Treatise Index
Not Just "Tendonitis"
Carpal Tunnel Syndrome (CTS) is often confused with tendonitis, but its origin is neuropathic. It is caused by mechanical compression of the median nerve within a narrow bony canal in the wrist. Unlike muscle pain, CTS pain is characterized by shock, tingling, and burning, often waking the patient up at night.
1. Introduction: The Digital Epidemic
Carpal Tunnel Syndrome is the most common compressive neuropathy of the upper limb, affecting about 3-6% of the adult population. With the global transition to digital work and the ubiquitous use of smartphones, the incidence of this pathology has increased significantly.
Classified as a RSI/WRMSD (Repetitive Strain Injury / Work-Related Musculoskeletal Disorder), CTS represents one of the main causes of work absenteeism and productivity loss, generating immense economic and social costs.
2. Anatomy: An Overcrowded Space
The carpal tunnel is a rigid and narrow canal located at the base of the palm. Its borders are:
- Floor and Walls: Carpal bones (scaphoid, lunate, triquetrum, etc.), which form a concave arch.
- Roof: The Transverse Carpal Ligament (Flexor Retinaculum), a thick and inelastic fibrous band.
Within this space of a few square centimeters, pass 9 flexor tendons of the fingers and the Median Nerve. Any swelling in the tendons or fluid accumulation increases internal pressure, and since the bone and ligament do not expand, the median nerve ends up being the "softest" tissue and vulnerable to being crushed.
3. Pathophysiology: Ischemia and Edema
Chronic compression of the median nerve triggers a cascade of pathological events:
- Venous Stasis: Pressure compresses the venules draining the nerve, causing intraneural edema (swelling).
- Ischemia: With increased edema, arterial supply is compromised, depriving the nerve of oxygen.
- Demyelination: Chronic ischemia leads to the loss of the myelin sheath (electrical insulator), resulting in slow nerve conduction and sensory symptoms (tingling).
- Axonal Damage: In advanced stages, the nerve fibers themselves die, causing irreversible muscle atrophy at the base of the thumb (thenar eminence).
4. Symptoms and Clinical Diagnosis
The clinical picture is classic but often ignored at the beginning:
- Paresthesia (Tingling): Affects the thumb, index, middle finger, and half of the ring finger. The little finger is typically spared (as it is innervated by the ulnar nerve).
- Night Pain: The patient wakes up in the middle of the night with a "numb" hand and needs to shake it ("Flick Sign") for relief. This occurs because we sleep with wrists flexed, which increases pressure in the tunnel.
- Weakness (Paresis): Difficulty holding small objects, buttoning shirts, or opening jars. Objects fall from the hand unexpectedly.
Diagnosis is confirmed by provocative tests (Phalen, Tinel) and, fundamentally, by Electroneuromyography, which measures nerve conduction velocity.
5. Occupational and Biological Risk Factors
Although ergonomics is crucial, biological factors make certain individuals more susceptible:
| Category | Risk Factors |
|---|---|
| Ergonomic | Repetitive wrist flexion/extension movements, use of vibrating tools, direct palm compression, forced ulnar deviation. |
| Endocrine | Diabetes (neuropathy), Hypothyroidism (myxedema), Pregnancy (fluid retention), Menopause. |
| Anatomical | Constitutionally narrow carpal tunnel (genetic), previous wrist fractures, rheumatoid arthritis (synovitis). |
6. Practical Ergonomics Guide
Prevention in the office focuses on keeping the wrist in a neutral position (straight), minimizing intracarpal pressure.
- Keyboard and Mouse: Should be at elbow height or slightly below. The wrist should not be bent upwards (extension) or resting directly on the desk edge.
- Vertical Mouse: Keeps the forearm in a neutral position (handshake), avoiding the twisting of arm bones that compresses the tunnel.
- Breaks: Every 45-60 minutes, take 5-minute breaks to stretch and relax the muscles.
- Global Posture: Tension in the neck and shoulders can compress nerves higher up (brachial plexus), generating a "double crush syndrome." The spine should be supported and feet flat on the floor.
7. Exercise Protocol: Nerve Gliding
Unlike static muscle stretching, Nerve Gliding exercises aim to mobilize the median nerve through the tunnel, preventing adhesions and improving circulation.
Basic Median Nerve Gliding Exercise:
- Fist Closed: Start with hand closed, thumb out.
- Fingers Extended: Open hand and extend fingers up.
- Wrist Extension: Bend hand back (dorsiflexion).
- Thumb Extended: Extend thumb to the side.
- Supination: Turn palm up (as if holding a tray).
- Thumb Stretch: With the other hand, gently pull the thumb back.
Perform 5-10 repetitions, gently, 3 times a day. Stop if there is pain or intense tingling.
8. Treatment: Conservative vs Surgical
Treatment depends on the severity of nerve injury:
- Mild/Moderate Stage: The use of night splints (braces) is the most effective intervention, keeping the wrist neutral during sleep. Local corticosteroid injections can temporarily reduce inflammation.
- Severe Stage (Atrophy/Sensory Loss): Carpal tunnel release surgery is indicated. The procedure cuts the Transverse Carpal Ligament, increasing the space available for the nerve. Recovery is usually excellent if performed before irreversible damage.
9. Conclusion
Carpal Tunnel Syndrome is not an inevitable sentence of modern life. With smart ergonomic adjustments, strategic breaks, and maintenance exercises, it is possible to protect hand health. Early recognition of symptoms (night tingling) is vital: treating early prevents progression to permanent nerve damage and loss of function.