Efectividad de la terapia manual y de la electroestimulación nerviosa transcutánea en la reducción del dolor en pacientes con cervicalgia mecánicaensayo clínico aleatorio en atención primaria

Abstract

Spasm of the neck muscles (mechanical neck pain) is a common phenomenon. It can be classified according to the duration of symptoms: acute neck pain (< 7 days), subacute neck pain (between 7 days and 7 weeks) and chronic neck pain (> 7 weeks). Neck pain (subacute or chronic) is one of the most common presenting symptoms of cervical spine disease treated in the primary care Physiotherapy Units. Manual therapy and Transcutaneous Electrical Nerve Stimulation (TENS) are recommended techniques when treating Mechanichal Neck Disorders in the primary care public sector physiotherapy services. Both therapies are accepted as standard clinical practice and the choice of one or the other depends on the physical therapist’s decision. Manual therapy treatment involves the “laying on of hands”. Manual therapies encompass all procedures in which the hands are used to mobilize, adjust, manipulate, apply traction, massage, stimulate or otherwise influence the spine and paraspinal tissues. Manual therapies include manipulation, passive mobilization, neuromuscular mobilization therapies and massage/soft tissue therapies. Transcutaneous electrical nerve stimulation (TENS) is a common modality for treating musculoskeletal pain consisting of electric currents in the affected area. According to the systematic reviews recommend some conservative interventions for neck pain, like manual therapy combined with exercise. However, none of these interventions was shown to have lasting benefit. There was no previous literature reporting the real effectiveness of TENS in patients with neck pain. Hypothesis: Manual Therapy is more effective than TENS to reduce pain intensity in patients with mechanical neck disorder (chronic or subacute) without signs of neurological damage. Objective: To compare the effectiveness of manual therapy with TENS to reduce pain intensity in patients with mechanical neck disorder (chronic or subacute), 6 months after the intervention and after this one. Design. A controlled multi‐centered clinical trial with parallel groups, by random assignment and with a blind evaluation of the response variable. Project approved by an ethical review board. This study was funded by the Instituto de Salud Carlos III, Fondo de Investigación Sanitaria/Fondos Europeos de Desarrollo Regional (04/1320). The trial has been registered as NCT01153737 at www.ClinicalTrials.gov. Thirteen primary health care physiotherapy units of the Madrid Region took part in the study and applied the interventions. Setting. Thirteen primary care Physiotherapy Units in Madrid Region, in health centres of these cities: Madrid, Alcalá de Henares, Torrejón de Ardoz, Arganda, Fuenlabrada and Humanes. The reference population was 1,317,977 people in the Madrid Region. Recruiting period: from may‐2005 to may‐2007. Patients. Mechanical neck disorder patient aged between 18 and 60 to be treated in primary health care physiotherapy units. The physical therapist valued selection criteria: Inclusion criteria: Diagnoses of subacute or chronic mechanical neck disorder without neurological damage; full physical and psychological capacity to follow the clinical trial’s requirements; and their consent to participate. Exclusion criteria: Pregnant women, previous neck rachis surgery, patients who received physical therapy or an alternative treatment of the neck or shoulder 6 months prior to the beginning of the study, those who intended to receive other treatments during the study or those with important psychiatric disorders. Patients with neck pain caused by an inflammatory, neurological or rheumatic disease, severe osteoporosis, fracture, luxation or vertebrobasilar insufficiency were also excluded from the study. Subject selection. The patients sent from the primary care doctors who satisfied the inclusion criteria were selected in a consecutive manner. Randomisation. Allocation was on the basis of block randomization in order to obtain two equivalent groups. Interventions. Each physical therapist applied the therapy assigned to each patient, either TENS or manual therapy. During the planning of the study the physical therapists received one session of training to assure homogeneity between the different interventions and a different session for the evaluation group (to collect and to register data). Each professional also received written documentation: development study protocol (one with the intervention procedure and another one with the evaluation procedure), notebooks to record the information, copies for the patients of the recommended postural skills and exercises. Ten treatment sessions of 30 minutes of manual therapy or TENS on alternate days were provided by primary care physical therapists. The TENS and manual therapy techniques were defined in the study protocol. TENS electrode placements were: in the painful area, in the metamere or in the nerve´s pathway. The following manual therapy techniques were carried out: neuromuscular te postisometric stretching, spray and stretching and non invasive treatment of the trigger points. Main measurements. Three evaluations were performed by physiotherapists who were unaware of which procedure each patient had received: before the intervention, when the intervention finished and six months after. The primary outcome was pain intensity measured in millimeters using the Visual Analogue Scale. Also quality of life, disability, adverse effects and sociodemographic and clinical/prognosis variables were measured. Analysis strategy. A descriptive analysis of the characteristics of the patients included in the study was performed. Moreover an effectiveness analysis and multivariable models were performed. An intention to treat analysis was performed in the main variable. The analysis of effectiveness was performed using the outcome measurements: pain reduction (mm in the VAS) and improvement in the general health state. It was performed comparing the differences obtained before and after the intervention (short term) and before and 6 months after the intervention (medium term) in both therapies. A bivariate statistical test and a multivariate analysis were performed to evaluate possible associations between the patients’ characteristics and the degree of satisfaction and expectations concerning the treatment. Adverse effects were also described. Results: A total of 90 patients were selected at random: 47 patients received manual therapy and 43 TENS. Overall, 71 patients (79%) completed the follow‐up measurement at six months. Three patients dropped out after the intervention (two of them for improvement and the other by no location). Along the track there were 16 new losses. Finally, 71 patients (79%) completed the follow‐up study (at six months). Baseline characteristics of the subjects in the intervention groups (manual therapy or TENS) were homogeneous. The physiotherapy treatment techniques tested produced a reduction in pain intensity clinically relevant (pain reduction greater than 20 mm on the VAS, in both groups), at the short term. The success rate decreased to one‐third of the patients 6 months after the intervention. However, the mean reduction in clinical significance pain in both groups (15 mm in manual therapy group and 13 mm in TENS group) disappears in the medium term. No differences can be found in the reduction of pain between both therapies. The quality of life (SF‐12, physical and mental component) improved in the manual therapy group at the short term and in the medium term (improvement average: 4/100 points). Improvement was below the average population level (< 50). No differences can be found in the improvement of quality of life between both therapies. There were no adverse effects associated with any of the therapies used (short term or medium term). All patients waited for some improvement (greater or lesser degree). 21% of patients waited for a full recovery (among the 73 patients with previous episodes of neck pain). This percentage was 54% in patients without previous episodes of neck pain. The evaluators asked the patients whether they were satisfied after the therapy and all of the patients with a clinically relevant reduction of pain (100%) were satisfied with the treatment, manual therapy or TENS (EVA reduction > 20 mm), p=0.05. Conclusions: TENS or manual therapy use in patients with mechanical neck disorders produces a decrease in pain intensity, at the short term and at medium term; however, this reduction is clinically relevant at the short term. The quality of life improvement was below the average population level (< 50), without changes from baseline. The quality of life (physical and mental component) improved in the manual therapy group at the short term and in the medium term. Improvements in both groups were small and there weren’t statistical differences (at short term and at medium term). The adverse effects of the therapies application were rare and little clinical relevance. Satisfaction of patients with the therapies was high. Patients who experienced a greater pain reduction were more satisfied, regardless of type of intervention applied, TENS or manual therapy, and their previous expectative.