Compensated Hypogonadism Identified in Males with Cluster Headache: A Prospective Case-Controlled Study

OBJECTIVE

Androgens have been hypothesized to be involved in the pathophysiology of cluster headache due to the male predominance, but whether androgens are altered in patients with cluster headache remains unclear.

METHODS

We performed a prospective, case-controlled study in adult males with cluster headache. Sera were measured for hormones including testosterone, luteinizing hormone (LH), and sex hormone-binding globulin in 60 participants with episodic cluster headache (during a bout and in remission), 60 participants with chronic cluster headache, and 60 age- and sex-matched healthy controls. Free testosterone (fT) was calculated according to the Vermeulen equation. Shared genetic risk variants were assessed between cluster headache and testosterone concentrations.

RESULTS

The mean fT/LH ratio was reduced by 35% (95% confidence interval [CI]: 21%-47%, p < 0.0001) in patients with chronic cluster headache and by 24% (95% CI: 9%-37%, p = 0.004) in patients with episodic cluster headache compared to controls after adjusting for age, sleep duration, and use of acute medication. Androgen concentrations did not differ between bouts and remissions. Furthermore, a shared genetic risk allele, rs112572874 (located in the intron of the microtubule associated protein tau (MAPT) gene on chromosome 17), between fT and cluster headache was identified.

INTERPRETATION

Our results demonstrate that the male endocrine system is altered in patients with cluster headache to a state of compensated hypogonadism, and this is not an epiphenomenon associated with sleep or the use of acute medication. Together with the identified shared genetic risk allele, this may suggest a pathophysiological link between cluster headache and fT. ANN NEUROL 2024;95:1149-1161.

Reduced plasma calcitonin gene-related peptide level identified in cluster headache: A prospective and controlled study

BACKGROUND

The role of calcitonin gene-related peptide (CGRP) in the cyclic pattern of cluster headache is unclear. To acquire biological insight and to comprehend why only episodic cluster headache responds to CGRP monoclonal antibodies, we examined whether plasma CGRP changes between disease states (i.e. bout, remission and chronic) and controls.

METHODS

The present study is a prospective case-control study. Participants with episodic cluster headache were sampled twice (bout and remission). Participants with chronic cluster headache and controls were sampled once. CGRP concentrations were measured in plasma with a validated radioimmunoassay.

RESULTS

Plasma was collected from 201 participants diagnosed with cluster headache according to the International Classification of Headache Disorders, 3rd edition, and from 100 age- and sex-matched controls. Overall, plasma CGRP levels were significantly lower in participants with cluster headache compared to controls (p < 0.05). In episodic cluster headache, CGRP levels were higher in bout than in remission (mean difference: 17.1 pmol/L, 95% confidence interval = 9.8-24.3, p < 0.0001). CGRP levels in bout were not different from chronic cluster headache (p = 0.266).

CONCLUSIONS

Plasma CGRP is unsuitable as a diagnostic biomarker of cluster headache or its disease states. The identified reduced CGRP levels suggest that CGRPs role in cluster headache is highly complex and future investigations are needed into the modulation of CGRP and its receptors.

Male and female sex hormones in primary headaches

BACKGROUND

The three primary headaches, tension-type headache, migraine and cluster headache, occur in both genders, but all seem to have a sex-specific prevalence. These gender differences suggest that both male and female sex hormones could have an influence on the course of primary headaches. This review aims to summarise the most relevant and recent literature on this topic.

METHODS

Two independent reviewers searched PUBMED in a systematic manner. Search strings were composed using the terms LH, FSH, progesteron*, estrogen*, DHEA*, prolactin, testosterone, androgen*, headach*, migrain*, "tension type" or cluster. A timeframe was set limiting the search to articles published in the last 20 years, after January 1st 1997.

RESULTS

Migraine tends to follow a classic temporal pattern throughout a woman's life corresponding to the fluctuation of estrogen in the different reproductive stages. The estrogen withdrawal hypothesis forms the basis for most of the assumptions made on this behalf. The role of other hormones as well as the importance of sex hormones in other primary headaches is far less studied.

CONCLUSION

The available literature mainly covers the role of sex hormones in migraine in women. Detailed studies especially in the elderly of both sexes and in cluster headache and tension-type headache are warranted to fully elucidate the role of these hormones in all primary headaches.

Peripheral Levels of BDNF and NGF in Primary Headaches

Neurotrophins, such as brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), have been implicated in the generation and modulation of pain. To investigate whether alterations in neurotrophin levels can be detected in subjects suffering from nociceptive disorders, such as primary headaches, we determined the peripheral (platelet and plasma) levels of BDNF and NGF in patients suffering from migraine, with or without aura, or cluster headache (CH), in the interictal phase, and in healthy volunteers. All primary headaches patients studied showed significantly decreased platelet levels of BDNF (migraine vs. controls P < 0.001; CH vs. controls P < 0.01), while a selective reduction of platelet NGF was observed in migraine sufferers and not in CH patients compared with control subjects (migraine vs. controls P < 0.001). These changes were not accompanied by significant modifications of neurotrophin plasma levels. Our findings show for the first time that changes in peripheral levels of neurotrophines (BDNF and NGF) occur in patients suffering from different types of primary headaches, suggesting a potential involvement of BDNF and NGF in the pathophysiology of these disorders, and raising the possibility that differences in peripheral neurotrophins may help to distinguish migraine biologically from CH.

Ergotamine Abuse. Do Patients Benefit from Withdrawal?

A follow-up study of 40 patients (migraine 39, cluster headache 1) previously treated for ergotamine abuse was conducted. Their statements regarding ergotamine intake were checked using butalbital (contained in the suppositories abused by 90% of the patients) as a tracer, and later by contact with the family doctor. Eleven patients abused ergotamine again during a median observation time of 21 months. Nineteen patients had more than a 50% reduction in headache days after withdrawal and half of the patients were relieved of other symptoms of ergotamine toxicity. Even with a failure rate of approximately 25% it is concluded that efforts to withdraw after abuse of ergotamine are worthwhile.

Plasma melatonin pattern in chronic and episodic headaches: evaluation during sleep and waking

To look for a relationship between pineal function in chronic migraine (CM), cluster headache (CH) (during active and remission periods), chronic tension-type headache (CTTH) patients and controls during NREM sleep, REM sleep and waking, we performed serial sampling of plasma melatonin in the different sleep stages during the first half of the night, in order to avoid chronobiological interferences. Plasma melatonin levels did not show a normal curve either in the CTTH or in the CM patients and no significant differences between these groups were found in any of the sleep stages studied. Plasma melatonin values of CH patients during the cluster period showed an abnormal pattern. The curve showed a pathological lack of peaks during the active period, melatonin levels remaining within normal daytime range throughout the study. A trend to normalization of the curve during the remission period was observed. On the basis of these different melatonin secretion patterns, it might be hypothesized that the involvement of the hypothalamus in chronic-type headaches differs from that displayed in episodic forms.

Nocturnal secretion of growth hormone, noradrenaline, cortisol and insulin in cluster headache remission

We have previously shown decreased, nocturnal lipolysis in both phases of cluster headache (CH). Lipolysis is stimulated by noradrenaline (NA), growth hormone (GH) and cortisol, and inhibited by insulin, hormones which are directly or indirectly regulated by the hypothalamus. Our aim was to investigate the nocturnal secretion of NA, GH, cortisol and insulin in nine CH patients in remission and 10 healthy controls. Nocturnal venous blood samples were collected in hourly intervals for analysis of NA, cortisol and insulin and in 30-min intervals for GH. We found a reduced increase in GH between 24.00 h and 01.00 h (anova, P < 0.05) in CH patients. Nocturnal secretion of NA, cortisol and insulin did not differ significantly between the groups. The altered nocturnal GH pattern that was seen in CH patients in remission might in part explain the altered nocturnal lipolysis previously found and further indicate a permanent hypothalamic disturbance in CH.

Platelet Levels of Dopamine Are Increased in Migraine and Cluster Headache

OBJECTIVE

To measure plasma and platelet levels of dopamine in patients with migraine with aura, migraine without aura, and cluster headache.

BACKGROUND

Clinical, genetic, and pharmacological evidences suggest that an abnormality of dopaminergic system plays a role in migraine pathogenesis. Direct evidence of an abnormal metabolism of dopamine in migraine, however, is lacking.

METHODS

Plasma and platelet levels of dopamine were measured in patients with migraine with aura or migraine without aura during headache-free periods and in patients with cluster headache during the remission and active periods, as compared with healthy control subjects, using a multichannel electrochemical high-performance liquid chromatography system.

RESULTS

Plasma levels of dopamine were not detectable with our methodology. Platelet levels of dopamine were higher in both types of migraine (migraine without aura = .20 +/- .17 ng/10(8) platelets; migraine with aura = .16 +/- .19 ng/10(8) platelets) than in control subjects (.10 +/- .11 ng/10(8) platelets), although in migraine with aura patients the difference was not significant. Patients with cluster headache showed the highest levels of platelet dopamine (.34 +/- .36 ng/10(8) platelets).

CONCLUSIONS

Our results support the hypothesis that the dopaminergic system is impaired in migraine and cluster headache and suggest that high platelet levels of dopamine may represent an abnormal biochemical phenotypic trait of these primary headaches.

Elevated levels of circulating trace amines in primary headaches

BACKGROUND

Trace amines, including tyramine, octopamine, and synephrine, are closely related to classic biogenic amines. They have been hypothesized to promote migraines and other types of primary headaches, but there is no direct evidence supporting this hypothesis.

METHODS

Using a multichannel electrochemical high-performance liquid chromatography system, the authors evaluated whether changes in circulating trace amines occur in subjects with migraine (with or without aura) during headache-free periods as well as in patients with cluster headache (CH) during the remission and active phases as compared with healthy control subjects.

RESULTS

Plasma levels of all trace amines were significantly higher in CH patients, in both the remission and the active phases, when compared with control subjects or subjects with migraine. In addition, intraplatelet levels of octopamine, synephrine, and tyramine were higher in CH patients than in control subjects. In migraine patients, plasma levels of octopamine and synephrine were higher compared with controls, although in migraine with aura, the difference was not significant.

CONCLUSIONS

Whereas the elevation of plasma trace amine levels in both migraine and CH supports the hypothesis that disorders of biogenic amine metabolism may be a characteristic biochemical trait in primary headache sufferers, the observation that such alterations are more prominent in patients with CH than migraine patients suggests that they may reflect sympathetic or hypothalamic dysfunction.

Circulating nociceptin levels during the cluster headache period

The trigeminal innervation of the dura and its vessels has a prominent role in the mechanism of cluster headache. Nociceptin, an opioid neuropeptide, is the endogenous ligand of the OP-4 receptor, with both algesic and analgesic properties depending on the site of action. Nociceptin and its receptor are expressed by trigeminal ganglion cells where they co-localize with calcitonin gene-related peptide, a marker peptide of the trigeminovascular neurones. Nociceptin inhibits neurogenic dural vasodilatation, a phenomenon related to trigeminovascular activation. To explore its possible involvement in cluster headache, we studied circulating levels of nociceptin when attack-free during the cluster period, and also after the termination of the cluster period, using radioimmunoassay. In 14 cluster headache patients nociceptin levels during the cluster period were significantly lower than in age-, and sex-matched controls (4.91 +/- 1.96 vs. 9.58 +/- 2.57 pg/ml, P < 0.01). After the termination of the cluster period nociceptin levels (8.60 +/- 1.47 pg/ml) were not statistically different from controls. Nociceptin levels did not correlate with age, length of disease or episode length. Lower nociceptin levels during the cluster period may result in a defective regulation of trigeminal activity that might not protect sufficiently against the attacks.

Nitric oxide pathway and response to nitroglycerin in cluster headache patients: plasma nitrite and citrulline levels

Nitric oxide (NO) may participate in the mechanisms underlying vascular headaches, such as migraine and cluster headache (CH), by triggering neurogenic inflammation and activation of fibres conveying nociceptive inputs to the trigeminal ganglion. Similarly to migraine, the administration of the NO donor glyceryltrinitrate (GTN) to CH patients is a known model of inducing spontaneous-like attacks. We carried out a GTN test (0.9 mg, sublingually) in 18 patients with episodic CH in active phase and 12 controls. The plasma levels of NO metabolite nitrites (NO2-), after conversion of nitrates to NO2-, were measured spectrophotometrically at baseline, at the maximum intensity of the induced response (or 45 min after GTN in controls), and 120 min after GTN administration. The basal plasma levels of L-citrulline were also assayed in patients and controls using high-performance liquid chromatography. Basal NO2- levels, similar in GTN-responsive patients and controls (48.3 +/- 10.6 and 44.6 +/- 9.5 micromol/l, respectively) were found to be increased significantly at pain peak in patients (76.1 +/- 10.2 micromol/l) and after 45 min in controls (78.2 +/- 9.6 micromol/l) (P < 0.01 vs. respective baseline values), but not after 120 min, without differences between groups. L-citrulline levels in basal conditions showed no differences between groups (patients 64.8 +/- 11.7, controls 67.3 +/- 10.8 micromol/l). These data do not support the presence of a basal hyperactivity of the L-arginine-NO pathway in CH patients. Increased NO production may be of importance in the mechanisms leading to CH attacks, but other factors are likely to render CH patients hyperresponsive to NO, and ultimately to cause the occurrence of pain and associated features.

Abnormal 5-HT1D receptor function in cluster headache: a neuroendocrine study with sumatriptan

The purpose of this study was to assess the sensitivity of 5-HT(1D) receptors in patients with episodic cluster headache using sumatriptan as a pharmacological probe. The drug, a selective 5-HT(1B/1D) agonist, stimulates the secretion of growth hormone and inhibits the release of prolactin, adrenocorticotropic hormone (ACTH) and cortisol. These effects may be used to explore the function of serotonergic systems in vivo. We administered subcutaneous sumatriptan and placebo to 20 patients with cluster headache (10 in the active phase and 10 in the remission period) and to 12 controls. The sumatriptan-induced increase of growth hormone concentrations was significantly (P < 0.05) blunted in patients with active cluster headache. Prolactin and ACTH responses to the drug were significantly (P < 0.05) reduced in patients with cluster headache, both in the active and in the remission period. Our results suggest that cerebral serotonergic functions mediated by 5-HT(1D) receptors are altered in patients with episodic cluster headache.

Cluster headache associated with sleep apnoea

This study of sleep changes in patients with cluster headache (CH) was conducted in view of the nocturnal predominance of this condition, the efficacy of oxygen and the fact that the attacks follow oxygen desaturation. Proposed mechanisms include impairment of carotid body activity secondary to hypothalamic vasomotor regulatory dysfunction. Sixteen patients with episodic CH and 29 healthy volunteers underwent nocturnal polysomnography. Five (31.3%) patients with episodic CH were found to have sleep apnoea (SA). Two patients with SA experienced two attacks during the study period. The attacks followed episodes of oxygen desaturation and were associated with REM sleep. In two patients with SA and CH, treatment with continuous positive airway pressure abolished their oxygen desaturation, sleep apnoeas and headaches. Our study confirmed the high percentage of CH associated with SA. We suggest that oxygen desaturation may be a trigger factor in some patients and play a role in the pathogenesis of CH.

Somatostatin infusion withdrawal: a study of patients with migraine, cluster headache and healthy volunteers

Migraine and cluster headache are the most common disabling primary headache syndromes and are typically episodic. A reliable method of triggering such headache attacks facilitates the study and treatment of these disorders. There is sufficient clinical and laboratory evidence to suggest that somatostatin withdrawal may be a useful way of triggering headache. We studied 15 subjects, eight migraineurs, four cluster headache sufferers and three healthy controls. Each subject had a standard somatostatin infusion, 250 microg/h for 3.5h. Subjects were followed for 24h post-infusion. Growth hormone was suppressed in each subject demonstrating a biologically active infusion of somatostatin. None of the non-headache sufferers had pain. Seven of eight migraine sufferers had no immediate headache and no delayed headache. One migraineur experienced short lasting headache with no migrainous features. Three of four patients with cluster headache had no significant pain with the infusion, while one had pain after 1h. The results suggest that somatostatin infusion is not a reliable way to produce headache in experimental settings in either migraine or cluster headache. The data do not exclude a role for somatostatinergic mechanisms in primary headache.

Platelet aggregation profiles in cluster headache

BACKGROUND

Platelets are activated in patients with cluster headache, during both the remission period and the active cycles.

OBJECTIVE

To delineate more clearly the origin of platelet activation in cluster headache. Methods.-Platelet aggregation induced by collagen (0.5 micro g/mL and 2 micro g/mL), adenosine diphosphate (10-5 M and 10-6 M), and platelet-activating factor (10-6 M and 10-7 M) was determined by the Born's method in 26 patients with cluster headache and 24 sex- and age-matched controls.

RESULTS

The platelets of patients with cluster headache aggregated significantly less to collagen at a concentration of 0.5 micro g/mL compared to those of controls (P =.04). The extent of platelet aggregation obtained with a higher dose of collagen (2 micro g/mL) was in the same range in both groups. Platelet aggregation obtained via adenosine diphosphate at a concentration of 10-6 M was significantly reduced in patients with cluster headache in comparison to controls (P =.002), but no differences were found at a concentration of 10-5 M. In contrast, the platelets of patients with cluster headache aggregated significantly more to platelet-activating factor at both the concentrations of 10-6 M (P =.001) and 10-7 M (P =.00001) compared to those of controls.

CONCLUSIONS

This study suggests that platelet aggregation is impaired in patients with cluster headache during the active phase of the disease. We found hypoaggregation in response to low doses of collagen and adenosine diphosphate, and hyperaggregation when platelets were stimulated with platelet-activating factor. Any interpretation of these results can only be speculative. It may be that impairment of platelet aggregation with collagen and adenosine diphosphate may indicate a derangement of nitric oxide function, while the hypersensitivity to platelet-activating factor may be due to fluctuations in its plasma levels.

Soluble interleukin-2 receptors increase during the active periods in cluster headache

OBJECTIVE

To investigate whether cytokines are altered during the active period of cluster headache.

BACKGROUND

Patients with cluster headache show activation of the hypothalamus in PET studies and via endocrinologic parameters. Data also suggest an inflammatory process occurs in cluster headache. A connection between the presumed inflammatory cause, an immunological activation, and the hypothalamus could be generated by certain cytokines.

DESIGN AND METHODS

ELISA was used to determine the serum levels of soluble interleukin-2 receptors, interleukin-1, interleukin-6, and 2 soluble interleukin-6 receptors (sIL-6R and soluble gp130) in 18 patients with cluster headache (6 women and 12 men) during the cluster period and in 17 healthy controls who were headache-free (3 women and 14 men).

RESULTS

Patients with cluster headache had significantly increased soluble interleukin-2 receptors (413.6+/-223 U/mL vs. 290.0+/-112 U/mL; P <.05) compared with controls. Serum levels of interleukin-1 (0.29+/-0.30 pg/mL vs. 0.13+/-0.13 pg/mL, n.s.), interleukin-6 (0.87+/-0.6 pg/mL vs. 0.91+/-0.7 pg/ml; n.s.), soluble interleukin-6 receptors (33,131+/-8,349 pg/mL vs. 35,063+/-7,606 pg/mL; n.s.), or soluble gp130 (289+/-59 pg/mL vs. 283+/-20 pg/mL; n.s.) did not differ between the 2 groups, although patients with cluster tended to have higher interleukin-1 values.

CONCLUSIONS

Because elevated soluble interleukin-2 receptors indicate T cell activation, our findings suggest immune activation during cluster headache. Because interleukin-2 can activate the hypothalamus and stimulate the release of Corticotropin-releasing Factor (CRF), interleukin-2 could link a putative immunological cause of cluster headache with the observed hypothalamic activation. Systemic changes of interleukin-1 or the interleukin-6 system do not seem to play a role in cluster headache, as no alterations of serum levels were observed. Even so, unchanged serum levels do not exclude limited local production.

Hyperbaric oxygen treatment of active cluster headache: a double-blind placebo-controlled cross-over study

Sixteen patients, 12 with episodic and four with chronic cluster headache (CH) according to the International Headache Society criteria (1), participated in the study. They were randomly selected to start with one out of two different hyperbaric treatments in a double-blind, placebo-controlled, cross-over study design. Both gases were administered by mask inside a multiplace hyperbaric chamber for 70 min at 250 kPa (2.5 ATA) in two sessions 24 h apart. Active treatment was 100% oxygen (HBO treatment), while placebo treatment was 10% oxygen in nitrogen (hyperbaric normoxic placebo = sham treatment) corresponding to breathing air at sea level. All patients were decompressed on air. The patients documented the number of headache attacks and their degree of severity according to a modified VAS scale (level 0-4, where level 0 = no headache and level 4 = very severe headache). A headache index (HI = sum of (number of attacks times degree of severity)) was calculated for the run-in week prior to and the week after each separate treatment. A treatment was regarded as effective if it reduced the HI by>50%. Blood samples were taken from the external jugular vein before and during hyperbaric treatment (after 30 and 70 min), 1 day and 1 week after each treatment for analyses of calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP) and neuropeptide Y (NPY) and in a few patients also endotheline and nitrate. No difference between HBO and sham treatment on the HI or the prophylactic effect was observed in our study. However, 83% of the episodic CH patients and 25% of the chronic ones responded to either of the two treatments with at least 50% reduction of HI or remission for shorter or longer periods. This response rate exceeds an expected high placebo response due to the study procedure. Two episodic CH patients still experienced remission on follow-up 1 year after sham treatment. Five patients reported mild or moderate CH attacks during the sham treatment, and none during the HBO treatment. Changes in neuropeptides, endotheline and nitrate levels did not differ systematically when comparing the two different hyperbaric treatments or with respect to responders and non-responders. We conclude that two HBO sessions were not more effective than two sham treatments in reducing the HI and interrupting the CH period when given in a well-established cluster period or in chronic CH. The hyperbaric condition itself seems effective in reducing the HI, at least in patients with episodic CH, although a powerful placebo response can not be ruled out.

Endothelin-1 plasma levels in cluster headache

BACKGROUND AND OBJECTIVE

A role for endothelin-1, a potent vasoconstrictor peptide, in some cerebrovascular diseases has been proposed. To obtain preliminary data about peripheral concentrations of endothelin-1 in acute cluster headache, we measured the plasma endothelin-1 secretory pattern in 10 men with cluster during and independent of a headache attack.

METHODS

We collected blood samples for plasma endothelin-1 determinations at 0, 15, 30, 45, 60, 90, and 120 minutes during a cluster attack and closely monitored blood pressures. We repeated the same sampling during an asymptomatic period.

RESULTS

The mean values of plasma endothelin-1 (before a cluster headache, 3.3 +/- 0.3 pg/mL) significantly increased (F = 2.578, P < .05) during an attack, reaching their peak at 30 minutes (5.0 +/- 0.5 pg/mL, P < .05). We found no significant variations in mean arterial pressure.

CONCLUSION

Endothelin-1 may play a role in the pathophysiology of cluster attacks. The increase in plasma observed during cluster attacks may be linked to alterations in systemic hemodynamics and vascular tone.

Hypofunctionality of Gi proteins as aetiopathogenic mechanism for migraine and cluster headache

The involvement of Gi proteins in the modulation of pain perception has been widely established, and mutations in G-proteins have already been identified as the aetiopathological cause of human diseases. The aim of the present study was to determine whether a deficiency or a hypofunctionality of the Gi proteins occurred in primary headache. The functionality and the level of expression of Gi proteins were investigated in lymphocytes from migraine without aura, migraine with aura and cluster headache sufferers. A reduced capability to inhibit forskolin-stimulated adenylyl cyclase activity in headache patients was observed. Migraine patients also showed basal adenosine cAMP levels about four times higher than controls. The reduced activity of Gi proteins seems not to be related to a reduction of protein levels since no significant reduction of the Gialpha subunits was observed. These results indicate Gi protein hypofunctionality as an aetiopathogenic mechanism in migraine and cluster headache.

Serotonin metabolism in cluster headache

Despite some evidence of the involvement of the serotonergic system in cluster headache (CH) pathophysiology, the serotonin (5HT) metabolism has so far been poorly studied. The aim of this study was to investigate plasma and platelet levels of 5HT and 5-hydroxyindoleacetic acid (5HIAA) in CH patients in the active period of the disease. Nineteen CH sufferers and 17 sex- and age-matched healthy controls were studied. CH patients showed significantly higher plasma levels of 5HT and 5HIAA compared to controls (5HT: 5.7+/-6.1 ng/ml vs 0.2+/-0.2 ng/ml; p=0.02; 5HIAA: 34.7+/-46.1 ng/ml vs 0.6+/-0.7 ng/ml; p=0.004). In platelet 5HT levels were slightly reduced in CH patients in comparison with those of control subjects (662.4+/-522.3 ng/10(-8) platelets vs 832.4+/-587.9 ng/10(-8) platelets; n.s.) and 5HIAA levels resulted significantly lower in CH sufferers than in control subjects (3.2+/-2.6 ng/10(-8) platelets vs 6.7+/-4.8 ng/10(-8) platelets; p=0.04). Our data suggest that CH is characterized by an increase of plasma serotonergic metabolism that could reflect an involvement of the central serotonergic system in the pathogenesis of CH.

Responsiveness of the trigeminovascular system to nitroglycerine in cluster headache patients

Nitroglycerine is known to induce a headache attack in cluster headache patients, which is indistinguishable from a spontaneous attack. It has recently been suggested that a release of calcitonin gene-related peptide (CGRP) from peripheral terminals of trigeminal nociceptive neurons, which supply cephalic blood vessels, underlies symptoms of cluster headache. The aim of this study was to investigate whether the provocative action of nitroglycerine in cluster headache is due, at least in part, to activation of the trigeminovascular system. Nineteen subjects suffering from episodic cluster headache participated in the study. Eleven of them were in an active period, whilst the others were in remission at the time of the study. CGRP-like immunoreactivity (CGRP-LI) was measured in blood samples from the extracerebral circulation before and after the sublingual administration of nitroglycerine. Baseline CGRP-LI plasma levels were higher (P < 0.05) in the patients who were in an active period. Only in these patients did nitroglycerine induce an attack, which was preceded by a latent period with a mean duration of 27 +/- 3 min. When compared with the baseline, a significant (P < 0.01) increase in plasma CGRP-LI was detected at the peak of the provoked attack; no such increase was detected during the latent period, or at the onset of the attack. The results of this study suggests that the provocative action of nitroglycerine in cluster headache is due, at least in part, to activation of the trigeminovascular system. This mechanism seems to be slow and unrelated to the well-known rapidly occurring vasodilator effects of the drug. Finally, activation of the trigeminovascular system only occurs in those patients already in an active cluster headache period who also have high basal CGRP-LI plasma levels. This suggests that a hyperactivity of trigeminal nociceptive fibres could make the trigeminovascular system of these patients sensitive to the triggering action of nitroglycerine.

Evaluation of beta-endorphin secretion in patients suffering from episodic cluster headache

In order to obtain data regarding peripheral levels of beta-endorphin in head pain syndromes, we evaluated the plasma beta-endorphin secretory pattern in 12 adult male patients suffering from cluster headache. Blood samples were drawn every 2 hours for a 24-hour period, and in addition at 30-minute intervals for 120 minutes during cluster attacks. The same sampling was repeated during an asymptomatic period. Cluster headache patients showed no significant beta-endorphin circadian rhythm and a delayed acrophase during cluster periods compared with that recorded in the remission period and in normal subjects. Eighteen cluster headache attacks were recorded during the study day, 13 (72%) of which were followed by a significant increase in beta-endorphin levels. No correlation was found between beta-endorphin maximum net increase and intensity and/or duration of pain. These data suggest the hypothesis of a temporary alteration of beta-endorphin circadian secretion, probably related to involvement of neural structures controlling biorhythm pacemakers.

[Reduced sympathetic nervous system activity during the cluster period of cluster-headache]

Cluster headache is a rare, very severe disorder that is clinically well characterized with a relatively poorly understood pathophysiology. Alterations of the hypothalamic-pituitary axis due to chronobiological changes, such as typical temporal pattern of both cluster periods and attacks, point to a central etiopathogenesis. Multiple local and systemic autonomic symptoms are compatible with an altered balance of the sympathetic and parasympathetic nervous system. In this connection, too, a central etiology is postulated. To evaluate the activation of the sympathetic nervous system, in 12 cluster headache patients we investigated the plasma catecholamines norepinephrine and epinephrine four times a day (7.00, 12.00, 17.00, 23.00) in the cluster period. In the cerebrospinal fluid we determined the transmitters norepinephrine, epinephrine, dopamine and the metabolites homovanillic acid (HVA), vanillymandelic acid (VMA) and 5-hydroxyindoleacetic acid (5-HIAA). Values of plasma norepinephrine in the morning (p < 0.01), in the evening (p < 0.01) and the daily mean value (223.8 = 58.3 nmol/ml) were significantly decreased in the cluster headache group in comparison to the control group (328.8 = 53.0 nmol/ml, p < 0.01). The plasma epinephrine showed no significant changes. In the CSF of cluster headache patients norepinephrine (p < 0.05), HVA (p < 0.01), and 5-HIAA (p < 0.01) were significantly decreased. Plasma norepinephrine was correlated with CSF values of HVA and 5-HIAA. The longer the duration of the disease, the lower the values of HVA and 5-HIAA in the CSF of cluster headache patients. Moreover, plasma norepinephrine showed a significant correlation with the duration, the intensity and the frequency of the attacks. The results of this study implicate decreased activity of the sympathetic nervous system with alteration of circadian rhythmicity during the cluster period. The decreased CSF transmitter values may support the hypothesis of a central etiopathogenesis of cluster headache. Moreover, plasma norepinephrine seems to be involved in triggering and continuing the attacks. The anatomical region in which this interface of sympathetic and neurogenic inflammatory processes might be located is the trigemino-vascular system.

Investigation on the mitochondrial transfer RNA(Leu)(UUR) in blood cells from patients with cluster headache

Various mutations in the mitochondrial tRNA(Leu)(UUR) gene give rise to a variety of neurological disorders. Among these, mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS syndrome) are frequently associated with a tRNA(Leu)(UUR) mutation at nucleotide position 3243 of the mitochondrial DNA. A supplementary clinical feature seen in these patients is headache in early life. Recently, a tRNA(Leu)(UUR) mutation at nucleotide position 3243 has been found in a patient presenting with cluster headache. This led us to examine the mitochondrial genomes of 22 patients presenting with cluster headache. None of the patients harboured the reported tRNA(Leu)(UUR) mutation or any other length variations of the mtDNA. Cluster headache is most likely not causally associated with the A3243G mutation of the mitochondrial DNA.

Intravenous magnesium sulfate relieves cluster headaches in patients with low serum ionized magnesium levels

Patients with cluster headaches have been reported to have low serum ionized magnesium levels. We examined the possibility that patients with cluster headaches and low ionized magnesium levels may respond to an intravenous infusion of magnesium sulfate. Thirty-eight infusions of magnesium sulfate were given to 22 patients with cluster headaches. The mean ionized magnesium level prior to 23 infusions which provided relief for at least 2 days and enabled the patient to skip two or more attacks, was 0.521 +/- 0.016 mmol/L; this value was 0.561 +/- 0.016 prior to 15 infusions which were ineffective. These latter 15 infusions were preceded by higher total magnesium levels. The ionized magnesium level prior to the 23 effective infusions was below 0.54 mmol/L in 19 patients. Five of the 15 ineffective infusions were accompanied by basal ionized magnesium levels below 0.54 mmol/L. In 76% of the infusions, there was a correlation between a response and an ionized magnesium level below 0.54 mmol/L. Nine patients (41%) obtained clinically meaningful improvement. Spontaneous remissions and a placebo effect might have accounted for some of the improvement. However, this should have applied equally to all patients, regardless of the ionized magnesium level. Measurements of ionized magnesium may prove useful in elucidating the pathogenesis of cluster headache and in identifying patients who may benefit from treatment with magnesium.

Raised plasma arginine vasopressin concentrations during cluster headache attacks

To obtain data about peripheral concentrations of arginine vasopressin in head pain syndromes, the plasma arginine vasopressin secretory pattern in 12 adult male patients with cluster headache was evaluated. Blood samples for plasma arginine vasopressin and osmolality determinations were collected before, and at 15, 30, 45, 60, 90, and 120 minutes during a cluster attack. Blood pressure was also monitored. The same sampling was repeated during an asymptomatic period. During cluster attacks, the mean values of plasma arginine vasopressin before an attack (2.3 (0.1) ng/l) significantly increased, reaching their peak at 45 minutes (4.8 (0.5) ng/l; P < 0.01 v baseline). No significant variations were found in mean arterial pressure and plasma osmolality. These data suggested involvement of neurotransmitter mechanisms regulating arginine vasopressin secretion and a possible role of arginine vasopressin in vasomotor phenomena accompanying cluster attacks.

Twenty-four-hour melatonin and cortisol plasma levels in relation to timing of cluster headache

The cyclic recurrence of cluster periods and the regular timing of headache occurrence in cluster headache (CH) induced us to study the circadian secretion of melatonin and cortisol in 12 patients with episodic CH, during a cluster period, and compare them with 7 age- and sex-matched healthy controls. Blood was sampled every 2 h for 24 h. All subjects were confined to a dark room from 22.00 to 08.00. Plasma melatonin levels were significantly reduced in CH patients (repeated measures ANOVA p < 0.03; mesor p < 0.02), and the cortisol mesor was significantly increased (p < 0.03). Amplitudes and acrophases did not differ between the groups. Individual cosinor analysis showed that 4/12 (33.3%) CH patients had no significant melatonin rhythm, and that 5/11 (45.5%) had no cortisol rhythm. Group analysis of cosinor revealed significantly rhythmicity of melatonin and cortisol secretion in both groups. In controls, the timing of melatonin and cortisol acrophase significantly correlated with each other, indicating that the biorhythm controllers for the secretion of these hormones were synchronized. Such correlation was not found in the CH patients; mesor, amplitude and acrophase of melatonin and cortisol did not correlate with duration of illness, duration of headache in course, or time since last headache attack.

Increase in plasma calcitonin gene-related peptide from the extracerebral circulation during nitroglycerin-induced cluster headache attack

In this study, changes in plasma levels of calcitonin gene-related peptide (CGRP) and substance P (SP) during a spontaneous-like cluster headache attack provoked by nitroglycerin were evaluated. Peptide variations after spontaneous or sumatriptan-induced remission were also assessed. Blood was collected from the external jugular vein homolateral to the pain side of 30 male cluster headache patients; 18 men were in an active and 12 in a remission one. Plasma levels of CGRP and SP were determined using sensitive radioimmunoassays for each peptide. CGRP-like immunoreactivity (CGRP-LI) was found to be augmented in patients in an active period and became elevated further at the peak of the provoked attack. A complete reversal occurred both after spontaneous and sumatriptan-induced remission. On the contrary, nitroglycerin neither provoked a cluster headache attack nor altered CGRP-LI in the patients in a remission period. The augmented levels of CGRP-LI measured before and after nitroglycerin administration, when the provoked attack reached the maximum intensity, suggest an activation of the trigeminovascular system during the active period of cluster headache. Moreover, the clinical and biochemical actions showed by sumatriptan stress the involvement of serotonin in cluster headache mechanisms.

Cluster headache: pulse rate changes evoked by hyperoxia and hypoxia

To test the influence of arterial O2 saturation (SaO2) on heart rate in cluster headache, changes in pulse rate induced by hyperoxia and hypoxia were monitored in 11 cluster headache patients (6 during cluster period, and 5 during remission). The results were compared with those obtained in 11 age and sex matched healthy individuals. The subjects were administered 5 min each of 100% O2 and 12% O2 in nitrogen in sequence. The aim of the latter procedure was to reduce SaO2 to approximately 80%. Pulse rate was recorded every minute from a finger pulse oximeter during the whole procedure. Cluster headache patients, in particular during the bout, had a slightly lower basal pulse rate than controls (P > 0.5, Student's t-test). This tendency was maintained throughout the test. Hyperoxia and hypoxia resulted in a marked, significant decrease and increase, respectively, in pulse rate from baseline values within each group. However, the difference between groups was not significant at any stage. Cluster headache patients therefore seem to have the same heart rate response to changes in SaO2 as healthy individuals. The marked heart rate changes which sometimes accompany cluster headache are unlikely to be caused by SaO2 changes.

Beta-endorphin levels are reduced in peripheral blood mononuclear cells of cluster headache patients

Opioid system hypofunction has been postulated in cluster headache (CH) on the basis of reduced opioid levels found in the cerebrospinal fluid (CSF). In this study beta-endorphin levels were monitored in the peripheral blood mononuclear cells of 65 episodic CH patients (32 in remission and 33 in cluster period) and 50 healthy controls. Beta-endorphin levels were significantly lower than controls in CH patients experiencing both phases of the illness (ANOVA, p < 0.0001). The persistence of this abnormality during pain-free remission suggests a primary alteration in the regulation of beta-endorphin in peripheral blood mononuclear cells. We speculate that these findings reflect reduced CNS levels of beta-endorphin in CH.

Serum interleukin-1 beta is increased in cluster headache

We measured serum interleukin-1 beta (IL-1 beta) in 24 episodic cluster headache (CH) patients and 45 normal controls using a specific ELISA method. There was an increase in IL-1 beta in all CH patients compared to controls. IL-1 beta was further increased during the ictal phase of CH compared to patients between attacks and normal individuals. Between attacks, IL-1 beta was also significantly increased compared to controls. We suggest that these results represent an activation of the immune system in CH.

[The cluster headache: a clinical model of immunologic receptor pathology?]

It is well established that cluster headache shows impaired functions at their neuroimmunomodulatory system level. Defect in receptor expression for 5-HT, IL-1 and IL-2 have been found in these patients. Sumatriptan, a molecule with agonistic activity for 5-HT1D receptor, truncates cluster headache attacks in 74% of patients. Flow cytometric analysis of monocytes expressing 5-HT receptor in cluster headache patients showed different trends clearly correlated with the clinical response to sumatriptan. Our findings strongly support the concept that cluster headache patients who are non responders to sumatriptan could present a block in their 5-HT receptor possibly due to specific autoantibodies for this receptor site.

Dexamethasone suppression test, melatonin and TRH-test in cluster headache

The origin of Cluster Headache (CH) is still unknown. The periodicty and presence of symptoms due to both sympathetic and parasympathetic activity suggest the involvement of central nervous system structures, particularly the hypothalamus. To investigate hypothalamic involvement in CH, we employed a neuroendocrinological approach. We observed a normal dexamethasone suppression test (DST) in all patients, increased cortisol plasma levels in remission patients at 8.00am before and at the end of the DST, while only in CH patients during cluster period did we find a reduced TSH response to TRH and a reduced night-time melatonin peak. The neuroendocrinological derangements found in CH may be consistent with hypothalamic involvement.

Cluster headache: phospholipid metabolism in polymorphonuclear cells

Our group has previously reported significant changes in the incorporation of precursors into glycerophospholipids, particularly phosphatidylserine, in polymorphonuclear cells obtained from the peripheral blood of cluster headache patients, when compared with controls. The potential of these results led to further work using both the previous methodology and a modified isolation technique to obtain polymorphonuclear cells in as pure a state as possible. Neither the new results obtained using the original technique, nor the results with high purity polymorphonuclear cells from controls and cluster headache patients, confirm the marked changes in precursor uptake into glycerophospholipids originally reported.

Platelet catecholamines in cluster headache

Platelet tyrosine and catecholamine (CA) content was measured in cluster headache sufferers during the different phases of the illness. Compared with controls, cluster headache sufferers had lower platelet levels of norepinephrine (NE) and epinephrine (E) in all phases of the syndrome. Tyrosine levels were increased significantly during the cluster headache attack. We suggest that these results provide biochemical evidence of sympathetic nervous system (SNS) hypofunction in cluster headache.

Sympathetic adrenomedullary activity in cluster headache

It is well known that autonomic phenomena, such as lacrimation, rhinorrhea, and Horner's syndrome, are associated with the pain attacks in episodic cluster headache. In order to elucidate the cause of these symptoms we studied plasma free and sulphoconjugated catecholamines in cluster headache patients during the pain attacks and in the following hours, as well as during the remission period. No change in these amine levels was found. We conclude that dysautonomic symptoms are not reflected in plasma catecholamine modification.

The insulin tolerance test and the ovine corticotrophin-releasing hormone test in episodic cluster headache

Clinical observations indicate a central nervous system, probably hypothalamic, involvement in cluster headache pathogenesis. In order to investigate the supposed hypothalamic involvement in cluster headache, we followed the hypothalamic-pituitary-adrenal axis and autonomic responses to the insulin tolerance test and the ovine corticotrophin-releasing hormone test in episodic cluster headache patients, both during remission and during the cluster period. The study revealed increased basal cortisol levels in all cluster patients. A blunted cortisol response to ovine corticotrophin-releasing hormone, in spite of a normal ACTH surge, was subsequently found in both illness phases. These findings suggest hypothalamic-pituitary-adrenal axis hyperactivity in both cluster phases. Furthermore, reduced ACTH and cortisol responses after insulin challenge were also observed in both remission and cluster period patients; a reduced norepinephrine surge was seen only in the cluster period. Taken together, these results suggest a hypothalamic involvement in the altered neuroendocrinological and autonomic responses found in our patients.

Orbital phlebography and signs of inflammation in episodic and chronic cluster headache

One of our 7 patients (14%) with chronic cluster headache had an abnormal orbital phlebogram; this was significantly less than the 61% encountered in our 13 patients with active episodic cluster headache who had this test done. There were no pathologically increased values for serum haptoglobin or orosomucoid in our 9 patients with chronic cluster headache, again significantly less than in our 43 patients with active episodic cluster headache, 51 percent of whom had pathologically increased values of haptoglobin or orosomucoid. These inflammatory signs decreased after the episodic cluster headache was over. Episodic cluster headache we suggest to be due to temporary sympathicoplegia caused by venous vasculitis in the cavernous sinus region; chronic cluster headache we attribute to permanent post-inflammatory sympathicoplegia in the middle fossa.

Platelet glycine, glutamate and aspartate in primary headache

Platelet levels of glutamic and aspartic acid and glycine were measured in patients with migraine with aura, migraine without aura, tension headache and cluster headache. High levels of these amino acids were found in patients with migraine with aura compared to normal subjects and other headache groups. During headache, glutamate levels further increased in migraine with aura patients. These findings may have relevance to the neurological symptoms of migraine with aura.

Blood leukotrienes in headache: correlation with platelet activity

Platelet hyperactivity, one of the commonest findings associated with migraine, has been related to increased release of biologically active substances such as catecholamines and arachidonic acid metabolites, which seem to play a role in the pathogenesis of migraine. In this study, in vitro platelet aggregation tests were performed on samples from patients with different types of headache. The presence of platelet hyperactivity was clearly demonstrated in 11 patients with classical migraine between attacks, but not in 4 patients between attacks of common migraine. Nevertheless, the presence of a marked platelet hyporesponsivity was found during the attack phase of both classical and common migraine. No difference in platelet aggregability was found between attack and post-attack phases in 5 patients with cluster headache. Blood leukotrienes were analyzed in 8 patients with classical migraine and in the 5 patients with cluster headache. During the attack phase of classical migraine both LTC4 and LTB4 were present in the peripheral blood, while the post-attack phase was characterized by the disappearance of LTC4 and the presence of LTB4 and its transisomer delta 6-trans-LTB4. Blood leukotrienes were constantly absent during both phases of cluster headache. Incubation of normal platelets with LTC4 or delta 6-trans-LTB4 was followed by inhibition of platelet response to epinephrine. delta 6-trans-LTB4, at higher concentrations, induced the opposite effect. A possible role of blood leukotrienes in the changes occurring in platelet aggregability during the different phases of classical migraine, is discussed.

Changes in neutrophil met-enkephalin containing peptides in episodic cluster headache

We have previously demonstrated an increase in plasma met-enkephalin levels during the pain attacks in episodic cluster headache. The present study was undertaken in order to clarify the source of the plasma met-enkephalin increase. Recent evidence has shown that peripheral blood polymorphonuclear cells contain peptides derived from the proenkephalin A system, which can be released by specific stimuli. We studied neutrophil met-enkephalin containing peptides (NMECP) in 27 episodic cluster headache patients: 24 in a cluster period (6 of them during a pain attack), and 3 in the remission period. Neutrophil met-enkephalin containing peptide levels (after sequential enzymatic digestion with trypsin and carboxypeptidase B) were determined by radioimmunoassay with specific antiserum. Neutrophil peptide concentration (pmol/mg prot) was lower (p less than 0.01) in patients during the pain attack (14.4 +/- 0.36) than after their pain had subsided (36.7 +/- 0.31) and lower than in the remission period patients (35.8 +/- 0.4). We conclude that neutrophil met-enkephalin containing peptides decrease during pain in episodic cluster headache, and that they may be involved in the concomitant plasma met-enkephalin increase.

Anticardiolipin antibodies in cluster headache

Antiphospholipid antibodies have occasionally been observed in migraine patients, but a recent study of a large series suggested the association was with other concurrent conditions, not specifically with migraine. We wondered about an association with other vascular headaches and measured anticardiolipin antibody levels in 20 cluster headache patients during the cluster period (three during an acute attack). Platelet counts were normal and VDRL negative in all patients. No elevated anticardiolipin antibody levels were found. There appears to be no important association between the presence of anticardiolipin antibodies and cluster headache, and we argue that there is no further rationale for seeking one.

Increase in plasma methionine-enkephalin levels during the pain attack in episodic cluster headache

Since high levels of endogenous opioids (endorphins, enkephalins) were found in brain areas classically related to nociception, their peripheral levels in humans were studied in different pain syndromes yielding contradictory results. This study was undertaken to assess changes in plasma methionine-enkephalin (met-enkephalin) levels in patients with episodic cluster headache associated with the pain period. Twenty-nine patients, 24 in the cluster period (6 of them during an attack) and 3 in the remission period were studied. Two other patients were subjected to a longitudinal follow-up. Plasma met-enkephalin levels were determined by radioimmunoassay (RIA) with specific antibody. Plasma peptide concentration (pmol/ml) was higher (p less than 0.001) in patients during the pain attack (3.97 +/- 1.18) than in controls (0.25 +/- 0.03). When measured 4 and 48 h after the pain attack lower levels were found (0.46 +/- 0.06) which decreased to control values after 24 h. These results may suggest involvement of peripheral enkephalins in pain modulation in patients with episodic cluster headache.

Association of sustained oxyhemoglobin desaturation and onset of cluster headache attacks

Ten episodic cluster headache patients in their active cluster period, ten patients in remission and five control subjects were monitored for minute to minute changes in oxygen saturation (SaO2) and pulse rate before and after nitroglycerin (NTG) administration. A transient but significant decrease in SaO2 and increase in pulse rate of 25 minutes duration occurred following NTG in all groups. These changes may reflect physiologic hemodynamic effects of NTG as a smooth muscle relaxant. Subsequently, SaO2 levels and pulse rate recovered to baseline values in remission and control groups. In contrast, SaO2 values in the active cluster group decreased further and after an extended period culminated in cluster headache attacks in 10/10 patients. Three major changes, therefore, distinguished active cluster patients from remission and control groups. First, the magnitude of oxygen desaturation increased after the physiological effects of NTG ceased. Second, oxygen desaturation was sustained for an additional 9 to 30 minutes duration. Third, the hypoxemic state culminated in attacks in all cases. Our findings suggest that the active cluster period may be characterized by an impaired mechanism to autoregulate, and thus compensate, for hypoxemia. It is further proposed that persistence of hypoxemia and the cluster attack onset may share a common mechanism, coupling the two events. We suggest that abnormal central and/or peripheral chemoreceptor activity may be responsible for these events.

Cluster headache: incorporation of (1-14C)oleic acid into phosphatidylserine in polymorphonuclear cells

As recently demonstrated by our group, polymorphonuclear cells (PMNs) from cluster headache patients have an increased ability to incorporate arachidonic acid (AA) and L-serine into phosphatidylserine (PS). To evaluate whether there is an increased incorporation into PS also from fatty acids not involved in eicosanoid metabolism, PMNs from controls (n = 14) and cluster headache patients (n = 12) were incubated with (1-14C)oleic acid. After 1 h 2.7% +/- 1.1 (mean value +/- SD) of the glycerophospholipid radioactivity was found in PS in controls, whereas 4.2% +/- 1.2 was found in cluster headache patients (p less than 0.005). For phosphatidylcholine (PC) the corresponding figures were 74.2 +/- 5.4 in controls and 66.7 +/- 7.6 in cluster headache patients (p less than 0.01). The results suggest that the de novo biosynthesis of PS is increased and the biosynthesis of PC is decreased in cluster headache. The results may have an effect on the role of PS as an obligate protein kinase C activator.

Increased incorporation of L-(U-14C)serine into phosphatidylserine in polymorphonuclear cells from cluster headache patients

It has recently been demonstrated by our group that polymorphonuclear cells (PMNs) from cluster headache patients incorporate more arachidonic acid (AA) into phosphatidylserine (PS) than PMNs from controls. In the present report, the incorporation of L-(U-14C)serine into PS in PMNs from 14 healthy volunteers and 12 cluster headache patients was studied. PMNs from controls incorporated 1194 +/- 578 (mean +/- SD) cpm of L-(U-14C)serine into PS, 268 +/- 292 cpm into phosphatidylethanolamine, and 57 +/- 71 cpm into sphingomyeline. The corresponding figures in cluster headache patients were 2365 +/- 841 cpm, 291 +/- 207 cpm, and 88 +/- 66 cpm, respectively. Incorporation of L-(U-14C)serine into PS was significantly increased (p less than 0.0004) in PMNs from cluster headache patients, whereas no significant difference was seen in other lipids. The results confirm that patients with cluster headache have an increased incorporation of precursors into PS in isolated PMNs, and they indicate that this is due to an increased de novo synthesis of PS.