Updated: 9/27/2021

Carpal Tunnel Syndrome

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  • 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
Technique Guides (4)
Flashcards (57)
1 of 57
Questions (23)
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(SBQ17SE.83) A 55-year-old female patient presents for post-operative followup 2 weeks after undergoing open carpal tunnel release. She admits to improved overall pain but increased weakness. Examination reveals weakness of PIP joint extension and MCP joint flexion of the index finger but no other abnormal findings. Which of the following nerves labeled in Figure A has likely been injured?

QID: 212018
















L 4 A

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(SBQ17SE.37) A 55-year-old male, construction worker, presents to your clinic with chronic left-hand pain. The pain is associated with paresthesias of the thumb and index finger. He has been wearing a removable wrist brace which has partially helped his symptoms. He has a positive Tinel's over his left wrist but otherwise unremarkable. He is mostly interested in non-operative management and asks you about a corticosteroid injection (CSI). With regards to this treatment, what advice can you give this patient?

QID: 211512

80% of patients with mild symptoms will have improvement with a CSI, 20% of those patients will have lasting effects up to 1 year



Methylprednisolone reduces symptoms at a greater rate than triamcinolone



The dosage of the steroid directly correlates to the duration of its effect



A poor response to the CSI is a good prognosticator for symptom relief from surgery



60% of patients will have improvement of symptoms with a CSI, 40% of those patients will have lasting effects up to 1 year



L 2 A

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(OBQ13.15) A 45-year-old man presents with a three-month history of unilateral symptoms in his right wrist and hand. He first noticed a palpable nodule over the volar aspect of his wrist about three months ago. The nodule would become painful after weekends of heavy drinking at which time he noticed tingling sensation in his index and middle fingers. He notes that ibuprofen has helped improve the pain in the past. On clinical examination, he has a palpable, nontender, solid nodule over the volar aspect of his wrist. He has no motor or sensory deficits and negative carpal tunnel provocative tests. An axial CT and MRI image are provided in figures A and B. What would be the most appropriate next step in the management of his symptoms?

QID: 4650

Fine needle aspiration






Night splints



Establish a tissue diagnosis and referral to a rheumatologist



Surgical excision



L 4 C

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(OBQ13.58) A healthy 50-year-old secretary is about to undergo an open carpal tunnel release. Which of the following peri-operative steps will have the greatest influence on minimizing the risk of a surgical site infection in this patient?

QID: 4693

Administration of cefazolin within 1 hour before incision



Administration of cefazolin within 1 hour before incision followed by 5 days of cephalexin post-op



Cleanse with bacitracin solution immediately before skin incision



Standard sterilization and prepping



Administration of one dose of cephalexin within 1 hour before incision



L 3 C

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(OBQ11.265) A 44-year-old male factory worker presents with a 7-month history of pain and paresthesias involving the palmar aspect of the left thumb, index finger, long finger, and the radial half of the ring finger. He reports that this often occurs at night when trying to go to sleep. He has a history of anemia and obstructive sleep apnea. Percussion over the volar wrist crease produces electric sensation distally in the hand and wrist flexion with the elbow in extension produces thumb paresthesias within 18 seconds. Figure A demonstrates a radiograph of the left hand. A sensory nerve conduction velocity test shows a distal sensory latency of 5.7 ms. Which of the following is the most appropriate next step in management?

QID: 3688

Phonophoresis and 6-week course of Vitamin B6 (pyridoxine)



Occupational therapy with wrist massage and activity modification



Wrist splinting



1-month course of nonsteroidal anti-inflammatory drugs [NSAIDs] and physical therapy



1-month course of bumetanide, smoking cessation, and physical therapy



L 3 C

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(OBQ08.34) All of the following are contents of the carpal tunnel EXCEPT:

QID: 420

Flexor pollicis longus (FPL)



Flexor digitorum sublimis (FDS)



Flexor digitorum profundus (FDP)



Flexor carpi radialis (FCR)



Median nerve



L 1 C

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(OBQ07.55) All of the following can be found on the electromyography (EMG) portion of an electrodiagnostic study during the evaluation of a patient with carpal tunnel syndrome EXCEPT:

QID: 716

Fibrillations at rest



Positive sharp waves



Decreased motor recruitment



Increased insertional activity



Increased distal sensory latency



L 5 D

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(OBQ06.242) A 50-year-old woman is diagnosed with carpal tunnel syndrome. She is prescribed a cock-up wrist splint at 30 degrees of extension to wear at night. This splint has what effect on the carpal tunnel?

QID: 253

Decreases carpal tunnel pressure



Increases carpal tunnel pressure



No effect on carpal tunnel pressure



Enlarges the carpal tunnel volume



Improves nerve conduction studies



L 4 C

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(OBQ05.55) All of the following are predictive findings for correctly diagnosing carpal tunnel syndrome EXCEPT:

QID: 941

Abnormal hand diagram



Abnormal Semmes-Weinstein testing in wrist-neutral position



Positive median nerve compression test (Durkan's sign)



Presence of night pain



Loss of small digit adduction (Wartenberg sign)



L 1 D

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(OBQ04.210) Approximately what percentage of pre-operative grip strength would be expected 3 months after carpal tunnel release?

QID: 1315
















L 2 D

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Evidence (57)
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