Effectiveness of an Invasive Physical Therapy Protocol in Carpal Tunnel Syndrome: Randomized Controlled Clinical Trial

Carpal Tunnel Syndrome (CTS) is the most common peripheral neuropathy due to entrapment, caused by compression of the median nerve as it passes under the transverse carpal ligament at the wrist. The prevalence of CTS is between 5% and 20% in the general population, according to the criteria used. It stands at 10% when following the criteria established by the National Institute for Occupational Safety and Health.

Within the prevalence, 1% are men and 7% women, with an incidence per year of 105 cases per 100,000 people. In 2019, the external consultant "statista" indicated that approximately 924,000 cases of CTS were registered in Spain. CTS generates large saturations in rehabilitation in primary care and in preoperative lists, for example, in 2008 there were 4,109 hospital admissions with a rate of 0.18 hospital discharges per thousand.

Risk factors for the development of CTS include female sex, older age, diabetes, menopause, hypothyroidism, obesity and pregnancy. Smoking appears to be a risk factor in the development of CTS. As well as wrist hyperflexion and hyperextension movements. The number of risk factors present progressively increases the prevalence of CTS.

CTS is characterized by the presence of neuropathic pain, nocturnal paresthesias and dysesthesia. It can be combined with loss of strength and atrophy of the tenar muscles. Therefore, the most severe cases produce very notable physical, psychological and economic consequences. For example, in the United States, CTS generates an annual primary care expenditure of $2 billion. Currently, the most recent clinical guidelines recommend the use of orthoses, exercises and manual therapy in the management of CTS, although there is no consensus on the most effective option. On the other hand, surgery is one of the most used therapeutic options. However, there is a great collapse of the health system and the waiting list for the intervention and it can take a long time.

The conservative therapeutic options used to date focus on the local approach to CTS at the wrist, and a recent systematic review has shown a high rate of surgical need (around 60%) at 3-year follow-up. This need for surgery may be reduced in the long term to 15% if the conservative approach includes maneuvers focused on desensitization of the central nervous system, performing an approach to the entire upper extremity. Current evidence suggests that CTS is a complex disorder, which presents sensitization mechanisms of the nervous system, and not only a peripheral nerve compression at the carpal tunnel level. Therefore, approaches and therapies with a central effect are hypothesized to be of future interest, in accordance with current nociceptive theories of CTS.

In the field of physiotherapy, novel techniques have been developed in recent years, such as ultrasound-guided percutaneous musculoskeletal electrolysis and ultrasound-guided percutaneous neuromodulation, in which different types of electrical current are applied through solid needles.

Different mechanisms of action have been associated with these invasive techniques, such as a potential effect on the activation of the descending pain inhibitory system pathways, the reduction of evoked motor potentials and an increase in intracortical inhibition, suggesting benefits in patients with central sensitization.

Invasive electrolysis and neuromodulation techniques have been applied in other studies at the nerve level, especially in the sciatic nerve at the piriformis and hamstrings level, in the popliteal fossa and in the foot. However, there is no study performed in patients with CTS.

To date, there is no clear consensus on the therapeutic approach to CTS, and the application of these invasive physiotherapy techniques is a novel approach that encompasses the local effect of treatment by means of local ultrasound-guided insertion of the needle in the carpal tunnel and the central neurophysiological effect produced by the current when it is applied. Taking into account the good empirical results found in private clinics and the precedents of studies carried out in other nerves, this treatment approach for outpatient application in primary care centers could relieve the demand for hospital care for patients referred for surgical treatment.