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.

Inclusion Criteria (subject diagnosed as CTS if meeting criterion 1 + at least one of criteria 2 or 3):

1. numbness and tingling in at least two out of the first four digits;
2. symptoms exacerbated during the night or in the morning, on holding the objects or repetitive use of the hand;
3. 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:

1. polyneuropathy, symptoms of polyneuropathy, and all conditions causing polyneuropathy (e.g., diabetes);
2. multiple mononeuropathy (e.g., hereditary neuropathy with liability to pressure palsies, syndrome Lewis Sumner);
3. motor neuron disorders (e.g., monomelic amyotrophy, amyotrophic lateral sclerosis - ALS);
4. brachial plexopathy;
5. other focal neuropathies affecting upper limbs (e.g., other median neuropathies, ulnar neuropathies, thoracic outlet syndrome); or
6. previous surgery or local injections for CTS.

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.