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Objectives: To provide a quantitative analysis of ultrasonographic measurements and possible pathophysiology of carpal tunnel syndrome by comparing cross-sectional areas of the median nerve, carpal tunnel, and nerve/tunnel index and the difference in ultrasonographic findings between affected and nonaffected hands and between sexes., Design: Blinded comparison study., Setting: Secondary referral and training hospital of institutional practice., Participants: Patients (N=51; 42 women, 9 men) with suspected carpal tunnel syndrome who underwent sonography within 1 week after the electrodiagnostic study., Interventions: Not applicable., Main Outcome Measures: Electrodiagnostic and ultrasonographic studies were conducted on both upper extremities. Cross-sectional areas of the median nerve and carpal tunnel were measured at 2 separate levels; proximal and distal cross-sectional areas of the carpal tunnel were each measured at the scaphoid-pisiform and trapezium-hamate levels, respectively., Results: Comparison between normative (n=24) and abnormal hands (n=78) revealed the following: the mean proximal cross-sectional areas of the median nerve, carpal tunnel, and nerve/tunnel index of electrodiagnostically normative hands were 10.941mm(2), 192.43mm(2), and 5.635%, respectively, whereas those of abnormal hands were 13.74mm(2), 208.87mm(2), and 6.693%, respectively, showing statistically significant differences for all (P<.05). Distal measurements of the cross-sectional area of the median nerve, carpal tunnel, and nerve/tunnel index were 10.088mm(2), 150.4mm(2), and 6.762%, respectively, in normative hands, and 11.178mm(2), 149.6mm(2), and 7.493%, respectively, in abnormal hands, showing no statistically significant differences (P>.05). In women, proximal cross-sectional areas of the median nerve and nerve/tunnel index of abnormal hands showed statistically significant differences, but no ultrasonographic measurement with a statistically significant difference was observed in men., Conclusions: Compared with nonaffected hands, the proximal cross-sectional areas of the median nerve and carpal tunnel were greater, but the distal ultrasonographic measurements were not in affected hands. Ultrasonographic findings of carpal tunnel syndrome were different according to sex., (Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Objective: To investigate the possible association of external and ultrasonographic measurements of the hand and wrist with median nerve conduction studies., Design: Two group comparison study., Setting: Outpatient neurophysiology laboratory and radiology department in a university hospital., Participants: Patient group (n=50; 40 women) with clinically overt and electrophysiologically proven idiopathic carpal tunnel syndrome and a control group of age- and sex-matched healthy volunteers (n=50)., Interventions: Not applicable., Main Outcome Measures: The following measurements were taken: (1) motor and sensory conduction studies of the median nerve; (2) external hand and wrist dimensions (hand ratio and wrist ratio); and (3) ultrasonographic dimensions of the carpal tunnel (carpal tunnel inlet ratio and carpal tunnel outlet ratio) and inlet cross-sectional area and outlet cross-sectional area of the median nerve at the tunnel., Results: Differences between patients and controls were significant for hand and wrist ratios and all ultrasonographic dimensions. Sensory conduction velocity and distal motor latency of the median nerve in all 100 subjects were well correlated with hand ratio, wrist ratio, carpal tunnel inlet ratio, and carpal tunnel outlet ratio estimates. Wrist ratio was significantly correlated with carpal tunnel inlet ratio and carpal tunnel outlet ratio., Conclusions: A particular hand and wrist configuration, that is, short and wide hand with square wrist matching to narrow and deep tunnel entrance demonstrated increased liability for idiopathic carpal tunnel syndrome. For screening purposes, it was suggested that simple external hand or wrist measurements could be used to predict the tendency for carpal tunnel syndrome., (Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Objective: To investigate the effects of hypertonic dextrose injection on the subsynovial connective tissue (SSCT) in a rabbit model. We hypothesized that dextrose injection would induce proliferation of the SSCT, hinder median nerve conduction, and alter SSCT mechanical properties, similar to what is observed in patients with carpal tunnel syndrome (CTS)., Design: Randomized, controlled prospective study., Setting: Not applicable., Participants: New Zealand white rabbits (N=28) weighing 4.0 to 4.5kg., Intervention: One forepaw was randomly injected with 0.1mL 10% dextrose solution. The contralateral paw was injected with a similar amount of 0.9% saline solution as a control. Animals were killed at 12 weeks after injection., Main Outcome Measures: Animals were evaluated by electrophysiology (EP), mechanical testing, and histology. EP was evaluated by distal motor latency and amplitude. Shear force was evaluated when the middle digit flexor digitorum superficialis tendon was pulled out from the carpal tunnel. The ultimate tensile load and the energy absorption were also measured. Tissue for histology was evaluated qualitatively., Results: EP demonstrated significant prolongation of distal motor latency. The energy absorption and stiffness were also significantly increased in the dextrose group. Histologically, the dextrose group showed thickening of the collagen bundles and vascular proliferation within the SSCT compared with the saline group., Conclusions: These results are consistent with the findings in patients with CTS and suggest that hypertonic dextrose injection has the potential to create a novel animal model in which to study the evolution of CTS.

New developments in clinical peripheral nerve imaging with MRI over the past few years, primarily those related to nerve entrapment syndromes, are reviewed. The basic principles of peripheral nerve imaging are described briefly. Relevant current or forthcoming technical innovations are described, and then recent work describing novel findings, organized by anatomic location (brachial plexus, upper extremity, and lower extremity), is reviewed. The review concludes with a summary and suggestions of areas in which future clinical research would be particularly helpful.

There is no significant disagreement about the major common entrapment neuropathies, such as carpal tunnel syndrome (CTS), ulnar neuropathy at the elbow, and peroneal neuropathy at the knee. In contrast, there is a group of entrapment syndromes about which there is major disagreement, including whether or not they even exist. There are other entrapment syndromes about which clinical questions arise on a regular basis, and which are the subject of this discussion. These include thoracic outlet syndrome, radial tunnel syndrome, ulnar nerve entrapment at the arcade of Struthers, piriformis syndrome, and tarsal tunnel syndrome.

The mechanisms of symptom production (other than a space-occupying lesion) and the diagnosis of tarsal tunnel syndrome remain controversial. To understand the diagnosis and treatment of tarsal tunnel syndrome in the presence of neuropathy, the known anatomy and pathophysiology related to the tarsal tunnel and the existing basic science and clinical evidence base related to these topics are reviewed. It is concluded that it is difficult to identify patients with tibial nerve compression at the ankle or foot region reliably with traditional electrodiagnostic techniques, even in the absence of neuropathy, and that the presence of a positive "Tinel" sign over the tibial nerve in the tarsal tunnel can identify this as a site of chronic nerve compression. For patients with tarsal tunnel syndrome and the comorbidity of diabetic polyneuropathy (DPN), it is concluded that a positive Tinel sign at the tarsal tunnel can predict a positive outcome for pain relief and restoration of sensation in 80% of the people who have decompression of the four medial ankle tunnels. With sensation improved, it is concluded that the natural history of DPN can be changed toward prevention of ulcers and amputation.

Carpal tunnel syndrome (CTS) is the most frequently encountered peripheral compressive neuropathy. Although the clinical diagnosis and treatment of CTS have been well defined, the pathophysiologic basis still is not understood completely. This article summarizes current thought and research pertinent to the pathophysiology of CTS.

An understanding of the normal anatomy of the carpal tunnel and a variety of associated anomalies is important for the physician treating carpal tunnel syndrome. There are many strong arguments for open surgical decompression of the median nerve where full visualization of the transverse carpal ligament and contents of the carpal tunnel can be expected. The authors describe their preferred operative technique and post-operative management for carpal tunnel release.

The use of carpal tunnel tome with a small palmar incision to release the transverse carpal ligament is discussed. The technique is fully illustrated, and the authors early clinical experience is reviewed.

The article details various pitfalls of endoscopic carpal tunnel release. Highlighted are the two-portal Chow technique and the single-portal Agee technique.

In this article, after a brief account of the history and evolution of endoscopic carpal tunnel release, limited incision techniques, and an overview of the relevant anatomy, the authors describe various methods and instrumentation. The results, complications, and contraindications are noted. Subsequent discussion of the objections to and the special requirements of new techniques leads to judgement on the choice of methods by the authors.

Clinicians commonly observe upper extremity signs and symptoms which result from median nerve entrapment and can develop at multiple sites along this nerve. Median nerve entrapment may occur at the distal humerus when the rarely present ligament of Struthers connects an anomalous bony spur of the humeral shaft to its medial epicondyle. The pronator syndrome refers to compromise of the median nerve in the proximal forearm region. This may result from entrapment between the 2 heads of the pronator teres, between the pronator teres and the flexor digitorum sublimis, or by the lacertus fibrosus extension from the biceps tendon. The anterior interosseous branch of the median nerve is subject to compromise near its origin. As a motor nerve it produces signs of weakness as indicators of anterior interosseous syndrome. This syndrome usually occurs spontaneously, but can be caused by fractures and fibrous bands. The carpal tunnel is a narrow fibro-osseous tunnel through which the median nerve passes with 9 tendons. Carpal tunnel syndrome is the most common of the median nerve entrapments. Its causes are many: anything which increases the volume of the tunnel contents or decreases the size of the tunnel. Electrodiagnostic abnormalities exist more frequently when this entrapment is present than for other median nerve entrapments. Anatomic variations of the median nerve occur frequently and may lead to diagnostic confusion if not recognized. Successful diagnosis and treatment of median nerve entrapment syndromes require awareness of possible involved sites and detailed knowledge of related anatomy.

Carpal tunnel syndrome is the most common and best known of the compression neuropathies in the upper extremity. The authors review their clinical experiences in the diagnosis and management of this entity and survey the extensive literature on the subject. An operative approach for decompression of the median nerve in the carpal canal is described that has proved to be most efficacious and safe.

Segments from the median nerve were removed from the distal fourth of the right forearm and the carpal tunnel area of 23 embalmed human cadavers (12 men, 11 women) to evaluate the proliferation of the intraneural connective tissue and its intrinsic vasculature. The findings suggest that: (1) The proliferative increase of the intraneural connective tissue, primarily, the epineurial layers, is a localized characteristic of the median nerve in the carpal tunnel; (2) this increase in a normal occurrence in males and females; and (3) thicker-walled arterioles and venules are common in the highly dense epineurial tissue; this condition, regarded as an adjunct protective feature, could oppose increased intratunnel pressure and lessen the chances of vascular collapse.