Summary Carpal Tunnel Syndrome (CTS) is a common acquired compressive neuropathy of the median nerve that presents with symptoms of numbness and tingling in the median nerve distribution of the hand. Diagnosis is made clinically with primary symptoms of night pain, hand weakness/clumsiness, and numbness in median nerve distribution along with positive provocative tests and/or EMG/NCS studies Treatment is usually conservative with night splints and corticosteroid injections. Operative treatment in the form of carpal tunnel release is reserved for refractory cases. Epidemiology Incidence affects 0.1-10% of general population Up to 70% of patients have bilateral carpal tunnel syndrome Demographics age manifests in adults aged 40-60 years old uncommon in children sex female:male 3:1 ratio Location carpal tunnel/canal at the wrist Risk factors female sex obesity pregnancy hypothyroidism rheumatoid arthritis trauma (acute CTS) - distal radius fractures or malunions, dislocation/or subluxation of the carpus repetitive motion activities acromegaly advanced age menopause chronic renal failure space-occupying lesion (e.g. ganglion cyst, neoplasm) use of oral contraceptives congestive heart failure diabetes smoking alcoholism mucopolysaccharidosis (children) mucolipidosis Etiology Pathophysiology increased pressure on the median nerve affects intraneural blood supply normal carpal tunnel pressure measures from 2.5mmHg at rest with the wrist in neutral to 30mmHg with wrist flexion at 20mmHg intraneural venous flow is impeded and edema occurs. Complete disruption of arteriolar flow occurring at 60-80mmHg in patients with CTS, carpal tunnel pressures range from 30-110mmHg mechanism exposure to repetitive vibratory exposure (e.g., typing on a keyboard) certain athletic activities cycling tennis throwing trauma (ie distal radius fractures, carpal bone fractures/dislocations) pathoanatomy most common causes of nerve compression pathologic (inflamed) synovium - most common cause of idiopathic CTS repetitive motions in a patient with normal anatomy space occupying lesions (e.g., gout) Associated conditions diabetes mellitus hypothyroidism rheumatoid arthritis pregnancy amyloidosis Anatomy Carpal tunnel borders scaphoid tubercle and trapezium radially hook of hamate and pisiform ulnarly transverse carpal ligament palmarly (roof) proximal carpal row dorsally (floor) Carpal tunnel contents four flexor digitorum superficialis (FDS) tendons four flexor digitorum profundus (FDP) tendons flexor pollicis longus (FPL) most radial structure median nerve Median nerve terminal branch of medial and lateral cords of brachial plexus; receives input from nerve roots of C5-T1 course travels with brachial artery between the biceps and brachialis then enters antecubital fossa medial to the biceps tendon travels deep to the lacertus fibrosis and gives a branch to the pronator teres branches anterior interosseous nerve (AIN) AIN arises from the median nerve approximately 4 cm distal to the medial epicondyle (and 5-8 cm distal to lateral epicondyle) travels between FDS and FDP initially, then between FPL and FDP, then it lies on the anterior surface of the interosseous membrane traveling with the anterior interosseous artery to pronator quadratus terminal branches innervate the joint capsule and the intercarpal, radiocarpal and distal radioulnar joints. palmar cutaneous branch of median nerve lies between PL and FCR at level of the wrist flexion crease arises approximately 5 cm proximal to wrist crease supplies sensation over the thenar eminence spared in the setting of CTS recurrent motor branch of median nerve Innervates abductor pollicis brevis, opponens pollicis, and the superficial head of the flexor pollicis brevis 50% are extraligamentous with recurrent innervation 30% are subligamentous with recurrent innervation 20% are transligamentous with recurrent innervation cut transverse ligament far ulnar to avoid cutting if nerve is transligamentous three common digital nerves supplying sensation to thumb, index, long, and radial half of ring finger branching proper digital nerves Carpal tunnel is narrowest at the level of the hook of the hamate Presentation History hand overuse, particularly with vibrating equipment or frequent computer use Symptoms numbness and tingling in radial 3-1/2 digits clumsiness pain and paresthesias that awaken patient at night Physical exam inspection thenar atrophy self administered hand diagram the most specific test (76%) for carpal tunnel syndrome palpation occasionally tender to palpation over the carpal tunnel (rare) provocative tests carpal tunnel compression test (Durkan's test) is the most sensitive test to diagnose carpal tunnel syndrome performed by pressing thumbs over the carpal tunnel and holding pressure for 30 seconds. onset of pain or paresthesia in the median nerve distribution within 30 seconds is a positive result. Phalen test wrist volar flexion against gravity for ~60 sec produces symptoms less sensitive than Durkan compression test Tinel's test provocative tests performed by tapping the median nerve over the volar carpal tunnel Semmes-Weinstein testing most sensitive sensory test for detecting early carpal tunnel syndrome measures a single nerve fiber innervating a receptor or group of receptors Innervation density test static and moving two-point discrimination A failure to discriminate two points held 5mm or less apart from one another is a positive test suggestive of CTS measures multiple overlapping of different sensory units and complex cortical integration the test is a good measure for assessing functional nerve regeneration after nerve repair CTS-6 Evaluation Tool: a validated clinical tool for diagnosis of CTS. A score >12 is indicative of 80% probability of CTS. A score of >5 is indicative of 25% probability. CTS-6 Evaluation Tool Numbness predominantly or exclusively in median nerve territory +3.5 Nocturnal Numbness +4 Thenar atrophy and/or weakness 4/5 weakness or less +5 Positive Phalen test +5 Loss of 2-point discrimination Threshhold of 5mm +4.5 Positive Tinel sign +4 Imaging Radiographs not necessary for diagnosis and not routinely indicated MRI or CT scan indicationsConsider for space-occupying lesion. rarely indicated may consider for space-occupying lesion. Ultrasound increased cross-sectional area (CSA) of the median nerve >10mm² at the level of the pisiform/proximal edge of transverse carpal ligament is associated with CTS Studies Diagnostic criteria numbness and tingling in the median nerve distribution nocturnal numbness weakness and/or atrophy of the thenar musculature positive Tinel sign positive Phalen test loss of two-point discrimination EMG and NCV overview provides objective evidence of a compressive neuropathy valuable in work comp patients with secondary gain issues not needed to establish diagnosis (diagnosis is clinical) AAOS clinical practice guideline currently holds a limited recommendation for its use nerve conduction velocity (NCV) prolonged latencies (slowing) of NCV distal sensory latency of > 3.5 ms motor latencies > 4.5 ms slower conduction velocities velocity of < 52 m/sec is abnormal slower conduction velocity less specific than prolonged latencies represents only the largest diameter, myelinated fibers in the nerve electromyography (EMG) test the electrical activity of individual muscle fibers and motor units details insertional and spontaneous activity potential pathologic findings increased insertional activity sharp waves fibrillations fasciculations complex repetitive discharges Electrodiagnostic study (EDS) results are associated with outcomes (prognosis) after carpal tunnel surgery Patients with severe EMG/NCV findings tend to improve less than patients with middle-range findings. Histology nerve histology characterized by edema, fibrosis, and vascular sclerosis are most common findings scattered lymphocytes amyloid deposits shown with special stains in some cases Differential AIN compressive neuropathy Pronator syndrome Ulnar tunnel syndrome Cervical radiculopathy Diagnosis Clinical and EMG/NCS diagnosis can be made purely based on history and physical examination and can be confirmed with EMG/NCS and ultrasound in equivocal cases, corticosteroid injections may be used to discriminate between other pathologies such as cervical radiculopathy Treatment Nonoperative NSAIDS, night splints, activity modifications indications first line of treatment modalities night splints (good for patients with nocturnal symptoms only) activity modification (avoid aggravating activity) steroid injections indications adjunctive nonoperative treatment diagnostic utility in clinically and electromyographically equivocal cases (ie cervical radiculopathy and pronator syndrome) outcomes 80% have transient improvement of symptoms (of these 20% remain symptom-free at one year) failure to improve after injection is poor prognostic factor surgery is less effective in these patients Operative carpal tunnel release indications failure of nonoperative treatment (including steroid injections) temporary improvement with steroid injections is a good prognostic factor that the patient will have a good result with surgery) acute CTS following trauma or ORIF technique open endoscopic earlier return to work, better key-pinch, and higher earlier patient satisfaction associated with endoscopic carpal tunnel release long term results same as open CTR ultrasound-guided percutaneous similar advantages to endoscopic may be effective with potential for shorter recovery times vs open carpal tunnel release outcomes pinch strength returns in 6 weeks grip strength is expected to return to 100% preoperative levels by 12 weeks postop rate of continued symptoms at 1 year is 2% in moderate and 20% in severe CTS improved patient outcomes with surgery at 6 and 12 months as compared to splinting, NSAIDs/therapy, and a single steroid injection revision CTR for incomplete release indications failure to improve following primary surgery incomplete release - most common reason outcomes 25% will have complete relief after revision CTR 25% will have no relief Technique Open carpal tunnel release antibiotics prophylactic antibiotics, systemic or local, are not indicated for patients undergoing a clean, elective carpal tunnel release approach Kaplan's cardinal line: first web space to hook of hamate that approximates the region of the superficial palmar arch ulnar border of the long finger use a natural crease if possible, cheat ulnar to avoid the recurrent branch of the median nerve technique internal neurolysis, tenosynovectomy, and antebrachial fascia release do not improve outcomes Guyon's canal does not need to be released as it is decompressed by carpal tunnel release lengthened repair of transverse carpal ligament is only required if flexor tendon repair is performed (allows wrist immobilization in flexion postoperatively) postoperative care and rehab can use night splinting with the wrist in neutral position for 2 to 3 weeks for patient comfort begin range of motion/nerve glide exercises immediately begin strengthening exercises after 4 weeks supervised hand therapy may be utilized to aid in recovery may use ultrasound and paraffin wax to reduce swelling and alleviate pain nerve-gliding exercises, massage, and trigger point release Endoscopic carpal tunnel release different systems available, some offering one versus two incisions technique a 1-2cm transverse incision is made just proximal to the wrist flexion crease dissection is carried down sharply just deep to antebrachial fascia a synovium elevator is used to develop a plane just deep to transverse carpal ligament a path is created in the carpal tunnel with dilators the camera/blade instrument is inserted and the transverse carpal ligament is cut under direct endoscopic visualization pros accelerated rehabilitation and return to work cons disadvantage is learning curve and cost most common complication is an incomplete division of transverse carpal ligament Ultrasound-guided percutaneous carpal tunnel release technique ultrasound identifies median nerve at the wrist and determines entry point in the palm and exit point in the wrist for the Tuohy needle entry and exit points are anesthetized with local anesthesia, with Tuohy needle being passed under carpal tunnel and above median nerve by hydro dissection needle tip pushed through exit point in the wrist and a cutting thread is passed the Tuohy needle is then passed subcutaneously above the transverse carpal ligament and the cutting thread is passed back through the needle, creating a loop that out of the entry point the cutting thread is then pulled back and forth, releasing the ligament Complications Scar tenderness (most common) incidence 19 to 61% treatment scar massage occupational therapy pillar pain deep-seated ache over the thenar or hypothenar region secondary to injury of small sensory branches of the median/ulnar nerves incidence 41% at 1 month, 25% at 3 months, 6% at 12 months treatment scar massage occupational therapy recurrence incidence 1% at 5 years 1.6% at 10 years risk factors endoscopic was associated with an increased hazard of revision CTR compared with open 14% are due to incomplete release of transverse carpal ligament treatment revision open carpal tunnel release injury to the recurrent branch of median nerve Incidence 0.7% (endoscopic) 3% (open) risk factors transligamentous motor branch of the median nerve treatment repair outcomes acute vs chronic repairs appear to be promising with nearly 100% return to function of thenar musculature iatrogenic injury to palmar cutaneous branch of the median nerve incidence 2.4% (endoscopic) 19% (open) treatment neuroma resection and nerve ablation injury to proper palmar digital nerve to the index finger incidence 0.25% (open) 1.45% (endoscopic) treatment observation occupational therapy arterial arch injury incidence 0.02% (endoscopic) 0% (open) treatment repair Prognosis Good prognostic indicators include night symptoms small incisions relief of symptoms with steroid injections not improved when incomplete release of transverse carpal ligament is discovered