Carpal Tunnel Syndrome (CTS): Background, Diagnosis, Management & Prescription

1. Background and Anatomy

2. Etiological Background (Metabolic & Mechanical)

A. Metabolic / Systemic Disease

Key point: Bradley and Daroff's Neurology states that pregnancy, diabetes, rheumatoid arthritis, hypothyroidism, sarcoidosis, acromegaly, and amyloid infiltration should be screened with blood studies in ALL newly diagnosed CTS patients. - Bradley and Daroff's Neurology in Clinical Practice, p. 549

B. Long-term Compression / Mechanical Factors (Over the Flexor Retinaculum)

• Repetitive forceful wrist and finger flexion/extension - occupational or hobby-related (e.g., assembly line workers, typists, musicians)
• Habitual sleeping with wrist in acute flexion - sustained wrist posture chronically compresses the tunnel
• Direct pressure on the carpal tunnel (e.g., handlebar pressure, vibratory tool use)
• Wrist fractures (Colles fracture, scaphoid fracture) or dislocations (lunate volar dislocation) increasing tunnel contents
• Space-occupying lesions: ganglion cysts, lipomas, hypertrophic synovium, hematoma
• Stenosing flexor tenosynovitis thickening the tendon sheaths within the tunnel

3. Clinical Presentation

Symptoms

• Paresthesia and numbness in the palmar surface of the thumb, index, long, and radial half of the ring finger (median nerve sensory distribution)
• Symptoms typically worse at night and may wake the patient - relieved by "flick" maneuver (shaking/elevating the hand)
• Diffuse deep aching or throbbing pain radiating up the forearm (may misleadingly extend to shoulder)
• Thenar muscle atrophy and weakness of thumb opposition/abduction (APB, opponens pollicis) in advanced disease
• Note: the palmar cutaneous branch leaves the median nerve proximal to the TCL, so thenar skin sensation is often preserved despite CTS - a useful diagnostic clue

Physical Examination Findings

4. Diagnostic Scoring: CTS-6

5. Investigations

Electrodiagnostic Studies (EMG/NCS) - Gold Standard for Confirmation

• Distal motor latency >4.5 ms - abnormal
• Sensory latency >3.5 ms - abnormal
• EMG: increased insertional activity, fibrillations at rest, decreased motor recruitment in APB
• 90% sensitive, 60% specific. May be normal in symptomatic patients (up to 25% false negative)
• Indicated before surgical intervention

Ultrasound

• Cross-sectional area (CSA) of median nerve >10 mm² at the pisiform level is diagnostic
• High-resolution US: sensitivity 73% using cutoff of 9.4 mm² at carpal tunnel inlet
• Useful when NCS is equivocal; increasingly preferred as first-line imaging

MRI

• NOT routinely recommended for CTS diagnosis
• Reserved for rare cases with suspected mass lesions or structural abnormality

Blood Work (Workup for Underlying Cause)

• TSH (hypothyroidism)
• Fasting glucose / HbA1c (diabetes mellitus)
• Renal function panel (CKD, dialysis-related)
• Rheumatoid factor / anti-CCP (rheumatoid arthritis)
• Serum protein electrophoresis / urine protein (amyloidosis / multiple myeloma)
• IGF-1 / GH if acromegaly suspected
• Pregnancy test if appropriate

6. Management

Predictors of Nonoperative Treatment Failure (Box 82.3)

1. Age >50 years
2. Duration >10 months
3. Constant (not intermittent) paresthesia
4. Stenosing flexor tenosynovitis
5. Positive Phalen test in <30 seconds

Step 1: Conservative (First-Line, Mild-Moderate Symptoms)

Activity Modification

• Identify and minimize repetitive wrist flexion/extension at work or home
• Ergonomic workplace assessment - wrist support pads, keyboard height
• Avoid habitual sleeping with wrist in flexion

Wrist Splinting

• Neutral wrist splint (0° extension), worn especially at night
• Effective for relieving nocturnal symptoms; most benefit in mild-to-moderate CTS
• Can also be worn during provoking activities

Nerve Gliding Exercises

• Routinely prescribed; evidence supports symptom relief when combined with splinting

Step 2: Pharmacological Management

Corticosteroid Injection (into the carpal tunnel)

• Methylprednisolone (or triamcinolone) injected into the carpal tunnel
• Provides reliable short-term symptom relief; useful as diagnostic tool (90% who get temporary relief respond to surgery)
• Long-term benefit in only ~10% of patients
• CAUTION: Inject palmar/ulnar to the palmaris longus tendon - never directly into the nerve

Oral Corticosteroids

• Short course oral prednisolone: evidence for short-term benefit
• Not a long-term solution

NSAIDs / Analgesics

• Evidence shows NSAIDs are no more effective than placebo for CTS symptom relief
• May be used for associated tenosynovitis or background inflammatory arthritis

Diuretics

• May provide short-term benefit in fluid-overload states (pregnancy, renal failure)

Step 3: Surgical Management (Moderate-Severe, or Failed Conservative)

Two Main Techniques

• Failure of conservative therapy after adequate trial (typically 3-6 months)
• Significant thenar atrophy or progressive motor weakness
• Severe or constant paresthesia (high CTS-6, prolonged NCS latencies)

Treatment Algorithm (from Campbell's Operative Orthopaedics 15e)

7. Prescription Summary

CONSERVATIVE PHASE:
1. Neutral wrist splint – wear nightly; can use during provoking activities
2. Nerve gliding exercises – daily programme, refer to hand therapist
3. Ergonomic assessment – workplace wrist positioning

INJECTION (moderate symptoms or diagnostic):
4. Methylprednisolone acetate 40 mg (1 mL) + 1% lidocaine 1 mL
   → Ultrasound-guided injection into carpal tunnel (palmar-ulnar to palmaris longus)
   → May repeat once if partial relief; limit to 2-3 total injections

PHARMACOLOGICAL ADJUNCTS:
5. Prednisolone 20 mg oral once daily x10-14 days (for acute flares)
   [NSAIDs – not recommended; no better than placebo for CTS]
6. Treat underlying cause:
   - Hypothyroidism → Levothyroxine titrated to TSH 0.5-2.0 mIU/L
   - Diabetes → Optimize glycemic control (HbA1c <7%)
   - RA → DMARDs per rheumatology; consider concurrent tenosynovectomy if surgery needed
   - Renal failure / dialysis amyloidosis → dialysis optimization; early surgery referral

SURGICAL REFERRAL (if ≥3 failure predictors, or progressive motor signs):
7. Carpal tunnel release – endoscopic or open mini-palm technique
   (preoperative NCS mandatory)

8. Special Situations

Recent Evidence

• Global CTS prevalence meta-analysis (PMID 39672798) - 2024 Systematic Review confirming CTS as highly prevalent globally, supporting proactive screening.
• Endoscopic vs. open CTR umbrella review (PMID 38768022) - 2024 meta-analysis confirms endoscopic approach is generally preferred with faster recovery.
• Ultrasound-guided nerve hydrodissection meta-analysis (PMID 39894044) - 2025 network meta-analysis supports hydrodissection as a nonsurgical option in selected patients.

Page 1 — Patient & Assessment

• Patient/Clinician details fillable fields (name, age, MRN, date, signature, stamp)
• Clinical assessment form - CTS-6 score, Phalen/Tinel/Durkan results, thenar atrophy grade, NCS/EMG values, ultrasound CSA, symptom duration and pattern, and underlying cause checkboxes
• Severity classification table - colour-coded (green/yellow/red) with clinical features and NCS criteria for Mild / Moderate / Severe; includes a "circle your level" column

Page 2 — Mild & Moderate Prescriptions

• Mild CTS: Neutral splint protocol, nerve gliding, ergonomics; methylprednisolone 40 mg intracarpal injection with technique notes; oral prednisolone as alternative; note that NSAIDs are not recommended; baseline metabolic workup checklist
• Moderate CTS: Full-time splinting, occupational therapy referral; injection protocol + surgical decision rule (90% responders → surgery); gabapentin/amitriptyline option for neuropathic pain; disease-specific treatment lines for hypothyroidism, DM, RA, pregnancy, CKD; NCS/EMG + ultrasound investigations

Page 3 — Severe Prescription + Reference Tables

• Severe CTS: Urgent surgical referral pathway; open mini-palm CTR technique; endoscopic CTR option; special intraoperative considerations by cause (RA tenosynovectomy, Camitz opponensplasty, dialysis amyloid, post-fracture)
• Underlying cause quick-reference table - 8 conditions (hypothyroidism, DM, RA, pregnancy, CKD/amyloid, acromegaly, obesity) with treatment targets and first-line agents
• Clinician free-text notes area; source citations and clinical disclaimer footer