Relation between Latency Changes and Functional Outcome in Carpal Tunnel Syndrome: Insights from Local Corticosteroid Injection Therapy

Dear Editor, We read with great interest the recent article by Shalu et al., “Relation between Latency Changes and Functional Outcome in Carpal Tunnel Syndrome: Insights from Local Corticosteroid Injection Therapy.”[1] The idea of correlating nerve conduction studies (NCS) with clinical outcomes in carpal tunnel syndrome (CTS) is admirable. They demonstrated that the local corticosteroid injections in CTS were not only effective in pain relief and improving functional status but also in improving NCS post-injections. We would like to add some comments that could be of interest to your readers. To our knowledge, this is the first study where the follow-up of NCS is done so precociously, only 4 and 6 weeks after local corticosteroid injections in CTS. In other similar studies, the follow-up NCS in CTS patients had been performed, as early, 3–6 months post-treatment, not after 4 and 6 weeks. In Demirci’s et al.’s study,[2] NCS performed 3–6 months after treatment, only the surgical treated patients improved their NCS, not the injected ones. In Naidu’s et al.’s study,[3] 50 patients were treated with decompressive surgery; in the 6-month follow-up, there was an improvement both clinically and in NCS. In Hui’s et al.’s randomised study,[4] 25 patients were assigned to decompressive surgery and 25 to local corticosteroid injections; in the 5-month follow-up, NCS only improved in the decompressive surgery group but not in the local corticosteroid injection group. In our randomised study by Andreu et al. (2014),[5] we included 163 wrists, 80 assigned to surgery and 83 to local corticosteroid injections; in the 12-month follow-up, despite clinical improvement was equal in both groups, only surgically treated wrists improved their NCS but not the injected ones. In summary, all of the previous studies could demonstrate NCS improvement in CTS treated with decompressive surgery, 3–12 months after treatment. On the contrary, none of these studies could demonstrate improvement in NCS after local corticosteroid injections in that period of time. All these results from different studies, taken into consideration together, may suggest to us that in CTS treatment, despite both local corticosteroid injections and decompressive surgery are very effective in treating CTS symptomatology, only surgery results in a long-term improvement of the NCS parameters, after 3- to 12-month follow-up. We believe that the contribution of Shalu et al.[1] is important because it shows that local corticosteroid injections not only improve clinical signs and symptoms of CTS in the short term, but also NCS can improve temporary, at least during these first weeks after treatment. Nevertheless, it is possible that both NCS and clinical improvement post-local injections may disappear in the long term (1-year) follow-up. It would be very interesting if Shalu et al. could repeat in the 12- or 24-month follow-up, updated NCS to ascertain if this improvement remains long term, both clinically and electrophysiologically. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.