Open Journal Systems

ORIGINAL CONTRIBUTIONS

Received: April 22^nd 2015

Accepted: July 21^st 2015

Biofeedback treatment for acute whiplash patients

Carmen Lizette Gálvez-Hernández,^a Ma. Dolores Rodríguez-Ortiz,^b Yolanda Del Río-Portilla^c

^aInstituto Nacional de Cancerología, Secretaría de Salud

^bLaboratorio de Psicofisiología, Facultad de Psicología, Universidad Nacional Autónoma de México

^cLaboratorio de Sueño y Coordinación de Psicofisiología, Facultad de Psicología, Universidad Nacional Autónoma de México

Ciudad de México, México

Communication with: Yolanda del Río-Portilla

Telephone: (55) 3988 5098

Email: iyrp@unam.mx

Background: The aim of this study is to evaluate the physiological and psychological effect after an electromyographic biofeedback treatment in combination with progressive muscular relaxation training in patients with acute whiplash.

Methods: Twelve patients with acute whiplash volunteered to participate in a quasi-experimental design and a control group. Inclusion criteria: Two months maximum after car accident, severity levels II and I. Exclusion criteria: previous history of persistent pain or serious previous injury. The groups were randomly divided in two (treatment and waiting list groups). We used electromyographic measures of the trapezius muscles with psychometric tests: Beck Anxiety and Depression Inventory; Oswestry Pain Disability Questionnaire; Visual Analog Scale of Pain; TAMPA Scale for Kinesiophobia. The treatment consisted in electromyographic biofeedback after progressive muscular relaxation training.

Results: There were significant intra-group differences before and after treatment in muscular symmetry and subjective pain perception in the treatment group.

Conclusions: We achieved a significant change (clinical and statistical) in subjective pain perception and muscular symmetry. This study highlights the importance of multidisciplinary work in acute pain patients and the effectiveness of clinical psychophysiological strategies with acute whiplash patients.

Keywords: Neurofeedback; Relaxation therapy; Cervical vertebrae; Whiplash injuries

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Biofeedback (BF) and relaxation techniques (RT) are therapeutic strategies derived from psychophysiological and psychological research. They have consistently demonstrated effective management of chronic musculoskeletal pain; specifically it has been observed that it decreases the perception of intensity, and patients have increased their functionality after the interventions.^1,2

One of the most painful musculoskeletal disorders that remains controversial in its understanding, because its unexpected chronic behavior, and that is also becoming more common because of its close relationship with traffic accidents, is Whiplash (WL). This is defined as a mechanism of acceleration-deceleration of energy transferred to the neck, causing soft tissue injury in the facet joint,³ the zygapophysial joint, the intervertebral discs, and the muscles of the neck and shoulders.⁴ The overall most current reported incidence of WL from traffic accidents from 2000 to 2009 is 235/100,000 inhabitants per year.⁵ WL can lead to a variety of clinical manifestations, which have been termed whiplash-related disorders;⁴ other symptoms in addition to neck pain are: pain in other areas of the spine, paresthesia, fatigue, nausea, cognitive problems, low level of self-perceived physical and psychological health,⁶ depressed mood and anxiety,⁷ and pain in various places, mainly in the posterior trunk.⁸

Symptoms are usually expected to abate in about 3 months. However, it is indicated that 30 to 50% of people report chronic symptoms; this problem has been called delayed or chronic whiplash syndrome, in which case the symptoms are present for more than 6 months and invade and limit the daily life of the patient, which can cause emotional distress and affect mental health, unplanned doctor visits, and days of inability to work, which may involve a financial burden for both the health institution and for the patient themselves.⁴

Given the frequency with which doctors and physiotherapists are confronted with these diagnoses, and in order to direct acute therapy, it seems necessary to seek to reduce healing time and prevent symptoms from becoming chronic.⁹

In this regard, in recent years indications for acute pain management have been proposed that suggest applying intervention based on the influence of cognitive and affective factors in pain interventions,¹⁰ mainly in patients who present incomplete relief after pharmacological intervention.

Conservative treatment of acute management in Mexico, according to Instituto Mexicano del Seguro Social (IMSS) suggests: using a neck brace (soft, semi-rigid, or rigid), assessing neurological status.

Pharmacological treatment: Diclofenac 100 milligram (mg) tablets; acetaminophen 500 mg tablets; adding ranitidine 150 mg tablets in case of acid-peptic disease.

Non-drug treatment: cryotherapy in the first 48 hours after injury. Then start applying surface heat with a hot water bottle, heating pad, or infrared rays on the affected area for 20 minutes or more to achieve vasodilation, muscle relaxation, and decreased pain.

General recommendations: relative rest, normal diet without irritants, communicate with rehabilitation service to request a teaching session or group information about postural hygiene measures for the spinal column.

The situation described leads to the question whether BF and RT may be clinically beneficial in subacute states (6 weeks to 3 months) coupled with traditional medical intervention. All this because the evidence is still scarce and unclear; a study realizes this need for more rigorous, extensive research with control groups, showing moderate certainty about the beneficial and non-beneficial effects of some interventions for acute WL and chronic neck pain.¹¹

In the case of BF, although it has been applied in cases of chronic WL,¹² no statistically significant results have been found; so the question remains whether it will be therapeutically useful for acute patients, and what psychophysiological variables it effects, beyond just measuring the effect through subjective report, for example studying the impact of interventions through recording the activity of muscle pairs (called muscle symmetry).

Even when the effect of multimodal care (e.g. manual therapy, education, and exercises) was evaluated, it was found that although it may be beneficial to patients with previous or persistent symptoms, it is not possible to identify whether any therapeutic package is more effective than another.¹³

The aim of this study was to evaluate the physiological and psychological effect of surface electromyography biofeedback (sEMG BF) in combination with progressive muscle relaxation (PMR) in patients with acute WL. 

Methods

Participants

A non-probability, homogeneous sampling was made of 11 Mexican patients of either sex diagnosed with WL. Inclusion criteria were: voluntary participation (signed informed consent), over 18 years, more than two months after the accident, with injury as a result of car accident, and WL diagnosed with a severity of I or II. Exclusion criteria were: patients with a history of persistent pain, or who have had a serious injury as a result of the accident such as: a) contusion; b) retrograde or post-traumatic amnesia; c) fracture; d) traumatic pathology of internal organs.

Importantly, the sampling was non-probabilistic due to the difficulty to recruit patients, as they only receive outpatient hospital care and, in general, require little extra attention, because of their acute condition.

Location

Facultad de Psicología de la Universidad Nacional Autónoma de México, Mexico City, Mexico.

Design

Quasi-experimental, with 1 control group. The groups were divided by random assignment (raffle) into:

• Group 1 (IG): WL diagnosis, immediate intervention: combined PMR technique and sEMG BF.
• Group 2 (NG): WL diagnosis: no intervention (waiting list).

Physiological responses and psychological variables were monitored, and at the end of the last assessment they were invited to receive the intervention.

Materials

Biofeedback equipment from J & J Engineering I-330-C2 + was used: the bilateral channel for surface electromyography.

Instruments

• Clinical Interview for patients with acute whiplash.
• Beck Anxiety Inventory (Spanish adaptation),¹⁴ is answered by self-report with 21 reagents on the Likert scale that assesses common symptoms of anxiety. The total score is 63, higher scores correspond proportionally to anxiety levels. The Mexican version showed high internal consistency (Alpha of 0.84 and 0.83, for students and adults, respectively), high test-retest reliability (r = 0.75), adequate convergent validity (correlation coefficients between the IAB and IDARE were moderate, positive, and had a p = < 0.05), and a factorial structure of four main factors consistent with that reported by other authors.
• Beck Depression Inventory (Spanish adaptation):¹⁵ a self-administered questionnaire of 21 items that assesses the severity / intensity of a broad spectrum of the examinee’s depressive symptoms at the current time and in the last week. The score ranges 0-63 points. The reliability for internal adaptation consistency was: Cronbach's alpha = 0.67. Factor analysis showed that the Mexican version matches the high values ​​of the original. It has concurrent validity with the Zung scale with a correlation of r = 0.708.
• Oswestry (functional) Disability Index (ODI):¹⁶ A questionnaire that measures the perception of functional disability as a result of the pain experienced. The total score is added, and the final score is described as a percentage. The instrument has proven convergent validity, predictive validity, test-retest reliability, and internal consistency.
• Visual Analog Scale, VAS: An instrument that indicates the subjective intensity of pain on a visual scale. It is regarded as a reliable, valid, and sensitive assessment tool for the intensity of pain.¹⁷
• Tampa Scale for Kinesiophobia (TSK). A questionnaire that evaluates the subjective perception of excessive, debilitating, and irrational fear of movement and physical activity. The total score can be from 17 to 68 points. It has proven criterion and construct validity.¹⁸

Process

First, to do sample collection, the project was submitted to various public health institutions that receive patients in acute stage after trauma, with high frequency due to the type of care offered, in order to locate the largest number of patients from the Secretaría de Salud: Instituto Nacional de Rehabilitación, Hospital General of Queretaro, and Hospital Juarez of Mexico. This was after project approval by the research committees of each institution. Collection took place in the emergency departments of each. Patients identified who met the inclusion criteria were offered a brochure about the project inviting them to participate. Those who contacted us were given an appointment at the UNAM Facultad de Psicología (in the case of hospitals in Mexico City and the State of Mexico); in the case of Queretaro Hospital, they were attended in an emergency or outpatient clinic within the same hospital. Patients recruited were those who agreed to go to the place of application and who signed informed consent. Then the interview was done, and the ODI and the Tampa scale were applied. Patients who were randomly selected for inclusion in the waiting list or non-intervention group were invited to participate at the end of the study.  

The study had the approval of a committee for responsible evaluation, belonging to the graduate school of the Facultad de Psicología of the Universidad Nacional Autónoma de México regarding issues of protection of privacy, confidentiality, and ethical management according to the Declaration of Helsinki.¹⁹

Psychophysiological recording of muscle activity

This was performed before and after the intervention: the active electrodes were placed bilaterally in the upper trapezius muscles. Two evaluation conditions were included:

• Passive (patient sits motionless), which consisted of: rest, cognitive stressor, rest, remembering the accident, and rest.
• Dynamic (patient has to perform movements in which they make their maximum muscle contraction without pain), which was divided into 3 times for each movement (40 seconds each): start, movement, and recovery. Each phase per condition lasted 2 minutes.²⁰

Intervention

This consisted of three sessions (60 minutes each), a week apart each, which took place in the following order: 1) the therapist served as a model for teaching the relevant RT exercises, especially PMR which consisted of teaching them to systematically tense and relax muscle groups related to the neck and back; 2) they were physically guided to correct them; 3) while the patient was connected to sEMG electrodes (in the two muscle pairs) they were visually shown the relationship between the information provided by the equipment and their physiological responses (properly sEMG biofeedback), and they were taught to relax muscularly through PMR practice. The physiological and psychological evaluation was applied again after the intervention.

Data analysis

The differences between the two groups of patients were evaluated for 1.1) physiological variables: muscle dynamic activity and symmetry; and 1.2) psychological variables: fear of movement, perception of disability due to pain, and emotional states: anxiety / depression.

After normality testing, through the Shapiro-Wilk W and homoscedasticity with the Levene test. In cases where the principles for parametric tests were violated, the corresponding nonparametric tests were chosen (Mann-Whitney U and Wilcoxon).  

Muscular symmetry: no significant difference in the level of activation of homologous muscles where ≤ 30% difference between muscles was considered a clinically healthy response.²¹ The arithmetical formula used was to multiply impaired muscle response by one hundred divided by high muscle response, minus one hundred. Percentage of clinical change: analyze differences in overall score expressed as a percentage, considered significant when ≥ 20%. The formula for calculating the percentage change (PC) is: PC = (score 2 - score 1)/score.²²

Results

50 patients were originally recruited, 15 did not meet criteria; 10 refused to participate citing lack of time and not needing it, since it was an acute injury. 14 people who had originally accepted did not continue due to lack of time and interest, and assessments were not completed. So a total sample of 11 patients was obtained in the end. Intervention group (IG) n = 6; non-intervention group (NG) n = 5 (Figure 1).

Patients in the intervention group were characterized by an average age of 32.33 years; 5 were women and 1 a man; while the non-intervention group was 34.11 years on average; 4 were women and 1 a man. All received traditional medical treatment: immobilization with soft neck brace and painkillers for an average of two to three weeks, although 3 patients took them up to 6 months. 50% chose to include complementary strategies such as help from hot water directly in the area of ​​pain. Only 17% was referred to physiotherapy (prior to the intervention offered by this study) (Table I).

Physiological effects of intervention in muscle activity

Symmetry analysis specifically showed that the IG significantly decreased its symmetry (z = 19,917; p = 0.0464). 80% of the NG decreased their symmetry, but it was not significant. It is emphasized that two of these patients achieved values ​​-60% difference in the activity of homologous muscles (Figure 2).

No statistically significant differences were found between groups regarding the effect of the intervention on the dynamic assessment (z = -1.0954; p = 0.2733). However, both groups tended to increase the amount of muscle activity; the NG especially achieved a maximum change from 40 to 50 μV (before and after), while the intervention group obtained 30 microvolts compared with the assessment before treatment (Figure 3).

Psychological effects of whiplash intervention

There was a statistically significant decrease in reported values ​​of the subjective perception of pain in the assessment before / after intervention in the intervention group (z = 2.0226, p = 0.0431), which was also reflected in the percentage of clinical change.

In the IG, the variables that changed clinically were anxiety symptoms (83% decreased their scores), followed by disability reported due to pain (66% decreased their scores). In the variable of depressive symptoms, only half of the IG benefited clinically. Meanwhile the fear of movement had no significant change.

In parallel, the NG showed no statistical differences, but did show clinically significant changes in anxiety symptoms- to a lesser proportion than those of the intervention group- (60% of patients decreased their reported scores). In depressive symptoms and disability, 40% reported clinical decline; in fear of movement they behaved like the IG.

Discussion

Our results show that the group exposed to BF in combination with PMR significantly decreased perception of pain and even paired muscle activity (symmetry), compared to their own baseline levels.

Note that the behavior of muscle symmetry after intervention, may show that the asymmetry is not a single sign of muscle dysfunction,²³ since this seems also to be shown through excessive symmetry, indicating that categorizing muscle activity as functional / dysfunctional seems to be within a continuum rather than a fixed concept or depending on the muscle location. However, even research on this subject is incipient. This is evident when comparing another study of symmetry with acute WL patients, which got results inconsistent with these.²⁴ This may have happened due to the grouping of patients by disability, which could lead to a different arrangement of data, besides those patients reporting higher levels of perceived disability than those reported by our patients. Above all, the need stands out for continued research with larger sample sizes and under different conditions of dynamic assessment, and different muscle sites for electrode selection, to consolidate the state of knowledge on the subject.

On the other hand, the increased muscle activity after treatment presented by the IG is understood through the adaptation model,²⁵ that is, we believe that it happened because the perception of danger changed while doing movements and, thus, the response of decreasing muscle activity during movement was no longer adaptive; in addition, this increase coincides with the muscular pattern found in healthy participants.²⁴ It is possible that in terms of adaptation theory, physiological increase involves the inhibition of some inhibitory interneurons and the facilitation of others in the excitatory pathway, which manifests in increased muscular activity.²⁵  

What remains unclear is why the IG would increase muscle activity levels to a lesser extent after intervention. We believe that the combination of techniques to reduce the sense of danger or stress¹² fostered a condition of relaxation, awareness, and muscle control,¹² which significantly increased muscle activation symmetrically between both trapezius muscles. These findings are consistent with another study of chronic WL patients,²⁶ where after four weeks of training in sEMG BF in the upper trapezius muscles, reduction in pain perception and normalization of the muscle activation pattern was reported. We cannot explain the NG’s increased muscle activity through their exposure to additional interventions, for example physiotherapy, because studies assessing their effects do not consider muscle activity as a variable dependent (plus only two of these patients received the intervention).^27,28 

The situation with the IG can be understood through the theory that proposes that BF encourages physiological changes; that is, having made the information available, the person relaxed muscularly and began to gain a sense of control,²⁶ which led to feeling less pain.  

Psychological changes found in the IG in intensity of pain and decreased clinical levels of disability and anxiety symptoms are consistent with those described by investigations that have evaluated the effect of sEMG BF in patients with chronic pain from WL.²⁹ A beneficial effect has recently been reported provided by this technique in neck and shoulder pain in patients with spinal cord injury¹ and pain associated with continuous passive motion after knee arthroplasty.² The consistency in the results obtained by psychological interventions has led them to be recommended for effective pain management to relieve post-traumatic stress, anxiety, and depression, even in subacute cases.^1,2,12,30

Although the NG also showed positive psychological changes, it is stressed that they did not have statistical significance (before / after), and clinically significant changes only in the anxiety variable; in general the results are modest, which is consistent with the effect shown in the evaluation of physiotherapy treatments (received by 2 patients);²⁷ that is, it has no apparent effect as a variable contributing to the differences between groups, given that according to the biopsychosocial model of chronic pain, management of chronic WL pain with only physical therapy is not sufficient to achieve a beneficial effect on patients.²⁸ 

Specifically, the clinically significant decrease in disability after surgery in the IG was similar to other research with chronic WL patients (without being statistically significant), where improvement was only reported in one of the evaluation categories (in carrying out daily activities);¹² this may be because the techniques have a greater effect on perception (psychological), than on physical and functional areas, so it may require a longer intervention protocol including other muscle groups, more physical practice, and the inclusion of tools to assess functionality.

The self-report variable that did not change with time, not even with intervention, was fear of movement. We believe that this may reflect the need for an intervention that addresses the cognitive component to change "non-rational" thoughts associated with movement,^30,31 which could indicate that relaxation intervention modifies the bodily sense of danger, not what it means for the person to move in relation to pain. 

This study highlights that, with few intervention sessions and a reduced sample, there was a (clinical and statistically) significant change in the perception of pain and joint activity of muscle pairs. On the other hand, we could understand the data obtained as the first therapeutic goals for psychophysiological intervention in patients with acute WL: decreasing perceived pain intensity and perception of anxiety as well as increasing the level of muscle activity. In this regard, it is relevant to consider that the therapeutic effects reported in this study were obtained in combination with traditional medical treatment.

Further studies are needed to assess whether the results are replicated in larger samples; to explore whether cognitive restructuring can be an effective tool in modifying the fear of movement; and the effect of different relaxation techniques applied to other muscle groups, etc.

One limitation of the study lay in the difficulty of collecting a larger sample size; we believe this could be due to the acute state of the health problem, as well as operational variables such as performing the study at an institution other than were the data collection happened, which may have increased the cost for participants to attend the study. It is thus recommended in future studies to reduce the effort involved for patients in studies where the patient has no serious and immediate consequences for their recent illness.

Conclusions

The results obtained in this study show that the physiological effect of BF in combination with PMR is related to a significant decrease of the joint activity of the two trapezius muscles (symmetry); while the psychological effect corresponds to the significant decrease in pain perception, according to initial / final values in the intervention group, which did not occur in the non-intervention group.

This study is a pioneer in evaluating the effect of sEMG BF in acute WL patients, since we found no previous research with which to compare it directly. It also stands out that we assessed the effect of the intervention in the muscle activity of patients, because it is a variable with greater precision and objectivity, which in combination with the self-reported variables provides a more complete picture of the phenomenon. These findings contribute by showing the importance of multidisciplinary care of acute pain through the use of psychophysiological clinical strategies to: a) reduce the intensity of perceived pain in acute and subacute WL patients; b) symmetrically increase the level of muscle activity; c) reduce symptoms of anxiety. 

Therefore, we can conclude that, since psychophysiological intervention in addition to traditional medicine directed at WL can be a valuable clinical option for these patients, further research is needed.

Acknowledgments

This work was done with the support of the CONACYT Graduate Scholarship and support from DGAPA.

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