In memoriam: Dr med. Hansruedi Isler

Within Switzerland, Dr med. Hansruedi Isler has been known as ‘the pope of headache’, which was true for both, patients and fellow physicians. He was founder (1984) and longtime president of the Swiss Headache Society, and established ‘Headache Neurology’ as a subspecialty in Switzerland, with a significant number of neurologists following suit. Internationally, Hansruedi Isler has also been well known – for his passion for headache disorders and patient care, but also for publications in his second field of interest, the history of medicine throughout his life. His monography and thesis about Thomas Willis who introduced the terms ‘neurologia’ and ‘psychologia’ and developed a 17th-century neuropsychiatric concept was seminal. However, for Hansruedi Isler, the dichotomy of body and soul embodied in neurology on the one side and psychiatry on the other side was not a sustainable scientific concept then and now. He extensively published on the history of neurology and discussed the evolving pathophysiological concepts of migraine and other primary headache disorders as well as their therapies. As the founder of the headache clinic (‘Kopfwehsprechstunde’) at the Neurological University Hospital in Zurich 1966, he systematically developed and studied interdisciplinary patient care within and outside the tertiary care headache center. Together with Colette Andrée he founded and developed the national patient’s organization, ‘Migraine Action’, which has been well received and is active until today. Some of his concepts reaching outside headache neurology are of importance for current neurological thinking, such as his work on ‘hemicrania epileptica’ together with Heinz Gregor Wieser. Among others, he published on the emergence of iatrogenic complications of migraine treatment, including medication overuse headache (MOH), recognizing ergots as important substances in this context and laid the clinical foundations for stratified MOH inpatient programs which are state-of-the-art today for the treatment of the most severely affected patients. Of great importance for the understanding of primary headache disorders was his work on the so-called Swiss cohort study, describing the longitudinal evolution of migraine and non-migrainous headaches over a period of 30 years. The study provided deep insights into the epidemiology and comorbidities of headaches in a ‘normal’ population. Furthermore, the longitudinal evolution showed that intraindividually a number of different nosologic entities were fulfilled, partly in sequence, when studied over time, suggesting that primary headaches which are separately classified following International Headache Society criteria might indeed be pathophysiologically related. Hansruedi Isler was also an exceptional person with multiple interests outside Neurology, a true humanist – with quasi-encyclopedic knowledge, and also multilingual. Nobody really found out the true number of languages he Dr med. Hansruedi Isler (1934–2019)