Summary

Carpal Tunnel Syndrome (CTS) is the most common entrapment neuropathy, caused by compression of the Median Nerve at the wrist. The carpal tunnel is a fixed fibro-osseous space containing nine tendons and one nerve; any increase in volume (pregnancy, hypothyroidism) or decrease in space (arthritis) causes ischaemia. The hallmark is nocturnal acroparesthesia (numbness waking the patient) relieved by shaking the hand (Flick Sign). Diagnosis is clinical, confirmed by Phalen's and Durkan's tests. Nerve Conduction Studies (NCS) grading determines the need for surgery. While splinting helps mild cases, decompression surgery is the definitive cure for those with motor involvement (Thenar Wasting). [1,2,3]

Key Facts

• Anatomy: The tunnel contains 9 flexor tendons (FDS x4, FDP x4, FPL) and the Median Nerve. The nerve is the most superficial structure, pressed against the Transverse Carpal Ligament.
• Most Sensitive Test: Durkan's Carpal Compression Test (Sensitivity 87%, Specificity 90%). It is superior to Tinel's.
• The "Million Dollar Nerve": The Recurrent Motor Branch of the median nerve supplies the Thenar muscles (LOAF). Damage leads to loss of opposition — a functioning hand becomes a "monkey hand" (simian).

Clinical Pearls

"The Flick Sign": If you ask "What do you do when it wakes you up?" and the patient demonstrates shaking their hand vigorously, the sensitivity for CTS is >90%.

"Spare the Palm": The Palmar Cutaneous Branch of the median nerve arises proximal to the tunnel. Therefore, skin sensation over the thenar eminence is spared in CTS. If the palm is numb, the lesion is proximal (Forearm/Pronator Syndrome).

"Double Crush": 30% of patients have a second compression site (e.g., Cervical C6 Radiculopathy). Always check the neck!

                 CARPAL TUNNEL SYNDROME
                          ↓
              SYMPTOMS MILD OR SEVERE?
              ┌───────────┴─────────────┐
             MILD                    SEVERE
       (Intermittent Numb)       (Wasting/Weakness)
              ↓                         ↓
         CONSERVATIVE                SURGERY
      (Splint + Activity)            (Release)
              ↓
           FAILS?
              ↓
          INJECTION
          (Steroid)
              ↓
           FAILS?
              ↓
           SURGERY

1. Splinting

• Type: Neutral wrist splint (cock-up splint).
• Regimen: Night time only.
• Rationale: Prevents flexion (Phalen's position) during sleep which spikes tunnel pressures.
• Success: 50% for mild cases.

2. Steroid Injection

• Role: Diagnostic and Therapeutic.
• Technique: Injection proximal to wrist crease, ulnar to Palmaris Longus (to avoid median nerve).
• Outcome: 80% temporary relief. 20% cure at 1 year. Good predictor of surgical success.

Carpal Tunnel Decompression (Release)

• Indication:
  • Failed conservative care.
  • Thenar wasting (Urgent).
  • Acute CTS (Trauma/Infection - Emergency).
• Technique:
  • Open: 3cm incision in palm. Direct division of Transverse Carpal Ligament.
  • Endoscopic: Smaller scar, faster return to work, higher cost/risk.
• Outcome: 95% satisfaction. Night pain resolves immediately. Numbness takes months. Wasting may never recover.

Surgical vs Non-Surgical (Gerritsen et al. 2002)

• RCT: Surgery vs Splinting.
• Result: Surgery group had significantly better symptom relief and functional outcomes at 18 months.

Endoscopic vs Open (Cochrane 2014)

• Both techniques are equally effective for symptom relief.
• Endoscopic has faster return to work (by 1 week) but higher complication rate (nerve injury) in early learning curve.

What is the Carpal Tunnel?

It is a tight tunnel in your wrist made of bones and a thick ligament. Nine tendons and one nerve have to fit through it. If the tendons swell or the ligament thickens, the nerve gets squashed.

Why does it hurt at night?

When you sleep, your blood pressure drops, and fluid pools in your hands. Also, most people sleep with their wrists curled (flexed), which pinches the hose.

Do I need surgery?

If "shaking it out" works and you have no muscle weakness, we can try a splint at night. If the splint stops working, or if the muscle at the base of your thumb starts to shrink, we need to operate to "cut the roof" of the tunnel and give the nerve space.

Recovery

• Night 1: The waking-up pain usually stops immediately.
• Week 2: Stitches out. You can drive.
• Month 3: Grip strength returns. Scar tenderness settles.

Q1: What are the contents of the Carpal Tunnel? A: 10 structures:

• Fluid.
• Median Nerve.
• 4 tendons of Flexor Digitorum Superficialis (FDS).
• 4 tendons of Flexor Digitorum Profundus (FDP).
• 1 tendon of Flexor Pollicis Longus (FPL). (Note: FCR has its own tunnel).

Q2: Differentiate Pronator Syndrome from Carpal Tunnel Syndrome. A: Both involve the Median Nerve. In Pronator Syndrome (compression at elbow), the palmar cutaneous branch is affected, so there is numbness over the Thenar Eminence. In CTS, the thenar skin is spared. Also, Pronator Syndrome lacks nocturnal symptoms.

Q3: What is the "Million Dollar Nerve"? A: The Recurrent Motor Branch of the Median Nerve. It supplies the Thenar muscles (Abductor Pollicis Brevis, Opponens Pollicis, Flexor Pollicis Brevis). It is extra-ligamentous in 50% of cases and highly vulnerable during release. Injury results in loss of opposition.

Q4: What is the significance of Thenar Wasting? A: It signifies severe, chronic compression with axonal loss. It is an indication for urgent decompression, but the prognosis for muscle recovery is poor.

(End of Topic)