Dry needling is possibly one of the most popular physiotherapy techniques in Spain and in the rest of the world in recent years,. This has been reflected in the high number of research studies and publications analysing the effectiveness of dry needling in the treatment of pain caused by myofascial trigger points (MTrPS). Studies comparing dry needling with non-physiotherapeutic treatments, such as infiltration of lidocaine or botulinum toxin, which demonstrates that dry needling is as effective as infiltration when both techniques provoke local twitch responses (LTR), i.e. involuntary contractions of the fibres in which the MTrP is housed. In fact, some research work shows that, in certain circumstances, dry needling is more effective than lidocaine infiltration1. When we talk about neurological physiotherapy, whether in adults or children, ˜ the physiotherapist encounters two main problems when it comes to defending the effectiveness of the techniques used in this field. On the one hand, as with orthotic, medical or surgical treatment, the changes achieved through physiotherapy are often so small or so difficult to quantify with the means usually available in consultation, or occur in such a long period of time in comparison with other fields of physiotherapy, which involves that the physiotherapist specialist in neurology has to set objectives and deadlines differently from those working in other fields. On the other hand, despite the fact that neuroscience studies tell us about the great plasticity of our central nervous system (CNS), it is common to find among affected patients and their families, and sometimes among health professionals themselves, an absolute lack of confidence and faith in the patient's chances of recovery. Unlike work in other areas of physiotherapy, the field of neurological physiotherapy tends in general to the application of treatments based on global concepts, often not considering certain analytical treatments. From our point of view, there is enugh scientific evidence to support the use of dry needling as a complementary tool in the treatment of patients with CNS lesions, as it can contribute to the achievement of certain effects that with other techniques do not seem a priori attainable. Dry needling treatment has also been applied in neurological patients for the treatment of shoulder pain2 with good results, although the application technique does not differ from those usually used for the treatment of pain of myofascial origin. However, since 2004 there have been experiences based on clinical cases developed by Spanish physiotherapists that show therapeutic effects of dry needling in hypertonia and spasticity3,4. Although these results must be taken with caution since the evidence shown by these clinical case studies does not allow establishing a cause-effect relationship, they do serve as an important starting point, as well as confirming the pioneering work being carried out in Spain. ˜ The study published by Herrero et al establishes essential and confirmatory diagnostic criteria by analogy with the published criteria for the diagnosis of myofascial pain syndrome5 and, furthermore, discusses both the neurophysiological bases justifying the use of the technique and a possible hypothesis as to why a reduction in hypertonia and spasticity is being achieved, all based on current knowledge of MTrPs and their neurophysiology. As a result of this publication and other unpublished studies, the so-called DNHS© (dry needling for hypertonia and spasticity) technique was developed, which includes in its registration document the essential and confirmatory diagnostic criteria, the neurophysiological bases on which it is based and the guidelines for its clinical application. The DNHS© technique is more a treatment concept than a technique in itself, in the sense that strict technical application can be made through technical procedures described by authors for the treatment of myofascial pain (Hong's rapid entry and exit technique or other forms of needle manipulation). The patient's approach is mainly the form of assessment, which is based on the analysis of hypertonic and spastic muscles, and the alteration of regional and general muscle function. In addition, it should be taken into acount that the activating and perpetuating factors in the patient with CNS injury differ substantially from the patient without CNS injury, as well as many other clinical aspects that condition the rest of the treatment and self-treatment, such as the difficulty in performing certain exercises autonomously. Based on these initial publications, a pilot study with a larger sample and a different pathology than the initial studies, was carried out This study, which was presented by Trenado et al6 in 2009 at the I Jornadas de Dolor Miofascial by means of an oral communication, investigated the effects of DNHS© on the affected upper limb of 5 patients with spastic hemiplegia. The results were improvement in the active and passive joint range, decrease in hypertonia and spasticity, and an increase in the subjective perception of improvement measured with the visual analog scale, although all of them were statistically non-significant. The diffusion of this concept of treatment in different communications, lectures and courses has served to form a group of physiotherapists and achieve that there are associated entities that offer this treatment within their portfolio of physiotherapy services, as is the case of the Association for Research on Motor Disability and the Foundation Dano˜ Cerebral Sobrevenido de Aragón, which have been applying the technique to an increasing number of patients. The clinical experiences obtained have allowed us to observe certain functional changes that cannot be explained by the changes derived from the local treatment of MTrP nor by the interrelations between the segmentally mediated agonist-antagonist muscles and influenced by the modification of reflex arcs, such as those that mediate in the LTR. These changes observed in patients with different pathologies have had a lot to do with the overall execution of the movement, an aspect that has been especially evident in patients with ataxia and spasticity, where a better control of the movement has been observed just after the needling, with maintenance of the effects for a period of no less than 4 weeks, as a general rule. Although the opening of certain pathways or channels of neuronal connection at the medullary level by analogy with the concept of central sensitization is a hypothesis of these changes, there are certain clinical changes in some treated patients that can only be due to changes in the processing of sensorimotor information at a higher level within the CNS. As a result of this need to explain clinical findings, the DNHS© research line has been created, linked to the consolidated research group GIMACES of the San Jorge University (USJ) and on which doctoral studies in physiotherapy are being developed. Along these lines, the initial team of physiotherapists was joined by a series of medical collaborators from different specialties (mainly neurologists and rehabilitation), experts in electroencephalography from the Bioinformation Research Group attached to the Aragonese Institute of Health Sciences and experts in pharmacoeconomics from the USJ to analyze from an economic point of view the use of the technique in comparison with other treatments, such as botulinum toxin type A. Returning to the comment made previously about the great plasticity of our CNS, DNHS© seems to have the possibility of acting on this remodelling and plasticity at different levels. At the local level, due to the changes produced in the MTrP after needling: cleaning sensitizing substances and mechanical disruption of the dysfunctional motor plates which, according to the most solvent etiopathogenic hypothesis, constitute the cause of the MTrP. The changes produced at this level, although they are still local structures, can influence the rest of the CNS to the extent that they modify the processing of sensorimotor information from the periphery. It should not be forgotten that, due to the specific characteristics of the patient with CNS disorders, the presence of MTrP seems, a priori, to be much greater than in the population without CNS pathology, in addition to presenting important perpetuation factors that in most cases will accompany ˜ the patient for the rest of his life. The treatment of these dysfunctional motor endplates would explain the changes in hypertonia, understood as "resistance to passive movement" due to the decrease in spontaneous electrical activity in the MTrP Furthermore, bearing in mind that LTR has been shown to be a medullar reflex, it could be hypothesized that LTR obtained with invasive treatment of MTrPs could have some neuromodulatory effect on another medullar reflex with which it shares some characteristic, the myothatic reflex, clearly implicated in the phenomena of spasticity and hypertonia. This segmental connection and its possible expansions to other medullary segments could explain the functional changes found in some patients (improved coordination between agonists and antagonists in certain motor executions). However, certain clinical findings could not be explained only by the changes described above, which is why disenó˜ was a pilot study with two patients who were measured electroencephalographic activity in different brain regions, both in absolute values and values of electroencephalic cord. Currently, advances in this line are focused on conducting studies with larger samples and with more objective means of assessment, such as electroencephalography mentioned above and movement analysis in motion analysis laboratory.
Como conclusión, nos gustaría destacar que la DNHS© puede ser una herramienta de trabajo muy útil para el fisioterapeuta, entendiéndose esta técnica como una más dentro del tratamiento que se ofrece a estos pacientes con lesión en el SNC y que además debe ser complementada con las mejores técnicas globales disponibles. Aunque existen muchas incógnitas sobre sus mecanismos de acción y muchas dudas sobre los mejores protocolos de aplicación, músculos diana, etc., se han sentado las bases de un trabajo que, por su carácter innovador y por su fundamentación neurofisiológica, debería abrir nuevas perspectivas en el tratamiento de este tipo de pacientes