What is the best treatment option for an adult patient with carpal tunnel syndrome (CTS) who has not responded to conservative treatments, possibly with a history of repetitive hand use or underlying medical conditions?

Steroid Injection for Carpal Tunnel Syndrome

Local corticosteroid injection into the carpal tunnel is an effective treatment that provides symptom relief for patients with carpal tunnel syndrome who have failed initial conservative measures like splinting, and should be offered before proceeding to surgery. 1, 2, 3

Treatment Algorithm for CTS

Initial Conservative Management (4-6 weeks)

• Nighttime wrist splinting in neutral position is the first-line conservative treatment and should be attempted for all patients with mild to moderate CTS 1, 2
• Discontinue ineffective NSAIDs (acetaminophen, ibuprofen) as they do not address median nerve compression and have limited efficacy for nerve entrapment 1
• Consider therapeutic exercises including stretching of wrist flexors/extensors, manual lymph drainage, and supervised physical therapy 4

Corticosteroid Injection as Second-Line Treatment

• If symptoms persist after 4-6 weeks of splinting, proceed with local corticosteroid injection (e.g., 6 mg betamethasone) into the carpal tunnel 2, 3
• Local injection provides superior and longer-lasting relief compared to oral corticosteroids, with 70% of patients reporting satisfaction versus 34% with placebo 3
• Injection can delay the need for surgery at one year and provides relief for more than one month 2
• Serial injections may be considered for recurrent symptoms, though most patients eventually require surgery for long-term control 3

Surgical Referral Criteria

• Proceed to surgical decompression if:
  • Symptoms persist after 4-6 months of conservative therapy including injection 1, 2
  • Severe CTS on electrodiagnostic studies 2
  • Thenar muscle wasting present 5
  • Patient desires definitive treatment 1

Evidence Quality and Nuances

The evidence strongly supports corticosteroid injection as an intermediate step between conservative management and surgery. A double-blinded placebo-controlled trial demonstrated significant improvement in both symptom relief and median nerve conduction parameters with steroid injection 3. However, the long-term cure rate with injection alone is modest—only 10% of patients remain asymptomatic at 1 year 5.

Predictors of successful response to injection include:

• Symptom duration less than 3 months 5
• Absence of sensory impairment at presentation 5
• No thenar muscle wasting 5

Critical Pitfalls to Avoid

• Do not inject corticosteroids within 3 months of planned surgery as this increases infection risk 1
• Do not proceed directly to surgery in patients with very mild electrodiagnostic findings without attempting conservative treatment, as 48-63% will respond to conservative measures 1
• Do not rely on oral NSAIDs or vitamin B6 as adequate conservative treatment—systematic reviews show these are no more effective than placebo 6
• Avoid prolonged immobilization beyond the initial splinting period as it can lead to muscle deconditioning 1

Monitoring and Follow-up

• For oral steroids (if used instead of injection), effects typically last only 8 weeks 7
• Monitor diabetic patients for blood glucose elevation with systemic steroids 7
• Consider PCP prophylaxis for courses longer than 12 weeks 7
• Re-evaluate at 4-6 months to determine if surgical referral is needed 1, 2