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12. Neuromodulation and Other Non-pharmacological Approaches in Tension-Type Headache
Keywords
Tension-type headacheNeuromodulationPreventive treatmentNon-pharmacological12.1 Introduction
Tension-type headache (TTH) and migraine are the second and third most prevalent disorders in the world [1]. In adults, episodic and chronic migraine (CM) affect 14.7% and 2% of the population, respectively, while episodic and chronic tension-type headache (CTTH) affect 62.2% and 3.3% of the population, respectively.
According to the International Classification of Headache Disorders, third edition beta version (ICHD-3 beta) [2], CTTH is defined as the occurrence of TTH at a frequency of ≥15 days per month, with typically bilateral, pressing, or tightening in quality, and of mild to moderate intensity, lasting hours to days, or unremitting. The pain does not worsen with routine physical activity but may be associated with mild nausea, photophobia, or phonophobia.
Although the mechanism underlying CTTH remains unclear, the role of central versus peripheral mechanisms has always been discussed while explaining the pathogenesis of CTTH. There is always a debate on differential diagnosis between CTTH and chronic migraine without aura which are regarded as different aspects of chronic daily headache spectrum because of many similarities and fuzzy boundaries.
Current first-line treatments for primary headaches include medications for the acute management of headache, such as triptans and nonsteroidal anti-inflammatory drugs, and prophylactic drugs with a variety of options, such as amitriptyline, topiramate, onabotulinumtoxin-A, and β-blockers [3]. In recent years, non-pharmacological treatments have emerged as a valid option for headache disorders: these include peripheral nerve or transcranial neurostimulation nutraceuticals, dietary interventions, and behavioral therapies [4].
The problem concerning the approach of tension-type headache has been always challenging as no effective treatments have been found for this form. The overall evidences of efficacy of TTH therapies remain scarce, and the scientific literature have to be interpreted critically as the therapeutic trials are noncontrolled or nonrandomized [5]. Treatment has to be individualized: the characters of the clinic picture, intensity, time course, and disability levels have to be considered together to the preference of patients regarding a possible therapeutic strategy. The acute treatment remains a cornerstone, as the most part of agents are not effective; on the other hand, prophylaxis has to be considered in frequent and chronic tension-type headache. Although the long-term prognosis of TTH is probably better than that of migraine, the functional impairment needs adequate prevention [5]. As mentioned, apart from the conventional pharmacological agents used for treatment of tension-type headache, in particular in chronic or high-frequency forms, other kinds of approaches have been developed to help patients: osteopathy, relaxation, physiotherapy, and physical therapy have shown good results [6–8].
Despite the high prevalence of tension-type headache, this disease receives much less attention from health authorities, clinical researchers, or industrial pharmacologists than migraine does because most people with tension-type headache do not consult a doctor but treat themselves, if necessary, with self-medication. However, chronic tensional-type headache is a major health problem with enormous socioeconomic effects.
12.2 Pathophysiology
The mechanisms of CTTH may be multifactorial, including peripheral mechanisms and central mechanisms, as well as genetic and psychological factors. Numerous studies have revealed central pain mechanisms play a dominant role in CTTH. The complicated interrelation among the various pathophysiologic aspects of CTTH just might explain why there are so many multimodal therapeutic strategies (pharmacological and non-pharmacological) to manage this disorder. Due to the topic in question, we will focus on the peripheral and central mechanism that are potentially modifiable by neuromodulation.
12.2.1 Peripheral Mechanism
Increased pericranial muscle tenderness and generalized pressure pain hypersensitivity are the most prominent findings in CTTH. Possible peripheral mechanisms leading to pericranial muscle tenderness and pressure pain include inflammatory reaction, decreased blood flow, increased muscle activity, and muscle atrophy. Lots of previous studies have provided in vivo evidences of peripheral muscle abnormal metabolism in the pathophysiology of CTTH. It has been demonstrated that muscle blood flow is decreased [9] in response to static exercise in tender points in CTTH patients. Women with CTTH showed greater co-activation of antagonist musculature during cervical extension and flexion contractions than that in healthy women, which may potentially lead to muscle overload and increased nociception [10].
12.2.2 Central Mechanism
In addition to peripheral mechanisms, central sensitization following continuous nociceptive input of pericranial muscles may play an important role in the pathogenesis of CTTH.
Patients with tension-type headache have a decrease in pain threshold and an increase in sensitivity, both to pain and anodyne stimuli, cranial and extracranial. It is due to the sensitization of dorsal antler neurons/trigeminal nucleus by an increase in nociceptive inputs from the pericranial myofascial tissues. The qualitatively altered nociception was probably due to central sensitization at the level of the spinal dorsal horn/trigeminal nucleus.
The continuous stimulation of the dorsal horns and the trigeminal nucleus C and Aδ would activate second-order neurons, increasing the efficiency and the number of synapses. Accordingly, continuous painful stimulation would decrease the threshold of activation and increase the receptive field of peripheral pain (homosynaptic facilitation). This continuous activation would also lead to a heterosynaptic facilitation, in which harmless stimuli received by the mechanoreceptors of the Aβ fibers would be misinterpreted as painful, causing allodynia and hyperalgesia [11].
In addition to the sensitization of the dorsal horn neurons/trigeminal nucleus, in the chronic tension-type headache, there is a sensitization of the supraspinal/trigeminal neurons and a decrease in the antinociceptive activity from central structures. Neurophysiological studies have shown the existence of a dysfunction of the descending inhibitory tracts that start from the anterior cingulate gyrus, amygdala, rostroventral bulb, and raphe nuclei, which are responsible for the inhibition of nociceptive reflexes in the dorsal horns in response to painful signals. In response, there is an activation of the motor neurons and secondarily an activation of the pericranial muscles.
The nociceptive input to supraspinal structures will therefore be considerably increased, which may result in increased excitability of supraspinal neurons as well as decreased inhibition or increased facilitation of nociceptive transmission in the spinal dorsal horn. The central neuroplastic changes may also increase the drive to motor neurons both at the supraspinal and at the segmental level, resulting in slightly increased muscle activity and in increased muscle hardness. It is possible that low-grade tension that normally does not result in pain does so in the presence of central sensitization. Moreover, it is possible that the biochemical changes in the dorsal horn may alter the properties of the sensory afferents so that these release inflammatory mediators, i.e., substance P and calcitonin gene-related peptide (CGRP), from the receptive endings in the myofascial tissues, thereby creating a vicious cycle. [12].
By such mechanisms, the central sensitization may be maintained even after the initial eliciting factors have been normalized, resulting in the conversion of episodic into chronic tension-type headache.
12.2.3 Neuromodulation of Chronic Tension-Type Headache
The medical treatment of patients with chronic primary headache syndromes is particularly challenging as valid studies are few, and in many cases, even higher doses of preventive medication is ineffective and adverse side effects frequently complicate the course of medical treatment.
In primary headaches, there is clinical and experimental experience with neuromodulation techniques in both cluster headache and migraine. However, in tension-type headache, the experience is limited, given that it is an undervalued pathology and that in most cases it is not seen by a group of headache experts. However, based on the advance in knowledge of its pathophysiological bases, certain neuromodulation modalities that have evidence of efficacy in other headache and pain conditions, could potentially be effective also in tension-type headache and they will be listed below.
12.2.3.1 Transcranial Direct Current Stimulation (tDCS)
This technique has been used to approach the treatment of chronic therapy-resistant headache and facial pain conditions. In particular, tDCS applied through the skull has been shown to directly modulate the excitability changes in the cortex, probably by shifting neuronal resting membrane potential and hereby modulating the spontaneous discharge rates of cortical neurons. At present, only proof-of-concept and pilot trials have explored the efficacy of this modality in primary headache and no evidence supports the use of tDCS in tension-type headache’s management.
Based on a concept of cortical hyperexcitability [13] in tension-type headache, tDCS is expected to normalize the cortical excitability either by prophylactic treatment in the interictal phase or by an acute treatment of headache attack.
12.2.3.2 Cranial Electrical Stimulation (CES)
CES is a noninvasive brain stimulation technology that uses a low-intensity alternating current applied to the head through one or more electrodes. Proposed mechanisms of action include stimulation of cortical and subcortical regions; effects on endogenous brain oscillations and cortical excitability; impact on neurotransmitters, hormones, and endorphins; and impact on autonomic nervous system. This is one of the few techniques in which there is evidence of benefit in tension-type headache [14].
One hundred patients were enrolled by Solomon et al. [15] in 1989 in a multicenter double-blind study to evaluate the safety and effectiveness of the Pain Suppressor Unit, a cranial electrotherapy stimulator for the symptomatic treatment of tension-type headaches. Treatment consisted of extremely low-level, high-frequency current applied transcranially. Pain scores before and after 20-min treatments of individual headaches as well as patient and physician global evaluations were the primary efficacy variables. Following use of the active unit, patients reported an average reduction in pain intensity of approximately 35%. Placebo patients reported a reduction of approximately 18%. The difference was statistically significant (p = 0.01). The active unit was rated as moderately or highly effective in 40% by physicians and in 36% by patients. Both physicians and patients scored the placebo unit moderately or highly effective for only 16%. The difference in ordered outcomes was statistically significant (p = 0.004). Approximately 10% of patients in each group reported at least one minor adverse experience. Cranial electrotherapy stimulation was safe and often effective in ameliorating the pain intensity of tension headaches.
Despite having been effective, no studies of this technique have been performed in chronic tension headache.
12.2.3.3 Transcutaneous Electrical Nerve Stimulation (TENS)
This is an external neuromodulation modality that involves delivery of electrical current through intact skin, over the course of a nerve. The restrictive definition of TENS is the administration by surface electrodes of electric current produced by device to stimulate cutaneous sensory nerves to reduce pain, both acute and chronic [14]. As the biological basis of analgesia by TENS remains speculative, the “gate control theory” of pain is the most tenable explanation, but release of endogenous opiates could be involved [16]. It is by far the most common application of peripheral neuromodulation in contemporary medical practice.
In a randomized controlled clinical trial by Mousavi et al. [17] in 2011, that was performed in hospital of Iran, 138 Iranian patients with confirmed CTTH were randomized to be treated either with imipramine or TENS method. In the imipramine group, treatment was performed by imipramine tablet, 25 mg, twice daily. In the TENS group, patients were treated thrice weekly for 10 weeks, each lasting 15 min in temporal and occipital regions. Three months after treatment, both the TENS and imipramine significantly reduced the severity of tension headache (p < 0.05). However, imipramine was significantly more effective than TENS in reduction of the headache severity (p < 0.05). The study was concluded that TENS method would be a good alternative method for patients suffering from CTTH.
Later, another Iranian group [18] compared the efficacy of neurofeedback behavioral therapy (NFB) and TENS in the treatment of primary headaches in healthcare providers. This study showed that NFB and TENS might have an effective role in reducing primary headaches of healthcare providers. In addition, comparing the two methods, treatment with NFB was more effective in reducing headache frequency and severity. In this study, no comparison was made between the different groups of primary headaches.
12.2.3.4 Stimulation of the Lateral Somatosensory Thalamus
One of the clinical features of tension-type headache is allodynia and hyperalgesia, and the anatomical area that is most related to these symptoms is the somatosensory thalamus: n. ventroposterolateralis (VPL) and n. ventroposteromedialis (VPM). The somatosensory thalamus is the major terminal of the neospinothalamic tract and is considered the important relay for pain. It was demonstrated that after lesioning this pathway, a somatotopic reorganization in the somatosensory thalamus takes place and that a mismatch between receptive fields and projections fields evoked by microstimulation develops. Stimulation of VPL inhibits spinothalamic tract neurons in the dorsal horn of monkeys and is able to reduce mechanical allodynia in an animal model using partial nerve injury [15].
12.2.3.5 Stimulation of the Periventricular or Periaqueductal Gray (PVG, PAG)
The mechanism of pain modulation with PAG/PVG stimulation is mainly related to an opioid dependent pathway, although also nonopioid-dependent mechanisms are involved. Elevation of endogenous opioids, such as β-endorphin and met-enkephalin, has been found in patients after PAG and PVG stimulation but not after VPL stimulation. This phenomenon of “stimulation-produced analgesia” [19] (SPA) was proven to be effective in acute and chronic pain states in humans, the neural substrates of this endogenous analgesia pathway also include the nucleus raphe magnus and the magnocellular part of the nucleus reticularis gigantocellularis.
As regards to tension-type headache, in a magnetic resonance morphometry study [20], a decrease in the density of the periaqueductal gray matter involved in pain control has been demonstrated. All this could support the implication of this anatomical area in the pathophysiology of tension-type headache.
12.2.3.6 Other Neuromodulation Techniques
Despite limited experience, there are techniques used in other types of headaches (e.g., cluster headache or migraine), such as major occipital nerve stimulation, which could have a hypothetical efficacy, since hyperactivation and secondarily contraction of the occipital pericranial muscles lead to major occipital nerve irritation and, given its trigeminal connections, generate more pain and more contraction. But as in the other techniques, its utility would be limited for very refractory cases, given its complexity.
12.3 Non-pharmacological Approaches for Tension-Type Headache
In the last decades, behavioral approaches have been employed for the treatment of tension-type headache, and in several cases with encouraging results. They include different treatment interventions aimed at changing maladaptive behavior and ways of thinking that could enhance headache-related burden and pain, in particular cognitive behavioral therapy (CBT), mindfulness, relaxation training (RT), and biofeedback (BFB). Research has shown the effects of behavioral interventions in the management of primary headache disorders in adults and children. These interventions are commonly used in clinical practice, particularly in specialized units. They are generally well tolerated and can be jointly used with pharmacological therapies, and their use is generally suggested when medication use should be limited or avoided due to known side effects, contraindications, and presence of medication overuse and is suitable for specific categories of patients, such as pregnant women and adolescents. However, the level of their effectiveness is still a matter of debate. As evidenced from the recent literature, behavioral approaches produced sizeable effects on the classical primary endpoint in headache field, namely, headache frequency, when used as preventive treatments in the management of patients with primary headaches. Irrespectively of the behavioral approach under examination, a reduction of headache frequency higher than 35% was found in more than half of studies (10 out of 18 addressing such a difference), thus confirming that these approaches have the potential to positively impact on headache frequency in a way that is similar to the results seen in medication trials [4, 21]. Behavioral treatments produce a reduction of stress and an increased sense of self-efficacy (i.e., the confidence in one’s ability to manage different aspects of his/her life) and reduce the external locus of control (i.e., the belief that nothing can be done to control life events) [4]. The biological mechanisms explaining the function of behavioral approaches have been recently investigated. Initial evidence exists on the ability of mindfulness to impact on interleukine-6, a marker of inflammation that is deemed to play a role in the regulation of pain threshold and to facilitate pain signaling during the development of migraine headaches. On the other hand, neuroimaging findings demonstrated the impact of behavioral treatments, and of mindfulness in particular, in producing functional modifications in those brain areas involved in the cognitive and affective components of pain. Different neuroimaging studies showed increased activity in the anterior cingulate cortex and anterior insula; orbitofrontal cortex activation and with thalamic deactivation; thickening of cortical regions associated with pain processing; reduced activation in the amygdala, hippocampus, and emotional/evaluative regions of the prefrontal cortex; as well as increased activation in the mid-cingulate cortex, thalamus, and insula.
In the following sections, some of the behavioral techniques applied for headaches and tension-type headache in particular will be discussed with results reported in literature from studies of the last decade.
12.3.1 Cognitive Behavioral Therapy (CBT)
Cognitive behavioral therapy is a psychosocial intervention that has been accurately tested and found to be effective in treating many different disorders. This technique aimed at helping patients to change their dysfunctional mental patterns (i.e., thoughts and beliefs) and behaviors through the teaching of new skills that they can use for the rest of their life. These skills involve identifying maladaptive thinking, modifying beliefs, and relating to others in different ways [22]. With regard to headache, CBT may be helpful in treating tension-type headache as it teach sufferers to identify and change headache-related beliefs and behaviors that generate stress and increase pain [23, 24]. Mo’Tamedi et al. [25] in 2012 examined the effectiveness of an Acceptance and Commitment Additive Therapy in reducing the experience of sensory pain, disability, and affective distress in a group of female outpatients suffering from chronic tension-type headache or chronic migraine. Participants were assigned randomly into two groups. One group served as the control group and received only medical treatment as usual, while the other group, the group-based ACT, in addition to standard medical care received 8 weekly sessions of group-based Acceptance and Commitment Therapy. The intervention aimed at building awareness of the difficulty in effectively controlling pain sensations, improving engagement in meaningful activities even in the presence of pain and distress, decreasing pain- and distress-avoidant behaviors, identification of and commitment in actions consisted with personally relevant values and goals, and improving present-focused awareness and mindfulness [26]. Statistically significant, this study supports the effectiveness of a brief group-based ACT in treating recurrent headache. In particular, patients in the treatment group in comparison with patients in the control group reported improvement in perception of pain intensity in terms of reducing disability and decreased affective distress. Martin et al. [27] in 2014 have proposed a behavioral management of headaches, including episodic and chronic tension-type headache. The randomized controlled trial provided different treatments: avoidance including involved education, identifying headache triggers, and managing headache triggers through avoidance; LCT (Learning to Cope with Triggers), i.e., identifying headache triggers and deciding what strategies to use for each of them; and avoidance combined with CBT and waiting list. The results showed that LCT resulted in greater improvement than the other three conditions on all measures of headaches and medication consumption, and IT was the only treatment condition that significantly differed from the waiting list control condition in terms of treatment responder rate and medications consumption. Christiansen et al. [28] in 2015 tested the long-term clinical effectiveness of an outpatient combined group and individual CBT for headache patients (including TTH) following standard medical care. The CBT treatment consisted of 10 weekly sessions lasting 100 min, and in addition, two follow-up sessions were conducted to booster efficacy after 3 and 6 months. The sessions included psychoeducation, progressive muscle relaxation, coping strategies for pain and stress, and goal-setting skills. All patients received headache-specific medication according to the current European guidelines before the CBT treatment started. Results showed a significant decrease in headache intensity, headache frequency, and catastrophizing attitude. Furthermore, coping strategies were increased. Unfortunately, although different studies and several clinical experiences have been conducted, the most part of them concern heterogeneous headache forms, and consequently the clinical results cannot be referred specifically to tension-type headache.
12.3.2 Mindfulness
Mindfulness refers to a psychological meditation technique developed from the precepts of Buddhism (but free from the religious component) aimed at bringing the subject’s attention in a nonjudgmental manner toward the present moment. According to the definition of Jon Kabat-Zinn, who first used it in the West starting in the 1970s as a medical discipline, mindfulness means “Pay attention in a particular way: intentionally, in the present moment and in a non-judgmental way” [29]. The practice of this technique consists of single-patient or small-group sessions where the subjects are accompanied by a guide voice, that of an expert psychologist which, through various exercises such as breathing practice or body scan, helps to achieve a state of relaxation and awareness as well as a change in some nonadaptive mental patterns [30].
Mindfulness has been recently included in rehabilitation programs for chronic pain conditions [31, 32]. In a recent review concerning psychological therapies in the neurorehabilitation of pain syndromes [33], mindfulness has been judged as effective (Grade Level A) for chronic pain syndromes with heterogeneous physiopathology, exclusive of headache disorders. The success with other pain conditions, however, has spurred researchers in the field of headache to increasingly turn their attention to mindfulness training as another viable alternative approach for supplementing patient care. The main goal of this approach is to increase patient awareness of their pain and improve their abilities to manage headache before resorting to their former medications. In brief, literature findings suggest that various mindfulness-based approaches may be helpful for headache sufferers [34, 35]. Considering tension-type headache, in particular chronic form, Cathcart et al. [36] in 2014 conducted a randomized controlled trial of a brief mindfulness-based therapy trial (MBT). Forty-two participants were randomly allocated to either the treatment or wait-list control condition. The intervention was conducted over a 3-week period involving twice-weekly group classes. Three formal mindfulness meditation practices were taught during the MBT sessions: (1) body scan meditation; (2) formal sitting meditation, focusing on mindfulness of breath and other experiences such as sounds and thoughts; and (3) 3-min breathing space, which involves focusing awareness of present internal experiences, focusing awareness on the breath, and expanding awareness to the body as a whole. Furthermore, patients were asked to practice mindfulness meditation at home with the help of a written instruction manual and a compact disk containing audio-recorded meditation practice instructions. Mindfulness determined a significant reduction in headache frequency. Day et al. [37] in 2014 conducted a pilot study in which mindfulness-based cognitive therapy (MBCT) was administered for the treatment of primary headache pain in adults. The 8-week MBCT for headache pain manual was adapted from an existing 8-week MBCT for depression protocol. During the 2-h session, participants were instructed to practice meditation in between group sessions. Results evidenced that MBCT for headache pain is feasible, tolerable, and acceptable for participants. MBCT patients also reported significantly greater improvement in self-efficacy and pain acceptance. MBCT completers also reported significantly improved pain interference and reduced pain-catastrophizing attitude. The randomized controlled clinical trial by Omidi and Zargar [38] in 2015 included 60 adults with TTH. Patients were assigned either to the experimental group where mindfulness-based stress reduction (MBSR) was given in addiction at standard of care or they were assigned to the control group where participants were treated as per standard of care. The experimental group was trained in 8 weekly sessions of 120 min each. During the MBSR sessions, participants were trained to be aware of their thoughts, feelings, and physical sensations nonjudgmentally. The MBSR intervention included two forms of meditation practices: formal and informal. Formal-type exercises consisted of trained sitting meditation, body scan, and mindful yoga. While in informal meditation, attention and awareness are focused not only on daily activities but also on feelings, thoughts, and physical sensation even when they are painful. Results showed that participating in the MBSR program enhanced general mental health assessed by the global severity index (GSI) of the Brief Symptom Inventory (BSI). In addition, the MBSR group showed lower scores in perceived stress in comparison with control group at follow-up evaluation.
12.3.3 Relaxation Training
Relaxation training (RT) refers to some non-pharmacological techniques aimed at reducing stress-induced negative emotion and physiological arousal and at increasing calmness to improve health. This intervention usually includes various strategies such as muscle relaxation, deep or controlled breathing, guided imagery, and distraction [24, 39]. With regard to headache sufferers, relaxation training has been used with the aim to increase the patients’ control over physiological responses to their headache, lower sympathetic arousal, and reduce stress and anxiety that play a key role in headache pain [24]. The effectiveness of such emotion- and arousal-reduction intervention in treating adults and children headache has been documented in several studies [40–42]. Andrasik et al. [42] compared a relaxation training program to a pharmacological therapy with amitriptyline for juvenile tension-type headache treating. The behavioral treatment consisted of four training sessions, once every 2 weeks, in small groups of patients. Each session consisted of 30 min with progressive muscle relaxation training for eight muscle groups. Also, relaxation exercise for daily home practice was given. From baseline to 2-year follow-up, headache frequency significantly decreased in both groups. However, although clinical improvements were similar in both groups, relaxation therapy seems to be more accepted than pharmacological therapy. Patients that underwent the behavioral treatment came regularly for the sessions, practiced routinely, and showed a lower percentage of dropouts. In a randomized controlled study conducted by D’Souza et al. [43], college students suffering from tension-type headache and migraine were assigned to one of three groups: relaxation training, an intervention based on Written Emotional Disclosure Paradigm (WED), and a neutral writing condition. The research protocol provided four sessions that were held over 2 weeks. During each session, patients that underwent the relaxation training sat in a comfortable chair in a private room and listened to different session of an audiotape. The program included training of different skills such as muscle relaxation, deep breathing, and autogenic relaxation using vivid imagery. Participants were also encouraged to home practice. For tension-type headache sample, relaxation training led to improved headache frequency and disability compared to both WED and control group. A more recent study carried out by Slavin-Spenny et al. [39] compared the effectiveness of relaxation training to Anger Awareness and Expression Training (AAET). In this randomize trial, young adults with headaches were assigned to one to three groups: relaxation training (RT), AAET, and a control group. The intervention provides three sessions in 3 weeks; then patients returned 4 weeks after the last session for the posttreatment outcome measure. In conclusion, relaxation training is a helpful technique to improve calmness and reduce arousal, anxiety, and stress, leading patients to manage physical responses associated with headache [42].
12.3.4 Biofeedback
Biofeedback (BFB) is a self-regulation technique based on operant conditioning, in which biological feedback is used to train patients to acquire a certain degree of control over physiologic functions. This intervention requires specialized recording equipment to convert body signals, that are usually under conscious control, into meaningful visual and auditory cues that can be easily understood and used by patients to improve conscious control of such involuntarily physiological activity [44, 45]. The most commonly monitored variables are heart rate, respiration rate, skin surface temperature (at the fingertips), skin conductance, brain waves, and muscle activity [46, 47]. This procedure also provides the option to track more physiological parameters simultaneously. With the help of a trained biofeedback practitioner, patients learn to use these real-time feedback to intentionally regulate their physiology, improving physical, mental, emotional, and spiritual health. Furthermore, this technique helps to make patients aware of thoughts, feelings, and behaviors related to their physiology. Over time, they can learn to pay attention and regulate physiological functions without the biofeedback instrument in front of them [48]. A typical biofeedback program consists of 10–20 sessions which last 20–60 min each, and it can be carried out individually or in group. This mind-body technique has been used in treatment of several medical and psychological conditions, such as hypertension, temporomandibular and attention deficit disorders, anxiety, and other medical conditions exacerbated by stress, with the purpose of improving patient’s ability to manage disease symptoms as well as their overall health and wellness through stress management training [48]. Numerous studies evaluated biofeedback efficacy, either applied alone or in combination with relaxation training or other behavioral techniques, in treating of headaches [49]. More specifically, concerning tension-type headache, Budzynski et al. [50] in 1970 introduced the use of EMG biofeedback in treating patients suffering from this specific form of primary headache. Since then, many studies have shown that various biofeedback modalities, combined or not with relaxation training, medication, or cognitive behavioral therapies, may be effective in the treatment of tension-type headache. In particular, biofeedback affects headache frequency, muscle tension, analgesic use, mood regulation, and self-efficacy evaluation [47]. One of the most recent studies about biofeedback efficacy was carried out by Blume et al. [51] in 2012. Children with different types of primary headache disorder, including tension-type headache, underwent seven biofeedback sessions. Each session included training in and measurement of hand-warming, relaxation, and visualization techniques. Between the first and the last training session, median headache frequency dropped from 14 to 8 headache/days per month, as well as median headache severity that significantly decreased from 6/10 to 5/10. Children with episodic headaches had the best response; however, 48% of those with chronic headaches, which are often more difficult to treat, had also a positive response to biofeedback therapy.
More specifically, concerning tension-type headache, Grazzi et al. [52] in 2001 investigated the effects of electromyographic biofeedback-assisted relaxation training on children and adolescents suffering from tension headache. The research protocol consists of two biofeedback training sessions per week for a total of ten sessions that last 20–21 min. The first four sessions were devoted to progressive muscle relaxation training, while the remaining six were dedicated to EMG biofeedback training. From pretreatment to 1-month posttreatment headache days markedly decreased; moreover, little additional improvements were found at 1-year follow-up.
Arndorfer and Allen [53] investigated the application of thermal biofeedback in a sample of five children with tension-type headache. In this multiple baseline design study, treatment was introduced sequentially across subjects and involved six 30-min biofeedback session: 4 weekly thermal biofeedback sessions and two additional follow-up and problem-solving sessions at 2-week intervals. In addition, participants were encouraged to practice their skills at home twice a day. All children demonstrated clinically significant improvements in one or more headache parameters (frequency, duration, and severity) following treatment. Finally, at 6-month follow-up, four of five participants were headache-free. The effectiveness of biofeedback in decreasing headache frequency and severity has been assessed also in adult population. Mullally et al. [54] performed a randomized study. Adult patients suffering from migraine or tension-type headache were randomly assigned to receive biofeedback training in combination with relaxation technique or relaxation technique alone. Biofeedback training consisted in ten sessions each lasting 50 min utilizing EMG biofeedback from the frontalis and trapezius muscles and thermal biofeedback using temperature from the third finger of the dominant hand. The procedure provided both auditory and visual feedback. Over time, both groups showed improvements in headache frequency and severity. Biofeedback provided no additional benefit for patients that have been subjected to training. After 3 months, 48% of those in the relaxation group reported fewer severe headache, while 35% of those in the biofeedback group reported fewer severe headache. After 6 months, 57% of patients undergoing biofeedback reported fewer severe headaches, while in the group subjected to relaxation techniques alone, the respective figure was 52%. In conclusion, biofeedback techniques can be helpful in treating headaches and in particular TTH sufferers by teaching patients an active role in controlling, changing, and preventing physiological and emotional processes that contribute to the genesis of headache pain [54].
12.4 Conclusions
There is little experience around neuromodulation for tension-type headache. As we show in the previous text, we only have data from the application of TENS in two randomized trials, with debatable results, and regarding CES, there are no more studies published since the last century. Deep brain stimulation, as a stimulus of VPL, VPM, PVG, or PAG, has a hypothetical efficacy but need more studies and experience. Accordingly, it can be said that the neuromodulation of tension-type headache is still an area to discover. In regard to non-pharmacological therapies, more studies and more randomized controlled trials are needed to confirm the utility of the individual behavioral approaches, possibly with blindness of the neurologist in charge of patients’ selection about the treatment allocation of each included patient. Moreover, most included study had a short-term follow-up, which does not enable to assess the stability of achieved results, and longer term follow-up will be necessary. An integration between traditional headache research endpoints (i.e., headache frequency and intensity, and medication intake) with standardized patient-reported outcomes should be considered in order to evaluate the effects of these treatments on patients’ disability, quality of life, and other relevant psychosocial aspects, such as symptoms of depression, self-efficacy, and coping abilities. Ideally, the evaluation of changes in biomarkers caused by behavioral approaches should be encouraged, including neuroimaging and biological markers to confirm the efficacy of these treatments. Eventually, predictive models could be tested in order to assist clinical practice. In fact, future studies might include a wide spectrum of clinical, psychosocial, and biological indicators with the aim of identifying which patients’ features are the most relevant to promote positive clinical changes after behavioral treatments.
