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Introduction
  • Most common compressive neuropathy  
    • pathologic (inflamed) synovium most common cause of idiopathic CTS
  • Epidemiology
    • 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
  • Pathophysiology
    • mechanism
      • precipitated by
        • exposure to repetitive motions and vibrations
        • certain athletic activities
          • cycling
          • tennis
          • throwing
    • pathoantomy
      • compression may be due to
        • repetitive motions in a patient with normal anatomy
        • space occupying lesions (e.g., gout)  
  • Associated conditions
    • diabetes mellitus
    • hypothyroidism
    • rheumatoid arthritis
    • pregnancy
    • amyloidosis
  • 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
Anatomy
  • Carpal tunnel defined by  
    • scaphoid tubercle and trapezium radially
    • hook of hamate and pisiform ulnarly
    • transverse carpal ligament palmarly (roof)
    • proximal carpal row dorsally (floor)
  • Carpal tunnel consists of 
    • nine flexor tendons
    • one nerve (median nerve)
    • FPL is the most radial structure
  • 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
    • self administered hand diagram
      • the most specific test (76%) for carpal tunnel syndrome
  • Physical exam 
    • inspection may show thenar atrophy  
    • 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 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
      • often the only objective evidence of a compressive neuropathy (valuable in work comp patients with secondary gain issues)
      • not needed to establish diagnosis (diagnosis is clinical) but recommended if surgical management is being considered
    • demyelination leads to
      • NCV
        • increase latencies (slowing) of NCV   
          • distal sensory latency of > 3.2 ms 
          • motor latencies > 4.3 ms 
        • decreased conduction velocities less specific than latencies
          • velocity of < 52 m/sec is abnormal
      • EMG
        • test the electrical activity of individual muscle fibers and motor units
        • detail insertional and spontaneous activity
        • potential pathologic findings
          • increased insertional activity
          • sharp waves
          • fibrillations
          • fasciculations
          • complex repetitive discharges  
  • 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
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 conservative treatment
      • outcomes
        • 80% have transient improvement of symptoms (of these 22% remain symptoms 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 return in 6 week
        • grip strength is expected to return to 100% preoperative levels by 12 weeks postop 
    • revision CTR for incomplete release
      • indications
        • failure to improve following primary surgery
          • incomplete release most common reason
      • outcomes
        • only 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 
  • Endoscopic carpal tunnel release
    • advantage is accelerated rehabilitation
    • long term results same as open CTR
    • most common complication is incomplete division of transverse carpal ligament
 

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Questions (8)

(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, painless, 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? Review Topic

QID:4650
FIGURES:
1

Fine needle aspiration

7%

(199/2898)

2

Open biopsy

9%

(253/2898)

3

Night splints

4%

(122/2898)

4

Referral to rheumatologist

54%

(1551/2898)

5

Surgical excision

26%

(761/2898)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

The clinical presentation is consistent with carpal tunnel syndrome caused by an atypical space occupying lesion - in his case, gout. The most appropriate next step in the management of his symptoms would be referral to a rheumatologist where medical therapy, such as prophylaxis with colchicine, could be initiated.

Carpal tunnel syndrome is the most common compressive neuropathy, affecting up to 10% of the general population. Risk factors include female sex, advanced age, obesity, and repetitive motion activities. Typically, patients will develop symptoms of median nerve compression including thenar muscle atrophy, numbness in the radial 3.5 digits, night pain, and positive Tinel's and Phalen tests. First line management is non-operative, including NSAIDs, night splints, and activitiy modification. Carpal tunnel release surgery is indicated for those who have failed conservative management.

Chen et al. described 23 unusual cases of CTS in which space-occupying lesions were responsible for the symptoms and signs of median nerve compression. In patients with an atypical presentation, such as male gender, non-middle-aged, or unilateral involvement, space-occupying lesions such as gout, synovial sarcoma, lipoma, and ganglions should be investigated as a cause.

Fitzgerald et al. discussed gout affecting the hand and wrist. The medical treatment of gout includes NSAIDs such as indomethacin or ibuprofen for acute flares, and colchicine and allopurinol for chronic prophylaxis.

Figures A and B represent axial CT and MRI images showing calcification and gouty tophi deposition in the carpal tunnel floor.

Incorrect Answers:
Answer 1: Aspiration is not a first line treatment for tophaceous gout.
Answer 2: The clinical picture is not suspicious for a malignancy, therefore a biopsy would not be indicated.
Answer 3: Night splints would not help diminish the space occupying lesion, in this case, tophaceous gout.
Answer 5: Chronic tophaceous gout that has failed medical therapy may require surgical excision.


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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? Review Topic

QID:4693
1

Administration of cefazolin within 1 hour before incision

19%

(493/2599)

2

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

1%

(24/2599)

3

Cleanse with bacitracin solution immediately before skin incision

1%

(17/2599)

4

Standard sterilization and prepping

76%

(1984/2599)

5

Administration of one dose of cephalexin within 1 hour before incision

3%

(71/2599)

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PREFERRED RESPONSE 4

The patient is undergoing a clean, elective hand surgery. Prophylactic antibiotics, systemic or local, are not indicated for these procedures.

Carpal tunnel syndrome is the most common compressive neuropathy. Individuals who fail medical management (night splints, NSAIDs, activity modification) are candidates for carpal tunnel release surgery (CTS). The surgery may be performed open or endoscopically. The reported incidence of post-operative infections following CTS varies between studies from 0% to 8%.

Whittaker et al. performed a prospective, randomized, double-blinded, placebo controlled trial investigating the use of antibiotic prophylaxis in clean, incised hand injuries. They found no significant difference in infection rates between patients who received IV flucloxacillin, IV followed by oral flucloxacillin, and an oral placebo (13% vs. 4% vs. 15%, p=0.19). They did not support the use of routine antibiotic prophylaxis prior to clean hand surgery.

Bykowski et al. retrospectively reviewed 8,850 outpatient elective hand surgeries and found no significant difference in the rate of surgical site infection, including patients with diabetes or history of smoking. They concluded that antibiotics should not be routinely administered prior to clean, elective hand surgeries.

Harness et al. found no statistical difference in the incidence of surgical site infection following CTS without prophylactic antibiotic compared with patients who received prophylactic antibiotics (0.7% vs. 0.4%, p=0.354). They did not recommend routine antibiotic prophylaxis.

Illustration A reviews the anatomic components of the carpal tunnel.

Incorrect Answers:
Answers 1, 2, 3, 5: Antibiotics do not decrease the risk of post-operative infection in clean, elective hand surgery. Surgeons should consider the potential risks of antibiotics prior to administration, including Clostridium difficile colitis, antibiotic allergies, bacterial resistance, and so on.

ILLUSTRATIONS:

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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? Review Topic

QID:3688
FIGURES:
1

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

1%

(9/1329)

2

Open carpal tunnel release

29%

(389/1329)

3

Wrist splinting

64%

(856/1329)

4

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

5%

(63/1329)

5

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

1%

(7/1329)

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PREFERRED RESPONSE 3

The patients history, examination, and nerve conduction velocity tests (normal distal sensory latency is <3.5 ms) are consistent with carpal tunnel syndrome. There is Level 1 and 2 evidence supporting local steroid injection or splinting for the nonoperative treatment of carpal tunnel syndrome. Phonophoresis, Vitamin B6 (pyridoxine), heat therapy, bumetanide, and physical therapy are not considered the most appropriate options for carpal tunnel syndrome management.

The AAOS clinical guidelines for carpal tunnel syndrome consist of 9 clinical recommendations supported with a grading of the recommendation and levels of evidence for the literature contributing to the recommendation.

The use of neutral wrist splints for carpal tunnel syndrome is most useful for improving night-time symptoms. However wrist splinting is most functional at 30 degrees of extension, and the neutral splints can be functionally limiting when used during productive daytime hours.


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

QID:420
1

Flexor pollicis longus (FPL)

3%

(65/1934)

2

Flexor digitorum sublimis (FDS)

1%

(16/1934)

3

Flexor digitorum profundus (FDP)

0%

(4/1934)

4

Flexor carpi radialis (FCR)

95%

(1840/1934)

5

Median nerve

0%

(1/1934)

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PREFERRED RESPONSE 4

The only neurovascular structure that runs in the carpal tunnel is the median nerve. Flexor carpi radialis is (FCR) is not a tendon within the carpal tunnel. In summary, the carpal tunnel contains the median nerve, FPL and 4 tendons each of the FDP and FDS. Of note, with respect to the FDS tendons, the 3rd and 4th FDS tendons are volar to the 2nd and 5th FDS tendons.


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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: Review Topic

QID:716
1

Fibrillations at rest

12%

(196/1575)

2

Positive sharp waves

7%

(112/1575)

3

Decreased motor recruitment

6%

(99/1575)

4

Increased insertional activity

41%

(647/1575)

5

Increased distal sensory latency

33%

(517/1575)

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PREFERRED RESPONSE 5

EMG's detect the electrical potential generated by muscle cells when these cells are electrically activated. They give information about the muscle motor unit and can display the presence of fibrillations, sharp waves, motor recruitment, and insertional activity of the muscle. The nerve conduction (NCV) portion of the electrodiagnostic study measures the speed at which the nerve impulse travels down the axon. Large, myelinated nerve fibers conduct impulses the fastest and thus only these fibers are evaluated in the nerve conduction portion of the electrodiagnostic study. Distal latencies and conduction velocities are measured with NCV's. General parameters for NCV diagnosis of carpal tunnel syndrome include a distal motor latency of >4.5 msec, a distal sensory latency of >3.5msec, or a conduction velocity of < 52 m/sec.

The articles by Brumback et al and Gooch et al is a review of electrodiagnostic studies for compression neuropathies.


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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? Review Topic

QID:253
1

Decreases carpal tunnel pressure

37%

(615/1642)

2

Increases carpal tunnel pressure

45%

(745/1642)

3

No effect on carpal tunnel pressure

8%

(137/1642)

4

Enlarges the carpal tunnel volume

8%

(134/1642)

5

Improves nerve conduction studies

0%

(7/1642)

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PREFERRED RESPONSE 2

This question is based on the fact that carpal tunnel canal pressure varies with wrist position. Use of neutral wrist splints for carpal tunnel syndrome is most useful for improving noctural symptoms. The reason for this is the functional position of the wrist is approximately 30 degrees of extension, and the neutral splints can be functionally limiting when used during productive daytime hours.

The reference by Gerritsen et al is a randomized controlled study of splinting versus surgery for carpal tunnel. They found a 80% success rate for surgery at final follow-up versus 54% for splinting at 3 months, which increased to 90% at 18 months for surgery and 75% for splinting.

The reference by Omer is a review of carpal tunnel, and it covers the diagnosis, treatment, and follow-up care of these patients. They note the need for careful diagnosis to avoid unnecessary or inappropriate surgery.

Weiss et al showed that carpal tunnel pressures are elevated when the wrist is in extension, and are lowest at near neutral. If one couples this with the inherent tunnel pressure increase from the disease itself, its easy to see that extension splinting is a double hit and can lead to increased symptoms.


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

QID:941
1

Abnormal hand diagram

4%

(57/1315)

2

Abnormal Semmes-Weinstein testing in wrist-neutral position

3%

(36/1315)

3

Positive median nerve compression test (Durkan's sign)

0%

(1/1315)

4

Presence of night pain

1%

(7/1315)

5

Loss of small digit adduction (Wartenberg sign)

92%

(1207/1315)

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PREFERRED RESPONSE 5

All of the listed physical exam findings, except for loss of small digit adduction (Wartenberg sign), has been found to be predictive for diagnosing carpal tunnel syndrome.

Szabo et al in a Level 3 study used a regression model to analyze the most predictive factors for correctly diagnosing carpal tunnel syndrome (CTS). Their analysis found that with an abnormal hand diagram, abnormal sensibility by Semmes-Weinstein testing in wrist-neutral position, a positive Durkan's test, and night pain, the probability that carpal tunnel syndrome will be correctly diagnosed is 0.86. They found the tests with the highest sensitivity were Durkan's compression test (89%), Semmes-Weinstein testing after Phalen's maneuver (83%), and hand diagram scores (76%). Night pain was a sensitive symptom predictor (96%). The most specific tests were the hand diagram (76%) and Tinel's sign (71%). The authors concluded that the addition of electrodiagnostic tests did not increase the diagnostic power of the combination of these 4 clinical tests, and proceeding with surgical release is appropriate even if the EMG is normal.

Wartenberg sign is persistent abduction and extension of the small digit when a patient is asked to adduct the digits and is seen in cubital tunnel syndrome, but not carpal tunnel syndrome.

Illustration V demonstrate the Durkan's Compression test for carpal tunnel syndrome.

ILLUSTRATIONS:

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

QID:1315
1

10%

0%

(1/2091)

2

25%

0%

(8/2091)

3

50%

14%

(293/2091)

4

100%

79%

(1646/2091)

5

150%

6%

(134/2091)

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PREFERRED RESPONSE 4

Gellman et al quantified grip and pinch strength post-operatively after carpal tunnel release. They found grip strength was 28% of preoperative level at 3 weeks; 73% by 6 weeks, returned to the preoperative level by 3 months, and 116% at 6 months. Pinch strength was 74% of preoperative level at 3 weeks, 96% at 6 weeks, 108% at 3 months, and 126% at 6 months.


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