Spontaneous and 5HT-induced cyclic contractions in superficial temporal arteries from chronic and episodic cluster headache patients

Cluster headache or giant cell arteritis?

We describe an elderly female patient with known polymyositis who presented with new onset temporal headache that was diagnosed as giant cell arteritis but subsequently had a typical clinical course of cluster headache. This case illustrates the potential for diagnostic confusion between giant cell arteritis (GCA) and cluster headache (CH) and the need to consider CH as a potential differential diagnosis in those newly presenting with headaches, even in the elderly, and relapsing headaches in subjects with a diagnosis of GCA. Importantly, this needs to include female patients, a group historically thought to be much less likely to develop CH.

Temporal Thermometry Fails to Track Body Core Temperature during Heat Stress

PURPOSE

The aim of this study was to assess the accuracy of temporal scanning thermometry in monitoring internal temperature increases during passive heating.

METHODS

Sixteen subjects (5 males and 11 females) underwent a whole-body passive heat stress (water-perfused suit) to increase internal temperature. Temperatures were obtained with a temporal scanner and with an ingestible-pill telemetry system that tracks intestinal temperature. Temperatures were recorded while subjects were normothermic (34 degrees C water-perfusing suit) and every 10 min during passive heating (48 degrees C water-perfusing suit).

RESULTS

Heart rate (ECG), mean skin temperature (weighted six-site average), skin blood flow (laser Doppler flowmetry), and sweat rate (capacitance hygrometry) were all significantly elevated at the end of heating (all P < 0.001). Pre-heat stress temporal-derived temperature was not different from intestinal temperature (36.98 +/- 0.09 vs 37.01 +/- 0.09 degrees C, respectively, P = 0.76). However, after 30 min of heating (the greatest duration of heating completed by all subjects), temporal-derived temperature decreased to below the pre-heat stress baseline (-0.22 +/- 0.11), whereas intestinal temperature increased by 0.39 +/- 0.07 degrees C (P < 0.001 between the two methods). After 50 min of heating (N = 11), intestinal-derived internal temperature increased by 0.70 +/- 0.09 degrees C, whereas temporal-derived temperature decreased by 0.29 +/- 0.10 degrees C (P < 0.001). The group average (+/- SEM) R2 and slope between the two methods were 0.29 +/- 0.08 and -0.34 +/- 0.14, respectively.

CONCLUSION

These results demonstrate that temporal scanning does not track internal temperature, as measured via intestinal temperature, during passive heating. Given these findings, it is recommended that this technique not be used to assess temperature in hyperthermic diaphoretic subjects.

Cluster headache is not associated with signs of a systemic inflammation

OBJECTIVE

To investigate whether there is clinical or biochemical evidence for a transient systemic inflammation during active periods of cluster headache.

METHODS

Twenty-seven male and female consecutively selected patients with episodic cluster headache filled in questionnaires aiming at detecting any concurrent systemic vasculitic or rheumatoid disease. They were physically examined by both a neurologist and a rheumatologist independent of each other. Blood and urine samples were taken one to three times during an active cluster period and once in remission. The following analyses were performed: hemoglobin, erythrocyte sedimentation rate, C-reactive protein, complete blood counts including differential counts, creatinine, albumin, creatine kinase, electrophoreses of serum (with haptoglobin, orosomucoid, IgG, IgM), von Willebrand's factor, antinuclear antibodies, rheumatoid factor, cytoplasmic antineutrophil cytoplasmic autoantibodies, perinuclear antineutrophil cytoplasmic autoantibodies, and routine urinary tests. An age- and sex-matched control group of 99 consecutive patients attending the Outpatient Department of Neurology for symptoms/diseases other than severe headache completed the same questionnaire as the patient group.

RESULTS

Only one patient with cluster headache showed clinical signs (livedo reticularis) that could have been due to an ongoing systemic vasculitis. Most symptoms were equally or even more prevalent in the control group than among the patients with cluster headache. However, cold feet were about twice as prevalent among female patients with cluster headache than in the control group. This was considered due to their smoking habits. Laboratory tests showed no statistically significant differences between the active cluster periods and remission. There were some slightly abnormal values in single laboratory tests, some of which were probably due to concurrent upper respiratory infections. The findings of laboratory tests for one patient could have been due to nephritis. All patients were negative for cytoplasmic antineutrophil cytoplasmic autoantibodies and perinuclear antineutrophil cytoplasmic autoantibodies.

CONCLUSIONS

These results were taken as evidence that no systemic inflammation is present during the active cluster headache period. However, whether a local retro-orbital inflammation underlies the pathophysiology of cluster headache remains obscure.

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.

Participation of 5-HT1-like and 5-HT2A receptors in the contraction of human temporal artery by 5-hydroxytryptamine and related drugs

1. We investigated the hypothesis that, as in some other large human arteries, 5-HT-induced contraction of the temporal artery is mediated through two co-existing receptor populations, 5-HT1-like- and 5-HT2A. Temporal arterial segments were obtained from patients undergoing brain surgery and rings prepared set up to contract with 5-HT and related agents. Fractions of maximal 5-HT responses mediated through 5-HT1-like and 5-HT2A receptors, f1 and f2 = 1-f1, were estimated by use of the 5-HT2A-selective antagonist ketanserin. 2. In rings with intact endothelium 5-HT evoked contractions with a -log EC50, M of 7.0. Ketanserin (10-1000 nM) antagonized part of the 5-HT-induced contractions. Ketanserin-resistant components of 5-HT-induced contractions were found with -log EC50, M of 6.9 and f1 of 0.17 (100 nM ketanserin) and -log EC50, M of 6.4 and f1 of 0.20 (1000 nM ketanserin). 3. In rings with endothelial function attenuated by enzymatic treatment, 5-HT caused contractions with a -log EC50, M of 7.2 that were partially blocked by ketanserin. Ketanserin-resistant components of 5-HT-induced contractions were found with -log EC50, M 7.4 and f1 of 0.16 (100 nM ketanserin) and -log EC50, M of 7.5 and f1 of 0.14 (1000 nM ketanserin). 4. The ketanserin-resistant component of 5-HT-evoked contraction was blocked by methiothepin (100-1000 nM) consistent with mediation through 5-HT1-like receptors. 5. In rings with intact endothelium the 5-HT1-like-selective agonist, sumatriptan, caused small contractions with a -log EC50, M of 6.5 and intrinsic activity of 0.21 with respect to 5-HT that were resistant to blockade by 1000 nM ketanserin but antagonized by 100 nM methiothepin. 6. In rings with intact endothelium the 5-HT2A receptor partial agonist SK&F 103829 (2,3,4,5-tetrahydro-8[methyl sulphonyl]-1H3-benzazepin-7-ol methensulphonate) contracted rings with a -log EC50, M of 5.0 and an intrinsic activity of 0.49 with respect to 5-HT; the effects were antagonized by ketanserin 1000 nM. 7. We conclude that 80-86% of the maximum 5-HT-evoked contraction of human temporal artery is mediated through 5-HT2A receptors, the remainder through 5-HT1-like-receptors, regardless of whether or not endothelium is functional. The 5-HT1-like-receptors are more likely to be 5-HT1D beta receptors than 5-HT1D alpha receptors and sumatriptan is a full agonist for these receptors. As found in arteries of other species, SK&F 103829 is a partial agonist for 5-HT2A receptors of human temporal artery.