Anomalous flexor digitorum superficialis muscle transposition for vascular coverage of the median nerve in recurrent carpal tunnel syndrome

Recurrent carpal tunnel syndrome is uncommon yet troublesome. Significant adhesions and scarring around the median nerve can render it relatively ischemic. A number of vascular flaps have been described to provide vascular coverage in attempts to decrease further cicatricial adhesions and to improve local blood supply around the median nerve. A rare case of an anomalous muscle in the distal forearm used as tissue to provide good vascularized coverage of the median nerve that was severely scarred in its bed is reported. The anomalous muscle was distal to the flexor digitorum superficialis tendon and inserted in the palmar fascia on the ulnar aspect of the hand. Referring branches from the ulnar artery provided vascular supply to the anomalous muscle. The muscle on these vascular pedicles was transposed over the median nerve, providing good, stable, unscarred coverage. The patient had an excellent result with resolution of the carpal tunnel symptoms. The redundant anomalous muscle provided a unique vascularized source for coverage of the median nerve in recurrent carpal tunnel syndrome.     

Median nerve compression in the palm of the hand by an anomalously enlarged ulnar artery

Median nerve compression in the carpal tunnel by a thrombosed persistent median artery and a large aberrant artery substituting for the radial artery has been described but there have been no reports of median nerve compression in the palm of the hand by an anomalously enlarged ulnar artery. A 46 year old man is described who presented with clinical and electrophysiological features consistent with a median neuropathy at the wrist but surgical exploration revealed median nerve compression in the palm of the hand by an anomalously enlarged palmar branch of the ulnar artery. This case highlights another treatable cause of median nerve compression and illustrates that symptoms suggestive of carpal tunnel syndrome may be produced by median nerve compression in the palm of the hand.     

Safety of carpal tunnel release with a short incision. A cadaver study

The standard long incision technique for carpal tunnel release causes inevitable damage to skin sensation, the inter-thenar plexus and especially the distal branches of the palmar cutaneous branch of the median nerve (PCM), and may cause long-term disabling pain and scar tenderness. There are many variations in the distal branches of the median nerve at the wrist. Anatomic studies of this region also have important clinical implications to prevent injury to important anatomic structures. The purpose of this study was to evaluate the short-incision carpal tunnel release in cadavers. Several important anatomic structures, with possible anatomic variations, pass through the carpal tunnel, and blind percutaneous transection of the transverse ligament seems to be a high risk procedure. Sixty hands from 40 fresh cadavers were evaluated. Both the transverse ligament and the distal third of the deep forearm fascia were released using a Smillie knife. At the end of each procedure, the hand was explored for injury to tendinous and neurovascular structures of the wrist. In all cases the release of the carpal tunnel and the distal third of the forearm fascia was found to be complete. The superficial palmar arterial arch, flexor tendons, ulnar nerve and vessels, digital nerves, median nerve and its recurrent accessory branches, the flexor tendons, and even the subcutaneous tissue over the transverse ligament were damaged in no instance. Guyon's canal was entered in 6 (10%) hands without damage to its components. The distal branches from the ulnar side of the palmar cutaneous branch of the median nerve (PCM) were injured in 8 (13.6%) hands, an injury that is almost unavoidable with the classic open technique.     

Anatomy of the ulnar artery as it relates to the transverse carpal ligament

The anatomic relationship between the ulnar artery and transverse carpal ligament (TCL) as an aid in planning for minimally invasive carpal tunnel surgery was investigated. The anatomic course of the ulnar artery and its branches toward the TCL and the location of the median nerve were determined in 24 fresh cadaver hands perfused with a silicone compound. The ulnar artery coursed from 7 mm ulnar to 2 mm radial to the hook of hamate. The average distance between the superficial palmar arch and the distal margin of the TCL was 12 mm as measured along the flexor tendon of the ring finger. The location of the median nerve extended an average of 11 mm radial to the hook of hamate. A small arterial branch (average diameter, 0.7 mm) from the ulnar artery ran transversely just over the TCL in 6 of the 24 specimens. This branch was consistently located within 15 mm proximal to the TCL distal margin. These and other microscopic observations indicated that transecting the ligament at approximately 5 mm radial to the radial margin of the hook of hamate may minimize postoperative bleeding and avoid iatrogenic vascular and neural injury. (J Hand Surg 2002;27A:101-104. Copyright © 2002 by the American Society for Surgery of the Hand.)     

The use of topographical landmarks to improve the outcome of agee endoscopic carpal tunnel release

A modified approach to endoscopic carpal tunnel release has been developed and tested in 60 cadaveric specimens by three surgeons using the Agee endoscopic carpal tunnel release system. The modified approach, which includes specific localization of the hook of the hamate, flexor retinaculum, and the superficial palmar arch utilizing topographical landmarks, avoids entry into Guyon's canal and injury to the ulnar artery and nerve, median nerve, and common digital nerves. Use of the anatomic approach resulted in significantly superior results. There were fewer incomplete releases, and fewer surgical passes were required, for the inexperienced surgeons. When these anatomic considerations were not included, the learning curve was much steeper. For surgeons planning endoscopie surgical release of the transverse carpal ligament, the described topographical approach improves the technical competence with the procedure and reduces the number of complications and learning curve associated with new procedures. We recommend the use of topographical landmarks and other anatomic considerations during endoscopic carpal tunnel release.     

The anatomy of the Berrettini branch: implications for carpal tunnel release

OBJECT: Dissections were performed in 100 fresh cadaver palms to determine the frequency with which superficial palmar communication between the median and ulnar nerves occurs and to what extent it might incur iatrogenic injury during endoscopic carpal tunnel release. METHODS: Superficial palmar communication between the median and ulnar nerves was present in 81% of the dissected hands. Superficial palmar communication, also known as the Berrettini branch, has been classified into four distinct types by Ferrari and Gilbert. Twelve hands were classified as Group 1 (communication in an oblique course from the ulnar to the median nerve originating >4 mm above the distal margin of the transverse carpal ligament [TCL]), 16 hands were classified as Group 2 (communication parallel to the distal margin of the TCL), and 53 hands were classified as Group 3 (communication in an oblique course from the ulnar nerve to the third common digital nerve, originating below the distal margin of the TCL). No hand fit the Group 4 classification (atypical communication). CONCLUSIONS: The Berrettini branch can be considered a normal anatomical finding. In 28% of the hands in this study, the branch was proximal to the edge of the distal ligament and, therefore, prone to iatrogenic injury in both one-portal and two-portal endoscopic surgery.     

Palmaris profundus tendon prohibiting endoscopic carpal tunnel release: case report

Palmaris profundus is an aberrant muscle of forearm and wrist anatomy. It has no discernible function, but its tendon has been implicated as a cause of carpal tunnel syndrome. Previously, all cases of palmaris profundus in the literature have been encountered during either open surgery or cadaveric dissection. We report a case of palmaris profundus encountered during attempted single-portal endoscopic carpal tunnel release, necessitating conversion to an open approach. There was a unique point of tendon insertion onto the undersurface of the transverse carpal ligament, more proximal than what has been previously described in the literature. There were other anomalies present as well, including a persistent median artery and bifid median nerve. Given the volar position of the structure, its proximal point of insertion, and its minimal bulk, we did not feel that this was the cause of our patient's carpal tunnel syndrome.     

Anatomic study of arborization patterns of the ulnar artery in Guyon's canal

PURPOSE: To show variations in arborization patterns of the ulnar artery in Guyon's canal and to investigate the relationship between the hypothenar muscles and the ulnar artery. METHODS: Thirty-five embalmed cadaveric hands were dissected and the existence and course of the superficial and deep palmar branches of the ulnar artery and the site of feeding branches to the hypothenar muscles were recorded. The anatomic relationship between the ulnar artery and the hypothenar muscle variations also was investigated. RESULTS: Four arborization patterns were identified. In type 1UA (n = 17 hands), an artery accompanying the deep branch of the ulnar nerve (AADBUN) formed a deep palmar arch (DPA). In type 2UA (n = 11 hands) the AADBUN continued to the feeding artery of the abductor digiti minimi and the distal deep palmar branch of the ulnar artery (DDPBUA) branched off distally. This arterial structure formed a DPA. In type 3UA (n = 6 hands) both the AADBUN and DDPBUA formed DPAs. In type 4UA(n = 1 hand), the AADBUN continued to the feeding artery of the abductor digiti minimi with no DDPBUA and therefore no DPA. A dorsal perforating artery of the ulnar artery also was found in 4 hands. This branch came from the AADBUN at the level of the distal edge of the pisiform and merged with the dorsal carpal arterial arch. We also investigated the relationship between the structural pattern of the hiatus for the deep branch of the ulnar nerve and ulnar artery variation but found no association. The most common pattern observed was a type 1 hiatus with a type 1UA arborization pattern. CONCLUSIONS: Our study confirmed considerable variations in the arborization pattern of the ulnar artery in Guyon's canal. To avoid injury to the arterial branches during surgery in this region care must be taken with respect to variations of the ulnar artery in Guyon's canal.     

Median innervated hypothenar muscle: anomalous branch of median nerve in the carpal tunnel

A hypothenar motor branch of the median nerve in the carpal tunnel was observed and its motor function was documented by direct intraoperative nerve stimulation in two patients having carpal tunnel releases. The hypothenar branch left the median nerve at the midcarpal tunnel area. It crossed the tunnel superficial to the flexor tendons and penetrated the transverse carpal ligament ulnarly to innervate the abductor digiti quinti. Such branching of the median nerve at this level has not been reported previously. Good visualization of the carpal tunnel and careful dissection of its content even in the so called safe zone ulnar to long axis of palmaris longus tendon is recommended.     

Practical anatomy of the carpal tunnel

The carpal tunnel is most narrow at the level of the hook of the hamate. The median nerve is the most superficial structure. It has specific relationships to surrounding structures within the carpal tunnel to the ulnar bursa, flexor tendons, and endoscopic devices placed inside the canal. The importance of the ring finger axis is stressed. Knowledge of topographical landmarks that mark the borders of the carpal tunnel, the hook of the hamate, superficial arch, and thenar branch of the median nerve ensure appropriate incision placement for endoscopic as well as open carpal tunnel release surgery. Anatomy of the transverse carpal ligament, its layers and relationships to adjacent structures including the fad pad, Guyon's canal, palmar fascia, and thenar muscles has been discussed. Fibers derived primarily from thenar muscle fascia with connections to the hypothenar muscle fascia and dorsal fascia of the palmaris brevis form a separate fascial layer directly palmar to the TCL and can be retained. This helps to preserve postoperative pinch strength. The fat pad in line with the ring finger axis overlaps the deep surface of the distal edge of the TCL and must be retracted in order to visualize the distal end of the ligament. Whereas the ulnar artery within Guyon's canal is frequently located radial to the hook of the hamate, injury to this structure has not been a problem during ECTR surgery. Variations of the median nerve and its branches, as well as the palmar cutaneous nerve distribution, have been reviewed. A rare ulnar-sided thenar branch from the median nerve, interconnecting branches between the ulnar and median nerves located just distal to the end of the TCL, and transverse ulnar-based cutaneous nerves can be injured during open or ECTR surgery. Anomalous muscles, tendons or interconnections, and the lumbricals during finger flexion may be seen within the carpal tunnel. These structures can be the cause of compression of the median nerve. The anatomy of the carpal tunnel and surrounding structures have been reviewed with emphasis on clinical applications to endoscopic and open carpal tunnel surgery. A thorough knowledge of the anatomy of the carpal tunnel is essential in order to avoid complications and to ensure optimal patient outcome. An understanding of the contents and their positions and relationships to each other allows the surgeon to perform a correct approach and accurately identify structures during procedures at or near the carpal tunnel.     

Evaluation of sympathetic vasomotor fibres in carpal tunnel syndrome using continuous wave Doppler ultrasonography

Sympathetic vasomotor fibres carried by the median nerve and ulnar nerve innervate their respective sensory territories. The sympathetic vasomotor fibres of the median nerve were evaluated in patients with carpal tunnel syndrome and in healthy volunteers using continuous wave Doppler ultrasonography. The pulsatility index of the radialis indicis artery and the radial palmar digital artery of the little finger were measured at baseline and after stimulation. The maximal increase in the pulsatility index of each artery was measured. This was significantly lower for the radialis indicis artery in the CTS group than in the healthy controls. However, there was no significant difference in the maximal increase in pulsatility index of the radial palmar digital artery of the little finger between both groups. Sympathetic vasomotor fibres of the median nerve are affected in carpal tunnel syndrome. Continuous wave Doppler ultrasonography is easy to use and should be investigated further as a possible diagnostic tool for the confirmation of carpal tunnel syndrome.     

The safest location for steroid injection in the treatment of carpal tunnel syndrome

Steroid injections are routinely performed for carpal tunnel syndrome. Direct needle injury of the median nerve is the major complication of these injections. The safest location of the injection remains controversial. The purpose of this study is to define safe guidelines to avoid nerve injury. The distances between the Median nerve, Palmaris Longus, Flexor Carpi Ulnaris and Flexor Carpi Radialis tendons were measured pre-operatively, 1cm proximal to the distal wrist crease in 93 endoscopic carpal tunnel releases. We found that the median nerve extended ulnarly beyond the Palmaris Longus tendon in 82 hands (88%). It is concluded that the median nerve is at risk if the injection is performed within 1cm on either the ulnar or radial side of the Palmaris Longus tendon. More ulnarly, there is risk to the ulnar pedicle. The safest location is to inject through the FCR tendon.     

Flexor pollicis brevis adductorplasty: an alternative method in ulnar nerve paralysis

Loss of pinch power associated with loss of coordinated movement of thumb and index fingers is the major disability in patients with ulnar nerve paralysis. Several tendon transfer methods utilizing different donor muscles have been used to restore adductor pollicis muscle function in ulnar nerve paralysis. In this paper, we discuss the transfer of flexor digitorum brevis muscle to the tendon of adductor pollicis muscle as an alternative method to restore key pinch in ulnar nerve paralysis. The technique was applied to 4 patients with ulnar nerve paralysis. Before clinical application, an anatomic study was carried out in 6 cadaver hands. In cadavers, radial and ulnar arteries were injected with latex and arterial pedicles of flexor pollicis brevis muscle were dissected under 4x magnification. Also, motor branches from the median nerve were shown at the entrance point to the muscle. In surgical practice, the superficial head of the muscle is detached from its insertion and the minor pedicle of the muscle is cut. Muscle is dissected proximally up to two thirds of its length. The dominant pedicle of the muscle originating from superficial palmar arcus is preserved, and the muscle is sutured to the tendon of the adductor pollicis muscle close to its insertion. Patients were evaluated in terms of key pinch strength preoperatively and at the postoperative sixth month using a pinch meter (Chattanooga Group, Inc). Key pinch strengths were recorded and expressed as percentage of the strength of the contralateral uninvolved hand. Mean key pinch strength of our patients was 29.7%.In conclusion, we believe in that flexor pollicis brevis adductorplasty may be an alternative method for restoration of adductor pollicis muscle function in ulnar nerve paralysis.     

The Cup of Diogenes: a fixed anatomical landmark for carpal tunnel surgery

Purpose

Carpal tunnel syndrome is a common entrapment neuropathy. When conservative management fails to relieve symptoms, carpal tunnel surgery is indicated. The surgical exposure for this procedure is commonly based on variable anatomic landmarks. The purpose of this study was to describe a fixed, easily referenced anatomical landmark for the distal extension of the transverse carpal ligament, the “Cup of Diogenes.”

Materials and Methods

Topographical landmarks including Kaplan cardinal line, palmaris tendon, and distal palmer crease were marked on six fresh frozen cadaveric wrist and hand specimens. The apex of the Cup of Diogenes is determined to be the confluence of the thenar and hypothenar musculature of the palm. Wrists were dissected and the distance between these landmarks and the superficial palmar arch, median nerve, transverse carpal ligament, and ulnar nerve were measured.

Results

In all specimens, the ulnar nerve was ulnar to this the apex of the Cup of Diogenes, while the median nerve was radial. The apex was proximal in all specimens to the superficial palmar arch. The apex marked the distal extent of the transverse carpal ligament in all specimens.

Discussion

Based on our results, we feel the apex of the Cup of Diogenes is a consistent, fixed anatomical marker for the distal extent of the transverse carpal ligament, marking a safe zone in the palm for surgical planning of incisions.

Level of Evidence

Level V - Therapeutic     

Median nerve function after tendon transfer for ulnar paralysis

This is a long term follow-up study of the median nerves of 128 leprosy patients who originally had pure ulnar palsy for which they had tendon transfers to correct claw hand. Of the thirty-one cases in which the carpal tunnel was not used as a pathway for tendon grafts, 16% developed median palsy in the subsequent years. Of the ninety-seven cases in which tendon grafts were passed through the carpal tunnel, 7% developed a transient median nerve palsy and 11% developed permanent median palsy. None of the median nerve palsies developed during the weeks or months of post-operative re-education or observation, but were noted at follow-up visits months or years later. It is concluded that the use of the carpal tunnel did not significantly affect the status of those high-risk median nerves in cases of leprosy.     

A foregoing thenar muscular branch of the median nerve

We present a 62-year-old female patient who had an anatomic variation in the median nerve of the left hand. During surgery for releasing the left carpal tunnel, an abnormally high level of origin of the thenar muscular branch of the median nerve was detected, at 2.5 cm above the proximal border of transverse carpal ligament. It traveled between the medial side of the flexor carpi radialis tendon and median nerve and entered the carpal tunnel. After exiting the carpal tunnel distally, the nerve, was noted to course towards the thenar area. Such variations in the median nerve should be kept in mind while performing carpal tunnel release.     

A reliable technique for avoiding the median nerve during carpal tunnel injections

Carpal tunnel injections are widely performed for diagnostic and therapeutic purposes. Injury to the median nerve is a serious and fairly common complication. There is no consensus regarding the safest injection site. The objective of this study was to determine the safest injection site based on anatomical data. During 124 endoscopic procedures for median nerve release at the carpal tunnel, we measured the distances separating the median nerve, palmaris longus (PL), flexor carpi radialis (FCR), and flexor carpi ulnaris 1 cm proximal to the wrist crease. The edge of the median nerve extended medially beyond the PL tendon in 82 (88%) hands. Thus, needle insertion within 1 cm of either edge of the PL tendon may cause median nerve injury; with injection sites located further toward the medial edge, the ulnar pedicle may be at risk. Consequently, we recommend that carpal tunnel injections be performed through the FCR tendon.     

Carpal tunnel syndrome: associated abnormalities in ulnar nerve function and the effect of carpal tunnel release on these abnormalities

Twenty of 59 hands (34%) of patients with carpal tunnel syndrome had abnormalities in sensibility testing of both median and ulnar nerves by either two-point discrimination, Semmes-Weinstein monofilament testing, or both. Before surgery, 53% of patients complained of paresthesias and/or numbness in ulnar nerve distribution. Eighty percent of the hands had abnormal Semmes-Weinstein monofilament testing of the ulnar nerve. Thirty-five percent had abnormal two-point discrimination. Forty-one percent had abnormal electromyographic testing of the ulnar nerve. All hands had median nerve decompression alone. Guyon's canal was not released. After surgery, 89% of patients had improvement in paresthesias and/or numbness of the ulnar nerve. Ninety-four percent had improvement in Semmes-Weinstein monofilament testing. Eighty-six percent had improvement in two-point discrimination. Patients with a residual abnormality in ulnar nerve sensibility also had continued abnormality in median nerve sensibility. A significant percentage of patients with carpal tunnel syndrome also have signs and symptoms of ulnar nerve compression. Most improved with carpal tunnel release alone.     

CARPAL TUNNEL SYNDROME CAUSED BY THE PALMARIS PROFUNDUS MUSCLE: Case report

The palmaris profundus muscle is a rare structure that originates from the radial portions of the forearm. Its discrete tendon passes through the carpal tunnel, attaching distally to the palmar aponeurosis. If it interferes with the median nerve it may cause carpal tunnel syndrome. The finding can be compared with similar observations in comparative anatomy.     

Carpal tunnel syndrome caused by the palmaris profundus muscle. Case report.

The palmaris profundus muscle is a rare structure that originates from the radial portions of the forearm. Its discrete tendon passes through the carpal tunnel, attaching distally to the palmar aponeurosis. If it interferes with the median nerve it may cause carpal tunnel syndrome. The finding can be compared with similar observations in comparative anatomy.