What is Carpal Tunnel Syndrome?

Carpal tunnel syndrome is a condition that causes numbness, pain and tingling in the hand and arm.

What is involved?

Median Nerve

Location

Median nerve entrapment at the Carpal Tunnel at the wrist

Common symptoms

• Greater severity in dominant hand
• Difficulty grasping or holding objects
• Numbness/tingling in hand/wrist radiating to Thumb, Index and/or Middle finger
• May radiate up the arm toward the shoulder
• Predominantly nocturnal symptoms; patients awaken and shake their hands for relief
• Often affects both sides, though sometimes only one side presents symptoms

Onset

Usually slow, insidious over months/years

Risk factors

• Women more than Men
• Diabetes or family history of Diabetes
• Pregnancy
• Weight changes
• Previous wrist injury or trauma
• HIV infection
• Occupational: repetitive hand use in secretarial, manufacturing, and computer-intensive roles

Exam

• Look for Abductor Pollicis Brevis (APB) atrophy (thenar eminence wasting)
• Test APB strength by asking patient to point thumb to ceiling against resistance
• Decreased sensation to touch and pinprick over thumb, index, and middle fingers
• Positive and painful Tinel sign (tingling upon tapping nerve) at the wrist with radiation to the thumb, index and middle fingers
• Positive Phalen’s test (wrist flexion reproduces symptoms)

EMG

EMG is very good for confirming Carpal Tunnel Syndrome and assessing severity.

Findings

• Prolonged Median Sensory distal latency (>3.5 ms)
• Prolonged Median Motor distal latency (>4.2 ms)
• Normal Ulnar Sensory/Motor distal latencies
• Comparison of Median to Ulnar sensory latencies useful for borderline cases
• If Median and Ulnar conductions are both abnormal, test the lower extremity to rule out Peripheral Neuropathy
• Active/Chronic denervation in APB on Needle Examination in moderate to severe cases

Severity Classification

• Mild: Prolonged sensory latency only, normal motor latency, no denervation
• Moderate: Prolonged sensory and motor latencies, no or minimal denervation
• Severe: Absent sensory response, prolonged motor latency, active denervation and/or thenar atrophy

Recommendations

• Mild cases: Nocturnal wrist splint in neutral position, avoid aggravating activities
• Moderate cases: Wrist splint, activity modification, corticosteroid injection
• Severe cases: Surgical release (carpal tunnel release) especially if thenar atrophy or active denervation present
• Stop/decrease cause (repetitive hand activities, keyboard use)
• Ergonomic modifications at workplace

What else could it be?

• Cervical root lesion (C6-C7), usually accompanied by neck and arm pain
• Pronator Syndrome (median nerve entrapment in the forearm)
• Thoracic outlet syndrome (very rare)
• Peripheral Neuropathy if bilateral and accompanied by other nerve involvement
• De Quervain’s tenosynovitis (affects thumb but no numbness)