Carpal Tunnel Syndrome

Clinical Severity Classification

Clinical severity guides urgency of treatment. Mild cases warrant conservative trial. Severe cases require urgent surgery.

Nerve Conduction Study Classification

Severity Based on NCS Findings:

Key NCS Parameters:

• Distal motor latency: Wrist to APB, normal less than 4.5ms
• Sensory latency: Wrist to index/middle finger, normal less than 3.5ms
• Sensory amplitude: Decreased in severe cases
• Motor amplitude: Decreased indicates axonal loss
• Compare to ulnar nerve: Internal control

EMG shows fibrillation potentials and positive sharp waves in APB if severe. Chronic changes include reduced recruitment and large motor unit potentials.

Palumbo Clinical Staging System

Palumbo staging is useful for clinical grading and counseling about prognosis. Stages 1-2 have excellent outcomes. Stages 4-5 may have incomplete recovery.

Nerve Conduction Studies (NCS)

Gold standard for diagnosis confirmation and severity grading.

Indications for NCS:

• Atypical presentation
• Bilateral severe symptoms
• Confirm diagnosis before surgery
• Medico-legal cases
• Young patients (under 40)
• Assess severity and prognosis

Technique:

• Sensory NCS: Orthodromic (digit to wrist) or antidromic (wrist to digit)
  • Stimulate at wrist, record from index or middle finger
  • Measure distal sensory latency and amplitude
  • Normal latency less than 3.5ms
• Motor NCS: Stimulate median nerve at wrist, record from APB
  • Measure distal motor latency
  • Normal latency less than 4.5ms
  • Compare to ulnar nerve (ADM)

Diagnostic Criteria:

• Prolonged median sensory latency greater than 3.5ms
• Prolonged median motor latency greater than 4.5ms
• Median-ulnar sensory latency difference greater than 0.5ms
• Median-ulnar motor latency difference greater than 1.0ms

Ultrasound

Increasing use as diagnostic tool:

• Cross-sectional area (CSA): Greater than 10-12mm² at tunnel inlet
• Flattening ratio: Anterior-posterior to medial-lateral diameter
• Bowing of retinaculum: Displacement greater than 2mm
• Dynamic assessment: Nerve movement with finger flexion
• Identify masses: Ganglion, persistent median artery

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Advantages:

• Non-invasive, no electrical stimulation
• Real-time visualization
• Identifies structural causes
• Can guide injection

Limitations:

• Operator-dependent
• Does not assess function
• Cannot quantify severity like NCS

MRI

Not routine, reserved for:

• Suspected mass lesion
• Atypical presentation
• Failed surgery
• Research purposes

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Findings:

• T2 hyperintensity of nerve
• Nerve enlargement
• Muscle edema (if acute denervation)
• Thenar atrophy (chronic)

Laboratory Studies

Screen for associated conditions:

• TSH (hypothyroidism)
• HbA1c (diabetes)
• Rheumatoid factor/anti-CCP (rheumatoid arthritis)
• Serum protein electrophoresis (amyloid if suspected)

Night Splinting

Technique:

• Wrist in neutral (0-5 degrees extension) NOT flexion or hyperextension
• Worn during sleep for minimum 6-8 weeks
• Full-time splinting not superior to night-only
• More effective in mild disease, pregnancy, recent onset
• Success rate 30-50% at 6 months

Activity Modification

Recommendations:

• Avoid sustained wrist flexion (computer use, driving)
• Take frequent breaks from repetitive tasks
• Ergonomic adjustments (keyboard height, mouse position)
• Modify sports grip (cycling, tennis)

Conservative management with splinting and activity modification is appropriate first-line treatment for mild to moderate CTS without thenar atrophy.

Corticosteroid Injection

Technique:

• Position: Wrist slightly extended
• Site: 1cm proximal to distal wrist crease, ulnar to palmaris longus
• Angle: 45 degrees distally
• Depth: Just past retinaculum (loss of resistance)
• Test: Inject 0.5ml saline first - should feel no resistance
• Medication: 1ml (10-40mg) methylprednisolone + 1ml local anesthetic
• Post-injection: Splint for 2 weeks

Outcomes:

• 70-80% short-term relief
• 20-30% long-term benefit
• Maximum 2-3 injections total

Injection provides diagnostic value and temporary relief. Most patients with moderate-severe disease will eventually require surgery.

Other Conservative Options

Limited Evidence:

• Oral corticosteroids (short course only)
• Vitamin B6 (no proven benefit in trials)
• NSAIDs (symptom control only, no disease modification)
• Diuretics (no evidence of efficacy)
• Therapeutic ultrasound (inconsistent evidence)
• Yoga/stretching (some evidence for symptom relief)

Most non-surgical interventions beyond splinting and injection have limited evidence supporting their use.

Open Carpal Tunnel Release

Indications:

• Failed conservative treatment (6+ months)
• Moderate to severe NCS changes
• Thenar muscle atrophy or weakness
• Persistent disabling symptoms
• Patient preference for definitive treatment
• Acute carpal tunnel (trauma, hemorrhage)

Setup:

• Supine position, arm on hand table
• Upper arm tourniquet (250 mmHg)
• Prep and drape hand and forearm
• Local anesthetic (1% lidocaine with epinephrine) OR regional block
• Mark incision with wrist flexed then extended to avoid transverse crease

Incision:

• Longitudinal incision in line with radial border of ring finger
• From distal wrist crease to mid-palm
• Length 3-4cm (extended release) or 2-3cm (mini-open)
• Stay ulnar to thenar crease
• Avoid crossing wrist crease transversely (hypertrophic scar)

Step-by-Step Technique:

1. Skin and Subcutaneous Dissection

   • Incise skin with knife
   • Identify and protect palmar cutaneous branch (travels superficially)
   • Divide palmar fascia in line with incision
   • Identify transverse carpal ligament (white, fibrous band)

2. Identify Landmarks

   • Palmaris longus: Surface landmark (ulnar to this)
   • Flexor carpi radialis: Radial boundary (avoid)
   • Ulnar neurovascular bundle: Ulnar boundary (stay radial to this)

3. Divide Transverse Carpal Ligament

   • Insert mosquito forceps UNDER ligament to protect nerve
   • Elevate ligament away from nerve
   • Divide ligament with knife or scissors under direct vision
   • Release distally to superficial palmar arch (feel "give")
   • Release proximally into antebrachial fascia (2cm proximal to crease)
   • Ensure COMPLETE division (run probe underneath)

4. Inspect Tunnel Contents

   • Visualize median nerve (should be flattened, may be hourglass)
   • Check for anatomical variations: Bifid nerve, persistent median artery
   • Look for masses: Ganglion, lipoma
   • Assess synovium: Proliferative synovitis may need debulking
   • DO NOT perform internal neurolysis (increases scar, worse outcomes)

5. Hemostasis and Closure

   • Release tourniquet
   • Achieve meticulous hemostasis (prevents hematoma)
   • DO NOT repair transverse carpal ligament (would recreate compression)
   • Close skin only with interrupted 4-0 nylon sutures
   • Apply bulky dressing in functional position
   • Allow immediate finger ROM

Technical Pearls:

• Divide ligament completely (incomplete release = most common cause of failure)
• Extend release into forearm fascia proximally
• Extend release to superficial arch distally
• Protect recurrent motor branch (exits ulnar side of nerve distally)
• If thenar muscles not visible, assume extraligamentous recurrent branch

Structures at Risk:

• Palmar cutaneous branch: Superficial, easily injured with skin incision
• Recurrent motor branch: Variable course (transligamentous in 20%)
• Superficial palmar arch: Distal limit of release
• Ulnar nerve and artery: Ulnar boundary of incision

Meticulous attention to anatomical landmarks and direct visualization of the transverse carpal ligament ensures safe and complete release with excellent long-term outcomes.

Endoscopic Carpal Tunnel Release

Advantages over Open:

• Smaller incision (1-2cm)
• Less pillar pain
• Faster recovery (grip strength at 2 weeks vs 6 weeks)
• Earlier return to work (2 weeks vs 4 weeks)
• Less scar tenderness

Disadvantages:

• Learning curve (30-50 cases)
• Slightly higher nerve injury risk (especially during learning)
• Cannot address masses or synovitis
• Cannot inspect nerve
• Requires specialized equipment
• Contraindicated in certain scenarios

Contraindications:

• Suspected mass lesion
• Previous carpal tunnel surgery
• Severe wrist arthritis with osteophytes
• Anomalous anatomy (bifid median nerve)
• Surgeon inexperience

Techniques:

Single Portal (Agee System):

• 1.5cm transverse incision at distal wrist crease
• Insert cannula with blade through tunnel
• Visualize ligament and divide under direct vision
• Exit point in mid-palm

Two Portal (Chow Technique):

• Proximal portal at distal wrist crease
• Distal portal in mid-palm
• Pass cannula through both portals
• Visualize and divide ligament from underneath

Outcomes:

• Similar long-term results to open (90-95% success)
• Faster initial recovery
• Meta-analyses show no difference at 6-12 months
• Choose based on surgeon experience

The decision between open and endoscopic techniques should be based on surgeon training and experience, patient anatomy, and clinical circumstances rather than perceived differences in long-term outcomes.

Revision Carpal Tunnel Release

Indications:

• Incomplete initial release (most common)
• Recurrent compression (scar tissue)
• Persistent symptoms despite adequate release
• Iatrogenic nerve injury

Workup Before Revision:

• Repeat NCS (compare to pre-operative)
• Ultrasound or MRI (assess for scar, masses)
• Rule out alternative diagnosis (cervical radiculopathy)
• Review operative note from initial surgery
• Consider wrong diagnosis initially

Technique:

• Extended open approach (wider exposure)
• Careful dissection through scar
• Identify median nerve proximally in forearm (safe zone)
• Neurolysis if encased in scar
• Extended release proximally and distally
• Consider hypothenar fat flap coverage of nerve
• Consider vein wrapping to prevent recurrent adhesions

Outcomes:

• Less predictable than primary release (70-80% improvement)
• Counsel about incomplete relief
• Higher complication rate

Patient expectations must be managed appropriately as revision surgery carries higher risks and lower success rates than primary release. Thorough pre-operative workup is essential to confirm the indication.

Pillar Pain

Most common complication (10-20% of patients):

• Mechanism: Separation of thenar and hypothenar origins from transverse ligament
• Presentation: Aching pain at bases of thumb and hypothenar eminences
• Worse with grip and pinch
• Typically resolves by 3 months, some up to 6-12 months
• Management: Reassurance, grip strengthening, thenar massage
• Prevention: Partial ligament release NOT recommended (risk incomplete decompression)

Incomplete Release

Second most common cause of persistent symptoms:

• Failure to divide ligament completely distally or proximally
• Inadequate proximal release of antebrachial fascia
• Failure to identify anomalous anatomy
• Diagnosis: Repeat NCS, ultrasound showing residual compression
• Management: Revision open CTR with extended release

Nerve Injuries

Median nerve laceration:

• Rare (0.1-0.3%) but devastating
• Present immediately post-op with dense numbness and weakness
• Management: Urgent exploration and primary repair
• May need nerve graft if gap

Recurrent motor branch injury:

• More common (0.3-1%), especially with transligamentous variant
• Present with thenar weakness
• Management: If identified within 72 hours, explore and repair
• Late recognition: conservative management, tendon transfers if needed

Complex Regional Pain Syndrome (CRPS)

Severe complication (1-5%):

• Disproportionate pain, stiffness, swelling
• Autonomic changes (temperature, color, sweating)
• Early recognition critical
• Management: Multidisciplinary (pain specialist, PT/OT, psychology)
• Gabapentin, vitamin C prophylaxis (some evidence)
• Sympathetic blocks if severe