In the PENS treatment, a biphasic continuous waveform current with a frequency of 2 Hz, a pulse width of 50 microseconds and an intensity that produces visible motor responses of the innervated muscles was used, below the patient's pain threshold. The NT6021 Percutaneous Neuromodulation equipment of the Nutek® brand distributed by Fisiolab Ibérica® was used. This equipment has the CE marking, which denotes compliance with the requirements of the legislation of Royal Decree 414/1996 of March 1, which regulates medical devices. B.O.E. of April 24, 1996

Useful to identify patients with a pain experience dominated by neuropathic mechanisms. It is based on the analysis of sensory description and exploration of sensory dysfunction at the patient's bedside. It consists of 7 items and is scored from 0 to 24. At a score of less than 12, the neuropathic component is considered unlikely. A score greater than or equal to 12 is considered probable neuropathic pain. It is a validated scale for patients with neuropathic pain.

Screening questionnaire for neuropathic pain. This scale consists of a section dedicated to pain intensity and another that is responsible for assessing the qualitative aspect of pain, i.e., identifying whether the pain is of neuropathic characteristics. In the total of this scale the maximum possible score is 38 points and the minimum -1. For screening purposes, a score less than or equal to 12 is considered an unlikely neuropathic component. A score greater than or equal to 19 concludes that the neurological component in pain is probable.

A unique 11-point numerical scale validated in patients with various painful conditions. Data obtained through NPRS are easily documented, intuitively interpretable, and meet regulatory requirements for pain assessment and documentation. This scale is reliable and validated for assessing patients with pain20. Score 0 corresponds to "no pain" and score 10 corresponds to "maximum possible pain". In this study, patients were asked to mark their maximum pain detected in the last week (NPRS Max) and their minimum pain detected in the last week (NPRS Min).

Nerves react to certain mechanical stresses and forces, but to establish positivity of such tests, the possibilities of "false positivity" due to other non-nerve structures must first be eliminated. The determination of a positive neural test is established by provocation and symptom relief techniques. In this outcome measure only a positive or negative test was considered. The test was positive if the patient's neural symptoms were reproduced during provocation, or negative if no such symptoms occurred.