Basics
Description
- 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.
Etiology
- 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
Signs and Symptoms
History
- 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"ť the hand
- Exacerbated by repetitive wrist movement and by activities in which the wrist is flexed (e.g., driving)
Physical Exam
- 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
Essential Workup
- 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 patients systolic BP for 2 min produces paresthesia in the median nerve distribution.
Diagnosis Tests & Interpretation
Lab
- Not indicated in most cases
- Thyroid function studies; rheumatoid factor and immune panel if indicated by history and physical exam
Imaging
- 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
Diagnostic Procedures/Surgery
Nerve conduction studies and electromyography are criterion standard tests.
Differential Diagnosis
- 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
Initial Stabilization/Therapy
None necessary
Ed Treatment/Procedures
- 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
Medication
- 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
Disposition
Admission Criteria
Acute carpal tunnel syndrome requiring surgical decompression
Discharge Criteria
Chronic carpal tunnel syndrome after adequate pain control
Followup Recommendations
Primary care physician or directly to a specialist in occupational medicine or hand surgery within 1-2 wk
Additional Reading
- Cranford CS, Ho JY, Kalainov DM, et al. Carpal tunnel syndrome. J Am Acad Orthop Surg. 2007;15(9):L537-L548.
- Keith MW, Masear V, Chung K, et al. Diagnosis of carpal tunnel syndrome. J Am Acad Orthop Surg. 2009;17(6):389-396.
- Kothari MJ. Treatment of carpal tunnel syndrome. In: Schefner JM, ed. UpToDate, Waltham, MA, 2013.
- Seror P. Sonography and electrodiagnosis in carpal tunnel syndrome diagnosis, an analysis of the literature. Eur J Radiol. 2008;67(1):146-152.
- Tosti R, Ilyas AM. Acute carpal tunnel syndrome. Orth Clin N Am. 2012;43:459-465.
Codes
ICD9
354.0 Carpal tunnel syndrome
ICD10
- G56.00 Carpal tunnel syndrome, unspecified upper limb
- G56.01 Carpal tunnel syndrome, right upper limb
- G56.02 Carpal tunnel syndrome, left upper limb
- G56.0 Carpal tunnel syndrome
SNOMED
- 57406009 Carpal tunnel syndrome (disorder)