Summary Carpal Tunnel Syndrome is a compressive neuropathy of the median nerve at the level of the wrist. Diagnosis is made by clinical signs and symptoms (night pain, hand weakness/clumsiness, numbness in median nerve distribution) and positive provocative tests (i.e Tinel's, Durkan's). Treatment is generally conservative with night splints and injections with carpal tunnel release reserved for refractory cases. Epidemiology Incidence affects 0.1-10% of general population Risk factors female sex obesity pregnancy hypothyroidism rheumatoid arthritis advanced age chronic renal failure smoking alcoholism repetitive motion activities mucopolysaccharidosis mucolipidosis Etiology Pathophysiology mechanism exposure to repetitive motions and vibrations certain athletic activities cycling tennis throwing 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 Branches of median nerve palmar cutaneous branch of median nerve lies between PL and FCR at level of the wrist flexion crease recurrent motor branch of median nerve 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 Carpal tunnel is narrowest at the level of the hook of the hamate Presentation Symptoms numbness and tingling in radial 3-1/2 digits clumsiness pain and paresthesias that awaken patient at night Physical exam thenar atrophy self administered hand diagram the most specific test (76%) for carpal tunnel syndrome carpal tunnel compression test (Durkan's test) is the most sensitive test to diagnose carpal tunnels 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 Durkin 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 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 Imaging Radiographs not necessary for diagnosis 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) 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. 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 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 ORIF of a distal radius fx outcomes pinch strength returns in 6 week 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 reported-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 50% some relief 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 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 only required if flexor tendon repair performed (allows wrist immobilization in flexion postoperatively) complications correlate most closely with experience of surgeon incomplete release progressive thenar atrophy due to injury to an unrecognized transligamentous motor branch of the median nerve lumbrical muscle weakness secondary to neuropraxia of the proper palmar digital nerve to the index finger Endoscopic carpal tunnel release advantage is accelerated rehabilitation long term results same as open CTR most common complication is an incomplete division of transverse carpal ligament Prognosis Good prognostic indicators include night symptoms short incisions relief of symptoms with steroid injections not improved when incomplete release of transverse carpal ligament is discovered