Comparison of Injection Techniques in Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS), the most prevalent peripheral compressive neuropathy, manifests primarily with sensory disturbances such as pain, numbness, and nocturnal paresthesia. Treatment options for CTS differ considerably depending on the severity of symptoms, and typically include splinting, physiotherapy, local injection therapies, and surgical release. Hydrodissection is an ultrasound-guided technique that has recently gained increased attention for its role in the management of nerve entrapment syndromes. The technique uses fluid injection to separate the nerve from nearby tissues. This may reduce perineural adhesions and improve the patient's symptoms. In hydrodissection, normal saline, 5% dextrose, or platelet-rich plasma (PRP) can be used as injectates. Recently, hydrodissection with 5% dextrose has become the most commonly used approach. Several studies in the literature have demonstrated that perineural hydrodissection with 5% dextrose provides more favorable outcomes than corticosteroid injections in patients with mild to moderate CTS, particularly at 4 to 6 months post-injection. However, it remains unclear whether hydrodissection leads to a reduction in the cross-sectional area of the median nerve. In addition, studies examining the procedural details of hydrodissection are limited. Therefore, further clinical research is needed to better understand and validate the technique.

Ultrasound-guided hydrodissection for CTS is performed using a 12 MHz linear array transducer probe (GE Logiq P9, GE Healthcare, Boston, MA). The median nerve (MN) is visualized at the scaphoid-pisiform level. In the intervention group, 2.5 ml of 5% dextrose is injected via an in-plane ulnar approach to separate the MN from the transverse carpal ligament, followed by an additional 2.5 ml of normal saline (NS) injected to separate the MN from the flexor tendons. In the control group, perineural injection of 1 ml betamethasone is administered around the MN using the same ultrasound device and probe.

• 5% Dextrose (Drug): Ultrasound-guided hydrodissection is performed using a 12 MHz linear transducer (GE Logiq P9, GE Healthcare) via an in-plane ulnar approach under sterile conditions. 2.5 ml of 5% dextrose will be injected via an in-plane ulnar approach to mechanically separate the median nerve from the transverse carpal ligament. Subsequently, an additional 2.5 ml of 5% dextrose will be administered to separate the nerve from adjacent flexor tendons. The total injection volume will be 5 ml.
• Betamethasone and local anesthetic (Drug): Ultrasound-guided perineural injection is performed using a 12 MHz linear transducer (GE Logiq P9, GE Healthcare) via an in-plane ulnar approach under sterile conditions. A total of 2 ml solution (1 ml betamethasone and 1 ml 2% lidocaine) is injected perineurally around the median nerve under ultrasound guidance at the scaphoid-pisiform level.

Primary outcomes

• Boston Carpal Tunnel Questionnaire [At baseline, at Month 1,3,6 (Visit 1,2,3)]: The Boston Carpal Tunnel Questionnaire (BCTQ) is a validated disease-specific assessment tool developed in 1993 to provide standardized clinical evaluation of carpal tunnel syndrome (CTS). It comprises 19 items divided into two subscales: the Symptom Severity Scale (BCTQ-SSS) and the Functional Status Scale (BCTQ-FSS). Scores on both subscales range from 1 to 5, with higher scores reflecting increased symptom burden and functional impairment associated with CTS.

Secondary outcomes

• Visual Analog Scale (VAS) [At baseline and at Month 1,3,6 (Visit 1,2,3)]: Patients rate their pain on a 0-10 scale. A lower score indicates reduced pain.
• Cross-Sectional Area (CSA) of the Median Nerve via Ultrasonography [At baseline and at month 3,6 (Visit 2,3)]: Median nerve CSA will be measured at the scaphoid-pisiform level. A reduction in CSA indicates improvement.
• Hand Grip Strength [At baseline and at Month 3,6 (Visit 2,3)]: Hand grip strength will be measured using a standard Jamar dynamometer. During the procedure, patients will be seated with the elbow flexed at 90° and the forearm in a neutral position. Three consecutive measurements will be taken, and the average value will be recorded. Improvement reflects functional recovery.

Sex: All, ages: 20 Years to 80 Years

Inclusion Criteria:

* Patients diagnosed with unilateral moderate carpal tunnel syndrome (CTS) confirmed by an electrophysiological study within the last 6 months
* Presence of at least one of the following symptoms lasting more than one month:

  * Paresthesia/dysesthesia accompanied by weakness and clumsiness in the hand, worsened by repetitive wrist use or sleep, and relieved by postural correction or shaking of the hand
  * Numbness due to sensory disturbance in the median nerve (MN) distribution
  * Thenar muscle weakness with atrophy
  * Positive Tinel's sign or Phalen's test
* Pain intensity of ≥4 out of 10 on the Visual Analog Scale (VAS) prior to treatment

Exclusion Criteria:

* History of previous wrist surgery, polyneuropathy, brachial plexopathy, or thoracic outlet syndrome
* Presence of systemic infection
* Pregnancy
* Prior corticosteroid injection for CTS