SOME OBSERVATIONS ON PAIN IN CLUSTER HEADACHE KARL EKBOM, M.D. From the Department of Neurology, Karolinska sjukhuset, and the Department of Neurology, Södersjukhuset, Stockholm, Sweden. THE PATHOGENESIS OF cluster headache incompletely known. Several authors consider the attack to be associated with local dilatation of extra-cranial vessels in the regions supplied by branches of the external carotid artery. According to Friedman and Mikropoulos1 this is suggested by the fact that during an attack one observes 1) a dilated temporal artery in some cases, 2) injection of conjunctiva and congestion of nasal mucosa, 3) local rise of skin temperature, 4) reduced ache on compression of the temporal artery, 5) a favorable response to vasoconstrictor agents. The pain has been assumed to be due to local release to the tissues around the dilated vessels of a substance which lowers the threshold of pain.2 However, it is probable that the internal carotid artery as well participates in the pathophysiological process in many cases of cluster headache. This is evidenced by the occurrence of a partial Horner's syndrome on the side of the pain.3,4 An attempt has been made in the present study to throw further light on the nature of the pain in cluster headache. The patients were thoroughly studied during attacks by means of simple clinical procedures aimed at relief of the pain. Some new observations will be discussed. PATIENTS AND METHODS Altogether 33 patients aged 20-55 years (mean age 33 years) were studied, 31 male and 2 female. All had typical symptoms in accordance with the diagnostic criteria reported in earlier papers.5 The patients were examined on one or more occasions during severe spontaneous and/or induced attacks. Altogether 45 provocations were made with nitroglycerine (1 mg) as described earlier.6 One or more spontaneous attacks were also observed in 11 patients. The aches were recorded according to their character, intensity, localization and duration. The patients were supine during the attacks. A number of maneuvers were performed in order to study their effect on the pain. Each maneuver was repeated at least three times. RESULTS Character of headache As described in a previous paper the attacks started with vague discomfort in the region of one eye, forehead or temple.5 Within a few minutes these symptoms became accentuated, assuming the character of real pain. This was usually very intense within 10-15 min. When the patient experienced maximum pain it was felt to be excruciating and generally occurred without fluctuations. Sometimes there were short repeated exacerbations of pain added to the continuous basic headache. The majority of patients stated that the pain was boring, pressing or burning in character. Only few experienced it as pulsating or throbbing. During the final stage of the attack there was a fairly rapid decrease of headache. The intensity was then often described as fluctuating. Towards the end of the attack some interesting observations were made. The pain was not seldom throbbing in character. Furthermore paroxysms of pricking or stabbing sensations were reported by 11 patients. These sensations were limited to the region of the eye, forehead or upper
jaw and generally lasted for less than a few seconds. They occurred once or several times in rapid succession and were separated by free intervals of a few seconds' duration. These paroxysms gradually subsided and the remissions finally extended to several minutes. It was generally stated by the patients that these symptoms usually indicated that the attack was coming to an end. Localization of headache The pain was always strictly unilateral. It was maximal in, behind or around the eye or immediately above the eye, in the region of the eyebrow. The radiation of pain took place in two different ways, as earlier reported by Ekbom and Kugelberg.4 The main radiation of pain was either supraorbital or infraorbital. In the former group (upper syndrome) the pain usually involved the eye, forehead and/or temple. Sometimes it also extended to the nape of the neck. In the second group (lower syndrome) it was often limited to frontal and/or temporal regions but it also (or exclusively) extended to the teeth of the upper jaw, or to the lower jaw, or both. In several patients it radiated to the lower jaw and ipsilateral side of the neck. The difference of symptomatology between the two groups might be ascribed to the involvement of different segments of the carotid artery during the attacks. The vascular process might be ascribed mainly to the external carotid artery in the upper syndrome, and mainly to the internal carotid in the lower syndrome.4,5 In some patients there are probably functional vascular changes in both carotid systems. Fourteen of the patients had pain of upper syndrome, 19 of lower syndrome type. Effect of digital compression of cranial arteries Superficial temporal artery The effect of digital compression of the superficial temporal artery was studied in 31 attacks in 18 subjects. The compression was brought to bear on the side of the pain for 10 sec and any changes in the intensity, quality and radiation of the headache were noted. The results are shown in Table 1. Compression of the temporal artery resulted sometimes in alleviation, sometimes in exacerbation of the pain. Ache in the temple was commonly relieved, but sometimes a characteristic redistribution of the pain was noted, the ache increasing in or around the eye, especially at the medial corner. This change of distribution of the pain was noted in patients both with upper and with lower syndrome. Carotid artery Compression was produced by exercising pressure with two fingers against the artery in the upper part of the neck for 10 sec, first on the symptomatic side and in some cases thereafter on the asymptomatic side. The effect of compression of the carotid was studied during 26 attacks in 20 patients. TABLE 1 Effect of digital compression of the ipsilateral superficial temporal artery during attacks of cluster headache. The patients have been classified into upper and lower syndrome on the basis of the radiation of the pain.4 Upper syndrome
Lower syndrome
Total
(n = 9)
(n = 9)
(n = 18)
Improvement
5
3
8
Deterioration
3
5
8
No change
1
I
2
Effect on headache
TABLE 2 Effect of digital compression of the ipsilateral carotid artery. Upper syndrome
Lower syndrome
Total
(n = 8)
(n = 12)
(n = 20)
Improvement
4
6
10
Deterioration
2
3
5
No change
2
3
5
Effect on headache
The results are shown in Table 2. Half of the patients experienced reduced ache in the region of the eye during the compression. In a few cases reduced ache in the region of the eye was felt simultaneously with some increase of ache in the forehead and/or temple. In 3 patients with ache in the forehead, eye and upper jaw, including the teeth, an interesting effect of the compression was observed. Two had a Horner's syndrome on the symptomatic side. All had lower syndrome. Compression of the carotid artery reduced the pain both in eye and upper jaw. This supports the assumption of the internal carotid artery as the seat of the vascular process in some cases of cluster headache. Radiological evidence of this has also been presented.7 Compression of the carotid artery on the opposing asymptomatic side usually had no definite effect, but in some cases an increased ache was felt. Effect of tight head bandage Method. A mercury manometer cuff (12 x 35 cm) with a firm bandage fitted over it was applied over the skull ad modum Wolff.8 The cuff covered frontal, temporal and occipital regions as closely as possible. Over the forehead the lower part of the cuff was on a level with the eyebrows. The cuff was inflated to above the systolic blood pressure (approx. 175 mm Hg) for 10 sec. When the effect on the ache had been recorded, the cuff was deflated as quickly as possible. Results. Seven patients were studied during severe attacks. In 5 cases (3 with upper, 2 with lower syndrome) the compression reduced the ache especially in the forehead and temple, but it was not markedly changed in the region of the eye. When the compression was removed, the headache reoccurred as before. One patient with lower syndrome experienced an increased headache and another noticed no effect of the compression. Rotatory head jolt The effect of rotatory head jolt for 10 sec was examined in 29 patients. According to observations by Kunkle9 and Wolff8 intracranial vascular headache is readily augmented by rotatory head jolt, presumably producing added distortion of dilated and tender arteries at the base of the brain. The results are shown in Table 3. It was striking that in almost all patients head jolt was either without effect or alleviated the headache. Seldom was there a very brief accentuation of the pain a couple of seconds after termination of head jolt. Many patients had themselves noticed during spontaneous attacks that head movements reduced the pain.5 Valsalva's maneuver The effect of Valsalva's maneuver was studied ad modum Kunkle.10 The headache was recorded before, during and after sudden sustained straining for 10 sec. According to Kunkle intracranial vascular headache is likely to diminish moderately in intensity, as the result of
Effect on headache Improvement Deterioration No change
Effect on headache Improvement Deterioration No change
TABLE 3 Effect of rotatory head jolt. Upper Lower syndrome syndrome (n = 13) (n = 16) 2 5 2 3 9 8
TABLE 4 Effect of Valsalva's maneuver Upper Lower syndrome syndrome (n = 7) (n = 15) 0 2 2 4 5 9
Total (n = 29) 7 5 17
Total (n = 22) 2 6 14
a mild fall in mean systemic arterial pressure coincident with a rise in intracranial cerebrospinal fluid pressure. Results. Twenty-two patients were investigated. The results are shown in Table 4. In the majority of the patients Valsalva's maneuver had no definite effect on the headache. There was no improvement in any patient with upper syndrome. In about one-quarter of all the patients the headache increased, roughly equally frequently in cases of upper and of lower syndrome. Sometimes the ache increased immediately after the Valsalva maneuver. Effect of compression of the brachial artery The arterial blood pressure of all patients was recorded at frequent intervals with a mercury manometer cuff applied over the right upper arm. In four patients, during seven attacks, it was discovered that inflation of the cuff caused increased ocular pain after a few seconds. This was noted both during mild and severe ache. A few seconds after deflation of the cuff the ocular pain decreased again. Towards the end of and after the attacks this procedure did not cause any exacerbation of the ache. These observations were made only in a few cases and were not consistently studied in all patients. In two other patients the blood pressure measurements produced no change of the ocular headache. The arterial compression during the blood pressure measurement manifestly gave rise to increased headache in some patients. An increased blood flow in critical regions of the cranial arteries may have occurred on a reflexogenic basis through emotional stimuli or central blood pressure changes. However, the latter explanation seems unlikely. Compression of the brachial artery did not result in a significant rise of pressure in the ascending aorta, when checked in some patients in conjunction with heart catheterization.11 DISCUSSION The effect of digital compression of cranial arteries has only been briefly discussed in earlier papers. According to Horton et al.12 compression of the common carotid artery and sometimes
the temporal artery frequently gave prompt relief in the first stages of an attack. Horton13 considered that the attacks arose through local dilatation of branches of the external carotid artery. Kunkle et al.,14 in a few patients, observed that the pain was eased during compression of the ipsilateral temporal artery (visibly) enlarged in one instance). In my patients the pain was predominant in the region of the eye, but radiated either above or below the eye, not seldom to the upper and/or lower jaw or to the neck. The component of pain referable to the internal carotid artery was manifest on brief digital compression of the ipsilateral superficial temporal artery. The pain was reduced in temporal regions, but it often increased in the region of the eye, especially at the medial corner. This was possibly caused by changes in the anastomosing circulation from the supraorbital artery, which is a branch of the ophthalmic arterial circulation. Compression of the carotid artery, on the other hand, in many cases resulted in a reduction or disappearance of ocular headache, and in some cases also in reduced ache in the maxillary region. The ocular circulation, as in more proximal portions of the internal carotid artery, appears to be characteristic of cluster headache. Ekbom and Greitz7 demonstrated in one patient a constriction in the carotid siphon as well as a dilatation of the ophthalmic artery during an attack. Hörven et al.15 found increased pulse-synchronous variations of the intraocular pressure on the symptomatic side during attacks of cluster headache. This indicates an increased blood volume in the ocular vascular bed, a factor probably contributing to the ocular pain. The present results appear to provide additional clinical evidence for this assumption. Kunkle et al.14 made trials in two cases of cluster headache with controlled elevation of intracranial pressure by intrathecal injection of normal saline, a procedure known to alleviate only headache associated with dilatation of intra-cranial arteries. The pain was unaffected by this procedure. These data suggested that in such individuals dilated branches of the external carotid artery were the principle contributory to the pain. Other patients in the same series felt increased pain on head jolt, indicating that in these cases the headache derived from intracranial vessels. In more than 80% of my patients rotatory head jolt either had no effect on or alleviated the pain. In the majority of eases Valsalva's maneuver was also without definite effect on the headache. This indicates that the headache arises by other means and within other vascular regions, than the classical forms of intracranial ache, e.g. histamine headache, subarachnoid hemorrhage or expanding lesions. In these states the arteries are particularly vulnerable to jolt forces.10 Patients with migraine exhibit many clinical symptoms which point to a significant intracranial component in the vascular headache. Violent head movements, forward bending, straining and physical exertion often accentuate their headaches. In patients with cluster headache the ache is usually unaffected by these procedures.5 This was clearly confirmed in the present study. My results appear to indicate that the pain in cluster headache arises distally in the internal carotid circulation, presumably in the region of the eye. In many cases there is in addition or exclusively, an involvement of the external carotid artery, especially the superficial temporal artery. The assumption that the pain arises in the ocular region is suggested by the fact that attacks of cluster headache are not seldom associated with a reduction of the heart rate so that pronounced bradycardia sometimes occurs. This may be due to an oculocardial reflex which
occurs in response to painful stimuli on or around the eye.16 In the majority of patients with cluster headache islands of hypothermia have been found in the medial supraorbital area supplied by extracranial branches of the internal carotid artery.17,18 The importance of the boundary region of the internal-external carotid arterial supply to the supraorbital region was demonstrated through the fact that many patients had cool islands precisely within this region. The pattern appeared to be characteristic of cluster headache and occurred only exceptionally in conjunction with other forms of headache. The authors presumed that the hypothermia marked a prolonged period of instability of vascular autonomic control.17 Hypersensitivity in terminal vessels within this territory might be produced by a lesion of postganglionic sympathetic fibers along the internal carotid artery. Many patients with cluster headache have an ipsilateral Horner's syndrome which may be accentuated during attacks.5 From the clinical aspect this strongly suggests that the internal carotid artery is often involved during attacks of cluster headache. SUMMARY In 33 patients with cluster headache the pain was investigated during spontaneous or induced attacks. Digital compression of the superficial temporal artery usually reduced the temporal ache but sometimes increased the pain in the region of the eye. Compression of the carotid artery commonly alleviated or eliminated ocular ache and in some cases also in the maxillary region. A tight head bandage over the scalp usually reduced ache over the upper part of the head but did not affect the ocular pain. Rotatory head jolt had either no effect or alleviated the headache in more than 80% of the patients. Valsalva's maneuver was in the majority of cases without effect on the headache. The results suggest that the pain in cluster headache arises distally in the internal carotid circulation, presumably in the region of the eye. In many patients branches of the external carotid artery in addition, or exclusively, are involved. REFERENCES 1.
Friedman, A.P., and Mikropoulos, H.E.: Cluster headaches. Neurology 8:653-663, 1958.
2. Ostfeld, A.M., Chapman, L.F., Goodell, H., and Wolff, H.G.: Studies in headache: Summary of evidence concerning a noxious agent active locally during migraine headache. Psychosom. Med. 19:199-208, 1957. 3. Kunkle, E.C., and Anderson, W.B.: Significance of minor eye signs in headache of migraine type. Arch. Ophthalmol. 65:504-508, 1961. 4. Ekbom, K. and Kugelberg, E.: Upper and lower cluster headache (Horton's syndrome). In: Brain and Mind Problems. Pensiero Sci. Publ. Roma pp. 482-489, 1968. 5. Ekbom, K.: A clinical comparison of cluster headache and migraine. Acta Neurol Scand. 46: suppl. 41, 1970. 6. Ekbom, K.: Nitroglycerin as a provocative agent in cluster headache. Arch. Neurol. (Chic.) 19:487-493, 1968. 7.
Ekbom, K. and Greitz, T.: Carotid angiography in cluster headache. Acta Radiol. (Diagn.) 10:177-186, 1970.
8. Wolff, H.G.: Wolff's Headache and other head pain. 3. Ed. (Revised by D.J. Dalessio). New York. Oxford Univ. Press 1972. 9.
Kunkle, E.C.: Vascular headache, including migraine. Intern. J. Neurol. 3:327-334, 1962.
10. Kunkle, E.C.: Headache mechanisms, with particular reference to migraine. Neurology 13: Nr. 3, part 2: 1-6, 1963. 11.
Karnell, J., and Ekbom, K.: Unpublished observations.
12. Horton, B.T., MacLean, A.R., and Craig, W.M.: A new syndrome of vascular headache: results of treatment with histamine: preliminary report. Mayo Clin Proc. 14:257-260, 1939. 13. Horton, B.T.: The use of histamine in the treatment of specific types of headaches. J. Amer. Med. Ass. 116:377-383, 1941. 14. Kunkle, E.C., Pfeiffer, Jr., J.B., Wilhoit, W.M., and Hamrick, Jr., L.W.: Recurrent brief headache in "cluster" pattern. Trans. Amer. Neurol. Ass. 77:240-243, 1952.
15. Hörven, I., Nornes, H, and Sjaastad, O.: Different corneal indentation pulse pattern in cluster headache and migraine. Neurology 22:92-98, 1972. 16. Ekbom, K.: Heart rate, blood pressure, and electrocardiographic changes during provoked attacks of cluster headache. Acta Neurol. Scand. 46:215-224, 1970. 17. Friedman, A.P., Wood, E.H., Rowan, A. J., and Frazier, Jr., S.H.: Observations on vascular headache of the migraine type. In: Background to Migraine (Ed. by J.N. Cumings). William Heinemann Medical Books Ltd, London, pp. 1-17, 1973. 18. Wood, E.H., and Friedman, A.P.: Thermography in migraine and cluster headache. Excerpta Medica International Congress Series No. 296, X Internat. Congress of Neurology, Barcelona, Spain Sept. 8-15, 1973, p. 29, 1973. Address reprint requests to: Karl Ekbom, M.D. Department of Neurology Södersjukhuset Stockholm, Sweden
jaw and generally lasted for less than a few seconds. They occurred once or several times in rapid succession and were separated by free intervals of a few seconds' duration. These paroxysms gradually subsided and the remissions finally extended to several minutes. It was generally stated by the patients that these symptoms usually indicated that the attack was coming to an end. Localization of headache The pain was always strictly unilateral. It was maximal in, behind or around the eye or immediately above the eye, in the region of the eyebrow. The radiation of pain took place in two different ways, as earlier reported by Ekbom and Kugelberg.4 The main radiation of pain was either supraorbital or infraorbital. In the former group (upper syndrome) the pain usually involved the eye, forehead and/or temple. Sometimes it also extended to the nape of the neck. In the second group (lower syndrome) it was often limited to frontal and/or temporal regions but it also (or exclusively) extended to the teeth of the upper jaw, or to the lower jaw, or both. In several patients it radiated to the lower jaw and ipsilateral side of the neck. The difference of symptomatology between the two groups might be ascribed to the involvement of different segments of the carotid artery during the attacks. The vascular process might be ascribed mainly to the external carotid artery in the upper syndrome, and mainly to the internal carotid in the lower syndrome.4,5 In some patients there are probably functional vascular changes in both carotid systems. Fourteen of the patients had pain of upper syndrome, 19 of lower syndrome type. Effect of digital compression of cranial arteries Superficial temporal artery The effect of digital compression of the superficial temporal artery was studied in 31 attacks in 18 subjects. The compression was brought to bear on the side of the pain for 10 sec and any changes in the intensity, quality and radiation of the headache were noted. The results are shown in Table 1. Compression of the temporal artery resulted sometimes in alleviation, sometimes in exacerbation of the pain. Ache in the temple was commonly relieved, but sometimes a characteristic redistribution of the pain was noted, the ache increasing in or around the eye, especially at the medial corner. This change of distribution of the pain was noted in patients both with upper and with lower syndrome. Carotid artery Compression was produced by exercising pressure with two fingers against the artery in the upper part of the neck for 10 sec, first on the symptomatic side and in some cases thereafter on the asymptomatic side. The effect of compression of the carotid was studied during 26 attacks in 20 patients. TABLE 1 Effect of digital compression of the ipsilateral superficial temporal artery during attacks of cluster headache. The patients have been classified into upper and lower syndrome on the basis of the radiation of the pain.4 Upper syndrome
Lower syndrome
Total
(n = 9)
(n = 9)
(n = 18)
Improvement
5
3
8
Deterioration
3
5
8
No change
1
I
2
Effect on headache
TABLE 2 Effect of digital compression of the ipsilateral carotid artery. Upper syndrome
Lower syndrome
Total
(n = 8)
(n = 12)
(n = 20)
Improvement
4
6
10
Deterioration
2
3
5
No change
2
3
5
Effect on headache
The results are shown in Table 2. Half of the patients experienced reduced ache in the region of the eye during the compression. In a few cases reduced ache in the region of the eye was felt simultaneously with some increase of ache in the forehead and/or temple. In 3 patients with ache in the forehead, eye and upper jaw, including the teeth, an interesting effect of the compression was observed. Two had a Horner's syndrome on the symptomatic side. All had lower syndrome. Compression of the carotid artery reduced the pain both in eye and upper jaw. This supports the assumption of the internal carotid artery as the seat of the vascular process in some cases of cluster headache. Radiological evidence of this has also been presented.7 Compression of the carotid artery on the opposing asymptomatic side usually had no definite effect, but in some cases an increased ache was felt. Effect of tight head bandage Method. A mercury manometer cuff (12 x 35 cm) with a firm bandage fitted over it was applied over the skull ad modum Wolff.8 The cuff covered frontal, temporal and occipital regions as closely as possible. Over the forehead the lower part of the cuff was on a level with the eyebrows. The cuff was inflated to above the systolic blood pressure (approx. 175 mm Hg) for 10 sec. When the effect on the ache had been recorded, the cuff was deflated as quickly as possible. Results. Seven patients were studied during severe attacks. In 5 cases (3 with upper, 2 with lower syndrome) the compression reduced the ache especially in the forehead and temple, but it was not markedly changed in the region of the eye. When the compression was removed, the headache reoccurred as before. One patient with lower syndrome experienced an increased headache and another noticed no effect of the compression. Rotatory head jolt The effect of rotatory head jolt for 10 sec was examined in 29 patients. According to observations by Kunkle9 and Wolff8 intracranial vascular headache is readily augmented by rotatory head jolt, presumably producing added distortion of dilated and tender arteries at the base of the brain. The results are shown in Table 3. It was striking that in almost all patients head jolt was either without effect or alleviated the headache. Seldom was there a very brief accentuation of the pain a couple of seconds after termination of head jolt. Many patients had themselves noticed during spontaneous attacks that head movements reduced the pain.5 Valsalva's maneuver The effect of Valsalva's maneuver was studied ad modum Kunkle.10 The headache was recorded before, during and after sudden sustained straining for 10 sec. According to Kunkle intracranial vascular headache is likely to diminish moderately in intensity, as the result of
Effect on headache Improvement Deterioration No change
Effect on headache Improvement Deterioration No change
TABLE 3 Effect of rotatory head jolt. Upper Lower syndrome syndrome (n = 13) (n = 16) 2 5 2 3 9 8
TABLE 4 Effect of Valsalva's maneuver Upper Lower syndrome syndrome (n = 7) (n = 15) 0 2 2 4 5 9
Total (n = 29) 7 5 17
Total (n = 22) 2 6 14
a mild fall in mean systemic arterial pressure coincident with a rise in intracranial cerebrospinal fluid pressure. Results. Twenty-two patients were investigated. The results are shown in Table 4. In the majority of the patients Valsalva's maneuver had no definite effect on the headache. There was no improvement in any patient with upper syndrome. In about one-quarter of all the patients the headache increased, roughly equally frequently in cases of upper and of lower syndrome. Sometimes the ache increased immediately after the Valsalva maneuver. Effect of compression of the brachial artery The arterial blood pressure of all patients was recorded at frequent intervals with a mercury manometer cuff applied over the right upper arm. In four patients, during seven attacks, it was discovered that inflation of the cuff caused increased ocular pain after a few seconds. This was noted both during mild and severe ache. A few seconds after deflation of the cuff the ocular pain decreased again. Towards the end of and after the attacks this procedure did not cause any exacerbation of the ache. These observations were made only in a few cases and were not consistently studied in all patients. In two other patients the blood pressure measurements produced no change of the ocular headache. The arterial compression during the blood pressure measurement manifestly gave rise to increased headache in some patients. An increased blood flow in critical regions of the cranial arteries may have occurred on a reflexogenic basis through emotional stimuli or central blood pressure changes. However, the latter explanation seems unlikely. Compression of the brachial artery did not result in a significant rise of pressure in the ascending aorta, when checked in some patients in conjunction with heart catheterization.11 DISCUSSION The effect of digital compression of cranial arteries has only been briefly discussed in earlier papers. According to Horton et al.12 compression of the common carotid artery and sometimes
the temporal artery frequently gave prompt relief in the first stages of an attack. Horton13 considered that the attacks arose through local dilatation of branches of the external carotid artery. Kunkle et al.,14 in a few patients, observed that the pain was eased during compression of the ipsilateral temporal artery (visibly) enlarged in one instance). In my patients the pain was predominant in the region of the eye, but radiated either above or below the eye, not seldom to the upper and/or lower jaw or to the neck. The component of pain referable to the internal carotid artery was manifest on brief digital compression of the ipsilateral superficial temporal artery. The pain was reduced in temporal regions, but it often increased in the region of the eye, especially at the medial corner. This was possibly caused by changes in the anastomosing circulation from the supraorbital artery, which is a branch of the ophthalmic arterial circulation. Compression of the carotid artery, on the other hand, in many cases resulted in a reduction or disappearance of ocular headache, and in some cases also in reduced ache in the maxillary region. The ocular circulation, as in more proximal portions of the internal carotid artery, appears to be characteristic of cluster headache. Ekbom and Greitz7 demonstrated in one patient a constriction in the carotid siphon as well as a dilatation of the ophthalmic artery during an attack. Hörven et al.15 found increased pulse-synchronous variations of the intraocular pressure on the symptomatic side during attacks of cluster headache. This indicates an increased blood volume in the ocular vascular bed, a factor probably contributing to the ocular pain. The present results appear to provide additional clinical evidence for this assumption. Kunkle et al.14 made trials in two cases of cluster headache with controlled elevation of intracranial pressure by intrathecal injection of normal saline, a procedure known to alleviate only headache associated with dilatation of intra-cranial arteries. The pain was unaffected by this procedure. These data suggested that in such individuals dilated branches of the external carotid artery were the principle contributory to the pain. Other patients in the same series felt increased pain on head jolt, indicating that in these cases the headache derived from intracranial vessels. In more than 80% of my patients rotatory head jolt either had no effect on or alleviated the pain. In the majority of eases Valsalva's maneuver was also without definite effect on the headache. This indicates that the headache arises by other means and within other vascular regions, than the classical forms of intracranial ache, e.g. histamine headache, subarachnoid hemorrhage or expanding lesions. In these states the arteries are particularly vulnerable to jolt forces.10 Patients with migraine exhibit many clinical symptoms which point to a significant intracranial component in the vascular headache. Violent head movements, forward bending, straining and physical exertion often accentuate their headaches. In patients with cluster headache the ache is usually unaffected by these procedures.5 This was clearly confirmed in the present study. My results appear to indicate that the pain in cluster headache arises distally in the internal carotid circulation, presumably in the region of the eye. In many cases there is in addition or exclusively, an involvement of the external carotid artery, especially the superficial temporal artery. The assumption that the pain arises in the ocular region is suggested by the fact that attacks of cluster headache are not seldom associated with a reduction of the heart rate so that pronounced bradycardia sometimes occurs. This may be due to an oculocardial reflex which
occurs in response to painful stimuli on or around the eye.16 In the majority of patients with cluster headache islands of hypothermia have been found in the medial supraorbital area supplied by extracranial branches of the internal carotid artery.17,18 The importance of the boundary region of the internal-external carotid arterial supply to the supraorbital region was demonstrated through the fact that many patients had cool islands precisely within this region. The pattern appeared to be characteristic of cluster headache and occurred only exceptionally in conjunction with other forms of headache. The authors presumed that the hypothermia marked a prolonged period of instability of vascular autonomic control.17 Hypersensitivity in terminal vessels within this territory might be produced by a lesion of postganglionic sympathetic fibers along the internal carotid artery. Many patients with cluster headache have an ipsilateral Horner's syndrome which may be accentuated during attacks.5 From the clinical aspect this strongly suggests that the internal carotid artery is often involved during attacks of cluster headache. SUMMARY In 33 patients with cluster headache the pain was investigated during spontaneous or induced attacks. Digital compression of the superficial temporal artery usually reduced the temporal ache but sometimes increased the pain in the region of the eye. Compression of the carotid artery commonly alleviated or eliminated ocular ache and in some cases also in the maxillary region. A tight head bandage over the scalp usually reduced ache over the upper part of the head but did not affect the ocular pain. Rotatory head jolt had either no effect or alleviated the headache in more than 80% of the patients. Valsalva's maneuver was in the majority of cases without effect on the headache. The results suggest that the pain in cluster headache arises distally in the internal carotid circulation, presumably in the region of the eye. In many patients branches of the external carotid artery in addition, or exclusively, are involved. REFERENCES 1.
Friedman, A.P., and Mikropoulos, H.E.: Cluster headaches. Neurology 8:653-663, 1958.
2. Ostfeld, A.M., Chapman, L.F., Goodell, H., and Wolff, H.G.: Studies in headache: Summary of evidence concerning a noxious agent active locally during migraine headache. Psychosom. Med. 19:199-208, 1957. 3. Kunkle, E.C., and Anderson, W.B.: Significance of minor eye signs in headache of migraine type. Arch. Ophthalmol. 65:504-508, 1961. 4. Ekbom, K. and Kugelberg, E.: Upper and lower cluster headache (Horton's syndrome). In: Brain and Mind Problems. Pensiero Sci. Publ. Roma pp. 482-489, 1968. 5. Ekbom, K.: A clinical comparison of cluster headache and migraine. Acta Neurol Scand. 46: suppl. 41, 1970. 6. Ekbom, K.: Nitroglycerin as a provocative agent in cluster headache. Arch. Neurol. (Chic.) 19:487-493, 1968. 7.
Ekbom, K. and Greitz, T.: Carotid angiography in cluster headache. Acta Radiol. (Diagn.) 10:177-186, 1970.
8. Wolff, H.G.: Wolff's Headache and other head pain. 3. Ed. (Revised by D.J. Dalessio). New York. Oxford Univ. Press 1972. 9.
Kunkle, E.C.: Vascular headache, including migraine. Intern. J. Neurol. 3:327-334, 1962.
10. Kunkle, E.C.: Headache mechanisms, with particular reference to migraine. Neurology 13: Nr. 3, part 2: 1-6, 1963. 11.
Karnell, J., and Ekbom, K.: Unpublished observations.
12. Horton, B.T., MacLean, A.R., and Craig, W.M.: A new syndrome of vascular headache: results of treatment with histamine: preliminary report. Mayo Clin Proc. 14:257-260, 1939. 13. Horton, B.T.: The use of histamine in the treatment of specific types of headaches. J. Amer. Med. Ass. 116:377-383, 1941. 14. Kunkle, E.C., Pfeiffer, Jr., J.B., Wilhoit, W.M., and Hamrick, Jr., L.W.: Recurrent brief headache in "cluster" pattern. Trans. Amer. Neurol. Ass. 77:240-243, 1952.
15. Hörven, I., Nornes, H, and Sjaastad, O.: Different corneal indentation pulse pattern in cluster headache and migraine. Neurology 22:92-98, 1972. 16. Ekbom, K.: Heart rate, blood pressure, and electrocardiographic changes during provoked attacks of cluster headache. Acta Neurol. Scand. 46:215-224, 1970. 17. Friedman, A.P., Wood, E.H., Rowan, A. J., and Frazier, Jr., S.H.: Observations on vascular headache of the migraine type. In: Background to Migraine (Ed. by J.N. Cumings). William Heinemann Medical Books Ltd, London, pp. 1-17, 1973. 18. Wood, E.H., and Friedman, A.P.: Thermography in migraine and cluster headache. Excerpta Medica International Congress Series No. 296, X Internat. Congress of Neurology, Barcelona, Spain Sept. 8-15, 1973, p. 29, 1973. Address reprint requests to: Karl Ekbom, M.D. Department of Neurology Södersjukhuset Stockholm, Sweden
