Preliminary reports have shown that hyperbaric oxygen (HBO) interrupts cluster headache (CH) attacks. In the present study, 6 of 7 patients with episodic cluster headache who were treated with hyperbaric oxygen experienced an interruption of the attack. In 3 of 6 responders the florid period of the cluster headache was interrupted. The other 3 patients remained without pain attacks for a period lasting from 3 to 6 days. In 6 different patients, a placebo treatment had no effect. The present findings clearly indicate that hyperbaric oxygen has not only a symptomatic effect on a single attack of cluster headache, but it also could prevent the occurrence of subsequent attacks.

1 Topical application of capsaicin to the human nasal mucosa induced a burning sensation and sneezing. A dose-dependent seromucous nasal secretion was also observed. Capsaicin (75 jig) was more potent than methacholine (50 mg) in producing nasal secretion, while topical histamine (200 jg

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Central excitatory circuits could be involved in the pathophysiology of pain; particularly, the genesis of chronic pain. The "second pain" is the sensation that follows the initial pain after an appropriate nociceptive stimulus. The second pain is amplified by repeating the stimulus after brief intervals (temporal summation). This phenomenon is the psychophysical correlate of the excitatory pain circuits. The temporal summation of the second pain was evaluated in four groups of subjects; one group affected by migraine without aura, one by episodic tension headache, one by chronic daily headache, and a group of healthy subjects. A percutaneous electrical shock was used as the nociceptive stimulus. The intensity of the second pain was significantly greater in the group of patients with chronic headache in comparison with the other groups. The patients with chronic headache were subdivided into three groups on the basis of their clinical history: a group with transformed migraine; a group with chronic headache ab initio, a form related to the first one; (both groups suffered from chronic daily headache with a frequent superimposition of episodes of migraine attacks) and the third group consisted of patients with chronic tension headache. The temporal summation of the second pain was altered in the first two groups. The patients with chronic migraine abused ergotamine given as a symptomatic drug. Those who were able to discontinue this drug were retested and reported a decrease of the second pain in comparison to the previous measurements. The results of the present study indicate that central excitatory circuits could be involved in the mechanism leading to the development of chronic daily headache.

Preliminary studies have shown that repeated nasal applications of capsaicin prevented the occurrence of cluster headache attacks. The present study was designed to verify the difference in efficacy of treatment with nasal capsaicin, depending on the side of application. Fifty-two patients affected by episodic form were divided into 2 groups, one receiving the treatment on the same side where the attacks occurred (ipsilateral side), the other on the controlateral side. Eighteen patients with a chronic form alternately received both ipsilateral and controlateral treatments. Seventy percent of the episodic patients, treated on the ipsilateral side, showed a marked amelioration whereas no improvement was noted in the patients treated on the contralateral side. The efficacy of ipsilateral treatment was emphasized by the results obtained in chronic patients. However, in these patients, the maximum period of amelioration lasted no more than 40 days. The difference between the effects of the 2 treatments (contralateral and ipsilateral) was statistically significant in both episodic and chronic sufferers. The efficacy of repeated nasal applications of capsaicin in cluster headache is congruent with previous reports on the therapeutic effect of capsaicin in other pain syndromes (post-herpetic neuralgia, diabetic neuropathy, trigeminal neuralgia) and supports the use of the drug to produce a selective analgesia.