Carpal tunnel syndrome consists predominantly of tingling and numbness in the typical median nerve distribution in the radial three and a half digits (thumb, index, long, and radial side of ring). Pain, described as deep, aching, or throbbing, occurs diffusely in the hand and radiates up the forearm. Muscles at the base of thumb undergo atrophy later in the course of the nerve compression. It occurs most often in patients 30 to 60 years old and is two to three times more common in women than in men.
1. Decrease in Size of Carpal Tunnel
- Bony abnormalities of the carpal bones – can be diagnosed on good quality digital radiographs.
- Flexion or extension of wrist
2. Increase in Contents of Canal
- Forearm and wrist fractures (Colles fracture, scaphoid fracture)
- Dislocations and subluxations (scaphoid rotary subluxation, lunate volar dislocation)
- Posttraumatic arthritis (osteophytes)
- Musculotendinous variants
- Aberrant muscles (lumbrical, palmaris longus, palmaris profundus)
- Local tumors (neuroma, lipoma, multiple myeloma, ganglion cysts)
- Persistent medial artery (thrombosed or patent)
- Hypertrophic synovium
- Hematoma (hemophilia, anticoagulation therapy, trauma)
3. Neuropathic Conditions
- Diabetes mellitus
- Double-crush syndrome (carpal tunnel with PIVD)
- Exposure to industrial solvents
4. Inflammatory Conditions
- Rheumatoid arthritis
- Nonspecific tenosynovitis
5.Alterations of Fluid Balance
- Thyroid disorders (especially hypothyroidism)
- Renal failure
- Long-term hemodialysis
- Raynaud disease
- Lupus erythematosus
- Paget disease
6. External Forces
- Direct pressure
When carpal tunnel syndrome occurs in pregnant women, the symptoms usually resolve after delivery.
- Paresthesia over the sensory distribution of the median nerve is the most frequent symptom.
- The Tinel sign also may be shown in most patients by percussing the median nerve at the wrist.
- Atrophy to some degree of the median-innervated thenar muscles has been reported in about half of patients treated by operation.
NCV and EMG may be needed for confirmation of the diagnosis.
EMG and NCV
- 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)
Local injection of steroids maybe tried in early carpal tunnel syndrome and may provide relief of symptoms.
Patients with intermediate and advanced (chronic) syndromes responded to carpal tunnel release – Open or endoscopic.