Numbness During Carpal Tunnel Injection: Normal Sensation vs. Complications
Transient numbness in fingers during a carpal tunnel injection is a warning sign that the needle may be too close to or directly injuring the median nerve and should prompt immediate needle repositioning.
Normal Sensations vs. Warning Signs
- Mild discomfort during injection is expected, but numbness, tingling, or shooting pain indicates possible needle contact with the median nerve 1
- Patients should not be heavily sedated during carpal tunnel injections so they can immediately report any paresthesia or numbness during the procedure 1
- Median nerve injury is the most serious complication of carpal tunnel injections, though the incidence is relatively low 1
Mechanism of Nerve Injury
- Direct needle trauma to the median nerve during injection can cause immediate shooting pain along with sensory disturbances 1
- Injection of steroid directly into the nerve rather than the surrounding carpal tunnel space can cause chemical irritation and damage 2
- Nerve injury may present with immediate shooting pain followed by persistent numbness, motor weakness, and potentially muscle atrophy if severe 1
Prevention of Nerve Injury
- Careful attention to anatomic landmarks is essential when performing carpal tunnel injections 2
- The patient should remain awake and alert during the procedure to report any abnormal sensations 1
- A safe injection technique involves inserting the needle between the tendons of the radial carpal flexor muscle and long palmar muscle on the volar side of the forearm 3
- Avoidance of local anesthetics during diagnostic injections may help prevent nerve injury by allowing the patient to feel warning symptoms 2
Management of Suspected Nerve Injury
- If numbness or paresthesia occurs during injection, the needle should be immediately withdrawn and repositioned 1
- Persistent numbness after injection may indicate nerve injury requiring further evaluation 4
- Severe cases of median nerve injury from injection may respond poorly to conservative treatment and might require surgical exploration 4
- Surgical treatment options include division of the transverse carpal ligament and neurolysis for confirmed cases of injection injury to the median nerve 2
Clinical Outcomes
- When performed correctly without nerve injury, local corticosteroid injections can provide short-term improvement in neurophysiological and clinical outcomes for carpal tunnel syndrome 3
- Benefits include reduced pain intensity, decreased symptom severity, and improved functional ability 3
- Electrophysiological improvements can be observed in sensory conduction velocities, sensory peak latency, and motor distal latency following proper injection 3
Important Considerations
- Carpal tunnel syndrome often coexists with other conditions that can cause numbness, such as polyneuropathy 5
- Carpal tunnel syndrome is a common neurological manifestation in certain systemic conditions and may precede polyneuropathy by many years 5
- Surgical decompression remains the most effective treatment for moderate to severe carpal tunnel syndrome 6
Remember that persistent numbness after injection is not normal and should prompt immediate evaluation to assess for potential nerve injury.