Carpal Tunnel Syndrome

See Also

Carpal Tunnel Syndrome Six Item Evaluation Tool
Median Nerve Injury at the Elbow
Double Crush Injury
Overuse Syndromes of the Hand and Wrist
Peripheral Nerve Injury

Epidemiology

Most common Entrapment Neuropathy of the arm
1. Prevalence: 3% of U.S. general population
2. Incidence: 3.8 per 1000 person-years (increasing with age)
Women outnumber men affected by 3 fold
Bilateral in 50% of cases
Associated with workplace repetitive hand activities
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]

Pathophysiology

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

Risk Factors
General

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
Local wrist or Hand Trauma
Many predisposing conditions (see below)

Risk Factors
Predisposing Medical Conditions

Obesity
Hypothyroidism
Diabetes Mellitus
Acromegaly
Rheumatoid Arthritis
Gouty Arthritis
Lyme Disease
Amyloidosis
Multiple Myeloma
Double-Crush Syndrome
Edematous condition
1. Third trimester of Pregnancy
  1. Symptoms subside after delivery
2. Congestive Heart Failure
3. Renal Failure
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

Symptoms

Image: Median Nerve Sensory Innervation
Pain and Paresthesias along Median Nerve course (palmar/volar surface)
1. Electrical Sensation or Dysesthesias
2. Radiation from the volar wrist into the thumb, index and middle finger
3. Commonly involves only palmar/volar aspect of Index and Middle fingers
  1. May affect palmar aspect of all Median Nerve innervated 3.5 fingers (thumb to fourth finger)
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)
3. Radiation from the neck may occur with double crush injury (especially with bilateral involvement)
Gradually increasing night pain (95% of patients)
1. Increase in wrist swelling with inactivity
2. Wrist flexion at night (may awaken patient)
Numbness
1. Describes "poor circulation" and "Stiffness"
2. Despite which hand feels warm
Weakness and Clumsiness of hand (severe cases)
1. Decreased grip strength, with weak thumb abduction and opposition
Timing
1. Spontaneous onset
2. Often interferes with sleep
Provocative of Sensory and Motor Symptoms
1. Repetitive wrist flexion or hand elevation
2. Precipitated by Typing, holding phone, driving, painting, and wrist motion
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%

Signs

Precautions
1. In addition to wrist and Hand Exam, also examine elbow, Shoulder and neck for referred pain source
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]
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, LR+ 1.3)
  2. Phalen's Maneuver (70-80% sensitive, 80% specific, LR+ 1.4)
5. Hand elevation test
  1. Hands raised overhead for one minute
  2. Positive test if Median Neuropathy symptoms are reproduced in the first minute
  3. Differentiate from Thoracic Outlet Syndrome provoked with overhead arm (Elevated Arm Stress Test or EAST Test)
  4. 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
Sensory deficit over Median Nerve
1. Sensory deficit predominates as Sensory Nerves are more susceptible to compression than Motor Nerves
2. Hyperalgesia in classic Median Nerve distribution has high Likelihood Ratio
  1. Patient draws areas of pain or numbness on hand diagram
3. Loss of Two Point Discrimination <=5 mm with caliper (33% Sensitive, 100% Specific)
4. Resolution of pain with persistent numbness suggests permanent sensory loss
5. DIP joint Sensation of the index and middle finger (anterior interosseous nerve) is often spared in Carpal Tunnel
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
Findings suggestive of alternative diagnosis
1. Findings of Cervical Radiculopathy
2. Wrist and hand with reduced range of motion (ROM should be unaffected in Carpal Tunnel)
3. 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

Diagnosis

See Carpal Tunnel Syndrome Six Item Evaluation Tool (CTS-6 Evaluation Tool)
Findings with highest predictive value
1. Classic hand symptoms in median distribution
2. Decreased Pain Sensation at index palmar surface
3. Weak thumb abduction
4. Thenar atrophy (99% Test Specificity)
References
1. D'Arcy (2000) JAMA 283:3110-7 [PubMed]

Differential Diagnosis

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
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)
Degenerative Joint Disease
1. Wrist Osteoarthritis
2. Thumb carpometacarpal Osteoarthritis
Vascular conditions
1. Raynaud Syndrome
2. Vibration white finger (occurs with vibratory hand tools)

Imaging

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
Wrist XRay (only if indicated)
1. Consider Wrist XRay if bone or joint disorders are suspected
2. Evaluate for local bony abnormality
Other diagnostic studies (CT, MRI)
1. Not typically indicated

Diagnostics

Nerve Conduction Studies (Electromyography, EMG)
1. Indicated in severe Carpal Tunnel, unclear cases or in pre-surgical assessment of severity
2. Delayed electrical conduction across wrist at the Median Nerve
3. Axonal loss or Muscle denervation is an indication for surgery
4. Efficacy: 56-85% sensitive, 94-99% specific
5. Normal in up to one third of patients with mild Carpal Tunnel

Grading
Severity

Mild Carpal Tunnel
1. Intermittent, occassional symptoms of pain and Paresthesias
Moderate Carpal Tunnel
1. Awakens with Carpal Tunnel pain frequently at night
2. Activity provokes symptoms, but does not impair function
3. No neurologic deficits on exam (motor or sensory)
Severe Carpal Tunnel
1. Thenar atrophy
2. Weak thumb abduction or opposition
3. Persistent sensory loss

Management
General Conservative Measures

Precautions
1. Severe Carpal Tunnel symptoms should prompt early EMG
2. Early referral to surgery if EMG positive for axonal loss or Muscle denervation
Efficacy
1. Spontaneous resolution in non-severe CTS with Placebo, within 2 years: 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
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)
Wrist Splint or Wrist brace (neutral position)
1. Polypropylene occupational Wrist Splint
2. Maintains wrist in neutral position
  1. Do NOT use a hyperextension (dorsiflexion) brace which may exacerbate symptoms
  2. Modify the cock-up (hyperextension) brace by straightening the aluminum bar inside the brace
3. Most effective if started early (within 3 months)
4. Use the splint for at least 1 to 2 months (up to 6 months) at nighttime
  1. Wearing splint only during the night appears as effective as continuous use (day and night)
    1. Walker (2000) Arch Phys Med Rehabil 81(4): 424-9 [PubMed]
  2. Original studies had best benefit when worn during both day and night (continuously)
    1. Burke (1994) Arch Phys Med Rehabil 75:1241-4 [PubMed]
    2. Sevim (2004) Neurol Sci 25:48-52 [PubMed]
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, not recommended)
  1. May theoretically untether a compressed Median Nerve
    1. However in practice, does not improve outcomes when added to Splinting
    2. Abdrolrazaghi (2023) Hand 18(2): 222-9 [PubMed]
  2. Technique
    1. Hyperextend hand against wall
    2. Wrist rotation against wall
    3. Repeat wrist rotation with neck lateral bending to either side
    4. Alternate finger extension with clenched fist
  3. Video Resource
    1. https://www.youtube.com/watch?v=B5goXA9MqCA
3. Other Exercise and therapy interventions that may offer benefit
  1. Yoga may decrease pain and increase grip strength
    1. Garfinkel (1998) JAMA 280(18): 1601-3 [PubMed]
  2. Hand therapy Ultrasound and Carpal Bone mobilization (insufficient evidence)
    1. Page (2012) Cochrane Database Syst Rev (6): CD009899 [PubMed]
Local or Systemic Corticosteroid
1. Carpal Tunnel Steroid Injection (preferred)
  1. May repeat injection after 6 months
  2. Rare risk of Median Nerve injury, tendon rupture
  3. Improves symptoms and function for 3 to 6 months
    1. Less need for surgery (NNT 7) at one year
    2. Similar outcomes to night Splinting at 6 months (slightly better than Splinting at 6 weeks)
    3. Ashworth (2023) Cochrane Database Syst Rev (2):CD015148 [PubMed]
    4. Chesterton (2018) Lancet 392(10156): 1423-33 [PubMed]
    5. Ly-Pen (2005) Arthritis Rheum 52:612-9 [PubMed]
2. Consider Systemic Corticosteroids (not recommended)
  1. Less effective and more adverse effects than with local injection
  2. First: Prednisone 20 mg orally daily for 14 days
  3. Next: Prednisone 10 mg orally daily for 14 days
  4. Chang (1998) Neurology 51:390-3 [PubMed]
Local Ultrasound
1. Six weeks of therapy provides up to 6 months relief
2. Reference
  1. Ebenbickler (1998) BMJ 316:731-5 [PubMed]
Analgesics: NSAIDs (e.g. Ibuprofen) or Acetaminophen
1. Variable efficacy (unlikely to offer benefit beyond transient pain relief)
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]

Management
Surgical Release Transverse Carpal Ligament

Indications
1. Early surgery for moderate to severe Median Nerve injury (by EMG)
2. Persistent symptoms refractory to conservative therapy after 3-4 months
3. Progressive or persistent motor weakness (grip strength) or thenar Muscle atrophy
Efficacy
1. General
  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
2. Longterm efficacy (>3 months after surgery)
  1. Mixed results in longterm studies of surgical versus non-surgical results
  2. Splinting and Corticosteroids injections may result in similar longterm outcomes to surgery
  3. Surgery may not lead to longterm significantly decreased symptoms or improved function
  4. Lusa (2024) Cochrane Database Syst Rev 1(1):CD001552 +PMID: 38189479 [PubMed]
3. Open versus endoscopic repair
  1. Earlier return to work by 8 days with endoscopic repair
  2. Fewer complications (infection, scarring) with endoscopic repair
  3. Equivalent longterm outcomes with either endoscopic or open repair
4. References
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
3. Postoperative rehabilitation is not typically recommended
  1. No evidence of benefit in outcomes
Adverse affects
1. No Disability from sectioning transverse ligament
2. Residual discomfort may continue from tenosynovitis
Complications (<2%)
1. Median Nerve branch injury
2. Hypertrophic, painful scar
3. Superficial Palmar Arch Laceration
4. Pillar pain adjacent to ligament release
5. Incomplete transverse ligament division
  1. May result in refractory, persistent symptoms requiring repeat surgery (3% of patients)

References