nerve transfer to deltoid muscle using the nerve to the long head of the triceps, part I: an anatomic feasibility study

PURPOSE

To experimentally evaluate the feasibility of restoring the motor function of the deltoid muscle in patients with complete C5-C6 root injury (upper brachial plexus injury) by transferring the nerve to the long head of the triceps to the anterior branch of the axillary nerve through a posterior approach.

METHODS

The study was performed on shoulder girdles of 36 formalin-embalmed cadavers. The number, diameter, and length of the branches of the axillary nerve at the level of the quadrilateral space were noted. The length and diameter of the nerves to the long head and to the lateral head of triceps at the level of triangular space were recorded. The distances from the acromion angle to the bifurcation of the anterior branch of the axillary nerve, to the origins of the nerve to the long head, and to the origin of the lateral head of the triceps were recorded as well. Nerve biopsy specimens of the axillary nerve and the nerve to the long head of the triceps were obtained from 6 fresh cadavers for histomorphometric evaluation.

RESULTS

The average length of the anterior branch of the axillary nerve in this study, measured from the quadrilateral space to the innervating site, was 44.5 mm (range, 26-62 mm), and the average length of the nerve to the long head of triceps, measured from its origin to the innervating site, was 68.5 mm (range, 30-69 mm). The average diameter of the anterior branches of the axillary nerve and the nerve to the long head of the triceps were 2.1 and 1.1 mm, respectively. The average number of axon fibers in the anterior branch of the axillary nerve was 2,704 and in the nerve to the long head of the triceps was 1,233.

CONCLUSIONS

Using the acromial angle as the landmark, the combined length of the two 2 nerves was longer than the distance between them. The diameter, the number of axons, and the anatomic proximity of the nerve to the long head of the triceps make it a potential source for reinnervation of the anterior branch of the axillary nerve by direct nerve transfer without nerve grafting through posterior approach for the management of upper brachial plexus injuries.

Murine motor neuron disease (the wobbler mouse): degeneration and regeneration of the lower motor neuron

The study of the temporospatial pattern of lower motor neuronal generation in the wr/wr mouse demonstrated that the pathological changes started in the neuronal perikaryon in the spinal cord. Thus the wr/wr mouse suffers from a primary motor neuronopathy. Axonal pathology predominated at the level of the ventral root and suggested a focal proximal axonopathy. Microtubular segregation, neurofilamentous accumulation in the axon, and axonal or adaxonal vacuoles appeared to be closely related to subsequent axonal degeneration. Large myelinated fibres in the cervical ventral roots progressively degenerated and diminished in number with age. On the other hand, significant axonal regeneration coincided, with the axonal degeneration in the cervical ventral roots. A dying-back type of degeneration and axonal atrophy were not present. This study demonstrated that a primary disease of the perikaryon may express itself as a focal proximal axonopathy characterized by axonal degeneration and attempted axonal regeneration.

The overlap pattern of the lateral antebrachial cutaneous nerve and the superficial branch of the radial nerve

The anatomic relationship between the lateral antebrachial cutaneous nerve (LABC) and the superficial branch of the radial nerve (SBR) is outlined in 53 cadaver and 41 clinical dissections. Either partial or complete overlap of the LABC with the SBR occurred in 75% of the cases. The LABC and the SBR innervated separate territories in only 25% of the dissections. We suggest that injury to the LABC may be a concomitant finding in patients with injury to the SBR and that this associated injury to the LABC may be one of the reasons why neuromas of the SBR have been thought to be more resistant to therapy than neuromas elsewhere.

Chronically implanted intrafascicular recording electrodes

A newly designed intrafascicular electrode for chronic neural recording was studied by implanting 12 electrodes in the radial nerves of 6 cats for 6 months. Action potentials were monitored at specified intervals throughout the experiment. The number and size of the signals recorded suggest that this type of electrode provides information that is appropriate for feedback control in functional electrical stimulation (FES) systems. Histology of the nerve revealed that the implants are biocompatible and that little damage is caused by the presence of the electrode.

Primary lymphoma of peripheral nerve: report of four cases

Lymphoma presenting as a solitary tumor of peripheral nerve is exceedingly rare, with only six previously reported cases. The authors describe an additional four cases of primary lymphoma of peripheral nerve involving the sciatic nerve (two cases), the radial nerve, and the sympathetic chain and spinal nerve. The patients were two men and two women with an average age of 55.5 years. All tumors were high-grade B-cell lymphomas. Two patients experienced relapse of disease with involvement of other nervous system sites and died of lymphoma. One patient is alive with stable local disease at 57 months. The fourth patient is alive with no evidence of disease at 54 months. Expression of neural cell adhesion molecule (CD56) has been reported to correlate with an increased incidence of central nervous system involvement in peripheral T-cell lymphoma; all their cases were CD56 negative. Recent reports indicate a high proportion of primary brain lymphomas show loss of CDKN2A/p16 gene expression. Therefore, CDKN2A/p16 was evaluated in their patients both by polymerase chain reaction and by immunohistochemistry for the p16 protein. The authors found homozygous deletion of the CDKN2A/p16 gene in one of three patients studied, confirmed immunohistochemically by absent staining for p16. The fourth patient showed absent staining for p16, suggesting inactivation of the gene in this case as well. The two patients with p16 loss both died of lymphoma, whereas the two patients with normal p16 expression are alive. Primary lymphoma of peripheral nerve is a rare neoplasm, usually of large B-cell type, has a variable prognosis, and appears to have less consistent loss of p16 expression than primary central nervous system lymphoma.

Susceptibility of the superficial sensory branch of the radial nerve to form painful neuromas

The superficial sensory branch of the radial nerve appears prone to develop painful neuromas out of proportion to its likelihood for injury. Based on cadaver dissections and intraoperative observations, an anatomical mechanism for this "predisposition" is suggested. Exit of this nerve beneath dense fascia and the tendons of brachioradialis and extensor carpi radialis longus provide a proximal tethering against which tension develops as the distal fixation point (neuroma) is pulled through the long excursion of wrist arc of motion. This long excursion and proximal tethering are not present anatomically for the dorsal cutaneous branch of the ulnar nerve nor the palmar cutaneous branch of the median nerve.

Bicipitoradial bursitis: MR imaging findings in eight patients and anatomic data from contrast material opacification of bursae followed by routine radiography and MR imaging in cadavers

PURPOSE

To use radiography and magnetic resonance (MR) imaging after contrast material opacification of the bursae in cadaveric specimens to demonstrate the anatomy of the bicipitoradial bursa and to report MR imaging findings in patients with bicipitoradial bursitis.

MATERIALS AND METHODS

Bicipitoradial bursa in eight cadaveric elbows were injected with a solution containing gadodiamide, iodinated contrast agent, and gelatin. Radiographs and MR images were obtained in each specimen, with both supination and pronation of the forearm. The morphology and relationships of the bursa were studied. Anatomic sections subsequently were obtained. MR imaging studies in eight patients with bicipitoradial bursitis were also evaluated.

RESULTS

The bicipitoradial bursa revealed a smooth outline and a wide base along the superficial aspect of the radius. The mean volume of contrast material that could be injected before extravasation was 4 mL. The mean size of the bursa was 1.8 x 2.5 cm. The bicipitoradial bursa enveloped the biceps tendon, with internal septation seen in two cases. Displacement of the superficial branch of the radial nerve by the bursa was found in two specimens. Communication between the bicipitoradial bursa and elbow joint was not observed. In patients, MR imaging demonstrated fluid collections in the bicipitoradial bursa in all cases, with compression of branches of the radial nerve in two cases.

CONCLUSION

The anatomy of the bicipitoradial bursa is demonstrated with radiography and MR imaging of bursae. MR imaging allows accurate diagnosis of bicipitoradial bursitis and its effects on adjacent structures.

A new resorbable wrap-around implant as an alternative nerve repair technique

Poly-3-hydroxybutyrate (PHB), a bacterial storage product, is available as bioabsorbable sheets and has been used in this study for primary nerve repair. The aim was to assess axonal regeneration following such repair and determine the inflammatory response to PHB. In 20 adult cats, the transected superficial radial nerve was wrapped in PHB sheets, while primary epineural repair was carried out in the contralateral limb. At 6 and 12 months, the repair sites were assessed immunohistochemically for macrophage infiltration and myelinated axons were counted in the distal nerve. Mean macrophage counts across the whole width of the nerve in both groups at 6 and 12 months showed no statistically significant difference. Nor was there any significant difference between the two groups at both time-points in axon counts, axon diameter, myelin thickness and g-ratio. There was a statistically significant increase in fibre diameters at 12 months, indicating that fibres were undergoing continuous maturation.

The elbow: MR features of nerve disorders

The authors retrospectively reviewed 15 magnetic resonance (MR) studies of elbows with radiographic evidence of nerve disorders. These 15 cases were selected from 55 MR studies of the elbow in patients referred for various complaints. MR images of the elbow of 10 healthy volunteers were also reviewed. Ulnar nerve disorders were seen in 11 cases. Three patients had median nerve disease, and one patient had a pathologic condition of the radial nerve. The following nerve abnormalities were detected: focal or diffuse nerve thickening, increased signal intensity on T2-weighted images, and course deviation due to either mass effect or spontaneous subluxation. Six of seven patients with nerve thickening, two of two patients with increased nerve signal intensity, and five of eight patients with nerve displacement complained of neurologic symptoms. Four of the patients underwent surgery; in each, surgical results confirmed the findings at MR. These results suggest that MR imaging has a potential role in the detection of nerve disorders at the elbow and in the guidance of treatment.

MR Imaging Features of Radial Tunnel Syndrome: Initial Experience

PURPOSE

To retrospectively assess magnetic resonance (MR) imaging features of radial tunnel syndrome.

MATERIALS AND METHODS

Institutional review board approval was obtained, and informed consent was waived for the retrospective HIPAA-compliant study. MR images of 10 asymptomatic volunteers (six men, four women; mean age, 30 years) and 25 patients (11 men, 14 women; mean age, 49 years) clinically suspected of having radial tunnel syndrome were reviewed for morphologic and signal intensity alterations of the posterior interosseous nerve and adjacent soft-tissue structures. MR images of the asymptomatic volunteers were reviewed to establish the normal appearance of the radial tunnel. MR images of the symptomatic patients were evaluated for the following: signal intensity alteration and morphologic alteration of the posterior interosseous nerve; the presence of mass effect on the posterior interosseous nerve such as the presence of bursae, a thickened leading edge of the extensor carpi radialis brevis, or prominent radial recurrent vessels; signal intensity alteration within the depicted forearm musculature such as edema or atrophy; and signal intensity changes at the origin of the common extensor and common flexor tendons, which would suggest a diagnosis of epicondylitis.

RESULTS

All images of volunteers demonstrated normal morphology and signal intensity within the posterior interosseous nerve and adjacent soft tissues. Two volunteers had borderline thickening of the leading edge of the extensor carpi radialis brevis. Thirteen patients (52%) had denervation edema or atrophy within muscles (supinator and extensors) innervated by the posterior interosseous nerve. One patient had isolated pronator teres edema. Seven (28%) patients had the following mass effects along the posterior interosseous nerve: thickened leading edge of the extensor carpi radialis brevis (n = 4), prominent radial recurrent vessels (n = 1), schwannoma (n = 1), or bicipitoradial bursa (n = 1). The rest of the patients had either normal MR imaging findings (n = 4) or lateral epicondylitis (n = 2).

CONCLUSION

Muscle denervation edema or atrophy along the distribution of the posterior interosseous nerve is the most common MR finding in radial tunnel syndrome.

Tennis elbow: treatment of resistant cases by denervation

Anatomical and clinical research has shown that the entire lateral epicondylar region is innervated only by radial nerve branches. Based on these investigations we have developed a surgical procedure for complete denervation which is indicated only in resistant cases of tennis elbow. Only one nerve pathway calls for careful exposure, otherwise denervation is accomplished blindly by disinsertion of certain muscles. The result of this procedure also depends on simultaneous indirect decompression of the posterior interosseous nerve. Excellent or good results were obtained in 90% on average. Results of denervation did not improve by additional direct radial nerve release.

Radial nerve entrapment at the elbow: surgical anatomy

The surgical anatomy of interest in the posterior interosseous nerve syndrome was studied to shed light on the ramifying pattern of the radial nerve, the number of its muscular branches and their branching levels, and to pinpoint the location of the fibrous bands that may cause radial nerve entrapment. The fibrous arch of the supinator muscle (arcade of Frohse) was found to lie 3 cm to 5 cm below Hueter's line, that of the extensor carpi radialis brevis muscle lay 0.5 cm to 1 cm proximal to the arcade of Frohse. Symptom patterns in terms of muscle weakness caused by radial nerve entrapment at different levels were also evaluated.

Prions in the peripheral nerves of bovine spongiform encephalopathy-affected cattle

With the use of increasingly sensitive methods for detection of the abnormal isoform of prion protein (PrPSc) and infectivity in prion diseases, it has recently been shown that parts of the peripheral nervous system (PNS) of bovine spongiform encephalopathy (BSE)-affected cattle may become infected. It has been reported that prions spread to the central nervous system (CNS) via the PNS in sheep scrapie, but the pathogenesis of BSE in cattle is less well understood. To determine whether parts of the PNS other than those implicated directly in the hypothetical pathogenetic spread of agent from the intestine to the CNS become involved before or after the CNS is affected, PrPSc distribution was investigated by a highly sensitive Western blotting technique in dorsal root ganglia, stellate ganglion, phrenic, radial and sciatic nerves, adrenal gland and CNS of cattle that were inoculated orally with BSE-affected brain and culled sequentially. In experimentally BSE-affected cattle, PrPSc was first detected in the CNS and dorsal root ganglia; subsequently, PrPSc accumulation was detected in the peripheral nerve trunks. PrPSc was also detected in the adrenal glands of cattle that showed clinical signs. No PrPSc was detected in the PNS of BSE-negative cattle. This study shows that, with respect to dorsal root ganglia, a paravertebral sympathetic ganglion and the somatic nerves examined, PrPSc is detected in the PNS during the disease course at the same time as, or after, it accumulates in the CNS.

Congenital insensitivity to pain with anhidrosis

A nine-year-old child presented with congenital insensitivity to pain and anhidrosis. Quantitative studies and electron microscopy of the cutaneous branch of the radial nerve revealed almost complete absence of small myelinated and unmyelinated fibers and a disproportionate number of nerve fibers with a diameter of 6-10 micrometers. A grouping of both type 1 and type 2 muscle fibers was also seen. We suggest that this disease entity is not caused by a hereditary sensory neuropathy, but rather that it derives from a developmental defect.

Two cases of localized hypertrophic neurofibrosis

Images

Nontraumatic paralysis of the radial nerve with multiple constrictions

PURPOSE

To present an uncommon lesion of radial nerve paralysis with multiple constrictions.

METHOD

Eight patients were treated in our department between January 1994 and August 2000. There were 4 men and 4 women with a mean age of 26 years (10-43 y). The radial nerves of all patients were explored. There were 1 to 5 segmental constrictive lesions at the main trunks of the radial nerves or the posterior interosseous nerves; no obvious extrinsic compression was noted. Epineurolysis was performed in 3 patients, in the other 5 patients the constricted portions of the nerves were resected, and neurorrhaphy was performed in 2 patients, nerve-grafting in 3. Histologic examination of the resected portions showed concentration of inflammatory cells around the vessels in the perineurium.

RESULTS

The patients were followed-up for 6 months to 4 years after surgery. Seven patients had at least grade 4 muscle strength in the involved muscles. One patient who was treated by external neurolysis 15 months after onset had no signs of recovery 10 months after surgery.

CONCLUSIONS

Nontraumatic paralysis of the radial nerve with multiple constrictions is very uncommon. The etiology may be a focal inflammatory response around the feeding arteries in the perineurium.

Morphological and morphometric study of peripheral nerves from rats with streptozotocin-induced diabetes mellitus

One year after beginning of the experiment seven streptozotocin-injected Wistar rats and seven controls were fixed by whole-body perfusion, the nervus radialis was dissected and processed for light and electron microscopy. After light-microscopic study standard photographs of nerve cross sections were measured by means of a semiautomatic image analyzer. The following measurements were obtained: (1) surface of fibers, axons, and myelin sheaths; (2) ratio of myelin to axon surface; and (3) percent of endoneural space. Group means and standard errors were calculated, and cumulated class distributions were made. Ultrathin sections from all animals considered morphometrically were studied qualitatively for ultrastructural changes. The quantitative study revealed in the diabetics reduction of average myelin surface, increase of endoneural space, and reduction of myelin/axon ratio. The main ultrastructural findings were lesions of Schwann and mesenchymal cells, followed by less frequent and less severe changes in axons and endothelium. These results suggest a primary Schwann cell lesion was responsible for the observed myelin reduction.

Lipofibromatous hamartoma of the radial nerve: a case report

Lipofibromatous hamartomas of the radial nerve are exceedingly rare. What is believed to be only the second such reported case is described, and a review of the pertinent histological findings necessary to make the diagnosis is given.

Hemangioblastoma of the radial nerve: case report

A case of hemangioblastoma of the right radial nerve is presented. Hemangioblastomas are rare vascular neoplasms characteristically associated with the Von Hippel-Lindau syndrome, in which they are found in the retina, the posterior fossa, and, less often, the spinal cord. Thought of as primary central nervous system neoplasms, hemangioblastomas are rarely found adjacent to the spinal cord involving proximal nerve roots, which represent border zones between the central and peripheral nervous systems. We could find no other report of a pure hemangioblastoma situated this far distally in the peripheral nervous system. The histological findings, immunohistochemistry, and electron microscopic findings of this lesion are discussed. This case supports the hypothesis that hemangioblastoma is not derived from astrocytes, because of the location of this tumor in the peripheral nervous system and glial fibrillary acidic protein negativity.