Rosen & Barkin's 5-Minute Emergency Medicine Consult (136 page)

BASICS

• Carpal tunnel syndrome is caused by compression of the median nerve as it passes through the carpal tunnel.
  
• The carpal tunnel is the area bound by the carpal bones and the transverse carpal ligament.
  
• The median nerve, flexor digitorum profundus, flexor digitorum superficialis (FDS), and flexor pollicis longus are located in the carpal tunnel.
  
• Carpal tunnel syndrome can be classified as acute or chronic.
  

• Acute:
  
  • Trauma
    
  • Infection
    
  • Snake bite
    
  • Hemorrhage
    
  • High-pressure injection injury
    
• Chronic:
  
  • Occupational/overuse syndromes—high impact, repetitive motion
    
  • Pregnancy, birth control pills
    
  • Granulomatous disease: Tuberculosis, sarcoidosis
    
  • Mass lesions with median nerve compression
    
  • Osteophytes
    
  • Amyloid
    
  • Multiple myeloma
    
  • Rheumatoid arthritis
    
  • Endocrine disorders: Hypothyroidism, diabetes mellitus, acromegaly
    
  • Chronic hemodialysis
    
  • Idiopathic
    

Idiopathic causes are rare in children; most cases have a correctable cause including:

• Trauma
  
• Mucolipidosis
  
• Hamartoma of the median nerve
  
• Anomalous FDS
  
• Hemophilia with hematoma
  

DIAGNOSIS

• Acute or chronic onset
  
• Numbness/paresthesia in a median nerve distribution:
  
  • Thumb, index, middle, and radial aspect of ring finger
    
• Pain:
  
  • Location: Wrist or hand, sometimes radiating to elbow, forearm, or shoulder
    
  • Often worse at night—relieved by “shaking out” the hand
    
  • Exacerbated by repetitive wrist movement and by activities in which the wrist is flexed (e.g., driving)
    

• Weakness of the abductor pollicis brevis and opponens muscles:
  
  • Innervated by the recurrent branch of the median nerve
    
  • Patient may complain of dropping things or having decreased fine motor control.
    
• Loss of 2-point discrimination:
  
  • Late finding, highly specific
    
• Atrophy of thenar muscles:
  
  • Late finding, highly specific
    

• History of characteristic nocturnal pain and paresthesia in the median nerve distribution.
  
• Muscle weakness and thenar wasting are later findings.
  
• Provocative testing:
  
  • Overall poor sensitivity and specificity
    
  • Phalen test:
    
    • Wrist flexion for 60 sec produces numbness or tingling in the median nerve distribution.
      
  • Tinel sign:
    
    • Gentle tapping over the median nerve at wrist produces tingling in the fingers in the median nerve distribution.
      
  • Carpal compression test:
    
    • Direct pressure applied over the proximal carpal ligament for 30 sec produces tingling in the fingers in the median nerve distribution.
      
  • Tourniquet test:
    
    • BP cuff inflated to just above the patient’s systolic BP for 2 min produces paresthesia in the median nerve distribution.
      

• Not indicated in most cases
  
• Thyroid function studies; rheumatoid factor and immune panel if indicated by history and physical exam
  

• Wrist radiograph if trauma or degenerative arthritis suspected
  
• CT in select cases (not routine):
  
  • May show encroachment of carpal tunnel
    
• MRI displays the soft tissues well but not recommended for routine diagnosis:
  
  • Findings: Palmar bowing of transcarpal ligament, flattened median nerve, median nerve or synovial swelling, fluid in carpal tunnel, signal abnormality of median nerve
    
• Ultrasound can be diagnostic:
  
  • Sensitivity of 44–95%; specificity of 57–100%
    
  • Findings: Median nerve swelling at proximal canal, median nerve flattening at distal canal, bowing of transcarpal ligament
    

Nerve conduction studies and electromyography are criterion standard tests.

• Cervical nerve root compression:
  
  • Origin of median nerve is at the 6th and 7th cervical roots.
    
  • Symptoms are aggravated by erect posture and neck movement.
    
• Hand–arm vibration syndrome:
  
  • Characterized by Raynaud, numbness and tingling in ulnar and median nerve distributions when exposed to cold or vibration, weakened grip, and upper extremity myalgias
    
  • Associated with prolonged exposure to vibration
    
• Thoracic outlet obstruction
  
• Osteoarthritis of the 1st carpometacarpal joint
  
• Brachial plexitis
  
• Generalized neuropathy
  
• Syringomyelia
  
• Multiple sclerosis
  

TREATMENT

None necessary

• Acute:
  
  • Hand surgery consultation for surgical release of transverse carpal ligament using either open or endoscopic technique
    
• Chronic:
  
  • Analgesics
    
  • Oral corticosteroids
    
  • Local corticosteroid injection
    
  • Avoidance of repetitive wrist movement
    
  • Splint wrist in neutral position (0°):
    
    • Worn at night until follow-up
      
  • Yoga
    
  • Referral:
    
    • Primary care physician
      
    • Occupational medicine for ergometric testing if caused by repetitive motion, and tendon gliding, nerve gliding, or carpal bone mobilization exercises
      
    • Hand surgeon for evaluation of surgical intervention
      

• Analgesics:
  
  • There are many choices
    
  • NSAIDs have not been shown to improve long-term outcome
    
• Oral corticosteroids—short-term benefit:
  
  • Prednisone: 20 mg daily × 7 days, 10 mg daily × 7 days
    
  • Prednisolone: 20–25 mg daily, tapered over 2–4 wk
    
• Local corticosteroid injection—transient relief in 2/3 of patients (many different regimens):
  
  • Hydrocortisone: 20 mg
    
  • Methylprednisolone: 15–40 mg
    
  • Triamcinolone: 20 mg
    
  • Usually combined with 0.15–0.5 mL 2% lidocaine
    

FOLLOW-UP

Acute carpal tunnel syndrome requiring surgical decompression

Chronic carpal tunnel syndrome after adequate pain control

Primary care physician or directly to a specialist in occupational medicine or hand surgery within 1–2 wk

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• Kothari MJ. Treatment of carpal tunnel syndrome. In: Schefner JM, ed.
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  , Waltham, MA, 2013.
  
• Seror P. Sonography and electrodiagnosis in carpal tunnel syndrome diagnosis, an analysis of the literature.
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• Tosti R, Ilyas AM. Acute carpal tunnel syndrome.
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CODES