Overlap of migraine and tension-type headache in the International Headache Society classification
Harley B Messinger, Egilius LH Spierings, Arnaud JP Vincent
Cephalalgia Messenger s HB, Spierings ELH Vincent AJP. Overlap of migraine and tension-type headache in the International Headache Society classification. Cephalalgia 1991;11:233-7. Oslo. ISSN 0333-1024 Using questionnaire data from two recent surveys, headache sufferers were classified as having either migraine, episodic, or chronic tension-type headache using the International Headache Society criteria. Of 410 subjects with a headache history of 2 years or more, 147 or 35.9% were assigned Code 1.7 (migrainous disorder not fulfilling the above criteria) or Code 2.3 (headache of the tension-type not fulfilling above criteria). In 79 of these 147 subjects (53.7%), either of the above codes would have been equally valid. Separate scores for "migraine" and "tension" symptoms may provide a way to handle this overlap and aid in choosing optimal therapy. • Classification, migraine, questionnaire data, tension-type headache Harley B Messinger, Arnaud JP Vincent, The John R Graham Headache Centre, The Faulkner Hospital; Egilius LH Spierings, Headache Section, Division of Neurology, Brigham and Women's Hospital, Boston, Massachusetts. Correspondence to Harley B Messinger, 226 Mystic Valley Parkway, Winchester, Massachusetts 01890, USA; Accepted 4 September 1991 For a recent study (1), headache sufferers Were classified as having either migraine, episodic, or chronic tension-type headache on the basis of the International Headache Society criteria (2). This revealed a surprising number of cases with ambiguous classifications. Because of the importance of the International Headache Society classification, this overlap is reported more fully here to document these findings. Recently, Iversen et al. (3). reported a study on the clinical characteristics of migraine and episodic tension-type headache in relation to the old (i.e. Ad Hoc (4)), and new (i.e. International Headache Society) diagnostic criteria. They also reviewed seven studies on the classification of headache, all performed before publication of the International Headache Society criteria. Among the 108 headache patients they examined, who had been diagnosed according to the Ad Hoc criteria, they found in nine instances that the International Headache Society criteria were fulfilled in half or less of the headaches. However, the original diagnoses did not need to be changed; rather, an additional diagnosis was needed in these patients. This was the first major study to compare the results of the Ad Hoc and International Headache Society classification systems. Material and methods
Two headache surveys were performed at different times among patients from the waiting room of the John R Graham Headache Centre at the Faulkner Hospital, Boston, as well as persons accompanying them and others attending the Faulkner-Sagoff Centre for Mammography. Survey I (5) focused on visual symptoms and eye strain factors in headache and Survey II (6) on muscular symptoms. In Survey I, 260 persons completed the questionnaire in a way adequate for analysis and in Survey II, 373 persons completed the questionnaire. Of these 633 respondents, 476 suffered from headache with only 29 having a headache history of less than 2 years. In 35 cases the age of onset of headaches was unknown, leaving 412 with a known history of 2 or more years. Two other cases were dropped for missing data. Questions were included to permit using the International Headache Society criteria for classification of the headaches as migraine (Code 1.1), episodic (Code 2.1), or chronic tension-type headache (Code 2.2). The criteria, as used here, are given in the Appendix. Only the 410 subjects from the two surveys with a headache history of 2 or more years and no essential missing data were included in the present analysis. Distinctions between the various forms of migraine were not made in this study. Rather, as in Iversen's study (3), the criteria for migraine without aura were employed (Code 1.1). We omitted the last criterion for each type of headache because the findings of the physical and neurological examinations were not obtainable from the questionnaire. The questionnaire did not ask for the cumulative total of headache episodes: the restriction of cases to those with a headache history of 2 or more years was felt to adequately cover the chronicity requirement of each headache diagnosis. To catalogue the various diagnoses, the criteria for episodic and chronic tension-type headache were tabulated for each level of migraine criteria met by
Table 1. Number of International Headache Society tension-type criteria fulfilled by number of satisfied migraine criteria. A. Subjects meeting one migraine criterion Episodic Chronic tension-type criteria tension-type criteria 3 4 2 2 11 3 Column total
5
0
7 38.9
11 61.1
Row total 13 72.2 5 27.8 18 100.0
B. Subjects meeting two migraine criteria Episodic tension-type criteria
Chronic tension-type criteria 1
2 1
3 7
4 5
2
8
10
41
3
6
15
0
15 16.1
32 34.4
46 49.5
Column total
Row total 13 14.0 59 63.4 21 22.6 93 100.0
C. Subjects meeting three migraine criteria Episodic tension-type criteria
Row total
Chronic tension-type criteria 0
0 0
1 0
2 9
3 10
4 0
1
1
19
12
35
5
2
0
9
21
4
11
3
0
1
1
8
0
29 19.9
43 29.5
57 39.0
16 11.0
Column total
1 0.7
19 13.0 72 49.3 45 30.8 10 6.9 146 100.0
D. Subjects meeting four migraine criteria Chronic tension-type criteria 0
1 0
2 48
3 22
4 0
1
7
20
36
0
2
1
16
1
1
3
0
1
0
0
85 55.6
59 38.6
1 0.7
Column total
Episodic tension-type criteria
8 5.2
Row total 70 45.8 63 41.2 19 12.4 1 0.6 153 100.0
the subjects. This device permitted representation of a three-dimensional contingency table one layer at a time. These "slices" are shown in Table 1 to make clear how Table 2 was obtained. In these tables, empty rows or columns are not shown. Table 1C is the only one showing all possible rows and columns. Results
The lowest level in migraine diagnosis was where only one criterion, i.e. criterion A, for migraine was met (all the subjects were selected to cover this chronicity requirement). Table 1A shows that 11 of these subjects met all the criteria for episodic and five those for chronic tension-type headache. Two patients fell one criterion short for each tension-type headache diagnosis. By using Code 2.3 ("headache of the tension-type not fulfilling the above criteria") for these last two patients, all subjects could be unambiguously classified. Table 1B shows the tabulation for subjects meeting two criteria for migraine. There were 46 episodic and 21 chronic tension-type headache cases with 25 of the rest of the cases codable into 2.3. Only one subject was not codable in any of the migraine or tension-type headache categories. That case was omitted from the summary table (Table 2). Table 1C shows the subjects meeting three criteria for migraine. Sixteen cases fully qualified for episodic and 10 for chronic tension-type headache diagnosis. Of 120 who were eligible for Code 1.7 ("migrainous disorders not fulfilling above criteria"), i.e. the rest of the table, 79 (65.8%) could just as easily have been given Code 2.3 if it were not for General Rule 7. This rule, which is arbitrary, requires that a headache fitting equally well the diagnostic criteria for both migraine and tension-type headache be coded as migraine because that category comes ahead of tension-type headache in the classification system. Thus all of these 79 subjects would have been classified as migraine (Code 1.7). The 153 cases in Table 1D with four migraine criteria satisfied Code 1.1 but one subject also fully met the criteria for Code 2.1, and one subject those for Code 2.2. Again, these last two cases would arbitrarily have been coded as migraine by Rule 7 but are shown in the tension-type categories in the summary table. Table 2 summarizes the diagnostic codes identified in the four cross-classification tables discussed above. At the first level, i.e. those meeting only one migraine criterion, there were only 18 cases. As these subjects definitely did not have migraine, one might have expected this to be the level with the greatest number of tension-type headache cases but it only ranked third.
Table 2. International Headache Society diagnostic codes by the number of satisfied migraine criteria. Number of migraine criteria 1
International Headache Society Codes 1.1 0
2.1 11
2.2 5
1.7 0
2.3 2
2
0
46
21
0
25
3
0
16
10
41
79†
4
151
1
1
0
0
Column total
151 36.9
74 18.1
37 9.1
41 10.0
106 25.9
*
Row total 18 4.4 92* 22.5 146 35.7 153 37.4 409* 100.0
Total excludes one case not eligible for any of the above codes.
† These cases qualify equally for Codes 1.7 and 2.3. Most of the subjects classified as Codes 2.1. and 2.2 cases appeared at the second level (67 of 111 or 60.4%) and most of those with Code 2.3 at the third (79 of 106 or 74.5%). (As noted above, the latter cases are those that General Rule 7 would put under Code 1.7.) The third level had more clear-cut tension-type headache cases than the first level (26 vs 16). This was also the level where the overlap between the diagnoses of migraine and tension-type headache was most pronounced, i.e. 120 of 146 subjects with Codes 1.7 or 2.3 (82.2%). Even at the fourth level, where all the subjects qualified as Code 1.1, there were two cases fully meeting the criteria for Code 2.1 or 2.2. These are shown that way in Table 2. Discussion
We were surprised to find: first, that the 1.7 and 2.3 codes had to be invoked so often, i.e. in 147 (35.9%) of the 410 subjects; and second, that while in 79 of these 147 subjects (53.7%) either code was equally valid, all of these cases would have to have been coded as migraine by Rule 7. This is over 19% of the 410 cases! The objection might be raised that many of these 147 subjects could have had one of the large number of other headache diagnoses, but how many patients with so many of the characteristics of both migraine and tension-type headache would suffer from something else? In Iversen's valuable study (3), there was a tabulation of the number of International Headache Society C and D criteria fulfilled for migraine and episodic tension-type headache in those conventionally diagnosed in those categories. Their Table 7 showed that nine of the 108 headache patients did not meet the International Headache Society criteria in half or more of their headaches. They concluded that while the International Headache Society classification did not "... alter the diagnostic tradition," it had not yet been formally demonstrated to improve the reproducibility and cross-national validity of headache diagnosis. It is of note, however, that their patients had been diagnosed before entry into the study and that patients with chronic tension-type headache had been excluded. A third of their patients were subject to both migraine and episodic tension-type headache. The International Headache Society classification was an important advance toward making headache diagnosis more objective. It was put forward to be tested, recognizing its limitations. In adapting it, the rule always favouring migraine over tension-type headache in what appears to be a common overlap is a possible candidate for modification. The overlap described in this study was a different kind of problem than the one noted in Iversen's study (3). Where that investigation uncovered an inconsistency of some headaches within the headache categories, this analysis dealt with difficulties in assigning categories in the first place. The international Headache Society criteria were derived judgementally, distilling many experts' years of clinical experience and the understanding gained from research work. However, before publication of the criteria, there should have been a formal trial phase to validate the criteria in practice. This could have assessed the magnitude of the overlap problem and a less arbitrary solution could have been sought. Drummond & Lance (7) analysed headache symptoms in 600 patients using data from a 40-item interview. All subjects had been diagnosed clinically into five groups using the Ad Hoc classification criteria. With warning signals well represented, classic migraine was well identified by discriminant analysis. Similarly, Horner's syndrome and other findings reliably identified the patients with cluster headache. However, they found many disagreements between the clinical and computer diagnoses among the patients with common migraine, tension-vascular and tension headache. They then went on to factor analyse a reduced set of variables and compute factor scores based on an oblique solution. By analysis of variance the means of the five clinical groups were found to be significantly different from each other by Scheffé's multiple-comparison technique. They concluded that, except for cluster headache, the headache categories represented distinct points on a continuum. However, it was the means of the groups that were shown to be different. If the original data were available, one could determine to what extent the groups overlapped at the individual case level. Another approach to representing migraine and tension headache problems on a continuum was
proposed by Bakal and Kaganov (8). They called it a severity model, referring to the extent to which headaches were viewed by the patients as a problem. They found that the frequency of all symptoms, both "migraine" and "tension" ones, increased with headache severity. While they did not use factor analysis, they did include a correlation matrix in their paper thus permitting such an analysis. To represent the severity model one would favour a single-factor solution and their correlation data were consistent with this. Using the same correlations, we tried a two-factor varimax factor analysis. The first factor turned out to include the "migraine" symptoms and the other the "muscle-contraction," i.e. tension-type, ones. The severity variable (measuring how often headache was a problem) was represented equally on the two factors. Factor scores rate a given subject on each factor. They should be high on only one of these two factors if migraine and tension-type headaches are distinct entities. If both kinds of symptoms are concordant, as in the severity model, then the scores should be also. To make an investigation as relevant as possible to the International Headache Society classification, data on symptoms should include all of the criteria used therein. These symptoms should be dealt with individually, as in the Bakal-Kaganov work, rather than using groupings such as criteria C and D in Codes 1.1 and 2.1 (see Appendix). For example: nausea, vomiting, photophobia and phonophobia should be separate items and not handled as in criterion D. Is the overlap reported here better explained by invoking the Bakal-Kaganov severity model or by assuming that the ambiguous cases have had both traditional migraine and tension-type headache attacks? A study such as that proposed above could help resolve this question. Appendix
The criteria for each code, as used in this study, are given below. Please note that the last criterion for each code, relating to the results of the physical and neurologic examinations, is not listed. Code 1.1. Migraine without aura A. At least five attacks fulfilling B-D. B. Headache attacks lasting 4-72 h (untreated or unsuccessfully treated). C. Headache has at least two of the following characteristics: 1. Unilateral location 2. Pulsating quality 3. Moderate or severe intensity (inhibits or prohibits daily activities) 4. Aggravation by walking stairs or similar routine physical activity. D. During headache at least one of the following: 1. Nausea and/or vomiting 2. Photophobia and phonophobia. Code 1.7. Migrainous disorder not fulfilling above criteria. A. Fulfills all criteria but one for one or more forms of migraine. B. Does not fulfill criteria for tension-type headache. Code 2.1. Episodic tension-type headache. A. At least 10 previous headache episodes fulfilling criteria B-D. Number of days with such headache 6 months fulfilling criteria B-D listed below. B. At least two of the following pain characteristics: 1. Pressing/tightening quality 2. Mild or moderate severity (may inhibit, but does not prohibit activities) 3. Bilateral location 4. No aggravation by walking stairs or similar routine physical activity. C. Both of the following. 1. No vomiting 2. No more than one of the following: nausea, photophobia or phonophobia. Code 2.3. Headache of the tension-type not fulfilling above criteria. A. Fulfills all but one criterion for one or more form of tension-type headache. B. Does not fulfill criteria for migraine without aura.
References
1.
Messinger HB, et al. Headache and family history. Cephalalgia 1991;11:13-18
2.
International Headache Society. Classification and diagnostic criteria for headache disorders, cranial neuralgias and facial pain. Cephalalgia 1988;8(suppl 7):1-96
3.
lversen HK, et al. Clinical characteristics of migraine and episodic tension-type headache in relation to old and new diagnostic criteria. Headache 1990;30:514-19
4.
Ad Hoc Committee on Classification of Headache. Classification of headache. JAMA 1962;179:717-18
5.
Vincent AJP, Spierings ELH, Messinger HB. A controlled study of visual symptoms and eye strain factors in chronic headache. Headache 1989;29:523-7
6.
Lebbink J, Spierings ELH, Messinger HB. A questionnaire survey of muscular symptoms in chronic headache: an age-and sex-controlled study. Clin J Pain 1991;7:95-101
7.
Drummond PD, Lance JW. Clinical diagnosis and computer analysis of headache symptoms. J Neurol Neurosurg Psychiatry 1984;47:128-33
8.
Bakal DA, Kaganov JA. Symptom characteristics of chronic and non-chronic headache sufferers. Headache 1979;19:285-9
Harley B Messinger, Egilius LH Spierings, Arnaud JP Vincent
Cephalalgia Messenger s HB, Spierings ELH Vincent AJP. Overlap of migraine and tension-type headache in the International Headache Society classification. Cephalalgia 1991;11:233-7. Oslo. ISSN 0333-1024 Using questionnaire data from two recent surveys, headache sufferers were classified as having either migraine, episodic, or chronic tension-type headache using the International Headache Society criteria. Of 410 subjects with a headache history of 2 years or more, 147 or 35.9% were assigned Code 1.7 (migrainous disorder not fulfilling the above criteria) or Code 2.3 (headache of the tension-type not fulfilling above criteria). In 79 of these 147 subjects (53.7%), either of the above codes would have been equally valid. Separate scores for "migraine" and "tension" symptoms may provide a way to handle this overlap and aid in choosing optimal therapy. • Classification, migraine, questionnaire data, tension-type headache Harley B Messinger, Arnaud JP Vincent, The John R Graham Headache Centre, The Faulkner Hospital; Egilius LH Spierings, Headache Section, Division of Neurology, Brigham and Women's Hospital, Boston, Massachusetts. Correspondence to Harley B Messinger, 226 Mystic Valley Parkway, Winchester, Massachusetts 01890, USA; Accepted 4 September 1991 For a recent study (1), headache sufferers Were classified as having either migraine, episodic, or chronic tension-type headache on the basis of the International Headache Society criteria (2). This revealed a surprising number of cases with ambiguous classifications. Because of the importance of the International Headache Society classification, this overlap is reported more fully here to document these findings. Recently, Iversen et al. (3). reported a study on the clinical characteristics of migraine and episodic tension-type headache in relation to the old (i.e. Ad Hoc (4)), and new (i.e. International Headache Society) diagnostic criteria. They also reviewed seven studies on the classification of headache, all performed before publication of the International Headache Society criteria. Among the 108 headache patients they examined, who had been diagnosed according to the Ad Hoc criteria, they found in nine instances that the International Headache Society criteria were fulfilled in half or less of the headaches. However, the original diagnoses did not need to be changed; rather, an additional diagnosis was needed in these patients. This was the first major study to compare the results of the Ad Hoc and International Headache Society classification systems. Material and methods
Two headache surveys were performed at different times among patients from the waiting room of the John R Graham Headache Centre at the Faulkner Hospital, Boston, as well as persons accompanying them and others attending the Faulkner-Sagoff Centre for Mammography. Survey I (5) focused on visual symptoms and eye strain factors in headache and Survey II (6) on muscular symptoms. In Survey I, 260 persons completed the questionnaire in a way adequate for analysis and in Survey II, 373 persons completed the questionnaire. Of these 633 respondents, 476 suffered from headache with only 29 having a headache history of less than 2 years. In 35 cases the age of onset of headaches was unknown, leaving 412 with a known history of 2 or more years. Two other cases were dropped for missing data. Questions were included to permit using the International Headache Society criteria for classification of the headaches as migraine (Code 1.1), episodic (Code 2.1), or chronic tension-type headache (Code 2.2). The criteria, as used here, are given in the Appendix. Only the 410 subjects from the two surveys with a headache history of 2 or more years and no essential missing data were included in the present analysis. Distinctions between the various forms of migraine were not made in this study. Rather, as in Iversen's study (3), the criteria for migraine without aura were employed (Code 1.1). We omitted the last criterion for each type of headache because the findings of the physical and neurological examinations were not obtainable from the questionnaire. The questionnaire did not ask for the cumulative total of headache episodes: the restriction of cases to those with a headache history of 2 or more years was felt to adequately cover the chronicity requirement of each headache diagnosis. To catalogue the various diagnoses, the criteria for episodic and chronic tension-type headache were tabulated for each level of migraine criteria met by
Table 1. Number of International Headache Society tension-type criteria fulfilled by number of satisfied migraine criteria. A. Subjects meeting one migraine criterion Episodic Chronic tension-type criteria tension-type criteria 3 4 2 2 11 3 Column total
5
0
7 38.9
11 61.1
Row total 13 72.2 5 27.8 18 100.0
B. Subjects meeting two migraine criteria Episodic tension-type criteria
Chronic tension-type criteria 1
2 1
3 7
4 5
2
8
10
41
3
6
15
0
15 16.1
32 34.4
46 49.5
Column total
Row total 13 14.0 59 63.4 21 22.6 93 100.0
C. Subjects meeting three migraine criteria Episodic tension-type criteria
Row total
Chronic tension-type criteria 0
0 0
1 0
2 9
3 10
4 0
1
1
19
12
35
5
2
0
9
21
4
11
3
0
1
1
8
0
29 19.9
43 29.5
57 39.0
16 11.0
Column total
1 0.7
19 13.0 72 49.3 45 30.8 10 6.9 146 100.0
D. Subjects meeting four migraine criteria Chronic tension-type criteria 0
1 0
2 48
3 22
4 0
1
7
20
36
0
2
1
16
1
1
3
0
1
0
0
85 55.6
59 38.6
1 0.7
Column total
Episodic tension-type criteria
8 5.2
Row total 70 45.8 63 41.2 19 12.4 1 0.6 153 100.0
the subjects. This device permitted representation of a three-dimensional contingency table one layer at a time. These "slices" are shown in Table 1 to make clear how Table 2 was obtained. In these tables, empty rows or columns are not shown. Table 1C is the only one showing all possible rows and columns. Results
The lowest level in migraine diagnosis was where only one criterion, i.e. criterion A, for migraine was met (all the subjects were selected to cover this chronicity requirement). Table 1A shows that 11 of these subjects met all the criteria for episodic and five those for chronic tension-type headache. Two patients fell one criterion short for each tension-type headache diagnosis. By using Code 2.3 ("headache of the tension-type not fulfilling the above criteria") for these last two patients, all subjects could be unambiguously classified. Table 1B shows the tabulation for subjects meeting two criteria for migraine. There were 46 episodic and 21 chronic tension-type headache cases with 25 of the rest of the cases codable into 2.3. Only one subject was not codable in any of the migraine or tension-type headache categories. That case was omitted from the summary table (Table 2). Table 1C shows the subjects meeting three criteria for migraine. Sixteen cases fully qualified for episodic and 10 for chronic tension-type headache diagnosis. Of 120 who were eligible for Code 1.7 ("migrainous disorders not fulfilling above criteria"), i.e. the rest of the table, 79 (65.8%) could just as easily have been given Code 2.3 if it were not for General Rule 7. This rule, which is arbitrary, requires that a headache fitting equally well the diagnostic criteria for both migraine and tension-type headache be coded as migraine because that category comes ahead of tension-type headache in the classification system. Thus all of these 79 subjects would have been classified as migraine (Code 1.7). The 153 cases in Table 1D with four migraine criteria satisfied Code 1.1 but one subject also fully met the criteria for Code 2.1, and one subject those for Code 2.2. Again, these last two cases would arbitrarily have been coded as migraine by Rule 7 but are shown in the tension-type categories in the summary table. Table 2 summarizes the diagnostic codes identified in the four cross-classification tables discussed above. At the first level, i.e. those meeting only one migraine criterion, there were only 18 cases. As these subjects definitely did not have migraine, one might have expected this to be the level with the greatest number of tension-type headache cases but it only ranked third.
Table 2. International Headache Society diagnostic codes by the number of satisfied migraine criteria. Number of migraine criteria 1
International Headache Society Codes 1.1 0
2.1 11
2.2 5
1.7 0
2.3 2
2
0
46
21
0
25
3
0
16
10
41
79†
4
151
1
1
0
0
Column total
151 36.9
74 18.1
37 9.1
41 10.0
106 25.9
*
Row total 18 4.4 92* 22.5 146 35.7 153 37.4 409* 100.0
Total excludes one case not eligible for any of the above codes.
† These cases qualify equally for Codes 1.7 and 2.3. Most of the subjects classified as Codes 2.1. and 2.2 cases appeared at the second level (67 of 111 or 60.4%) and most of those with Code 2.3 at the third (79 of 106 or 74.5%). (As noted above, the latter cases are those that General Rule 7 would put under Code 1.7.) The third level had more clear-cut tension-type headache cases than the first level (26 vs 16). This was also the level where the overlap between the diagnoses of migraine and tension-type headache was most pronounced, i.e. 120 of 146 subjects with Codes 1.7 or 2.3 (82.2%). Even at the fourth level, where all the subjects qualified as Code 1.1, there were two cases fully meeting the criteria for Code 2.1 or 2.2. These are shown that way in Table 2. Discussion
We were surprised to find: first, that the 1.7 and 2.3 codes had to be invoked so often, i.e. in 147 (35.9%) of the 410 subjects; and second, that while in 79 of these 147 subjects (53.7%) either code was equally valid, all of these cases would have to have been coded as migraine by Rule 7. This is over 19% of the 410 cases! The objection might be raised that many of these 147 subjects could have had one of the large number of other headache diagnoses, but how many patients with so many of the characteristics of both migraine and tension-type headache would suffer from something else? In Iversen's valuable study (3), there was a tabulation of the number of International Headache Society C and D criteria fulfilled for migraine and episodic tension-type headache in those conventionally diagnosed in those categories. Their Table 7 showed that nine of the 108 headache patients did not meet the International Headache Society criteria in half or more of their headaches. They concluded that while the International Headache Society classification did not "... alter the diagnostic tradition," it had not yet been formally demonstrated to improve the reproducibility and cross-national validity of headache diagnosis. It is of note, however, that their patients had been diagnosed before entry into the study and that patients with chronic tension-type headache had been excluded. A third of their patients were subject to both migraine and episodic tension-type headache. The International Headache Society classification was an important advance toward making headache diagnosis more objective. It was put forward to be tested, recognizing its limitations. In adapting it, the rule always favouring migraine over tension-type headache in what appears to be a common overlap is a possible candidate for modification. The overlap described in this study was a different kind of problem than the one noted in Iversen's study (3). Where that investigation uncovered an inconsistency of some headaches within the headache categories, this analysis dealt with difficulties in assigning categories in the first place. The international Headache Society criteria were derived judgementally, distilling many experts' years of clinical experience and the understanding gained from research work. However, before publication of the criteria, there should have been a formal trial phase to validate the criteria in practice. This could have assessed the magnitude of the overlap problem and a less arbitrary solution could have been sought. Drummond & Lance (7) analysed headache symptoms in 600 patients using data from a 40-item interview. All subjects had been diagnosed clinically into five groups using the Ad Hoc classification criteria. With warning signals well represented, classic migraine was well identified by discriminant analysis. Similarly, Horner's syndrome and other findings reliably identified the patients with cluster headache. However, they found many disagreements between the clinical and computer diagnoses among the patients with common migraine, tension-vascular and tension headache. They then went on to factor analyse a reduced set of variables and compute factor scores based on an oblique solution. By analysis of variance the means of the five clinical groups were found to be significantly different from each other by Scheffé's multiple-comparison technique. They concluded that, except for cluster headache, the headache categories represented distinct points on a continuum. However, it was the means of the groups that were shown to be different. If the original data were available, one could determine to what extent the groups overlapped at the individual case level. Another approach to representing migraine and tension headache problems on a continuum was
proposed by Bakal and Kaganov (8). They called it a severity model, referring to the extent to which headaches were viewed by the patients as a problem. They found that the frequency of all symptoms, both "migraine" and "tension" ones, increased with headache severity. While they did not use factor analysis, they did include a correlation matrix in their paper thus permitting such an analysis. To represent the severity model one would favour a single-factor solution and their correlation data were consistent with this. Using the same correlations, we tried a two-factor varimax factor analysis. The first factor turned out to include the "migraine" symptoms and the other the "muscle-contraction," i.e. tension-type, ones. The severity variable (measuring how often headache was a problem) was represented equally on the two factors. Factor scores rate a given subject on each factor. They should be high on only one of these two factors if migraine and tension-type headaches are distinct entities. If both kinds of symptoms are concordant, as in the severity model, then the scores should be also. To make an investigation as relevant as possible to the International Headache Society classification, data on symptoms should include all of the criteria used therein. These symptoms should be dealt with individually, as in the Bakal-Kaganov work, rather than using groupings such as criteria C and D in Codes 1.1 and 2.1 (see Appendix). For example: nausea, vomiting, photophobia and phonophobia should be separate items and not handled as in criterion D. Is the overlap reported here better explained by invoking the Bakal-Kaganov severity model or by assuming that the ambiguous cases have had both traditional migraine and tension-type headache attacks? A study such as that proposed above could help resolve this question. Appendix
The criteria for each code, as used in this study, are given below. Please note that the last criterion for each code, relating to the results of the physical and neurologic examinations, is not listed. Code 1.1. Migraine without aura A. At least five attacks fulfilling B-D. B. Headache attacks lasting 4-72 h (untreated or unsuccessfully treated). C. Headache has at least two of the following characteristics: 1. Unilateral location 2. Pulsating quality 3. Moderate or severe intensity (inhibits or prohibits daily activities) 4. Aggravation by walking stairs or similar routine physical activity. D. During headache at least one of the following: 1. Nausea and/or vomiting 2. Photophobia and phonophobia. Code 1.7. Migrainous disorder not fulfilling above criteria. A. Fulfills all criteria but one for one or more forms of migraine. B. Does not fulfill criteria for tension-type headache. Code 2.1. Episodic tension-type headache. A. At least 10 previous headache episodes fulfilling criteria B-D. Number of days with such headache 6 months fulfilling criteria B-D listed below. B. At least two of the following pain characteristics: 1. Pressing/tightening quality 2. Mild or moderate severity (may inhibit, but does not prohibit activities) 3. Bilateral location 4. No aggravation by walking stairs or similar routine physical activity. C. Both of the following. 1. No vomiting 2. No more than one of the following: nausea, photophobia or phonophobia. Code 2.3. Headache of the tension-type not fulfilling above criteria. A. Fulfills all but one criterion for one or more form of tension-type headache. B. Does not fulfill criteria for migraine without aura.
References
1.
Messinger HB, et al. Headache and family history. Cephalalgia 1991;11:13-18
2.
International Headache Society. Classification and diagnostic criteria for headache disorders, cranial neuralgias and facial pain. Cephalalgia 1988;8(suppl 7):1-96
3.
lversen HK, et al. Clinical characteristics of migraine and episodic tension-type headache in relation to old and new diagnostic criteria. Headache 1990;30:514-19
4.
Ad Hoc Committee on Classification of Headache. Classification of headache. JAMA 1962;179:717-18
5.
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![[Management of chronic daily headache in migraine patients: medication overuse headache and chronic migraine. French guidelines (French Headache Society, French Private Neurologists Association, French Pain Society)].](/assets/img/hold.png)
