Updated: 2/7/2019

Carpal Tunnel Syndrome

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Questions
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Evidence
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Cases
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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 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
      • 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) 
    • demyelination leads to
      • NCV
        • prolonged latencies (slowing) of NCV   
          • distal sensory latency of > 3.5 ms 
          • motor latencies > 4.5 ms 
        • slower conduction velocities less specific than latencies
          • velocity of < 52 m/sec is abnormal
        • represents only the largest diameter, myelinated fibers in the nerve
      • 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  
    • Electrodiagnostic study (EDS) results are associated with outcomes (prognosis) after carpal tunnel surgery
      • Patients with severe findings on EDS or minimal to no 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
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 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 
        • rate of continued symptoms at 1+ year is 2% in moderate and 20% in severe CTS 
    • 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 an incomplete division of transverse carpal ligament
 

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Technique Guides (4)
Questions (18)
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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%

(93/2798)

2

Flexor digitorum sublimis (FDS)

1%

(28/2798)

3

Flexor digitorum profundus (FDP)

0%

(9/2798)

4

Flexor carpi radialis (FCR)

95%

(2653/2798)

5

Median nerve

0%

(3/2798)

ML 1

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PREFERRED RESPONSE 4

(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?
Review Topic

QID: 4650
FIGURES:
1

Fine needle aspiration

7%

(299/4406)

2

Chemotherapy

6%

(284/4406)

3

Night splints

5%

(224/4406)

4

Establish a tissue diagnosis and referral to a rheumatologist

54%

(2396/4406)

5

Surgical excision

27%

(1177/4406)

ML 4

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PREFERRED RESPONSE 4

(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%

(15/2476)

2

Occupational therapy with wrist massage and activity modification

17%

(419/2476)

3

Wrist splinting

76%

(1879/2476)

4

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

5%

(126/2476)

5

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

1%

(21/2476)

ML 3

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PREFERRED RESPONSE 3
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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%

(233/1916)

2

Positive sharp waves

7%

(142/1916)

3

Decreased motor recruitment

6%

(124/1916)

4

Increased insertional activity

40%

(772/1916)

5

Increased distal sensory latency

33%

(638/1916)

ML 5

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PREFERRED RESPONSE 5

(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

16%

(697/4407)

2

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

1%

(35/4407)

3

Cleanse with bacitracin solution immediately before skin incision

1%

(49/4407)

4

Standard sterilization and prepping

79%

(3502/4407)

5

Administration of one dose of cephalexin within 1 hour before incision

2%

(105/4407)

ML 3

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PREFERRED RESPONSE 4

(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

36%

(744/2050)

2

Increases carpal tunnel pressure

45%

(925/2050)

3

No effect on carpal tunnel pressure

9%

(175/2050)

4

Enlarges the carpal tunnel volume

9%

(190/2050)

5

Improves nerve conduction studies

0%

(7/2050)

ML 4

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PREFERRED RESPONSE 2

(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%

(69/1746)

2

Abnormal Semmes-Weinstein testing in wrist-neutral position

3%

(45/1746)

3

Positive median nerve compression test (Durkan's sign)

0%

(4/1746)

4

Presence of night pain

1%

(10/1746)

5

Loss of small digit adduction (Wartenberg sign)

92%

(1607/1746)

ML 1

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PREFERRED RESPONSE 5

(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%

(4/3367)

2

25%

0%

(14/3367)

3

50%

13%

(452/3367)

4

100%

79%

(2669/3367)

5

150%

6%

(213/3367)

ML 2

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PREFERRED RESPONSE 4
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