Tension-type headache: one or more headaches?

Summary

In this context, the focus will be on the homogeneity of tension-type headache (T-TH): is it a disease? Or: is it more likely to be a syndrome? A multiplicity of disorders from as drastically different fields of medicine as disorders caused by environmental gases, intra-psychic conflicts, and nuchal/cervical disorders can putatively fake T-TH.

T-TH is in all probability a conglomerate of disorders and not one solid, homogeneous disorder.

Introduction

Tension-type headache (T-TH) is one of the most difficult-to-diagnose and poorest defined headaches in the whole headache field. T-TH is a diagnostic challenge for the novice and expert alike. The picture, as it appears in scientific communications and classifications, is that of a vague, symptom-poor, mild-moderate, non-throbbing, bilateral, mainly female, idiopathic headache, which is hard to classify and more or less non-remediable.

Already one particular statement in the IHS classification ( 1 ) prompts one to sharpen one’s senses: “its lifetime prevalence in the general population ranges [……] from 30 to 78%”, i.e. a ratio of 2.6. In the “worst” scenario, then, T-TH would afflict >3/4 of the population, being, by far, the largest of all headache groups. A priori , one would imagine that it can hardly be the composition of different population groups that varies that much, even though some variation in the prevalence could stem from this, e.g. from a difference between rural ( 2 ) and metropolitan ( 3 ) populations.

Tension-type headache can probably be characterized as a waste-basket type of diagnosis: many (most?) difficult-to-classify headache cases may have been given this label. If this point of view is anywhere near being a reflection of reality, it would be unrealistic to assume that T-TH patients form a homogeneous mass. T-TH patients, rather, represent a conglomerate of cases, or of groups ( 4 ) .

A good proportion of the evidence presented herein is based on our own experience.

The different modes of clinical headache diagnostics

Through the efforts of the IHS, the level of headache work as such has been raised considerably in many fields. The shortcomings in diagnostics are, nevertheless, manifold. Practicing headache medicine/diagnostics is, in many researchers’ view, too time-consuming, and, for that reason, short-cuts have been introduced, enabling mass investigations within short times.

There are telephone interviews and questionnaire studies that exclude the possibility of in-depth exploration or physical examination, even though both are necessary ingredients in, for example, cervicogenic headache (CEH) diagnostics ( 5 – 7 ) . These ingredients are also desirable components in the diagnosis of headache subsequent to whiplash ( 8 ) and “neck-related, posterior headache” ( 9 ) ; all three of these headaches may be differential diagnostic alternatives to T-TH. Questionnaire studies allow mass production of data, but they keep the truth partly arm’s length. It is important to realize what the inherent problems are with this type of approach in headache research. Conversely, there is headache work without time restrictions.

The list of aspects here brought into focus with regard to the diagnosis of T-TH may not be even nearly complete.

Can T-TH arise from an intra-psychic conflict?

The author has personal experience with four patients, who deserve particular scrutiny. Only few details will be given in the following case histories, due to the sensitivity of the subject. They were all females, married and rather young. No information as regards anterior/posterior predilection of pain is available in these cases, since the minute details regarding pain localization in T-TH had not yet become an issue at the time they were seen. The first patient was the most illustrative one. She kept coming for consultations for a continuous, non-throbbing, moderate, symptom-poor, global headache, which clearly had affected her wellbeing for several months. Various therapeutic approaches were attempted, all without avail. Mental factors were also touched upon, without any in-depth exploration. In spite of the poor progress that was made, she arranged for new consultations. Then, after many months, she asked to bring along a male friend. The two laid all their cards on the table. They lived in two separate flats in a condominium, with their respective partners, and the two couples socialized. Between our patient and the husband in the other couple, an amorous affair had developed, which was kept secret while the socializing continued. The situation weighed very heavily on the conscience both of the patient and of her male friend. The headache had started at the time the infidelity started. Due to the good patient-physician relationship that she felt had developed, they both wanted the physician to help them make a decision regarding their future marital situation. They would accept his decision. This was a tough responsibility to put on the shoulders of a young physician. He, on his part, demanded to see them several times, in order to become better acquainted with the male party. In the end, the physician gave the following advice: Hold a meeting with all the persons involved and disclose the full story. This was done. The “sinners” were eventually pardoned and, in the end, married. The deceived parties, who already knew each other well, became infatuated – and also married. The headache totally disappeared, within a short time. Long-term follow up found a happy couple, and the headache did not reappear.

Approximately 25 years later, a young female came along, complaining of a global, medium-grade, constant, but symptom-poor headache that had started suddenly some months earlier. Apparently, there was no mental trouble. At the end of the first consultation, O.S. asked whether there had been any infidelity problem. The young lady looked completely taken aback. How on earth did O.S. know?! The headache had started at the same time as the extra-marital affair. She was asked whether she wanted to get rid of the headache, or continue the extra-marital affair, since there would not, in all likelihood, be any possibility of obtaining both. She was in no doubt: she wanted to get rid of the headache. The love affair was discontinued immediately, and the headache vanished a short time after that. Follow up showed that it stayed away.

Two young wives had a troublesome relationship with their respective mothers-in-law. The physical closeness of the two generations seemed to have taken its toll: a bothersome, rather mild headache of the global type had started, insidiously, in connection with the beginning of the exposure to the problem, many months previously. Within a short time, it had become more or less continuous. During short-term, psychiatric treatment, the headache, in both cases, disintegrated completely and did not reappear over time.

Comments

A common denominator in the two first case histories was the extra-marital affair. The clinical picture these two patients presented cannot be distinguished from T-TH ( 1 ) ; at least the present author is unable to make such a distinction.

There were no known exterior, causal factors that could explain the sequence of events. Nor were there any signs of somatic disease. There was actually little doubt as to the timing of the events: the headache started with the introduction of the conflict and disappeared promptly upon its resolution; there was, in other words, a temporal concurrence of two events, at two different times, in two persons: a total of eight events. With such a clear temporal association, a cause-and-effect relationship between conflict and headache became plausible. But how and by what mechanisms were the symptoms produced? Could it be via muscles? Or, via “tension”? Or, via blood vessels? Alternatively, was it set in motion without any bodily correlate? To find a clear temporal association between events and to diagnose hysterical pain in such cases is difficult in clinical practice ( 10 , 11 ) . Given the circumstances under which the marital affair headache arose and was subsequently resolved, there is, nevertheless, ample reason to suspect that it could have arisen directly from the unresolved conflict: such a pseudo-solution would fit in with a conversion mechanism ( Table I ). The term “psychogenic headache” ( 1 ) may be a little too imprecise in this context, as it could also comprise depression and stress, in addition to hypochondriasis and hysteria/conversion ( Table I ).The conflict, per se, clearly seemed to have been at the conscious level. However, the nature and massive scale of the conflict might have made it totally unsustainable for the superego. The conflict could not easily be resolved at the intellectual level; the symptoms were beyond volitional control. Thus, a repression to the subconscious level may have taken place. In short, the conflict seemed to have had its own dynamics. The ensuing somatization might have served to take away the focus from the emotionally charged, insolvable conflict.

Table I .

Mental factors, possibly underlying headache

Mental stress Depression “Headache from an idea” “Psychogenic headache” ( 1 ) “Tension”- (of what?) Intra-psychic conflict Conversion/hysteria Hypochondriasis

Patient 1 to the very end hoped that the infidelity and the headache were two different, unrelated events. It is remarkable how easily the physician could have given up on patient 1. The daughters-in-law both had a high degree of suspicion as to a causal relationship.

In our patients, the headache manifested itself only during a time-limited period. During this period, the marital problem patients were naturally worried about their situation, but not in a hypochondriac way. Their attitude was, as far as the present author is concerned, not a consequence of immaturity, egocentricity, emotional lability, preoccupation with disease, etc. There were no signs at all of Briquet’s syndrome, which is characterized by symptoms from many different symptom groups, for protracted periods of life ( 11 – 14 ) . In that syndrome, patients may for example fall into the category: “headaches, sickly most of life”. There was no hysterical personality, with “histrionic” behavior, “belle indifference”, motivation (hard to find, at least in patient 2), or “gain” (with the exception, possibly, of patient 1) ( 10 , 14 , 15 ) . In other words, there seemed to have been conversion symptoms in the presence of non-hysterical personalities. This discrimination seems to be acceptable among specialists (e.g. 11 , 12 ).

Although the mechanisms behind the symptom generation in all four patients may have been the same, the therapeutic situation in the extra-marital affair cases was the easier one to handle: just like turning off a switch. The mother-in-law, however, could not be “switched off”/done away with, just like that. She had to be scaled down, made harmless. This was the task of the specialist – the psychiatrist. In both situations, the therapy can be characterized as radical.

Thus, in some cases, there seems to be a causal relationship between intra-psychic conflict and a headache that, under the present guidelines, cannot be distinguished from T-TH. Although such mechanisms cannot be expected to explain all cases of T-TH, the marital problem cases, in essence, tend to demonstrate that either: i) this mechanism may be much more frequent in genuine T-TH cases than hitherto understood (in which case, the conflict may generally be more inaccessible than in these specific cases), or ii) we are faced with a T-TH syndrome , with various similar, but nevertheless essentially different subgroups.

If mechanism i) explains most T-TH cases, then conversion mechanisms are likely to be part of the mental outfit/habitus of ordinary people.

The marital problem cases also have a bearing upon therapy in T-TH in general. While analgesics, anti-depressants, physiotherapy and biofeedback may not be entirely futile in T-TH in general, one can imagine how absolutely futile each of these approaches would be in our cases. Some of the frustration that surrounds therapy in T-TH, both for the patient and the therapist, can be understood against this background.

It should also probably be emphasized that the chances of discovering the truth in these two (but probably all four) case histories would be close to zero in a questionnaire study.

Environmental gases

Disorders caused by environmental gases may masquerade as T-TH. H2S intoxication, which must be assumed to be extremely rare ( 16 ) , will be dealt with in particular.

In the Vågå study ( 16 ) , there were three affected individuals. They all worked/had worked at the local sewage purification works. At the end of the working day, a creeping, low-grade, vague, symptom-poor, mainly anteriorly located headache became steadily more noticeable. It was hardly noticeable/absent in the morning, prior to work. And this happened day in, day out. It seemed, in other words, to be work-related. In the end, an H2S meter was installed in the facilities, and the concentration was 100 ppm, always. The needle moved rapidly to the top of the scale and then stayed there. How high the actual concentration at the time might have been will, therefore, never be known. The maximal allowable concentration under working conditions is around 10 ppm. Concentrations of >50 ppm require immediate evacuation. It remains somewhat uncertain at what level headache can start ( 17 , 18 ) .

Measures were adopted: shorter working hours, more frequent breaks and, above all, ventilation. The H2S concentration fell, and the headache disappeared. Acute H2S intoxications are well known from factory disasters; death may be instantaneous. Low-grade intoxications are less well known. The headache can, generally, hardly be distinguished from T-TH. At its peak, the headache might be accompanied by some pulsating pain, which possibly may serve as a distinguishing feature (one of the three workers).

Other environmental gases/ambient air compositions that can cause headache are mentioned in Table II . CO may be a headache-provoking factor ( 17 ) . In slow, rush-hour traffic on large metropolitan streets, the CO concentration has been assumed to reach noxious levels. Fork-lift headache, or warehouse workers’ headache ( 1 ) , is another carbon monoxide-induced headache, with a resemblance to T-TH. Headache connected to the burning of trash/old grass may putatively also be caused by CO ( 16 ) .

Table II .

Gases and changes in the composition of ambient air causing conditions masquerading as T-TH?

Oxygen deficiency Mountaineers’ headache (high-altitude headache) Sleep apnea syndrome CO accumulation Warehouse workers’ headache (fork-lift headache) Rush hour traffic Trash burning, etc. H2S Methane

Low environmental oxygen concentration, as in mountaineers’ headache (high-altitude headache), is a well-known cause of global headache. In obstructive sleep apnea syndrome, morning headache frequently occurs ( 19 , 20 ) . This headache may outlast the morning hours; it is symptom-poor, and it is frequently located anteriorly ( 20 ) , both traits resembling T-TH. Thus, this sleep apnea syndrome may also have to be reckoned with, quantitatively speaking.

Methane can be noxious, particularly in the context of mining and in concentrations >10% ( 21 ) . In such situations, a creeping headache, mostly as forehead pressure, may arise. However, the level of vigilance with regard to methane contributes to a low level of risk.

Migraine without aura

The impact of migraine without aura (M-A) is probably on a quite different scale from that of the hitherto mentioned headaches. Migraine is probably the second largest headache group. It differs broadly from T-TH, migraine being a hereditary disorder with marked “vascular” properties. It can, nevertheless, be confused with T-TH. Migraine may assume various guises, some of which showing, in part, a clear similarity to T-TH. There may be several reasons for this. Migraine in its full-blown form is characteristic enough, with a complete set of autonomic symptoms and signs and a throbbing and unilateral pain, and with a particular temporal profile. However, two striking developments may occur, changing this picture:

1. A spontaneous improvement may occur with age. Bille ( 22 ) described this in childhood migraine, in which headache attacks may eventually disappear. In the intervening years, the headache eased, becoming more and more innocuous. Eventually, the original form, having been experienced in the distant past, may even be “forgotten”. The spontaneous, actual account of a single patient will frequently concern any present headache, which is what counts for the patient. The remaining migraine headache may resemble that of the second or third day of a three-day-long migraine attack. It is about to lose its punch and could, in many circles, be categorized as T-TH. There is, however, every reason to believe that this headache basically is a migraine. As most of us see it today, migraine and T-TH are not interchangeable headaches. Each keeps its basic structure. A spontaneous improvement may also occur in the elderly, and not only in connection with the climacterium. If evaluated for the first time during that stage of development of the headache, without proper knowledge of the previous stages, T-TH would for many clinicians be the natural diagnosis to choose.

2. Nowadays, inadvertent use of attack medication has not infrequently changed the overall headache picture from migraine to a more or less continuous headache, resembling T-TH. The culprits can be ergotamine, triptans or analgesics. There may still be exacerbations along the time axis, giving rise to terms like “mixed-headache”. In most (?) cases, this headache may primarily seem to be a migraine; therefore, a more correct term would probably be: “migraine with interval headache”.

In some parts of the world, attack medication may be used to a higher extent in municipal than in rural areas. In Vågå ( 23 ) , where attack medication was only sparsely used at the time of the study, an ordinary migraine attack pattern regularly persisted, and the prevalence of M-A was remarkably high, i.e. 31%, if cases with a combination of T-TH and M-A were included (23% if this combination were removed). This was almost at the level of T-TH, i.e. 34% ( 4 ) . The sum, migraine+T-TH, i.e. 65%, was lower than this sum in other, comparable series ( 3 , 24 ) . However, if the figures concerning CEH etc. (see later) are added, the total figures from the three papers (3,24 and the present work) correspond. The relatively high prevalence of migraine in Vågå may be, at least partly, a consequence of the low consumption of attack medication in that area.

In areas with a high consumption of migraine drugs, this may have been the single most important factor contributing to an unfortunate shift of the T-TH/M-A proportion, quantitatively speaking.

Of course, T-TH (or: a T-TH-like picture) can develop independently, alongside M-A. How frequently such a development will occur in comparison with the changes in migraine here depicted, is not known. The aforementioned figures from the Vågå study, where anti-migraine medication was sparse, might provide some indications.

Headache of cervical/nuchal origin, mimicking T-TH

T-TH is, in principle, a bilateral headache. There is some evidence to the effect that it may be mainly an anterior headache ( 9 ) . One of our own series ( 25 ) also provides evidence for a mainly anterior location of the headache: in 20 T-TH patients (14 chronic T-TH) and 20 group-matched controls, headache and neck pain were invariably lower in controls (invariably 0) in the unprovoked situation than in patients. Forehead pain level in patients was 22 (VAS, median value), and this was clearly higher than that in the other areas, such as temples: 12; neck: 11; shoulders: 0.

There are several headaches with a cervical origin ( 9 ) , some of the main ones being: CEH, headache subsequent to whiplash, and “neck-related, posterior headache” ( Table III ).

Table III .

Neck/occipital area

Disorders that can masquerade as T-TH? Cervicogenic headache Headache subsequent to whiplash Tractor drivers’ headache Protracted neck ache, with subsequent posterior headache (“neck-related posterior headache”) ( 9 ) Ponytail headache ( 33 )

These headaches, added together, are probably not a minor factor in the entire headache panorama. Patients with a bilateral and mainly anterior pain location may be the ones that first and foremost cause classification problems vs T-TH. In none of the mentioned headaches do these features seem to predominate, but they may be present in much more than exceptional cases. In “neck-related, posterior headache”, the pain is generally bilateral, and mainly posterior. In CEH, the headache in principle is unilateral and, moreover, starts in the nuchal area, but subsequently, it generally involves the whole hemicranium. In core cases, the similarity with T-TH may thus be marginal.

The headaches mentioned in this section, are real ones, even though in many headache series their existence is not mentioned. Where have they ended up then? In all probability, they have, grossly, been thrown into one big sack: T-TH. Where else?

The special handling of these data in the Vågå study, i.e. the fact that CEH and “neck-related posterior headache” were reported as separate groups (and not included among the T-TH cases), is probably one reason for the relatively low figure for T-TH observed in that study ( 4 ) .

Various other headaches with a T-TH-like clinical picture

Such headaches include caffeine withdrawal headache, analgesic-overuse headache, and headache due to protracted, low-grade fever ( Tables IV and V ). Chronic, open-angle glaucoma may also belong here. But if intraocular pressure has been measured, a headache with such a background will be ruled out. But, can one really expect every participant in a questionnaire study of 20,000 or 40,000 individuals, or whatever, to have had their intraocular pressure measured, and relatively recently?

Table IV .

Nutrients, drinks, drugs

Disorders mimicking T-TH? Caffeine withdrawal headache Alcohol. Hangover headache, “light” Indomethacin over-dosage headache Analgesic-overuse headache Chinese restaurant syndrome (MAO-inhibitors)

Table V .

Miscellaneous disorders, putatively causing differential diagnostic problems

Glaucoma Arterial hypertension, severe # Intracranial hypertension CSF hypotension Low-grade fever Blood sugar imbalance Squint (?) Compulsory quietude ( 26 ) Anxiety combined with waiting ( 26 )

# e.g. pheochromocytoma

A couple of conditions: “compulsory quietude” and “anxiety combined with waiting”, as emphasized by Lundberg ( 26 ) , may produce a low-degree discomfort/unpleasantness in the head, and so can the maintenance of stereotyped positions (and not necessarily during work), even though the neck is seemingly in a physiological position. There may be a considerable similarity between the latter condition and “compulsory quietude”. The correct place for the latter conditions could be under the heading: “Can headache arise from an intra-psychic conflict?” Other examples are mentioned in Tables IV and V .

Effect of muscular activation

The word “tension” has a central place in the term tension-type headache. Tunis and Wolff ( 27 ) stated that: “it has been established that some headaches arise from sustained contraction of skeletal muscle about the face, scalp and neck”. Later, there seemed to be, generally speaking, a growth of skepticism over the role of musculature in T-TH ( 28 – 31 ) .

The topic of adverse cranial musculature involvement in T-TH has also been addressed by our group ( 25 ) . In 20 patients in an active period and 20 group-matched controls, a complex, one-hour, two-choice, reaction-time test was carried out, with additional, five-minute pre-test and 20-minute post-test periods. Superficial EMG activity was monitored, and local pain was registered in the forehead, temple, neck, and trapezius muscle bilaterally.

Pain increased in all areas, except the temples, during the test, while the EMG activity increased significantly only in the neck/trapezius areas and not in the forehead, where pain increased. There was no significant difference between the two sides. These findings can be interpreted in various ways: EMG activity (at the level observed) is of no importance for the head pain, since forehead pain increased without any corresponding EMG activity. Or: the pain is referred, the forehead pain stemming from the neck/shoulder area, where EMG activity increased (this may be the most likely explanation). Or: the experimental stress set-up is not commensurate with real-life situations. The study does not convincingly show that muscular activity is of no importance for T-TH, but this seems to be one of the alternative explanations for the findings.

Theoretically, botulinum toxin, applied locally, could be useful in the treatment of T-TH. In our own, preliminary study, 16 years ago, one side was left untreated and used as a control for the other ( 32 ) . The study gave a negative result. A number of studies have since been carried out ( 33 ) . The overall impression as regards efficacy of the toxin in T-TH is that the matter still is sub judice.

Low-grade, bilateral, headache/astenopia may accompany strabismus (heterophoria) ( Table V ). A worsening of such complaints during exposure counts as evidence for a causal relationship between the headache and squint. In the solitary case, however, one can hardly go beyond the level of suspicion as regards causality ( 34 ) .

Concluding remarks

The marital problem/“mother-in-law” and similar cases will in all probability not, per se, play any considerable, quantitative role in T-TH. The conflict in our cases was, after all, relatively easy to get at. If mental problems play a role in T-TH in general, they are likely to be less easily detectable and harder to deal with than those in the present cases.

It is not that methods to detect particular, causal factors under optimal conditions do not exist, as in the case, for example, of the marital problems in T-TH. The question is whether such methods function under non-optimal conditions, such as questionnaire studies/telephone interviews.

What about the muscular factor in such situations? As soon as the principal problem was solved in the marital problem cases, the question of abnormal muscular activity was no longer of much importance. The major role that, mainly in the past, has been allotted to muscular “tension”/activation in T-TH as such may not have been justified.

Different headaches, such as H2S headache and caffeine withdrawal headache, will be close to impossible to distinguish from T-TH without thorough questioning ( Tables II and IV ). Even “ponytail headache” ( Table III ) may come in here ( 35 ) . These headaches help to demonstrate that T-TH is likely to be a syndrome, not a disease.

The “posterior headaches”: CEH/“neck-related, posterior headache” ( 9 ) may constitute a sizeable group. In short, these headaches, in their bilateral form, and in the absence of a clinical examination cannot always easily be distinguished from T-TH. When these headaches and, in addition, wrongly treated M-A cases (i.e. cases that have assumed the guise of T-TH) are subtracted from the T-TH group, the latter group may start attaining a correct size. The ultimate T-TH group will probably be: i) less voluminous; ii) purer; iii) to a higher degree characterized by bilateral headache; iv) less dominated by “posteriorly”-located cases. One may then dimly sense the contours of a core T-TH, a more homogeneous group. All this amounts to a dominant sensation that TTH as such is going to survive. But the term “tension” may have to be replaced/redefined.