Median nerve compression and trigger finger in the mucopolysaccharidoses and related diseases.

Patients with Hurler's syndrome (MPS-1H), I-cell disease (ML-II) and pseudo-Hurler's syndrome (ML-III) had median nerve compression and triggering of the fingers which limited finger extension. To our knowledge, this combination has not been reported previously in patients with mucopolysaccharidoses and related disorders. In all of our 3 cases the median nerve was compressed by thickened flexor tenosynovium. Synovectomy and resection of the volar carpal ligament improved the hand function in all, including the mentally retarded patient with Hurler's syndrome. Release of the fibroosseous tunnel in two patients was followed by an increased range of motion (but not full extension). A fourth patient, without a mucopolysaccharide storage disorder, also had the combination of trigger finger and carpal tunnel syndrome.     

The incidence of recurrence after endoscopic carpal tunnel release

Endoscopic carpal tunnel release has been used to decompress the median nerve in carpal tunnel syndrome for over the past decade, with an advantage (over the traditional "open" release) being decreased pain in the postoperative period. The goals of this study were to attempt to define the recurrence rate after endoscopic carpal tunnel release and to determine if it differs from that of open technique. The charts of 191 consecutive carpal tunnel syndrome patients treated operatively at the University of Missouri were reviewed. For this study, recurrent carpal tunnel syndrome was defined as documented cases in which the symptoms had resolved following surgical release but subsequently recurred, requiring surgical rerelease of the carpal tunnel. All endoscopic releases were performed using the Chow two-portal technique. Statistical analysis was performed using Fisher's exact test. A total of 103 patient hands had open carpal tunnel releases; 88 were endoscopically released. Total follow-up time (from the initial release) averaged 29 months for the open group and 22 months for the endoscopic group. There were no recurrences in the open group and six recurrences in the endoscopic group (7 percent, p = 0.008). All six recurrences were in worker's compensation patients. The median time between endoscopic release and rerelease was 8.5 months. There seems to be a statistically higher incidence of recurrence of carpal tunnel syndrome after endoscopic release compared with the traditional "open" release in our cases. Although the pathogenesis of this increased rate of recurrence is not clear, this should be considered when planning surgical release of the volar carpal ligament for carpal tunnel syndrome.     

Volar/dorsal compressive mechanical behavior of the transverse carpal ligament

Mechanical insult to the median nerve caused by contact with the digital flexor tendons and/or carpal tunnel boundaries may contribute to the development of carpal tunnel syndrome. Since the transverse carpal ligament (TCL) comprises the volar boundary of the carpal tunnel, its mechanics in part govern the potential insult to the median nerve. Using unconfined compression testing in combination with a finite element-based optimization process, nominal stiffness measurements and first-order Ogden hyperelastic material coefficients (μ and α ) were determined to describe the volar/dorsal compressive behavior of the TCL. Five different locations on the TCL were tested, three of which were deep to the origins of the thenar and hypothenar muscles. The average (± standard deviation) low-strain and high-strain TCL stiffness values in compression sites outside the muscle attachment region were 3.6 N/mm (±2.7) and 28.0 N/mm (±20.2), respectively. The average stiffness values at compression sites with muscle attachments were notably lower, with low-strain and high-strain stiffness values of 1.2 N/mm (±0.5) and 9.7 N/mm (±4.8), respectively. The average Ogden coefficients for the muscle attachment region were 51.6 kPa (±16.5) for μ and 16.5 (±2.0) for α, while coefficients for the non-muscle attachment region were 117.8 kPa (±86.8) for μ and 17.2 (±1.6) for α. These TCL compressive mechanical properties can help inprove computational models, which can be used to provide insight into the mechanisms of median nerve injury leading to the onset of carpal tunnel syndrome symptoms.     

The Tinel sign: a historical perspective

The Tinel sign is one of the most well-known and widely used clinical diagnostic tools in medicine. Aside from Jules Tinel, after whom the sign is named, several authors have described the famous "tingling" sign seen in regenerating injured nerves. In fact, Tinel was not the first to present the sign to the scientific community. The clinical value and utility of the Tinel sign have remained in question since its introduction; many may misinterpret the sign as a prelude to complete functional recovery of injured nerves, when in fact it only signals the progress of nerve regeneration. Today the Tinel sign is widely associated with the diagnosis of carpal tunnel syndrome and in the evaluation of regenerating peripherally injured nerves. Knowledge of the history and misconceptions surrounding the sign provides clinicians today with a greater appreciation of current debates on the use of the Tinel sign.     

Electron Microscopy of a Plant-Pathogenic Virus in the Nervous System of Its Insect Vector

The central nervous system of wound tumor virus (WTV)-infected Agallia constricta was studied by electron microscopy to obtain information concerning the virus distribution in the nervous system. Wound tumor virions were mostly found in the cytoplasm of the ganglion cells and less frequently in the glial cells. WTV was occasionally observed in the perineurium cells, nerve axons, tracheoblasts, and lateral nerves. In the ganglion cells, virions appeared as individual isolated particles (V(1)), in tubular formation (V(2)), and occasionally in aggregates (V(3)). In the glial cells, the virions were mostly seen in the V(3) formation, and very seldom in the V(1) and V(2) formations. In the perineurium cells and tracheoblasts, only small V(3) formations were observed. The isolated virions were usually surrounded with polyribosomes, and often appeared around the foci of the viroplasm. Sometimes degenerating ganglion cells infected with the WTV were encountered. These damaged cells strongly indicated that WTV exerted a cytopathogenic effect on the nerve cells.     

Facial diplegia with hyperreflexia-a mild Guillain-Barre Syndrome variant, to treat or not to treat?

Schwannomas are common, benign nerve tumors originating from the sheath of peripheral nerves. In this article, a 54 year old woman suffered from sudden onset motor and sensory deficit at her first radial three fingers on her right hand. Radiological investigations were normal. Electromyography diagnosed a median nerve entrapment neuropathy and urgent surgery was performed. Interestingly, a hemorrhaged mass was detected in the median nevre at the proximal end of the carpal ligament and was resected totally. Histopathological diagnosis was Schwannoma. The patient maintained a healthy status for five years.     

Tight junction proteins ZO-1, occludin, and claudins in developing and adult human perineurium.

In peripheral nerves, groups of Schwann cell-axon units are isolated from the adjacent tissues by the perineurium, which creates a diffusion barrier responsible for the maintenance of endoneurial homeostasis. The perineurium is formed by concentric layers of overlapping, polygonal perineurial cells that form tight junctions at their interdigitating cell borders. In this study, employing indirect immunofluorescence and immunoelectron microscopy, we demonstrate that claudin-1 and -3, ZO-1, and occludin, but not claudin-2, -4, and -5, are expressed in the perineurium of adult human peripheral nerve. We also describe the expression of occludin, ZO-1, claudin-1, -3, and -5 in the developing human perineurium, showing that the expressions of claudin-1 and -3, ZO-1, and occludin follow similar spatial developmental expression patterns but follow different timetables in achieving their respective adult distributions. Specifically, claudin-1 is already largely restricted to perineurium-derived structures at 11 fetal weeks, whereas claudin-3 and occludin are weakly expressed in the perineurial structures at this age and acquire a well-defined perineurial distribution only between 22 and 35 fetal weeks. ZO-1 appears to acquire its mature profile even later during the third trimester. The results of the present and previous studies show that the perineurial diffusion barrier matures relatively late during human peripheral nerve development.     

Developmental changes in the ultrastructure of the lamprey lateral line nerve during metamorphosis

The ultrastructure of the trunk lateral line nerve of larval and adult lampreys was studied with transmission electron microscopy. We confirmed that lampreys' lateral line nerve lacks myelin. Nevertheless, all axons were wrapped by Schwann cell processes. In the larval nerve, gaps between Schwann cells were observed, where the axolemma was covered only by a basal lamina, indicating an earlier developmental stage. In the adult nerve, glial (Schwann cell) ensheathment was mostly complete. Additionally, we observed variable ratios of axons to Schwann cells in larval and adult preparations. In the larval nerve, smaller axons were wrapped by one Schwann cell. Occasionally, a single Schwann cell surrounded two axons. Larger axons were associated with two to five Schwann cells. In the adult nerve, smaller axons were surrounded by one, but larger axons by three to eight Schwann cells. The larval epineurium contained large adipose cells, separated from each other by single fibroblast processes. This layer of adipose tissue was reduced in adult preparation. The larval perineurium was thin, and the fibroblasts, containing large amounts of glycogen granules, were arranged loosely. The adult perineurium was thicker, consisting of at least three layers of fibroblasts separated by collagen fibrils. The larval and adult endoneurium contained collagen fibrils oriented orthogonally to each other. Both larval and adult lateral line nerves possessed a number of putative fascicles weakly defined by a thin layer of perineurial fibroblasts. These results indicate that after a prolonged larval stage, the lamprey lateral line nerve is subjected to additional maturation processes during metamorphosis. J. Morphol. 2009. © 2009 Wiley‐Liss, Inc.     

In Vivo Study of Transverse Carpal Ligament Stiffness Using Acoustic Radiation Force Impulse (ARFI) Imaging

The transverse carpal ligament (TCL) forms the volar boundary of the carpal tunnel and may provide mechanical constraint to the median nerve, leading to carpal tunnel syndrome. Therefore, the mechanical properties of the TCL are essential to better understand the etiology of carpal tunnel syndrome. The purpose of this study was to investigate the in vivo TCL stiffness using acoustic radiation force impulse (ARFI) imaging. The shear wave velocity (SWV) of the TCL was measured using Virtual Touch IQ^TM software in 15 healthy, male subjects. The skin and the thenar muscles were also examined as reference tissues. In addition, the effects of measurement location and ultrasound transducer compression on the SWV were studied. The SWV of the TCL was dependent on the tissue location, with greater SWV values within the muscle-attached region than those outside of the muscle-attached region. The SWV of the TCL was significantly smaller without compression (5.21 ± 1.08 m/s) than with compression (6.62 ± 1.18 m/s). The SWV measurements of the skin and the thenar muscles were also affected by transducer compression, but to different extents than the SWV of the TCL. Therefore to standardize the ARFI imaging procedure, it is recommended that a layer of ultrasound gel be maintained to minimize the effects of tissue compression. This study demonstrated the feasibility of ARFI imaging for assessing the stiffness characteristics of the TCL in vivo, which has the potential to identify pathomechanical changes of the tissue.     

Arteriovenous malformation of a persistent median artery with a bifurcated median nerve

A patient with arteriovenous malformations of the volar forearm and hand arising from a persistent median artery with an associated bifid median nerve is presented. Surgeons should be aware of high median nerve bifurcations, particularly when a persistent median artery is identified, and should remember that additional structures that can lead to nerve compression may be present in the carpal tunnel. Specifically, more than one median nerve may need to be identified and protected in such cases.     

MEDIAN NERVE INJURIES IN FRACTURES IN THE REGION OF THE WRIST

Injuries of the median nerve in fractures in the region of the wrist are not uncommon.Median nerve palsy is frequently the result of immobilizing the wrist in acute palmar flexion.Good reduction and immobilization of the wrist in neutral position are the best means of preventing median nerve injury.In any fracture in the region of the wrist, the status of the median, ulnar, and radial nerves should be examined before and after reduction of the fracture.The majority of patients with median nerve neuritis recover completely without operation. In some cases, the duration of the sympathetic nerve paralysis is unpredictable.Where neurological symptoms persist, neurolysis with or without sectioning of the transverse carpal ligament will improve the neurological status of the patient.     

Forearm compartment syndrome: anatomical analysis of surgical approaches to the deep space

Forearm compartment syndrome is a surgical emergency that usually requires release of the superficial muscle compartments. In some clinical situations it is imperative to also explore the deep muscle compartments. There are no anatomical guides for surgical exploration of the deep compartments that would minimize collateral damage to surrounding vessels, nerves, and muscles. Surgical injury in the setting of ischemia, especially vascular injury, compounds the tissue damage that has already occurred. The authors evaluated four surgical approaches (three volar and one dorsal) to the deep forearm by performing detailed anatomical dissections on 10 embalmed and plastinated cadavers. They used a scoring system to rate the approaches for their ability to visualize the deep space without causing iatrogenic injury to superficial muscles, arteries, and nerves. In the volar forearm, an ulnar approach to the deep space is simple, causes the least iatrogenic surgical injury, and provides access to the deep volar forearm structures. The plane of dissection is between the flexor carpi ulnaris and the flexor digitorum superficialis. Dividing one or two distal segmental branches of the ulnar artery to the distal flexor digitorum superficialis exposes the pronator quadratus. Lifting the ulnar neurovascular bundle with the flexor digitorum superficialis in the middle third of the forearm exposes the flexor digitorum profundus and the flexor pollicis longus. This approach to the deep space requires no sharp dissection. In the dorsal forearm, a midline approach between the extensor digitorum communis and the extensor carpi radialis brevis is simple and safe.     

Clinical experience with the CO2 laser during carpal tunnel decompression

Scar tissue formation along the cut edges of the transverse carpal ligament has been found to be among the primary causes for persistent median nerve compression following carpal tunnel release with the steel scalpel. Since laser surgery has been shown to be effective in reducing incisional inflammatory reactions, hypertrophic scarring, and postoperative pain and edema, in achieving better hemostasis, the application of the carbon dioxide laser may be a more efficient surgical tool than the steel scalpel for carpal tunnel release. In 46 cases of carpal tunnel syndrome, the carbon dioxide laser was utilized to vaporize the transverse carpal ligament and seal its edges. The patients were then reevaluated at 1 week, 2 weeks, 6 months, 1 year, and 2 years. No intraoperative complications were encountered. Patients reported minimal postoperative pain, rapid return of sensibility, decreased paresthesia, and increased motor function. After 2 years, there have been no recurrent symptoms of median nerve compression in these patients.     

Median nerve neuropathy in the forearm due to recurrence of anterior wrist ganglion that originates from the scaphotrapezial joint: Case Report

Background

Median nerve neuropathy caused by compression from a tumor in the forearm is rare. Cases with anterior wrist ganglion have high recurrence rates despite surgical treatment. Here, we report the recurrence of an anterior wrist ganglion that originated from the Scaphotrapezial joint due to incomplete resection and that caused median nerve neuropathy in the distal forearm.

Case presentation

A 47-year-old right-handed housewife noted the appearance of soft swelling on the volar aspect of her left distal forearm, and local resection surgery was performed twice at another hospital. One year after the last surgery, the swelling reappeared and was associated with numbness and pain in the radial volar aspect of the hand. Magnetic resonance imaging revealed that the multicystic lesion originated from the Scaphotrapezial joint and had expanded beyond the wrist. Exploration of the left median nerve showed that it was compressed by a large ovoid cystic lesion at the distal forearm near the proximal end of the carpal tunnel. We resected the cystic lesion to the Scaphotrapezial joint. Her symptoms disappeared 1 week after surgery, and complications or recurrent symptoms were absent 13 months after surgery.

Conclusions

A typical median nerve compression was caused by incomplete resection of an anterior wrist ganglion, which may have induced widening of the cyst. Cases with anterior wrist ganglion have high recurrence rates and require extra attention in their treatment.     

Three-dimensional organization of the collagen fibrils in the rat sciatic nerve as revealed by transmission- and scanning electron microscopy

Summary The organization of collagen fibrils in the rat sciatic nerve was studied by scanning electron microscopy after digestion of cellular elements by sodium hydroxide treatment, and by conventional transmission electron microscopy. The epineurium consisted mainly of thick bundles of collagen fibrils measuring about 10–20 m in width; they were wavy and ran slightly obliquely to the nerve axis. Between these collagen bundles, a very coarse meshwork of randomly oriented collagen fibrils was present. In the perineurium, collagen fibrils occupied the interspaces between the concentrically arranged perineurial cells; in each interspace, they formed a sheet of characteristic lacework elaborately interwoven by thin (about 3 m or less in width) bundles of collagen fibrils. In the subperineurial region, there was a distinct sheet of densely woven collagen fibrils between the perineurium and underlying endoneurial fibroblasts. In the endoneurium, collagen fibrils surrounded individual nerve fibers in two layers as scaffolds: the inner layer was made up of a delicate meshwork of very fine collagen fibrils, and the outer one consisted of longitudinally oriented bundles of about 1–3 m in width. The collagen fibril arrangement described above may protect the nerve fibers against external forces.     

A reversible abnormal form of myelin: an X-ray scattering study of human sural and rat sciatic nerves

A sural nerve dissected from a recently dead patient displayed an unusual X-ray diffraction pattern, suggesting that in situ and at the time of the patient's death the myelin sheaths were in a swollen state. Diffraction patterns of the swollen type were also recorded from: (1) a sural nerve from the corpse of a neurologically healthy person after soaking the nerve with Ringer solution at pH 5.5; (2) sciatic nerves dissected from rat cadavers at increasing time after death. In all the cases the swollen patterns reversed to the native type upon superfusion with Ringer solution at pH 7.3. The postmortem effect is to decrease the pH of the fluids surrounding the nerves in the cadavers. Our experiments show that the early postmortem processes have the effect of acidifying PNS nerves and that as a consequence of acidification the myelin sheaths swell.     

Differential expression of gap junction proteins connexin26, 32, and 43 in normal and crush-injured rat sciatic nerves. Close relationship between connexin43 and occludin in the perineurium.

We immunohistochemically and morphometrically examined the expression of gap junction protein connexin (Cx) in normal and crush-injured rat sciatic nerves using confocal laser scanning microscopy. Cx26 was localized in the perineurium and Cx43 was present in the perineurium and the epineurium, whereas Cx32 was confined to the paranodal regions of the nodes of Ranvier. Double labeling for connexins and laminin revealed that Cx43 was localized in multiple layers of the perineurium, whereas Cx26 was confined to the innermost layer. Double labeling for connexins and a tight junction protein, occludin, showed that occludin frequently coexisted with Cx43 but existed separately from Cx26 in the perineurium. After crush injury, the pattern of normal Cx32 expression was initially lost but recovered, whereas Cx43 rapidly appeared in the endoneurium and its expression was subsequently attenuated. Although crush injury produced no apparent alteration in Cx43 and occludin in the perineurium, a rapid increase and a subsequent decrease in the frequency of Cx26-positive spots during nerve regeneration were shown by morphometric analysis. These results indicate that Cx26, Cx32, and Cx43 are expressed differently in various types of cells in peripheral nerves and that their expressions are differentially regulated after injury. The expression of connexins and occludin in the perineurium suggests that perineurial cells are not uniform in type and that the regulation of gap junctions and tight junctions is closely related in the perineurium.     

Comparison of partial excision with simple section of the transverse carpal ligament in the treatment of carpal tunnel syndrome

In the surgical treatment of carpal tunnel syndrome, debate has commonly focused on whether decompression should be performed by open or blind techniques. Contrarily, the goal of the present study was to determine whether instead of simple section, partial excision of the transverse carpal ligament has contributed to better results. Because complete healing of the transverse carpal ligament observed during reoperations has been reported elsewhere, the charts of 75 carpal tunnel syndrome patients who had been treated with open technique at Dokuz Eylül University were reviewed. Statistical analysis was performed using the Fisher's exact test and Student's t test when appropriate. Thirty-five patients had been treated with simple section of the transverse carpal ligament, whereas 40 had been treated with partial excision. Internal neurolysis was also performed in 19 of the patients, 11 of whom were treated with partial excision. The average follow-up time was 3.8 years. The comparisons regarding the overall operative outcomes did not show any significant difference between the two different techniques of releasing the transverse carpal ligament. In patients treated without neurolysis, results of partial excision of the transverse carpal ligament improved when compared with those of simple section, but this superiority was not statistically significant. There seemed to be statistically higher reoperation rates and worse outcomes after neurolysis (p < 0.05). Reoperation was required in eight patients (11 percent). Five of the patients who underwent reoperation had initially been treated with partial excision and neurolysis, whereas two had been treated with simple section and neurolysis. Another patient who had undergone reoperation had initially undergone only simple section. The mean time to return to work or daily activities did not differ between the types of applied technique for releasing the transverse carpal ligament. However, neurolysis lengthened these periods significantly when performed (p < 0.05). In the present study, partial excision of the transverse carpal ligament without adding neurolysis offered relatively better results than simple section. Verification of this finding endoscopically, if applicable, may improve the success rate of surgical therapy in patients with carpal tunnel syndrome.     

The effect of various adjuncts on the surgical treatment of carpal tunnel syndrome secondary to chronic tenosynovitis.

A series of 22 patients with carpal tunnel syndrome secondary to chronic tenosynovitis was divided into two groups. The first group was treated by transverse carpal ligament release alone. The second group was treated by transverse carpal ligament release, external neurolysis of the median nerve, flexor synovectomy, and intraoperative corticosteroid instillation. Both groups were comparable preoperatively as to symptoms, signs, and electrophysiological data. At two years postoperatively there were no statistically significant differences in the symptoms, signs, and electrophysiological data in the two groups. The only difference was that patients undergoing release alone were able to return to work earlier than those patients who had the adjunctive procedures.