II. Epidemiology

  1. Most common Entrapment Neuropathy of the arm
    1. Incidence: 3% of U.S. general population
  2. Women outnumber men affected by 3 fold
  3. Bilateral in 50% of cases
  4. Associated with workplace repetitive hand activities
  5. Hand Paresthesias occur in 30% of computer users
    1. Only 10% of these meet criteria for Carpal Tunnel
    2. Only 3.5% of these have abnormal EMGs
    3. Stevens (2001) Neurology 56:1568-70 [PubMed]

III. Pathophysiology

  1. Compression of Median Nerve
    1. Occurs between transverse carpal ligament and underlying Carpal Bones
    2. Median Nerve adjacent to 9 inflamed and enlarged synovial lining of flexor tendons
  2. Sensory deficits predominate
    1. Motor Nerves are much less susceptible than Sensory Nerves to compression

IV. Risk Factors

  1. Repetitive motion of hand and wrist
    1. Most common cause, and typically work related
    2. More common if significant force applied or hand-operated vibratory tool
  2. Local wrist or Hand Trauma
  3. Obesity
  4. Many associated conditions (see below)

V. Associated Conditions

  1. Hypothyroidism
  2. Diabetes Mellitus
  3. Acromegaly
  4. Rheumatoid Arthritis
  5. Gouty Arthritis
  6. Lyme Disease
  7. Amyloidosis
  8. Multiple Myeloma
  9. Edematous condition
    1. Third trimester of Pregnancy
      1. Symptoms subside after delivery
    2. Congestive Heart Failure
    3. Renal Failure
  10. Aberrant or Anomalous Muscles in wrist
    1. Proximal lumbrical insertion
    2. Distal extension of flexor superficialis Muscle
    3. Persistent thrombosed median artery
    4. Abnormal palmaris longus tendon
    5. Ganglion Cyst
    6. Lipoma
  11. Double-Crush Syndrome

VI. Symptoms

  1. Image: Median Nerve Sensory Innervation
    1. NeuroMedianNerve.jpg
  2. Paresthesias along Median Nerve course (palmar surface)
    1. Electrical Sensation or Dysesthesias
    2. Commonly involves only palmar Index and Middle fingers
      1. May affect palmar aspect of all Median Nerve innervated 3.5 fingers (thumb to fourth finger)
  3. Pain in distal, palmar surface of wrist or arm
    1. Distal radiation into thumb, index and middle finger
  4. Radiation
    1. Proximal radiation into Forearm (may rarely radiate proximally into Shoulder and neck)
    2. May even present as Chest Pain (has resulted in ED Chest Pain cardiac work-ups)
  5. Gradually increasing night pain (95% of patients)
    1. Increase in wrist swelling with inactivity
    2. Wrist flexion at night (may awaken patient)
  6. Numbness
    1. Describes "poor circulation" and "Stiffness"
    2. Despite which hand feels warm
  7. Weakness and Clumsiness of hand
    1. Decreased grip strength
  8. Timing
    1. Spontaneous onset
  9. Provocative of Sensory and Motor Symptoms
    1. Repetitive wrist flexion or hand elevation
    2. Precipitated by Typing, holding phone, driving, painting, and wrist motion
  10. Palliative
    1. Shaking or moving hand
    2. Allow hand to hang down
    3. Flick Sign
      1. Flicking wrist as if shaking down Thermometer (often after night-time awakening)
      2. Test Sensitivity 93%, Test Specificity 96%

VII. Signs

  1. Precautions
    1. In addition to wrist and Hand Exam, also examine elbow, Shoulder and neck for referred pain source
  2. Observation
    1. Square-shaped wrist (depth dimensions approaches wrist width, esp in Obesity, OR 4.56)
      1. Shiri (2015) Muscle Nerve 52(5): 709-13 [PubMed]
  3. Modifying factors
    1. Pain not worse with resisted motion
    2. Flick Test (see above)
    3. Carpal Compression Test (64-90% sensitive, 83-90% specific)
      1. Direct pressure applied over the transverse carpal ligament for 30 seconds
      2. Positive for sensory symptoms within first 30 seconds
    4. Classic exam findings have individual poor predictive value (but combined 80% sensitivity, 92% Specificity)
      1. Tinel's sign (44-70% sensitive, 94% specific)
      2. Phalen's Maneuver (70-80% sensitive, 80% specific)
    5. Hand elevation test
      1. Hands raised overhead for one minute
      2. Positive test if symptoms are reproduced in the first minute
      3. Ahn (2001) Ann Plast Surg 46(2): 120-4 [PubMed]
    6. Tourniquet Test (not recommended as not sensitive and not specific)
      1. Inflate Blood Pressure Cuff on upper arm above systolic Blood Pressure
      2. Positive if Paresthesias and Numbness after inflation in first 60 seconds
  4. Sensory deficit over Median Nerve
    1. Sensory deficit predominates as Sensory Nerves are more susceptible to compression than Motor Nerves
    2. Hypalgesia in classic Median Nerve distribution has high Likelihood Ratio
      1. Patient draws areas of pain or numbness on hand diagram
    3. Two Point Discrimination <6 mm with caliper (33% Sensitive, 100% Specific)
    4. Resolution of pain with persistent numbness suggests permanent sensory loss
  5. Motor deficits (late finding in severe Median Neuropathy)
    1. Weak thumb abduction and weakness
      1. Weak on grasping items, opening jars, buttoning clothing
    2. Thenar Muscle atrophy
      1. Associated with decreased grip strength
      2. Only present in severe, long-standing disease
      3. Other hand and wrist neuropathies will cause this as well
    3. Abductor pollicis brevis weakness
      1. Abduct thumb perpendicular to palm against examiner's resistance
  6. Findings suggestive of alternative diagnosis
    1. Wrist and hand with reduced range of motion (ROM should be unaffected in Carpal Tunnel)
    2. Thenar eminence with reduced Sensation
      1. Innervated by Median Nerve's palmar cutaneous branch (origin is proximal to Median Nerve)
      2. Suggests a Median Nerve injury in the neck or proximal arm

VIII. Diagnosis

  1. Findings with highest predictive value
    1. Classic hand symptoms in median distribution
    2. Decreased Pain Sensation at index palmar surface
    3. Weak thumb abduction
  2. References
    1. D'Arcy (2000) JAMA 283:3110-7 [PubMed]

IX. Differential Diagnosis

  1. Tenosynovitis
    1. Flexor carpi radialis Tenosynovitis
      1. Extends from proximal 1st Metacarpal to medial epicondyle
    2. De Quervain's Tenosynovitis
      1. Affects extensor pollicis brevis, abductor pollicis longus
  2. Other Neuropathy
    1. Cervical Radiculopathy (C6 nerve)
    2. Median Nerve compression at elbow (Pronator Syndrome)
    3. Ulnar Tunnel (or Cubital Tunnel)
    4. Peripheral Neuropathy (e.g. Diabetes Mellitus)
  3. Degenerative Joint Disease
    1. Wrist Osteoarthritis
    2. Thumb carpometacarpal Osteoarthritis
  4. Vascular conditions
    1. Raynaud Syndrome
    2. Vibration white finger (occurs with vibratory hand tools)

X. Radiology: Wrist XRay

  1. Evaluate for local bony abnormality

XI. Diagnostics

  1. Nerve Conduction Studies (Electromyography, EMG)
    1. Indicated in unclear cases or in pre-surgical assessment of severity
    2. Delayed electrical conduction across wrist at the Median Nerve
    3. Efficacy: 56-85% sensitive, 94-99% specific
    4. Normal in up to one third of patients with mild Carpal Tunnel
  2. Ultrasound
    1. See Median Nerve Measurement on Ultrasound
    2. Highest efficacy when wrist Median Nerve cross sectional area is compared with Forearm measurement
    3. Noninvasive, painless test with high efficacy (for experienced operators) and evaluates other wrist structures
  3. Other diagnostic studies (CT, MRI, XRay)
    1. Not typically indicated
    2. Consider Wrist XRay if bone or joint disorders are suspected

XII. Management: General Measures (Conservative)

  1. Efficacy
    1. Spontaneous resolution with Placebo: 50%
      1. Goodyear-Smith (2004) Ann Fam Med 2:267-73 [PubMed]
    2. Short-term: 80% respond
    3. Long-term: 80% of responders recur after one year
  2. Eliminate cause and modify work conditions
    1. Avoid repetitive Trauma
    2. Avoid the extremes of wrist flexion or extension
    3. Avoid vibratory tool use
    4. Employ ergonomics (wrist rest, adjust chair/desk, voice recognition software)
  3. Wrist Splint or Wrist brace (neutral position)
    1. Polypropylene occupational Wrist Splint
    2. Maintains wrist in neutral position
      1. Avoid cock-up (hyperextension) brace
    3. Most effective if started early (within 3 months)
    4. Wear during both day and night (best results)
      1. Burke (1994) Arch Phys Med Rehabil 75:1241-4 [PubMed]
      2. Sevim (2004) Neurol Sci 25:48-52 [PubMed]
  4. Wrist and Hand Exercises
    1. Brief (1 minute) Exercise performed intermittently (e.g. during or after work)
      1. May be taught by physical therapy, hand therapy or by online video
    2. Nerve glide Exercises (repeat each 10-15 repetitions)
      1. May theoretically untether a compressed Median Nerve
      2. Hyperextend hand against wall
      3. Wrist rotation against wall
      4. Repeat wrist rotation with neck lateral bending to either side
      5. Alternate finger extension with clenched fist
      6. https://www.youtube.com/watch?v=B5goXA9MqCA
  5. Local or Systemic Corticosteroid
    1. Carpal Tunnel Steroid Injection (preferred)
      1. Risk of Median Nerve injury, tendon rupture
      2. May repeat injection after 6 months
      3. As effective as surgery with benefits lasting more than 10 weeks (often >1 year)
        1. Ly-Pen (2005) Arthritis Rheum 52:612-9 [PubMed]
    2. Consider Systemic Corticosteroids
      1. Less effective and more adverse effects than with local injection
      2. First: Prednisone 20 mg PO qd for 14 days
      3. Next: Prednisone 10 mg PO qd for 14 days
      4. Chang (1998) Neurology 51:390-3 [PubMed]
  6. Local Ultrasound
    1. Six weeks of therapy provides up to 6 months relief
    2. Reference
      1. Ebenbickler (1998) BMJ 316:731-5 [PubMed]
  7. NSAIDs (e.g. Ibuprofen)
    1. Variable efficacy (unlikely to offer benefit beyond transient pain relief)
  8. Pyridoxine may be indicated in pregnancy
    1. Dose: Pyridoxine 25-50 mg PO tid
    2. Unproven benefit
    3. Reference
      1. (1993) Can Fam Physician, 39:2122-7 [PubMed]

XIII. Management: Surgical release transverse carpal ligament

  1. Indications
    1. Early surgery for moderate to severe Median Nerve injury
    2. Persistent symptoms refractory to conservative therapy after 3-4 months
    3. Progressive or persistent motor weakness (grip strength) or thenar Muscle atrophy
  2. Efficacy
    1. Results in prompt, permanent pain relief
    2. Very effective in 66% of patients (some studies report 70-90% of cases)
    3. May be effective even if EMG normal
    4. Earlier return to work by 8 days with endoscopic repair (but equivalent longterm outcomes to open repair)
    5. References
      1. Katz (2001) Arthritis Rheum 44:1184-93 [PubMed]
      2. Gerritsen (2001) Br J Surg 88:1285-95 [PubMed]
  3. Course
    1. Sensory, Motor function improvement may take months
    2. Post-operative Splinting is not recommended
      1. Results in increased stiffness and does not improve outcomes
  4. Adverse affects
    1. No Disability from sectioning transverse ligament
    2. Residual discomfort may continue from Tenosynovitis
  5. Complications
    1. Median Nerve branch injury
    2. Hypertrophic, painful scar
    3. Superficial Palmar ArchLaceration
    4. Pillar pain adjacent to ligament release

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