Effects of Cerebral & Peripheral Electrical Stimulation on Pain and Function in CTS

This is a randomized, double-blind, multi-center, factorial clinical trial to study the effectiveness of cerebral and peripheral electrical stimulation on pain and functional limitations associated with carpal tunnel syndrome (CTS). The study subjects will be randomly into four groups; (1) active trans-cranial direct current stimulation (tDCS) + active trans-cutaneous electrical nerve stimulation (TENS), (2) active tDCS + sham TENS, (3) sham tDCS + active TENS and (4) sham tDCS + sham TENS. The patient will be assessed by Brief Pain Inventory (BPI), Beck Depression Inventory (BDI), The Douleur Neuropathique en 4 questions (DN4), Quantitative sensory testing (QST), Pain Pressure Test (PPT) with algometer, Conditioned pain modulation (CPM), Patient ratings of improvement, or worsening, of the pain condition, Quality of Life short-form (SF)-36, Visual Analog Mood Scale (VAMS), Mini Mental Status Exam (MMSE) and Adverse Events Questionnaire (AEs). This study aims to investigate whether cerebral and peripheral electrical stimulation combined are more effective in relieving pain and functional limitations than the separate application of electrical stimulation in patients with CTS.

The study will be carried out on patients attending (1) Physical Medicine, Rheumatology and Rehabilitation outpatient clinic in Suez Canal University Hospital, Ismailia, EGYPT, (2) Hiroshima University, (3) Department of Physical Medicine \& Rehabilitation, Juan Ramón Jiménez University Hospital, Huelva, Spain, and (4) University of Sherbrooke, Canada and diagnosed with CTS according to clinical examination and to the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) practice recommendations for CTS.

Study subjects will be divided into four groups:

Group (1): (active comparator = tDCS-real (r) + TENS-r) will include 45 patients with CTS and will receive active anodal tDCS of M1 for 20 minutes, at 2 mA plus active TENS (the cathode will be placed on the carpal ligament, and the anode electrodes on the palmar area of the hand) for 20 minutes, and a total of 15 sessions for 3 weeks (5 per week) will be completed.

Group (2): (experimental group= tDCS-r + TENS-sham (s)) will include 45 patients with CTS and will receive active tDCS M1 for 20 minutes plus sham TENS for 20 minutes, and a total of 15 sessions for 3 weeks (5 per week).

Group (3): (experimental group= tDCS-s + TENS-r) will include 45 patients with CTS and will receive sham tDCS M1 for 20 minutes (the set will be turned off after 30 seconds) plus active TENS for 20 minutes, and a total of 15 sessions for 3 weeks (5 per week).

Group (4): (sham comparator = tDCS-s + TENS-s) will include 45 patients with CTS and will receive sham tDCS M1 for 20 minutes (the set will be turned off after 30 seconds) plus sham TENS for 20 minutes, and a total of 15 sessions for 3 weeks (5 per week).

The study sample will be collected from all patients with CTS fulfilling the eligibility criteria, will be eligible to join the study (either referred for electrophysiological study or presented to the clinic for primary assessment). To make sure that no bias should enter the assessment of the results, neither the patient nor the clinicians will be aware whether active tDCS/TENS will be applied to a particular case. To ensure this result, one symbol of these four symbols (square, circle, star and triangle) will be applied to one group of the four groups in the physiotherapy sheet and only the physiotherapist knew the key for each symbol. At the end of the study, the four groups will be revealed in order to analyze the results according to proper statistical measures.

Eligibility Criteria:
Inclusion Criteria:

* Males and females aged \>18 years and \<65 years.
* Paresthesia, pain or vasomotor symptoms through the distribution of median nerve (persistence \> 2 months).
* Positive result for Phalen's, Tinel's and/or carpal compression tests during physical examination.
* Mild-to-moderate severity of CTS according to American Association of Neuromuscular \& Electrodiagnostic Medicine (AANEM) 2002 (mild: abnormal sensory peak latency \[≥3.5ms\] with normal motor distal latency \[\<4.4\]; moderate: abnormal sensory \[≥3.5ms\] and motor \[≥4.4ms\] latencies).

Exclusion Criteria:

* Previous history of wrist surgery
* Presence of predisposing etiological factors for CTS (e.g., diabetes mellitus).
* Trauma, neurological, psychiatric, rheumatic diseases, renal failure, pregnancy, hypothyroidism, and hyperthyroidism.
* Presence of conditions that might cause numbness in the hand, including cervical radiculopathy, cervical ribs, plexopathy, and polyneuropathy.
* Pharmacological treatment with oral steroids or non-steroidal anti-inflammatory drugs within the previous month.
* Participation in a physical therapy program.
* Administration of steroid injection(s) within the previous 6 months.
* Previous treatment with TENS \<6 months.
* Previous treatment with tDCS.
* Use of pacemakers or other implanted devices.
* Pregnancy or breastfeeding.
* Refuse to participate.