Entrapment Point Research Articles

MR Neurography and Diffusion Tensor Imaging: Origin, History and Impact

Abstract Objective – Methods were invented that made it possible to image peripheral nerves in the body and to image neural tracts in the brain. Over a 15 year period, these techniques – MR Neurography and Diffusion Tensor Imaging – were then deployed in the clinical and research community and applied to about 50,000 patients. Within this group, about 5,000 patients having MR Neurography were carefully tracked on a prospective basis. Method – In the study group a uniform imaging methodology was applied and all images were reviewed and registered by referral source, clinical indication, efficacy of imaging and quality. Various classes of image findings were identified and subjected to a variety of small targeted prospective outcome studies. Those findings demonstrated to be clinically significant were then tracked in the larger clinical volume data set. Results – MR Neurography demonstrates mechanical distortion of nerves, hyperintensity consistent with nerve irritation, nerve swelling, discontinuity, relations of nerves to masses, and image features revealing distortion of nerve at entrapment points. These findings are often clinically relevant and warrant full consideration in the diagnostic process. They result in specific pathologic diagnoses that are comparable to electrodiagnostic testing in clinical efficacy. Conclusions – MR Neurography and DTI neural tract imaging have been validated as indispensable clinical diagnostic methods that provide reliable anatomical pathological information. There is no alternative diagnostic method in many situations. With the elapse of 15 years, tens of thousands of imaging studies, and hundreds of publications, these methods should no longer be considered experimental.

Anatomy of Nerve Entrapment Sites in the Upper Quarter

The purpose of this article is to review the anatomical features of the most common nerve entrapment sites of the brachial plexus and major peripheral nerves of the upper limb. In this account, the term “entrapment” is considered to be caused by compression, tension, or friction, or any combination of these factors. The anatomy, including important relationships of the brachial plexus, is reviewed and the points of potential entrapment of the plexus are described. Entrapment of the suprascapular and long thoracic nerves is also included. Particular attention is paid to the five major peripheral nerves that result from the brachial plexus and supply the peripheral aspect of the upper limb, i.e., the median, ulnar, musculocutaneous, radial, and axillary nerves. In each case, the nerve's course is described and the anatomical details of the entrapment points described. Where possible, the sites of entrapment are illustrated in cadaveric photographs.

내반주 변형에 의한 지연성 척골 신경 마비

Purpose : Cubitus varus deformity has been reported to cause ulnar neuropathy. We present five cases of tardy ulnar nerve palsy due to cubitus vus and analyzed the factors related to the nerve plasy caused by the deformity. Materials and Methods : Three men and two women were reviewed retrospectively and the mean age of the patients were 26 (range, 14-38). The average interval from initial fracture to nerve palsy was 19 years (8-32 years). The severity of symptoms, according to McGowan's classification, was grade I of 2 patients, grade Ⅱ of 3 patients. Carrying angle was an average of 18。 (30° -45° ). Internal rotation angle measured by Yamamoto's method was an average of 33° (30° -45° ). Results ㆍ The mean follow-up period was 53 months (35-70 months). Elbow pain and numbness of the fingers were relieved shortly after surgery. It revealed that anterior subluxation of the nerve due to internal rotation deformity and compression of the nerve between the medially shifted medial head of triceps and the medial epicondyle. Conclusion : The major entrapment point of the nerve is the fibrous band between the two heads of the flexor carpi ulnaris. The severe internal rotation deformity may contribute the cause of tardy ulnar nerve palsy in cubitus varus deformity.

Cubital Tunnel Syndrome – Endoscopic-Assisted Anterior Submuscular Transposition of the Ulnar Nerve: A Feasibility Study Using a Cadaver Model

The purpose of this project was to perform endoscopic-assisted release of the ulnar nerve with submuscular transposition using a single 4 cm incision at the cubital tunnel level in fresh cadaver limbs. A successful cubital tunnel release decompression depends on the precise release of all potential entrapment points. Twelve fresh cadaver limbs (from six human cadavers) were used for this project. A 4 cm incision was made along the course of the ulnar nerve at the cubital tunnel. While the ulnar nerve was under constant magnified visualization and protection, all surrounding fascial tissues were released freely from the nerve. The medial intermuscular septum and arcade of Struthers were adequately visualized and divided. The overlying superficial fascia of flexor carpi ulnaris being dissected freely from the nerve, the nerve was transposed and repair of the flexor aponeurosis to the medial epicondyle was completed. Release of the ulnar nerve with submuscular transposition was accessible through one small skin incision with the aid of the endoscope. This new procedure may have clinical applications with a surgical outcome similar to the traditional approach. This technique prevents long scarring, decreases patient postoperative pain and shortens the rehabilitation period.

Air entrainment in two-dimensional turbulent shear flows with partially developed inflow conditions

In plunging jet flows and at hydraulic jumps, large quantities of air are entrained at the intersection of the impinging flow and the receiving body of water. The air bubbles are entrained into a turbulent shear layer and strong interactions take place between the air bubble advection/diffusion process and the momentum shear region. New air-water flow experiments were conducted with two free shear layer flows: a vertical supported jet and a horizontal hydraulic jump. The inflows were partially developed boundary layers, characterized by the presence of a velocity potential core next to the entrapment point. In both cases, the distributions of air concentration exhibit a Gaussian distribution profile with an exponential longitudinal decay of the maximum air content. Interestingly, the location of the maximum air content and the half-value band width are identical for both flow situations, i.e. independent of buoyancy effects.

A NEW OPERATIVE TECHNIQUE: CUBITAL TUNNEL DECOMPRESSION WITH ENDOSCOPIC ASSISTANCE

The final outcome of a surgical decompression of the ulnar nerve depends on the precise release of all potential entrapment points. Careful attention must be given to all anatomic structures around the ulnar nerve and elbow area to ensure adequate dissection and surgical accuracy. In the authors' new endoscopic technique, glass tubes have been specially designed to house an endoscope and guide a meniscus knife, allowing for the release of all involved structures up to 10 cm both proximally and distally through a 3-cm skin incision. The authors present their experience in a cadaver trial and with 26 patients with follow-up of at least 6 months.

観血的治療を行った外側足背皮神経絞やく性障害の４例

We report four cases of entrapment neuropathy of the lateral dorsal cutaneuos nerve that were operated on.The cardinal findings included pain and dysesthesia along the lateral border of the foot and tenderness at the entrapment point. Infiltration of a local anesthetic at the entrapment point is both a very useful diagnostic test and treatment. Conservative treatment was unsuccessful in all cases and neurolysis was performed. The lateral dorsal cutaneuos nerve was released and covered with a pedicle fat flap. The postoperative course was uneventful in three cases, who became completely symptom-free. In the other patient pain returned one year after the operation and resection of the nerve was performed. After the second operation the patient was completely symptom-free.

絞やく性神経障害時のＭ波について

Latency and wave form of M-responses change in entrapment neuropathy, because of segmental demyelination and axonal degeneration. Normally, latency decreases gradually (0.2ms/cm) as the cathode moves proximally and the wave form does not change due to the phase cancellation having little influence. In entrapment neuropathy a steep latency change occurred across the entrapment point and in many cases the wave form changed across the entrapment point, influenced by the increasing phase cancellaltion.

非定型的正中神経不全麻ひを呈した２症例の検討

Two cases of atypical incomplete median nerve palsy are reported. A 33 and a 26 year-old male had severe pain around the radial forearm and elbow joints. Several weeks later, they found they could not flex the IP joint of their thumbs. On physical examination FPL, FCR, pronator teres and pronator quadratus were not functioning but there was no sensory change in the median nerve region. The patients did not show any signs of recovery and were operated on within 6 months of onset. Surgical exploration revealed no entrapment points along the median nerve, however, some of the median nerve fasciculus was semitransparent along its entire length. Histological examination of the terminal branch of the anterior interosseus nerve revealed Wallerlian degeneration without inflammatory changes. The FPL was reconstructed with tendon transfer using PL or BR with both patients regaining early function of the thumb.

Thoracic dorsal ramus entrapment

Entrapment of the dorsal ramus of a thoracic spinal nerve is described in a patient with chronic back pain and sensory disturbance in the cutaneous territory served by the T3-5 dorsal rami. The dorsal ramus of the T-4 nerve was found to be compressed by a bone spur involving the inferior T-4 apophyseal facet. The point of entrapment was a tunnel bounded by the transverse process, apophyseal joint, rib, and superior costotransverse ligament.

The Anatomy of Lumbar Spondylosis

To identify the major osseous, ligamentous, and neural relations of the lumbar spine pertinent to understanding the pathogenesis, diagnostic imaging, and therapy of lumbar spondylosis, 25 bony lumbar spines and 25 intact cadaver spines were studied both qualitatively and quantitatively. Pedicle anteroposterior dimension and obliquity and the relative interarticular process-interpedicle dimensions were found to be important osteologic determinants of the presence and size of lateral recesses at different vertebral levels and of the increasing size of each lateral recess as it descends. The varying length and relations of the osteoligamentous nerve root canals at different lumbar levels are a function of a progressively earlier exit from the dural sac by the lower lumbar nerve roots. Both the osteoligamentous nerve root canals and their terminal intervertebral canals showed significant normal narrowing at the level of the opposed intervertebral discs and facet joint capsules. This caused the normal nerve root canals to have a beaded appearance and the osteoligamentous intervertebral canals to have the appearance of long-necked gourds. These normally narrow areas correlate well with the spondylotic neural entrapment points. Narrowing of the disc interval is an important cause of many of the interdependent degenerative changes in the lumbar spine. Hence, its reconstitution should be a major goal of spondylotic surgery.

Superior gluteal nerve entrapment syndrome

Entrapment of the superior gluteal nerve can occur as a result of compression by anterior-superior tendinous fibers of the piriformis muscle and cause aching claudication-type buttock pain, weakness of abduction of the affected hip with a waddling gait, and tenderness to palpation in the area of the buttock superolateral to the greater sciatic notch. Instilling anesthetic into the point of entrapment may relieve the pain completely, but superior gluteal neurolysis may be required to effect a permanent cure.

Snaring of a Swan-Ganz catheter

Insertion of a Swan-Ganz catheter for measurement of pulmonary artery and pulmonary capillary wedge pressures is common for operative management of patients with borderline left ventricular function, particularly patients undergoing cardiac surgery. The transatrial course of the catheter may allow it to lie against the lateral and anterior walls of the right atrium, where it can be caught in a suture used to control bleeding. This report documents such a complication of cardiac surgery: A Swan-Ganz line was caught by a right atrial suture. The tip of the Swan-Ganz catheter was in the distal right pulmonary artery, so that the usual means of removal with a loop-snare catheter was impossible. Instead, a Teflon sleeve, inserted percutaneously was used to stabilize the right atrium while gentle traction was used to break the catheter at its point of entrapment. In this manner, the proximal portion of the catheter was removed. The distal segment of the catheter then was removed with a biopsy forceps inserted percutaneously through the femoral vein.

On the Entrapment Neuropathy of the Saphenous Nerve

36 cases of the entrapment neuropathy of the saphenous nerve were reviewed. 10 cases were treated as other diseases. Complaint of the most patients was marked pain at the medial aspect of the knee when they step up and down. In most cases were found various degrees of the sensory disturbances in the area of the distribution of the infra patellar branch but was not involved the descending branch. Tenderness was marked at the opening of the Hunter's canal. All cases were treated by infiltration at the entrapment point with dexamethazone and procainehydrochloride.

The carpal tunnel syndrome

ERIPHERAL NERVES may be affected by a variety of injuries. If a peripheral nerve is injured in a specific location as the result of a mechanical irritation by some anatomical phenomenon, the condition is called an entrapment neuropathy. This type of nerve injury has been described by the term neuropraxia’ to characterize absence of action in an otherwise intact nerve. Neuropraxia may be caused by contusion, concussion, traction, or compression. Most peripheral nerves in their anatomic course pass through tough inelastic fibro-osseous tunnels, and are accompanied by tendons and/or blood vessels. These areas are well known and are frequently the landmarks used for local anesthetic nerve blocks. The best known of all these potential entrapment points is the carpal tunnel. Located on the volar aspect of the wrist joint it contains the median nerve. It is at this point in its peripheral course that the median nerve is most frequently injured so that it exhibits the physical symptoms and signs of neuropraxia. Although Paget in 1854 described median nerve compression at the wrist secondary to fracture callus, only in thhe past two decades has compression of the median nerve been appreciated as a distinct clinical entity and aggressively treated.*13 FUNCTIONAL ANATOMY The usual muscular distribution of the median nerve in the hand is to four and one-half muscles. They are: lumbricals I and II (the two most radial lumbricals), the abductor pollicis brevis, the opponens pollicis, and the superficial (main head) of the flexor pollicis brevis. These muscles act in conjunction with the long thumb flexor, thumb extensors, and abductor to produce almost all motions at the thumb metacarpophalangeal and carpometacarpal joints.4 The usual sensory supply of the median nerve is to the volar (palmar) side of the hand. This includes the radial half of the palm, most of the volar skin of the thumb, index, middle fingers, and radial half of the ring finger. Recently considerable attention has been given to the anatomical course of the motor branch of the median nerve which supplies the bulk of the thenar musculature. Its course may be variable both within the carpal tunnel and as it passes terminally to innervate the thenar muscles .5-7 The carpal canal also contains all the long flexor tendons to the fingers and thumb. Occasionally aberrant blood vessels are also present in the canal. All of these structures are covered by the strong transverse carpal ligament (flexor retinaculum) which extends across the concavity of the carpal arch. This ligament is attached medially to the pisiform bone and to the hamulus of the hamate bone; laterally it is attached to the tubercle of the navicular and to the greater multangular. The floor of the carpal tunnel is formed by the central carpal bones.

Entrapment neuropathy of the ilioinguinal nerve.

AN entrapment neuropathy of the ilioinguinal nerve can cause pain and disability that may present serious diagnostic difficulties. The nerve is analogous to an intercostal nerve since it has both motor and skin sensory functions. The muscular branches innervate the lowest portions of the transversus abdominis and internal oblique muscles and fascia. The peripheral distribution of the nerve is to the skin over the inguinal ligament and the base of the scrotum (or labia). A narrow strip of skin over the iliac crest is innervated by a recurrent branch. The entrapment point of the nerve is medial to the anterosuperior . . .