Cluster headache patients experience frequent episodes of very intense, one-sided pain in and around the eye and temple. Patients describe the pain as an intense pressure behind the eye that feels as though it is being pushed out of the socket. The episodes are brief, and associated symptoms include nausea, sensitivity to light, drooping and/or watery eyes, and a stuffed then runny nose. The pain usually last from 45 to 90 minutes but can be as long as 3 hours.
Despite the well-known clinical description for CH, it is often misdiagnosed because of a limited understanding of the disease and its accompanying symptoms. Dutch neurologists Dr. van Vliet of Leiden University Medical Center in Leiden, Netherlands, and colleagues, undertook a study to identify reasons for the delay in diagnosing CH.
Approximately 560 neurologists and 5,800 GPs across the Netherlands were asked to recruit patients with CH or resembling CH to join the questionnaire-based study. Participating patients had to meet the International Headache Society (IHS) criteria for CH. Those meeting the criteria were given a second, more detailed questionnaire.
A total of 1163 participants completed and returned the second questionnaire (913 men, 250 women). Only 22% said they were initially diagnosed with CH. Twenty-one per cent were initially diagnosed with sinusitis, 17% migraine, and 11% with a dental related condition. Sixteen percent had made the CH diagnosis themselves after reading about the symptoms. Sixteen percent had undergone tooth extraction and 12% an ears, nose and throat operation as treatment for their headaches.
In their report, published in the Journal of Neurology Neurosurgery and Psychiatry in August 2003, Dr. van Vliet and colleagues say that clinical symptoms such as sensitivity to light, nausea and vomiting most likely lead physicians to diagnose migraine even though they are also common CH symptoms.
Another point of confusion may lie in the IHS criteria for CH that includes one-sided pain as an identifying feature. The pain, however, while one-sided, may switch from side to side between attacks, although this is considered rare. Switching attack sides was reported in 11% of study cases and these patients experienced a delay in diagnosis. The researchers suggest that this feature be included in future criteria of the IHS.
As well, while most CH patients experience their first attack at around 30 years of age, it occasionally occurs in childhood. Physicians seeing a child with CH would almost certainly consider other diagnoses initially, potentially delaying the proper diagnosis for many years.
CH patients with episodic attacks were also among those with a delayed diagnosis. The long attack-free periods between attacks could postpone the diagnosis for several years since the patient may be free of symptoms for months or years.
The study also found that 16% of the subjects, mostly chronic patients, reported a mild, continuous headache in between their CH attacks. The researchers say that this feature, to their knowledge, has not been described before in CH. They say it may be cause by chronic daily headache concomitant with CH, but also may be an aspect of CH medication or CH itself.
One of the benefits of this study, apart from gaining a better understanding of CH, is that a large population of GPs and neurologists in the Netherlands were made aware of CH. Dr. van Vliet says this may "lead to more accurate diagnosis in some patients." In the future, he says, it is hoped that "more attention will [be] paid to educate first line physicians to recognize CH, to improve the diagnostic process and so to expose patients to earlier and better treatment of CH."
Van Vliet JA, Eekers PJE, Haan J, Ferrari MD. Features involved in the diagnostic delay of cluster headache. J Neurol Neurosurg Psychiatry 2003;74:1123-1125.
Rapoport AM, Sheftell FD, Tepper SJ. Conquering Headache, 4th Ed. Hamilton: Decker DTC, 2003.