Dextrose, Corticosteroids and Surgical Release in Carpal Tunnel Syndrome

Efficacy of Dextrose Injections, Corticosteroids Injections and Surgical Release for Treatment of the Carpal Tunnel Syndrome: a Prospective, Randomized, Double-blind Controlled Trial

The objective of the present study is to compare the effectiveness of 5% dextrose, local corticosteroids injections and surgical release in patients with electrodiagnostically (EDx) mild to moderate carpal tunnel syndrome (CTS). The investigators hypothesize that in patients with mild to moderate CTS (1) local 5% dextrose injections is non-inferior to local corticosteroid injections at 12 months after treatment, and that (2) local 5% dextrose injections are of non-inferior effectiveness compared to surgical release at 6 months.

Surgical release of the carpal ligament is a standard treatment of the median nerve entrapment at the wrist. Local corticosteroid injections are also an established alternative, particularly for EDx mild or moderate CTS, although majority of patients still needs surgical decompression within 1 year. Majority of studies concluded that after more than 6 months of treatment surgical decompression is better than local corticosteroids injections. Furthermore, corticosteroids also have a number of side effects, including crystal induced synovitis, tendon rupture, axon and myelin degeneration, soft tissue atrophy, skin thinning, steroid flare and hot flushes. Therefore, it would be very useful to have an effective alternative substance for injections, without these problems. Perineural injection of dextrose also seems to be a promising treatment for entrapment neuropathies. To date only two studies investigated the effectiveness of 5% dextrose injections in patients with CTS. Authors concluded that this is an effective treatment, that is for patients with mild or moderate CTS even more beneficial than corticosteroid injections at 6 months follow-up. It was suggested that perineural injection of 5% dextrose decreases neurogenic inflammation. As 5% dextrose has osmolarity similar to normal saline, this formulation seems particularly promising. These expectations were supported in studies including animals and humans reporting no harmful effects.

Patients with bilateral CTS symptoms and EDx mild to moderate CTS will be included. In the first part of the study examiner will randomize substance for left hand infiltration using a dice (odd number - corticosteroids; even number - 5% glucose). Right hand will be infiltrated with the remaining substance. In the second part of the study examiner will randomize treatment procedure for left hand using a dice (odd number - corticosteroids or 5% glucose; even number - surgery). Substance for injection will be determined according to the results of the first part of the study - more effective one, or in case of non-inferiority 5% glucose will be used. In all patients included in the second part of the study surgical release will be performed by the same plastic surgeon. Both treatments will be performed maximally 2 months after diagnosis, with maximum period between them of 1 week.

Each of three investigators performing one part of diagnostic evaluation (history and focal neurologic examination, EDx and (3) ultrasonographic (US) studies) will be blinded for findings of other parts of evaluation. Furthermore, patients will be blinded for laterality of the injected substance.

In the first part of the study examiner will randomize substance for left hand infiltration using a dice (odd number - corticosteroids; even number - 5% glucose). Right hand will be infiltrated with the remaining substance.

In the second part of the study examiner will randomize treatment procedure for left hand using a dice (odd number - corticosteroids or 5% glucose; even number - surgery). Substance for injection will be determined according to the results of the first part of the study - more effective one, or in case of non-inferiority 5% glucose will be used. Surgical release will be performed by the same plastic surgeon. Both treatments will be performed maximally 2 months after diagnosis, with maximum period between them of 1 week.

US guided injection of corticosteroid in one hand and 5% glucose in the other will be performed in accordance with randomization. In a syringe both substances will be diluted using 0.9% NaCl to a total injection volume of 6 ml. In-plane ulnar approach will be used to visualize the median nerve at the level of the pisiform bone. A standard 23 gauge needle will be inserted in the carpal tunnel with the needle tip positioned between retinaculum and median nerve.

Injection will be performed unilaterally, after randomization of sides, by the same examiner as in the first part of the study. In all patients included in the second part of the study surgical release will be performed by the same plastic surgeon. The procedure will be performed under local anesthesia, following the same standard protocol. Both treatments will be performed maximally 2 months after diagnosis, with maximum period between them of 1 week.

The Visual Analog Scale (VAS) will be used to assess severity of digital paresthesia/dysesthesia and wrist or hand pain on 11-point grading scale. Scores ranges from from 0 to 10 points, with higher scores indicating greater severity of CTS symptoms (0 - no symptoms; 10 - extremely severe symptoms).

At 1-, 3-, 6- and 12-month follow-up assessments, CTS symptoms relief after treatment will be evaluated and categorized as one of the following: (1) much improved, (2) improved, (3) no change, (4) worse, or (5) much worse. Patients in category 1 or 2 will be considered to have effective treatment.

The self-administered Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) (Levine et al., 1993) includes 2 subscales of symptoms severity (11 questions) and functional status (8 questions). It is the most commonly used measurement for CTS. Scores ranges from 0 to 5 points for each question, with higher scores indicating greater severity and dysfunction.

Distal motor latency (DML) will be measured with median nerve stimulation 8 cm proximal to the active electrode over the abductor pollicis brevis muscle in each hand before and at 1-, 3, 6 and 12 months after treatment.

Ulnar and median antidromic sensory nerve action potentials (SNAPs) from 4th finger will be recorded on the nerve stimulation 14 cm proximal to recording electrode placed at the middle of the first phalange and SNAP latency difference calculated.

Cross-sectional Area (CSA) of the median nerve will be measured at the wrist and 15 cm proximal at the forearm using a trace method with exclusion of the hyperechoic rim.

Palmar bowing of the flexor retinaculum is a measure used to quantify the internal pressure exerted on the retinaculum from the contents within the carpal tunnel as the perpendicular distance between flexor retinaculum and tangential line between the tip of the pisiform and scaphoid bone.

Inclusion Criteria (subject diagnosed as CTS if meeting criterion 1 + at least one of criteria 2 or 3): numbness and tingling in at least two out of the first four digits; symptoms exacerbated during the night or in the morning, on holding the objects or repetitive use of the hand; symptoms relieved by shaking the hand or reposition of the arm. In addition to these clinical criteria for recruitment EDx confirmation will also be needed. Only patients with bilateral EDx mild to moderate CTS will be included. Exclusion Criteria: polyneuropathy, symptoms of polyneuropathy, and all conditions causing polyneuropathy (e.g., diabetes); multiple mononeuropathy (e.g., hereditary neuropathy with liability to pressure palsies, syndrome Lewis Sumner); motor neuron disorders (e.g., monomelic amyotrophy, amyotrophic lateral sclerosis - ALS); brachial plexopathy; other focal neuropathies affecting upper limbs (e.g., other median neuropathies, ulnar neuropathies, thoracic outlet syndrome); or previous surgery or local injections for CTS.

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