Distal median- and ulnar nerve compression syndromes Education & Training
Transcription
Distal median- and ulnar nerve compression syndromes Education & Training
Education & Training Distal median- and ulnar nerve compression syndromes Jens Haase Introduction Best understood in this context are the median- and ulnar nerve compression syndromes.3-5,11-13,15-17,21,23,26-28,31,35,36,47 (p38-45) Most common among these is the median nerve compression in the carpal tunnel = carpal tunnel syndrome (CTS). Compression syndromes may be treated conservatively e.g. by a splint or by steroid injections.14,17 Similarly they may be treated surgically.3,5,12,17,47 Most important and relevant to all kinds of surgery is the question ‘‘Will the actual procedure relieve symptoms caused by the disease and are the complication rates low and/or insignificant?’’. In Denmark with 5.4 million inhabitants a total of 5,000 hands with CTS are operated upon each year, and equivalent figures are found in Sweden and US. These high numbers make it therefore relevant to discuss involved surgical technique, as complications are possible with all surgical interventions. discussion elsewhere.15,17 The median nerve may most often be compressed at the carpal tunnel distal to the wrist and the position of the median nerve under the TCL and can clearly be seen with ultrasound imaging (Fig. 1). Hook of hamate Pisiform Transverse carpal ligament Figure 1 - Ultrasound image of the carpal tunnel. Most common surgical procedure since 1854, has been the open surgical release (OCTR) of the median nerve by cutting the transverse carpal ligament (TCL).17 The first endoscope procedure (ECTR) for transecting the TCL was introduced in 1987 and many modifications have been described since then.1,8,22,32,40,49 A combination of open surgery and endoscope surgery has been introduced recently.24 Surgical treatment of ulnar nerves has been performed since the19th century.5 Despite the fact that this procedure seems to be a rather trivial and simple operation, the problems of learning to perform these operations requires thorough training.11,18,25 Median nerve compression - CTS For diagnosing CTS the reader is referred to a more detailed Faculties of Engineering, Science & Medicine Department of Health Science & Technology Aalborg University Denmark Correspondence: Prof. Jens Haase Faculties of Engineering, Science & Medicine Department of Health Science & Technology Aalborg University Fredrik Bajers Vej 7, E-4 9220 Aalborg Denmark 38 For a compressed median nerve an increase of the carpal tunnel space can be obtained by cutting the TCL by two different surgical methods e.g. 1) OCTR or 2) ECTR.17 The major difference between an OCTR and an ECTR procedure is the way the TCL is cut. With the OCTR the surgeon cuts the TCL from outside the carpal tunnel thereby viewing all structures in - for the surgeon - a normal 3D fashion. This is in contrast to the ECTR where the TCL is cut from inside the carpal tunnel viewing it in a - for the surgeon - new, and only 2D fashion.17 This endoscopic procedure is for many reasons much more difficult and must be learned thoroughly through training and regular practice.18 Through literature validation, both surgical methods seem to lead to the same results but the complications of the methods are different, apparently being more severe among the endoscope method.1,9,11,17,34,39, 46, 49,50 To carry out carpal tunnel release surgery the surgeon needs anaesthesia, and anaesthetic complications must be added to the surgical failures.6,17 Anaesthesia for CTS treatment comprise of: 1. Local infiltration anaesthesia (LA) PAN ARAB JOURNAL OF NEUROSURGERY DISTAL MEDIAN– AND ULNAR NERVE COMPRESSION SYNDROME • Haase 2. 3. 4. Local infiltration anaesthesia with use of tourniquet Intravenous anaesthesia with use of tourniquet and General anaesthesia. The author prefers the first simple method (LA) where the skin is infiltrated in the hand by injection of lidocain 1% with adrenaline. Hand surgeons in many countries traditionally use LA combined with extremity exsanguinations to obtain a bloodless field. Whereas a bloodless field is absolutely mandatory for dissecting tendons and synovial tissue, it is not the case for nerve dissection. The entrapment (CTS) cause cyanotic colour changes of the nerve and/or distended vessels on the nerves, which cannot be visualized in a bloodless field.19,30 Postoperative venous haemorrhages in the operative field are also more common following use of tourniquet. However, if one compares blood oozing by the use of tourniquet and simple local lidocain + adrenaline, the simple infiltration of skin with adrenalin is superior to tourniquet.6 Intravenous anaesthesia combined with tourniquet is a standard for many hand surgical procedures, but is more complicated than LA. carpal tunnel from the proximal wrist crease. After 4 - 5 minutes the quality of sensation is tested with small pin pricks at the anaesthetic area and outside. Thereby the patient will relax, learning the difference between normal painful areas and the operative analgesic area. The hand is then placed on a well-bolstered separate arm table. If it is the right hand, the right-handed surgeon places himself at the ulnar side of the hand to be operated upon. Visa versa if the surgeon is left-handed. The reason being that the surgeon then, in all cases, will cut and dissect from proximal towards distal, whereby the risk of injuring nerve branches that diverse from proximal to distal is reduced. Before the operation, the surgeon prepares the microscope. The surgeon must set the oculars and interpupillary distance correctly and the microscope may be draped. He must also determine if his own glasses shall be used or not. The operative field is, with this type of surgery, rather stationary so draping can be excluded as the hand can be moved to maintain focus. The operative microscope is now brought to its place (Fig. 2). General anaesthesia may be indicated in cases of reoperations with significant scarring or if the patients are very nervous. Surgical techniques Open carpal tunnel release Open surgical section of the TCL has been the gold standard surgical treatment for patients with CTS since 1854.12,17,21,23 Cutting the TCL with a scalpel under direct vision produces reliable symptom relief in the vast majority of cases.17 However, despite this high clinical success rate, transient postoperative symptoms such as ‘‘pillar pain’’, scar tenderness, or hand weaknesses are known to occur.22, Figure 2 - Operative microscope. 37,44 Preoperatively the patient is carefully informed about how the operation is carried out. It is thus described how local anaesthesia is used and that he/she can feel “something”, but no pain during the operation. During the operation additional local anaesthetics can be applied, if necessary. Instruments needed are simple: a surgical knife with a 15blade, a small retractor, that is used to hold the skin edges apart, and an operative microscope for better viewing and light. Magnifying loupes may be used in case a microscope is not available. The author always advocates use of some kind of magnification. The hand/arm is carefully prepped with hexidine alcohol or similar disinfection material. With a thin needle 4 - 5 cc lidocain 1% with adrenaline is infiltrating the skin over the VOLUME 14, NO. 2, OCTOBER 2010 The author uses two separate pairs of gloves for the surgery for prevention of infection from skin flora.45 A 3 - 4 cm long incision is made with a 15-blade from the distal crease of the hand towards the interdigital space 3/4. All bleeding vessels must be carefully occluded with bipolar coagulation, with a low setting.29 Thereby postoperative blood oozing in the wound is very seldom experienced. The small retractor is placed to hold the skin edges. With aid of the microscope the palmar aponeurosis is now visualized and cut longitudinally. Eventual cutaneous nerve structures or vessels are avoided. It is at this time exchange of the first pair of gloves that are always contaminated with skin bacterial flora is done. The TCL with its white transverse fibres is now visualized and is opened by cutting with a 15blade in the middle, slightly ulnar to the midline. When the carpal tunnel contents are encountered, the incision is 39 DISTAL MEDIAN– AND ULNAR NERVE COMPRESSION SYNDROME • Haase carried further distally to the rim of the TCL until the normal yellow fat is visualized. Then the proximal part of the ligament is cut and eventually part of the antebrachial fascia, again keeping ulnar (Fig. 3). above systolic pressure are often necessary to obtain a bloodless field. The introduction of the endoscope into the carpal tunnel may increase pressure on the median nerve and cause unpleasant sensations for the patient if carried out in LA.17 Even with perfectly planned endoscope surgery the surgeon must be prepared to change to an open type of surgery if anatomical landmark identification is not possible. Single-portal techniques are those in which a single skin incision is made in the proximal wrist crease.1,22 Dualportal techniques are those in which a second supplementary small incision is made in the palm when the endoscope/obturator has reached this area.8,40 Both methods require some degree of hyperextension and fixation of the hand during surgery. This hyperextension decreases the volume of the carpal tunnel, as does the introduction of the endoscope equipment. Figure 3 - Median nerve inside the carpal tunnel. The palmar motor branch of the median nerve is usually never seen with this approach. The median nerve is visualized in the tunnel and hourglass shape and eventual cyanosis indicating the compression site is seen (Fig. 4).17 Figure 4 - Hourglass shape of compressed median nerve. Movements of the tendons and the median nerve are obtained by pulling the fingers and secures that the contents in the canal is free. The TCL edges are coagulated with bipolar coagulation and the skin closed in one layer with single 5 - 0 sutures. The wound is covered with a band-aid and the hand bolstered leaving the fingers free for active movements immediately after surgery. The hand is kept high for the first day and skin sutures removed after 12 - 14 days. Decreased wrist movements are common after two weeks (relative immobilization) and should be treated by active movements after the skin sutures have been removed. Endoscopic carpal tunnel release techniques Visualization of anatomical structure is of course of paramount importance when performing endoscope procedures.20 Blood obscures vision and extremity exsanguinations with an Esmarch bandage followed by inflation of tourniquet 40 1) ECTR single-port technique: A small incision is made in the distal hand crease on the ulnar side of the long palmar muscle tendon. Through this an obturator is introduced blindly into the carpal tunnel developing a channel for the endoscope. The endoscope sheet is then inserted directly in the carpal tunnel through this channel followed by introduction of the endoscope. A window near the tip of the system angled upwards makes it possible to continuously view the undersurface of the TCL through the endoscope. A hook knife cutting blade is then inserted via the endoscope and cutting of the TCL takes place often from distal to proximal viewing the ligament, but not the median nerve.1,17 2) ECTR dual-port technique: With the two portal techniques the introducer/obturator is also passed blindly through the carpal tunnel through a similar small transverse cut in the distal skin crease. When the obturator reaches the palm a supplementary contra incision is made here and the tip of this introducer is thereafter pushed out through the skin (Fig. 5). Loop around median nerve Long flexors tendons TCL - cut edges Figure 5 - Two-portal endoscope technique. PAN ARAB JOURNAL OF NEUROSURGERY DISTAL MEDIAN– AND ULNAR NERVE COMPRESSION SYNDROME • Haase The endoscope is then passed into the introducer from the proximal end of the carpal tunnel and the channel is inspected for contents. The custom designed instrumentation protects the median nerve and flexor tendons, and positioning of the slotted cannula through the two portals ensures a stable surgical environment.8,40 The surgeon inserts a hook knife via the proximal port and advances it behind the distal end of the TCL. The TCL is caught by the knife and the ligament is cut with a backwards pull. Complications due to operative treatments: Nowadays, complications range from 0 - 24%.17 This huge variation documents the influence of the surgical learning curve/ and or surgical competence. According to recent studies, the overall complication rate should be in the range of 1 - 2% in experienced hands for both ECTR and OCTR surgery.2,10,13,34,41,42,44,49-51 The most common complication due to OCTR and ECTR is inadequate cutting of the distal part of the TCL.17 These patients will not experience the immediate normal relief of the painful hand paraesthesia after the operation. So, if the patient still complains of painful paraesthesia after 2 - 3 days the surgeon must consider this complication. Other complications are direct surgical lesion of the median nerve including its motor branch and compression neuropathy due to pressure by the endoscope. A lesion of the palmar cutaneous branch of median nerve may often lead to a complex regional pain syndrome.17 Hypertrophic hypersensitive skin scar is only seen if the skin incision has been carried proximal to the distal wrist crease, whereas slight pillar pain is common in the first weeks after OCTR surgery. Injury to the superficial vascular arch distal in the hand and wound infection are rarely encountered. Decreased grip strength is common with both methods for the first 2 - 3 postoperative months, but will normally gradually disappear. Erroneous decompression of the ulnar nerve in Guyon´s canal instead of the median nerve may be the result of lack of experience, both in OCTR and in ECTR.17,30 incisions must take aim of visualization of the ligament and then the contents of the carpal tunnel. Lack of magnification and light both disturb the possibilities of viewing the carpal ligament sufficiently. Many open cases are rather closed as a “Mickey”-probe is introduced into the canal and the TCL thereafter cut on this probe that is supposed to prevent lesions of the median nerve. Similarly, some surgeons use a pair of scissors to cut the ligament with e.g. introducing one branch blindly into the canal. They cannot see the distal cut of the TCL. “To see” for the author, is the first and most important factor for reducing complications in OCTR.17 With the technique described here, the median nerve is clearly viewed due to magnification and excellent light in the operative field provided by the operative microscope. Performing the skin incision the larger cutaneous nerves may be seen and protected. The white transverse fibres of the TCL are also easily visualized with the microscope. Another important point is that the author never uses a tourniquet, thereby all degrees of nerve compression including colour changes and vessels stasis are clearly shown. The motor branch of the median nerve is never found during this dissection and thus never sectioned because you see all necessary details of the procedure nothing is blind. For teaching / learning activities it is also possible to preserve the whole operation on a DVD or as slides in a PowerPoint presentation for validation (MöllerWedelc). Most series published are "personal" and thus not suited for generalization - which is still done. The surgical learning curve is important and because one great endoscope surgeon or micro-neurosurgeon can carry out CTS operations with minimal complications this does not invariably indicate that all surgeons will accomplish the same.17 Endoscope techniques has many proponents who cite the potential benefits of faster patient recovery time, less incision pain and improved grip strength recuperation.1,10,11,22,31,32,34,40-43 No controlled randomized series exist to prove these statements. Application of endoscopy techniques has not decreased operative expenses, nor increased operative efficiency, or improved intraoperative visualization (compared with conventional OCTR).42 Results of surgical treatment of CTS Carpal tunnel syndrome must be graded in different stages.17,39 In the early stages of CTS, total relief of pain and nightly paraesthesia is obtained in close to 96% of all cases within 24 - 48 hours. In later stages of CTS, full return of sensation and muscle power cannot be anticipated, as regeneration of the axonal injured nerve fibres will take up to several years. The influence of postoperative training - or “remodeling the brain” - is very important.38 Evans stated in an editorial in Journal of Handsurgery: “The serious complications (… to CTS operations) must be regarded as the result of: careless or inexperienced surgery and the established principle of surgery under direct vision has provided reliable protection against disaster".11 One of the main causes for surgical mistakes in OCTR is improperly placed incisions.12,21 Hands are different and Ulnar nerve entrapments VOLUME 14, NO. 2, OCTOBER 2010 Proper formal training in both open and endoscope techniques must be obtained. 18 Ulnar nerve anatomy: Many variations in the ulnar 41 DISTAL MEDIAN– AND ULNAR NERVE COMPRESSION SYNDROME • Haase nerve anatomy exist. The ulnar nerve follows the medial head of the triceps muscle and enters the retrocondylar groove behind the olecranon heavily protected in a fibroosseous tunnel. Distally the nerve gives off sensory branches to the elbow joint and skin at the olecranon and motor branches to the ulnar carpal flexor- and the medial half of the deep flexor muscles.2,5,23,24,35,36 The space just outside and distal to the groove created by an arcuate aponeurosis (“Osborne ligament”) and the two heads of the ulnar carpal flexor muscle is also called the Osborne compartment.33 The ulnar nerve digs down and continues into the forearm, lying between the ulnar carpal flexor muscle and the deep long flexor muscle closely joined with the ulnar artery. Distal at the wrist it enters Guyon´s canal where it divides into sensory branches to the volar ulnar part of the hand and 4th and 5th fingers, and superficial and deep motor branches to the small hand muscles.19 Nerve anastomosis between the ulnar- and median nerves exists in the forearm and distally in the palm in many patients. A gliding movement of up to 4.7 cm of the only 2 - 4 fascicles of the ulnar nerve is taking place during flexion/extension of the elbow in the average person.47 The fibro-osseous canal size decreases during flexion and increases during extension. In contrast, the Osborne compartment space decreases with elbow extension. Therefore, we may anticipate two different types of entrapment and subsequently two different operative treatments. The strain at elbow flexion is maximal directly behind the medial epicondyle with pressures that increases up to 3 times by elbow flexion. The ulnar nerve may very rarely be compressed proximal to the sulcus. Most common it is found in younger patients compressed at the level of medial epicondyle due to recent elbow fractures. If the fibro-osseous tunnel size is reduced by trauma, the ulnar nerve may easily be entrapped here. In the cubital compartment an elbow flexion causes stretching of the ligament and the compartment flattens leading to pressure on the ulnar nerve.27,33,36 Conservative treatment: Involves prevention of bending the elbow or compressing the nerve by sitting with the elbow on the table, which is the most common treatment.17 Surgical treatment must be reserved for long-lasting symptoms and thorough documentation. For indications to surgery, the readers are kindly asked to read the more detailed discussion.5,7,27,48 For the simple “Osborne” decompression LA is sufficient. Additional anaesthetics can be applied if necessary and no tourniquet is needed.2,17,33 With transposition procedures general anaesthesia is preferred.2,36 The minimal invasive technique by endo/ micro-surgery may have an advantage, but needs long-term validation.24 Simple decompression techniques 1) “Osborne” operation: The skin distal to the ole- 42 cranon is infiltrated with 5 cc of local anaesthetics. The skin is then opened from the middle of the line between the olecranon and the epicondyle distal to the groove. The muscle aponeurosis over the cubital tunnel is opened but the retrocondylar groove is left untouched. After cutting the muscle-aponeurosis the Osborne compartment is opened and the ulnar nerve is located and dissected beneath the two heads of the ulnar carpal flexor muscle. The author always uses operative microscope at this stage. When the fascia has been opened, the arm is moved to see how the nerve is sliding. The author, does not open the fibro-osseous tunnel (retrocondylar groove) unless compression here is suspected by inspection. If opened, it is only the distal half of the fibro-osseous tunnel that is cut to allow release of the ulnar nerve. Other authors do open the whole fibro-osseous tunnel routinely releasing the nerve and leaving it to lie freely only covered by connective tissue. The patient needs to have a deep condylar groove in these cases. The risk of a new postoperative chronic nerve irritation may easily develop if the released nerve slides over the epicondyle with elbow flexion. The skin is closed in two layers. The patient is urged to move the elbow freely immediately after surgery. At night an elbow bandage is used to prevent maximum elbow flexion for the next 2 - 3 weeks. Skin sutures are removed after 14 days.16,33 Open surgery is still the standard but cubital tunnel release with endoscope assistance has been advocated with a new micro/endo version in 2006.24 The author has no personal experience with this method. 2) Epicondylectomy: Medial epicondylectomy is another hypothetical way to release pressure on the ulnar nerve at the elbow. This operation demands general anaesthesia. Excision of the proper amount of bone is critical to the success of this procedure. If too much bone is excised damage to the medial collateral ligament of the elbow, deep in the groove, may lead to a valgus position of the elbow joint and painful instability of the medial elbow. Osteomyelitis is another severe complication to this operation. Heterotope ossification may be the result of osteotomy and thereby continuous minor trauma to the nerve may occur as it is now unprotected.23,36,37 The author has also never carried out this operation. 3) Ulnar nerve decompression with transpositions of the nerve: Surgical decompression of the ulnar nerve with subsequent anterior transposition to the medial epicondyle is often suggested. Hereby the position of the ulnar nerve should be shorter and tension of the nerve thus be relieved. Interfascicular gliding should similarly be improved. The ulnar nerve may be positioned subcutaneously above the muscle fascia or submuscular either under or inside the pronator teres muscle.2,5,23,24,27 Lesions of PAN ARAB JOURNAL OF NEUROSURGERY DISTAL MEDIAN– AND ULNAR NERVE COMPRESSION SYNDROME • Haase cutaneous branches to the olecranon/ elbow joint may result from transposition techniques and long dissection of muscular and cutaneous branches may also be needed. technique exist. Postoperatively, the elbow is immobilized in 45 degrees of flexion in a post mould or cast for 3 - 4 weeks.2,23 A) The subcutaneous technique: An incision starts some 8 cm proximal to the medial epicondyle and continues in front of this to 6 cm distal over the flexor carpi ulnaris muscle. Branches of the medial antebrachial cutaneous nerve are carefully protected to prevent lesions and neuroma development. The ulnar nerve is found proximally and then dissected distally. It is freed from all septa, Osborne ligament and flexor carpi ulnar fascia. The distal medial intermuscular septum should also be cut protecting major vessels. The ulnar nerve is mobilized in front of the medial epicondyle preserving the motor branches to the flexor muscles. If necessary, the articular branch to elbow joint should be preserved too. The nerve now lies on the fascia and the subcutaneous fat is sutured to the tip of the medial epicondyle with non-absorbable sutures, thereby a subcutaneous tunnel is created. It is ensured that the nerve lies and moves freely (Fig. 6). 4) Guyon´s canal - wrist - decompression: A surgical decompression is carried out most often from the volar side of the wrist with a straight incision with a Z- at the wrist creases. Another approach is from the ulnar side of the hand via a Z-shaped incision lateral along the hypothenar. Hereafter the pisiform bone is removed whereby the deep motor branch is decompressed. Minor postoperative problems are the result of this latter procedure.2,19 Ulnar nerve transposed Osborne compartment opened Sulcus Olecranon Cutaneous branch for olecranon Figure 6 - Ulnar nerve transposed subcutaneously. Then the skin is sutured in two layers. Postoperatively, the elbow is immobilized in a post mould or cast at 45 degrees of flexion for 2 weeks. Active mobilization can start after two weeks. This is the simplest transposition technique but must be carried out meticulously to prevent later kinking of the nerve both proximally and distally.2,7,27 B) Submuscular techniques: In submuscular transposition the initial dissection is as with the subcutaneous technique. The idea is to position the ulnar nerve deeper inside the muscle tissue. Therefore the origin of the flexorpronator muscle group is released and the nerve positioned under these lying on the brachial muscle. Then the flexorpronator muscle is reattached securely. Variations of this VOLUME 14, NO. 2, OCTOBER 2010 Results of surgical treatment of ulnar nerve compression The ulnar neuropathy is manifested by multiple pathogenesis factors. This manifests in different clinical situations with similar symptoms. The acute ulnar nerve neuritis is a completely different entity then that of an ulnar nerve neuropathy or a median nerve neuritis. We have no controlled and validated information with regard to which surgical treatment to offer.2,7 We must accept this and be cautious in our suggestions of what type of treatment the patients should receive. Prevention seems better than any surgical cure in the first stadium of the ulnar nerve diseases. It seems more than relevant to carry out a careful electrophysiological examination before surgery is decided upon.17,19 Conservative treatment is based primarily on prevention of compression. Keep the elbow as straight as possible if elbow flexions provoke symptoms. Use headsets instead of mobile telephone, adjust workspace if necessary and use elbow protectors if compression seems to be leading to symptoms. This will, in most cases lead to reduced symptoms. Only if these treatments fail, surgery can be considered.2 Basically, the operative treatments consist of the "simple" decompression with a minimum of complications. Simple decompression will, in the majority of cases, be the best choice of surgery.7 The technically, much more complicated nerve-transposition procedures of the ulnar nerve, leads to many complications.2,7,27,33 Transposition is carried out in cases where medial dislocation of the nerve is a prominent feature and the choice of subcutaneous and submuscular transposition is not clear - the author favours the simplest choice. Complications A kinking of the ulnar nerve can easily occur against the medial intermuscular septum and under the aponeurosis arch between the two heads of the ulnar flexor carpi muscle. This happens if sufficient decompression is not carried 43 DISTAL MEDIAN– AND ULNAR NERVE COMPRESSION SYNDROME • Haase out.2,7 Most common complications to operative treatment are injury to the nerve while decompressing it or transposing it and neuromata of the medial antebrachial cutaneous nerve.36 Endoscope decompression has been described, but only lately with the combined endo-micro technique and it seems to be a tool to be taken seriously in the future.24 Conclusion Surgical treatment of median- and ulnar nerve compression syndromes are very rewarding. The operations demands similar micro techniques as with aneurysm surgery. All techniques must be properly learned before being applied to our patients. References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 44 Agee JM, McCarroll HR Jr, Tortosa RD, Berry DA, Szabo RM, Peimer CA: Endoscopic release of the carpal tunnel: a randomized prospective multicenter study. J Hand Surg (Am) 1992, 17(6): 987-995 Assmus H, Antoniadis G (eds): Nervenkompressions-syndrome. Germany, Steinkopff Verlag 2008 Assmus H, Antoniadis G, Bischoff C, Haussmann P, Martini AK, Mascharka Z, Scheglmann K, Schwerdfeger K, Selbmann HK, Towfigh H, Vogt T, Wessels KD, Wüstner-Hofmann M: Diagnosis and therapy of carpal tunnel syndrome. Handchir Mikrochir Plast Chir 2007, 39(4): 276-88 Atroshi I, Larsson GU, Ornstein E, Hofer M, Johnsson R, Ranstam J: Outcomes of endoscopic surgery compared with open surgery for carpal tunnel syndrome among employed patients: randomised controlled trial. BMJ 2006, 332: 1473 Bartels RHMA: History of the surgical treatment of ulnar nerve compression at the elbow. Neurosurg 2001, 49: 391-400 Braithwaite BD, Robinson GJ, Burge PD: Haemostasis during carpal tunnel release under local anaesthesia: A controlled comparison of a tourniquet and adrenaline infiltrations. 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