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.

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