Renaut body distribution at sites of human peripheral nerve entrapment

In an autopsy study of the pathology of chronic subclinical nerve entrapment Renaut bodies showed a strong predilection for sites of nerve entrapment. They were present at these sites in 43 of 74 peripheral nerves but in none of the control sections of the same nerves. Renaut bodies were most frequently encountered in the median nerve at the wrist and in the lateral femoral cutaneous nerve at the inguinal ligament but were rarely seen in sections of the common peroneal nerve at the neck of the fibula. Renaut bodies were closely associated with thickened subperineurial capillaries and, in successive transverse sections, they terminated in a fibrous mass of these thickened vessels. In several nerves Renaut bodies showed a similar orientation within adjacent fascicles, suggesting that mechanical factors were related to their pathogenesis; despite this finding there was no relationship between their numbers at entrapment sites and the presence of pathological changes in myelinated nerve fibres at the same level. These findings suggest that while mechanical factors are important in the pathogenesis of Renaut bodies there is no evidence to support the theory that these structures protect nerve fibres from mechanical stress.     

The experimental production of Renaut bodies

Renaut bodies are loosely-textured whorled, cell-sparse structures found in the subperineurial space of peripheral nerves. Although described in 1881, their significance is still debated. Rats were placed in wire-mesh cages for 4 days to 6 weeks and the lateral and medial plantar nerves were sequentially removed. The initial change was the presence of endoneurial edema which dissected and displaced nerve fibers producing an endoneurial cleft. With the influx of fibroblasts, these clefts became discretely separated by circumferentially oriented processes. Over time the clefts enlarged and became filled with loosely-textured amorphous and fibrillar material as well as collagen. The Renaut bodies ranged from 15 to 80 microns in diameter. In this model the Renaut bodies formed at the maximum site of compression of the lateral plantar nerve. The fibroblasts appeared to be derived from the endoneurial connective tissue and were not the result of degenerating endoneurial structures. Renaut body formation was independent of axonal degeneration. The present study strongly suggests that Renaut bodies are a response to repeated mechanical stress.     

Adult polyglucosan body myopathy with subclinical peripheral neuropathy: case report and review of diseases associated with polyglucosan body accumulation

A 65-year-old female had polyglucosan body myopathy, usually called "polysaccharide storage myopathy" that presented with increasing distal paresis and only slight weakness of the proximal limb girdle musculature. Muscle biopsy revealed dystrophic changes that could have been mistaken for muscular dystrophy, and the characteristic light as well as electron microscopic features of polyglucosan bodies varying in number at the three sites of muscle biopsies studied (deltoid, quadriceps femoris, and anterior tibial muscle). In addition, there were occasional nonspecific paracristalline mitochondrial inclusions. No abnormal polyglucosan deposits were found in the sural nerve biopsy. Morphometric evaluation of nerve fiber cross sectional areas revealed some degree of demyelination and remyelination, and of nerve fiber degeneration and regeneration. Unlike a series of 10 unselected control sural nerves with Renaut bodies, hypomyelinated nerve fibers were more numerous adjacent to Renaut bodies. This is the first case of polyglucosan body myopathy in which the axon/myelin ratio and the axonal circularity factor in the sural nerve is evaluated and in which a definite lack of polyglucosan bodies or other abnormal glycogen storage products in a peripheral nerve is documented.     

Lectin binding to Renaut bodies

Localization of sugar residues of Renaut bodies in human sural nerves was studied using lectin histochemistry. Lens culinaris specific to mannose and Triticum vulgaris specific to glcNAc bound to the capsular and core portions of Renaut bodies strongly. Arachis hypogaea specific to galb(1-3)galNAc and Ulex europaeus I specific to L-fucose bound to Renaut bodies granularly. Lectins specific to galactose or terminal galNAc bound to nowhere. The perineurium showed similar lectin binding to Renaut bodies. Our result suggests that Renaut bodies are rich in mannose and glcNAc. Renaut bodies may be originated from the perineurium.     

CHRONIC HUMAN NERVE COMPRESSION – A HISTOLOGICAL ASSESSMENT

While compression neuropathy is a common clinical problem, the opportunity to study human nerve material is rare. A histological assessment of the superficial radial nerve of four human cases with entrapment syndrome is reported. Changes in the perineurium and the endoneurial microvessels as well as the presence of Renaut bodies were the earliest histological abnormalities noted. Connective tissue changes included epineurial and perineurial fibrosis. Nerve fibre pathology varied from fascicle to fascicle. The myelinated and unmyelinated fibre populations responded differently to this compression. In the myelinated fibre population, marked thinning of the myelin was noted. In the unmyelinated fibre population, a shift in the fibre histogram due to a new population of very small fibres was observed suggesting degeneration with subsequent regeneration of this fibre population.     

Anatomical study of sciatic nerve and common peroneal nerve compression

BACKGROUND： Many diseases of the common peroneal nerve are a result of sciatic nerve injury. The present study addresses whether anatomical positioning of the sciatic nerve is responsible for these injuries. OBJECTIVE： To analyze anatomical causes of sciatic nerve and common peroneal nerve injury by studying the relationship between the sciatic nerve and piriformis. DESIGN, TIME AND SETTING： Observe and measure repeatedly. The experiment was conducted in the Department of Anatomy, Tianjin Medical College between January and June 2005. MATERIALS： Fifty-two adult cadavers 33 males and 19 females, with a total of 104 hemispheres, and fixed with formaldehyde, were provided by Tianjin Medical College and Tianjin Medical University. METHODS： A posterior cut was made from the lumbosacral region to the upper leg, fully exposing the piriformis and path of the sciatic nerve. MAIN OUTCOME MEASURES： （1） Anatomical characteristics of the tibial nerve and common peroneal nerve. （2） According to different areas where the sciatic nerve crosses the piriformis, the study was divided into two types-normal and abnormal. Normal is considered to be when the sciatic nerve passes through the infrapiriform foramen. Remaining pathways are considered to be abnormal. （3） Observe the relationship between the suprapiriform foramen, infrapiriform foramen, as well as the superior and inferior space of piriformis. RESULTS： （1） The nerve tract inside the common peroneal nerve is smaller and thinner, with less connective tissue than the tibial nerve. When pathological changes or variations of the piriformis, or over-abduction of the hip joint, occur, injury to the common peroneal nerve often arises due to blockage and compression. （2） A total of 76 hemispheres （73.08%） were normal, 28 were abnormal （26.92%）. The piriformis can be injured, and the sciatic nerve can become compressed, when the hip joint undergoes intorsion, extorsion, or abduction. （3） The structures between the infrapiriform and suprapi     

Acute peroneal compartmental syndrome. Report of a case

Among the compartmental syndromes the necrosis of peroneal muscles is unusual. We report a case in which the swelling of peroneal muscle causes a compression of the common peroneal nerve below the peroneal head. A disturbance of both the motility and sensibility of the deep and superficial peroneal nerve is present with different pathogenesis. In fact, EMG suggested a muscular damage of the peroneal compartment and a denervation of the pretibial muscle. Interfascicular neurolysis along the peroneal nerve was performed to decompress the common and the deep peroneal nerve. A recovery in the territory of the tibialis anterior deep peroneal nerve confirmed the different mechanisms of paralysis.     

The leakage of serum proteins across the blood-nerve barrier in hereditary and inflammatory neuropathies

Summary The suprascapular nerve from 14 horses, which had no clinical evidence of spinatus muscle atrophy, were obtained to determine whether the nerve was sub-clinically compressed at the scapular edge. The nerves were divided into three portions, proximal and distal to the scapular edge and as it reflected around it. In nine horses there was evidence of a chronic neuropathy which varied in severity and which was most severe at the site of reflection, where the nerve appeared constricted by a tendinous band. At this site the predominant change was that of chronic demyelination and remyelination, with many scattered thinly myelinated fibres and occasionally profuse onion bulb formation. There were also occasional regenerating clusters, which were the only abnormalities seen in the distal nerve. Renaut bodies appeared to be more common and larger in nerves with chronic focal neuropathy. Teased fibres confirmed the chronic myelin sheath changes, and the presence of many paranodal swellings suggested a possible chronic compressive aetiology. This is the first reported spontaneous entrapment neuropathy in the domestic animals.Supported by a grant from the Grayson Foundation     

Hereditary peroneal muscular atrophy in the mouse: An experimental model for congenital contractures (arthrogryposis)

A new mutant, peroneal muscular atrophy (pma) mouse in CF#1 strain has an autosomal recessively inherited equinovarus (club foot deformity) of the hind legs because of the absence of the common peroneal nerve branch of the sciatic nerve. We found the peroneal muscles were hypoplastic with histochemical and electron microscopic characteristics of fetal muscle. The anterior horn cells in the spinal cord were not reduced in number and they appeared to be normal. The density and size of the myelinated fibers in the anterior spinal roots of L3, L4, and L5 and the sciatic nerve in the affected side were not different from those in the unaffected. Therefore, the absence of the common peroneal nerve in the pma mouse is thought to result from the misdirection of these nerve bundles into other peripheral nerves. As the anomalous condition was present at birth with no progression, the pma mouse may be an experimental model for the study of arthrogryposis multiplex congenita or club foot deformity, and may lead to the understanding of the muscle and nerve interaction during development.     

Idiopathic peripheral neuropathy in the horse with knuckling: muscle and nerve lesions in additional cases

We have previously reported a pathological investigation of peripheral neuropathy in a horse with knuckling. This report describes details of the muscle and peripheral nerve lesions in two additional cases of light horse yearlings with knuckling. The skeletal muscles showed neurogenic atrophy characterized by scattered single angular fibers, fiber grouping, and fiber-type grouping. The severity of muscle lesions increased distally; that is, both fore- and hindleg muscles were affected more severely than cervical and dorsal muscles. In the peripheral nervous system, a number of Renaut bodies appeared to be common in the nerve fascicles. Pathological alterations indicating demyelination, remyelination and regeneration of nerve fibers were occasionally observed. The most common abnormality was myelin ovoids or myelin debris infiltrated by macrophages. Occasionally, myelinated axons were seen containing accumulations of organelles, often associated with buckling of the myelin. The myelin sheath occasionally formed axonal outpouching containing accumulations of mitochondria and dense lamellar bodies. Histochemically, intramuscular nerve fibers presented multiple arborization and collateral ramification, indicating relapsing denervation and reinnervation. Also seen were the fibers with myelin balloons or swollen segments considered as being degenerative processes. The distribution patterns of muscular lesions in the affected animals were indicative of systemic distal denervation atrophy. In addition, peripheral nervous lesions that selectively involve the distal parts of axons and an absence of abnormalities in neuronal cell bodies in the spinal cord suggest a dying-back neuropathy. It was concluded that this disease should be classified as a distal axonopathy. Received: 29 December 1997 / Revised, accepted: 19 March 1998     

Collagen content in human ulnar nerve

Summary A quantitative analysis of ulnar nerve collagen in the arm and forearm was undertaken in nine subjects. While endoneurial collagen was found to be significantly increased within the cubital tunnel, extrafascicular collagen did not increase at the elbow except in two nerves showing fusiform enlargements. Renaut bodies increased in frequency at sites of high endoneurial collagen content. Morphological determinations of cross-sectional area along the ulnar nerve did not correlate with quantitative collagen data.     

Activation by high intensity peripheral nerve stimulation of adrenergic and opioidergic inhibition of a spinal reflex in the decerebrated rabbit

The short-latency sural to gastrocnemius reflex in the decerebrated rabbit was depressed for 20-30 min following high intensity conditioning stimulation of the common peroneal nerve. This effect was observed in animals with or without spinal section, but was greater in non-spinalized preparations. Graded conditioning stimuli showed that it was necessary to activate fine myelinated common peroneal axons to inhibit the reflex. In spinalized rabbits, maximal inhibition was achieved with conditioning stimulation of fine myelinated axons and was completely reversed by the opioid antagonist naloxone. In non-spinalized rabbits, maximal inhibition was only obtained with conditioning stimuli which activated non-myelinated axons. In these preparations the effects of common peroneal nerve stimuli were only blocked by co-administration of naloxone with the alpha 2-adrenoceptor antagonist idazoxan. Thus high intensity peripheral nerve stimuli activated a segmental opioidergic and a supraspinal adrenergic suppression of the sural-gastrocnemius withdrawal reflex. Such long-lasting suppression of reflex excitability may contribute to recovery from intensely noxious stimuli.     

Soma size and oxidative enzyme activity in normal and chronically stimulated motoneurones of the Cat''s spinal cord

In normal adult cats we measured the density of staining for the activity of succinate dehydrogenase (SDH staining) in ventral horn cells of different sizes. The measurements were restricted to that part of the lumbar ventral horn (L6-L7) which is known to contain motoneurones of the peroneal nerve. A statistically significant tendency was found for the SDH staining to be denser in smaller than in larger neurones within the size range of a motoneurones (soma diameter greater than 40 microns). These results are consistent with recently published evidence for ventral horn cells of rats and qualitatively similar relationships between size and SDH staining have also been observed among skeletal muscle fibres (confirmed for mixed muscle of cat in present study). In hindlimb muscles, size as well as SDH staining are known to be markedly activity-dependent. We tested whether this is the case for peroneal motoneurones as well by analyzing the effects of chronic nerve stimulation on the properties of neurones within the appropriate region of the ventral horn. Prior to the final acute experiment, these cats had been subjected to a left-side dorsal rhizotomy and hemispinalization. By aid of a portable mini-stimulator, the left-side common peroneal nerve was activated by repetitive pulses during 50% of total time per day (intra-activity rate: 10, 20 or 40 Hz). After 8 weeks of such treatment, cell sizes as well as the densities of SDH staining showed hardly any differences between peroneal ventral horn cells of the experimental and control sides of the spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)     

Selective deep peroneal nerve injury associated with arthroscopic knee surgery

We report 3 cases of isolated deep peroneal nerve injury as a complication of arthroscopic knee surgery. At the level of the knee joint, the deep and superficial peroneal nerves are usually joined as the common peroneal nerve. However, because of the fascicular structure, a partial nerve injury can result in an isolated injury to the deep peroneal nerve fibers. Due to the intraneural topography of the peroneal nerve, electrodiagnostic studies in a partial nerve injury may erroneously indicate a more distal lesion. © 1993 John Wiley & Sons, Inc.     

Nerve-mast cell interaction in normal guinea pig urinary bladder

Urinary bladders of normal adult female guinea pigs were analyzed for anatomical evidence of nerve-mast cell interaction using light microscopy and electron microscopy. Nerves, ganglia, and individual nerve fibers were visualized on paraffin sections using immunohistochemistry with antisera against the neural antigens neurofilament protein and protein gene product 9.5, and sections were also immunoreacted with antisera against the neuropeptides substance P and calcitonin gene-related peptide. Separate mast cell populations were identified by counterstain ing with toluidine blue and alcian blue; Mast cells of both types were found within nerves and intramural ganglia and were in close contact with individual nerve fibers displaying substance P- and calcitonin gene-related peptide-like immunoreactivity. Moreover, serotonin-immunoreactive mast cells were innervated with nerve fibers that reacted with antiserum against vasoactive intestinal polypeptide. At the ultrastructural level, these fibers were almost exclusively identified as unmyelinated primary sensory afferents. Mast cells contacted these fibers with lamellipodia that wrapped around and enclosed the fibers deeply within the cell. Close association between mast cells, nerves, and vessels was common. Ultrastructural evidence suggests that bidirectional communication occurs between nerve fibers and mast cells. These structures may participate in axon reflexes that regulate normal vascular and detrusor smooth muscle function and cause vasodilation, edema, inflammation, and bladder hyperreactivity. In summary, a close relationship exists between mast cells and peptidergic nerve fibers, including primary sensory afferents. Results suggest that bidirectional interaction could occur between nerves and mast cells. © 1995 Wiley-Liss, Inc.     

Coexistent Hoffmann reflexes in human leg muscles are commonly due to volume conduction

The existence of "concomitant" (coexistent) electromyographic reflex responses in soleus and tibialis anterior muscles, produced by posterior tibial nerve stimulation, has been cited as evidence for "reciprocal excitation" between these antagonistic muscles normally reflexly linked by reciprocal inhibition. Using the Hoffmann reflex procedure and posterior tibial nerve stimulation, the existence of true reciprocal excitation was tested in six subjects with no neuromuscular impairment. Coexistent EMG responses were observed in all subjects. In no instance, however, could the tibialis anterior EMG volley to posterior tibial nerve stimulation of the soleus muscle be antidromically blocked by common peroneal nerve stimulation applied at 10 to 20 ms offset latencies. A second stimulation pulse applied to the common peroneal nerve at similar offset latencies did antidromically block a tibialis anterior reflex response to common peroneal nerve stimulation. Therefore, volume conduction of reflex activity from the posterior tibial compartment to the anterior tibial compartment was a common observance. We suggest that coexistent EMG reflex responses, presumed to reflect reciprocal excitation, should be tested by the procedure described to reject the possibility of EMG cross-talk as a confounding variable or as the actual variable under investigation.     

ATYPICAL AXON-SCHWANN CELL RELATIONSHIPS IN THE COMMON PERONEAL NERVE OF THE DYSTROPHIC MOUSE: AN ULTRASTRUCTURAL STUDY

Abstracts Jaros E. & Bradley W.G. (1979) Neuropathology and Applied Neurobiology 5, 133–147
Atypical axon-Schwann cell relationships in the common peroneal nerve of the dystrophic mouse: an ultrastructural study
Several atypical features of myelination of the peripheral nervous system are reported in common peroneal nerve of dystrophic mice (129 Re J dy/dy): ( i ) central nervous system-like contact between myelin sheaths of adjacent nerve fibres; ( ii ) nodes and internodes of myelinated fibres enwrapped with cytoplasmic processes of Schwann cells from adjacent nerve fibres; ( iii ) Schwann cells of adjacent nerve fibres co-operating in formation of a single myelin sheath; and ( iv ) a single Schwann cell myelinating two separate axons. In view of the presence of similar features of myelination in the central nervous system, where the myelin producing cells lack basement membrane, we suggest that in the dystrophic peripheral nerves the development of these features can be attributed to the partial deficiency of the Schwann cell basement membrane. Two types of widened nodes of Ranvier are also identified: ( i ) nodes with paranodal damage; and ( ii ) nodes without paranodal damage. In addition, abnormal features of myelination are described which are likely to represent altered Schwann celliaxon relationships during demyelination and remyelination and/or decreased myelinating ability of Schwann cells. We interpret these findings as indicating a metabolic disorder of Schwann cells. They provide an experimental model for the investigation of factors involved in the origin and maintenance of the structural organization of peripheral nerve.     

Peripheral neuropathy in the hypereosinophilic syndrome: a case report

We observed a patient with the hypereosinophilic syndrome that showed as a prominent clinical feature peripheral nerve dysfunction. The neuropathy evolved over 4 months and affected sensory and motor functions. Nerve conduction studies and EMG were compatible with axonal neuropathy. Nerve and muscle biopsies revealed severe axonal degeneration with neurogenic atrophy of muscle. Morphometry of peroneal nerve showed marked axonal loss, more prominent in large myelinated fibers. There was no evidence of vasculitis process. Neuropathy is produced by eosinophil-released substances exerting a neurotoxic effect through direct altered vascular endothelial permeability and local mast cell histamine release.     

AAEM minimonograph #2: Important anomalous innervations of the extremities

Anomalous innervations of the extremities are common and influence the interpretation of electrophysiologic studies in normal patients and those with peripheral nerve lesions. The following anomalous innervations are reviewed: median to ulnar nerve communication; ulnar to median nerve communication; variations in the innervation of intrinsic muscles of the hand; accessory deep peroneal nerve; and tibial to peroneal nerve communication. The electrophysiologic recognition of these anomalies and the manner in which they affect the interpretation of electrodiagnostic studies in various conditions is emphasized.