UniversitätsSpital Zürich: 80 years of neurosurgical patient care in Switzerland

The advent of neurological surgery in Switzerland was undoubtedly due to Hugo Krayenbühl (born 3 December 1902 in Zihlschlacht; died 9 January 1985 in Zurich) [72]. The predecessor of today’s Department of Neurosurgery UniversitätsSpital Zürich (USZ) was founded 80 years ago, on 6 July 1937, by Professor Hugo Krayenbühl, as the first independent Swiss clinic dedicated to neurosurgical patient care. Additional specialised neurosurgical units were later established at the four other Swiss University Hospitals in Basel (Wilhelm Driesen, 1952), Bern (Hans Markwalder, 1953), Geneva (Aloys Werner, 1956), and Lausanne (Eric Zander, 1959), and at non-university hospitals in Chur (Charles Probst, 1967), St. Gallen (Gerhard Weber, 1970), Aarau (Charles Probst, 1973) and Lugano (Rezio Renella, 1989). Besides providing high-quality medicine for both the local and wider population, the department was chaired by eminent leaders of neurosurgery who strongly influenced the scientific and clinical neurosurgery of their time (Tables 1 & 2). As we shall see, several chairmen have played decisive roles in the development of microsurgical techniques in neurosurgery; techniques that have revolutionised modern neurosurgery and are today applied worldwide.

Since its foundation, the USZ has been regarded as one of the top neurosurgical teaching and research hospitals in Switzerland and in Europe. On the occasion of its 80th anniversary (Fig. 1), this article highlights the early development of the department and the challenges it faced, and places them into the historical context of European neurosurgery. Special emphasis is placed on the founding era of Hugo Krayenbühl.

A literature review was conducted using MEDLINE, Embase, Science Direct, and Google Scholar. We also searched the archives of the USZ and the city of Zurich, as well as those of Swiss journals (Swiss archives of Neurology, Psychiatry and Psychotherapy; Revue Médicale Suisse; Praxis; Correspondenz-Blatt für Schweizer Aerzte) to extract relevant published articles, books, historical reports and pictures. The USZ Department of Medical History, the Medizinhistorisches Museum Zürich, and the Swiss National Library (Nationalbibliothek) were contacted to provide source material. To further verify the content, (emeritus) faculty from the USZ and external experts on the history of Swiss neurosurgery (mentioned in the acknowledgements) reviewed the manuscript.

For reasons of simplicity, the name of today’s USZ, formerly the Hegibach ward of the surgical clinic (before 1952), the Kantonsspital in Zurich (1952–1977), and the University Hospital Zurich (since 1978), is homogenously referred to as the USZ throughout this article.

In the Western world, modern neurosurgery began its rise in the late nineteenth century and the beginning of the twentieth century. At that time, selected neurosurgical procedures were usually performed by general surgeons. In Zurich, Rudolf Ulrich Krönlein (1847–1910) was the chief surgeon at the USZ from 1881 to 1910 [36, 37]. The earliest published neurosurgical work at the USZ dates back to 1882. This work demonstrates that Krönlein supported the surgical treatment of impressed skull fractures; in particular, in patients with signs of elevated intracranial pressure (ICP) [50]. Relating his clinical observations to modern theories of cerebral topography, as proposed by Fritsch and Hitzig, Ferrier, and others of that time [90], Krönlein was among the first to reconfirm the association of Rolando’s cortical area with motor function in humans. In 1895, he reviewed the literature up to 1894 and noticed a rapid increase in brain tumour surgery, from only 15 patients before 1890, to 67 patients between the years of 1890 and 1894, despite a high mortality rate of nearly 30% [51]. For surgery on lesions that were either not found or could not be completely resected, mortality was as high as 75%, and he concluded that only a small percentage of brain tumours could be cured surgically at that time [51]. In the same year, he performed the first trepanation for a cerebral tumorous lesion (tuberculoma). The surgery under ether anaesthesia took 1 h, and the patient was reported to have lived 10 years post-surgery [36]. Krönlein’s important contributions to neurosurgery have recently been summarised elsewhere, and it is beyond the scope of this article to go into further detail on this topic [36].

About 100 km west of Zurich, the 1909 Nobel Prize laureate Emil Theodor Kocher (1841–1917) served as chief surgeon at the university hospital, the Inselspital in Bern. His main neurosurgical interests were in epilepsy surgery [88], the surgical therapy of spinal trauma and brain tumours, as well as theories on ICP and cerebral blood flow (CBF) [27, 37, 39, 88]. As early as 1887, he reported having performed an osteoplastic trepanation of the left occipital lobe to resect a 2-cm brain tumour after transcortical exposure in a patient presenting up to 30 epileptic seizures per month [44]. Kocher was the first surgeon in a Swiss clinic to perform transnasal surgery for a pituitary tumour in a patient with acromegaly (1909) [27, 39], only 2 years after Hermann Schloffer in Innsbruck, Austria [55]. Kocher was also among the first to surgically treat trauma and diseases of the spine and spinal cord (from 1872 onwards), as evidenced from his 245-page publication on this topic [45, 46]. The early illustration of a dermatome chart in his publication has recently been highlighted [39]. Together with Ernst von Bergmann (1836–1907, Berlin), Krönlein and Kocher built a triumvirate of academic pioneers with similar intentions and priorities for the emerging field of neurosurgery in the German-speaking countries. However, the establishment of neurosurgery as an independent discipline was inconceivable at that time [37]. Moreover, Kocher thought that general surgery could adequately cover the field of neurological surgery if neurologists, respectively internists, helped with the diagnostic part:

Wo Internisten und Chirurgen einander in die Hände arbeiten, wo jeder Gehirnfall von vornherein von beiden angesehen und beurteilt wird, da lässt sich Grosses erreichen. (Cited after [99])

(Where internists and surgeons work hand in hand, where neurological emergencies are a priori evaluated by both, great [results] can be achieved.)

At the USZ, the head of surgery, Paul Clairmont (born 10 January 1875; died 1 January 1 1942), performed trepanations in cases of traumatic brain injury (TBI) and suspected intracranial haemorrhage. In 1923, he reviewed the 275 patients with TBI from his clinic between 1918 and 1922. In his article, he described the surgical technique of trepanation and reported on the value of lumbar puncture as a diagnostic and therapeutic tool in TBI [18]. The Zurich neurologist Otto Veraguth reported one of the first successful surgical treatments of a lumbar disc herniation {performed in 1927 by a surgeon from Lucerne, Hans Brun (1874–1946). [38]}. This happened well before Dandy, or Mixter and Barr’s so-called landmark paper of 1934 [86]. Both Veraguth and Brun proved to be pioneers in regards to the surgical treatment of intramedullary spinal lesions: in 1910, Hans Brun became the third surgeon (after Anton von Eiselsberg in Vienna and Charles Elsberg in New York) to successfully remove an intramedullary lesion in a patient [38, 85].

In the French-speaking part of Switzerland, first reports include surgery on a pituitary tumour using a transnasal approach, performed by the general surgeon Albert Jentzer (Geneva) in 1924. Jentzer also designed a trephine for craniotomies, which was incorporated into the medical instrument set of the Swiss Army [72]. Likewise, François Ody, from the surgical department in Geneva, reported on attempted suboccipital decompression procedures for patients with traumatic oedema [65]. He is likewise known for an adventurous emergency operation performed on a friend with a perforating cranio-cerebral injury, after an accident at 9,200 ft (3,051 m) in the refuge des Grands Mulets in the Mt. Blanc range, where he used forks, his pocket knife and handkerchiefs for a temporary decompression ([66] cited by [72]).

It was the US surgeon Harvey Cushing (1869–1939) who first established neurosurgery as a distinct speciality in the early 1900s [21]. In the following decades, many young surgeons travelled to his clinic at Harvard Medical School in Boston in order to be trained. One of his European pupils, Sir Hugh Cairns (1896–1952) from London, would be the future teacher of Hugo Krayenbühl.

Hugo Krayenbühl (Fig. 2; Supplementary Figs. S1 and S2) was the first neurosurgeon at the USZ. He had studied for over 15 years in Geneva, Zurich, Kiel, Paris, St. Gallen and Berlin. On his return from working with Hugh Cairns, with whom he had spent two additional years as a graduate student in London and maintained a life-long friendship (Supplementary Fig. S3), he performed six major neurosurgical operations at the end of 1936 (on four patients with brain tumours, one patient with trigeminal neuralgia and one with a traumatic intracranial haemorrhage) [99]. Krayenbühl set up the new 12-bed neurosurgical clinic (Klinik Hegibach, Heliosstrasse, Zürich; Fig. 3) on 6 July 1937, under the patronage of his chief, the Professor of Surgery, Paul Clairmont, and injecting personal funds (Fig. 3a–d) [33, 99, 113]. Krayenbühl provided surgical instruments that he had bought in London, such as a surgical headlamp (Figs. 3e and 4), retractor, tweezers, chisel, flexible spatulas, Pennybacker bone rongeur, nerve root hooks and angled scissors (Fig. 5). The Rockefeller foundation donated an X-ray machine. The first intervention was a ventriculography performed on a 34-year-old man on 13 July 1937. Krayenbühl operated on the first brain tumour patient with the independent unit (a 37-year-old woman with sphenoid ridge meningioma) on 19 July 1937. This intervention took almost 9 h. It was performed under local anaesthesia. The long-term follow-up indicated that the patient was in good health for 30 years [33]. By the end of 1937, a total of 60 patients had been hospitalised in the new neurosurgical unit, including 25 patients with brain tumours, of which 18 were treated surgically [99]. Lumbar disc surgery was also performed on a regular basis from 1938 [72]. From the 1940s onward and for operations in the prone position (posterior approach to the spine, cerebellar operations) in particular, Krayenbühl used the technique of endotracheal intubation. It is reported that he preferred to operate at night, as there were fewer distractions [33], and with the assistance of general surgeons or medical students that he selected during his lectures [99]. He demanded that at the time of surgery, all relevant patient information was summarised on a red piece of paper that he considered an essential part of the patient file, attesting to his well-organised character. The chosen surgical approach and the intraoperative findings were often documented by drawings (see below; Fig. 6a–d). Only recently have the hand-written notes of his Operationsbuch (= surgical records) been systematically reviewed (Supplementary Fig. S5) [33]. Supplementary Fig. S6 shows the rapid increase in the number of diagnostic and surgical interventions in the initial years between 1937 and 1945. Techniques enabling efficient and safe surgery were systematically introduced under his lead [72]: cerebral angiography from 1937, intratracheal anaesthesia with nitrous oxide, enallylpropymal (Narconumal) and ether between 1938 and 1944, electroencephalography in 1948, stereotaxy in 1957, neuropsychology in 1966 and microneurosurgery in 1967.

In 1941, Krayenbühl attained the academic rank of Privatdozent with a thesis on cerebral aneurysms (Supplementary Fig. S4) [47]. In 1948, he became ausserordentlicher Professor (= extraordinary professor). In 1951, the neurosurgical unit was transferred to the new Kantonsspital building, where Krayenbühl received a 60-bed unit and two operation theatres. Finally, in 1963, Krayenbühl was promoted as full professor in neurosurgery. At the time of his retirement in 1973, at the age of 71 (Supplementary Fig. S7), the neurosurgical department at the USZ consisted of 16 neurosurgeons, who treated 2,000 patients annually in a 73-bed unit [118].

Krayenbühl has been described as one of the world’s leading physicians/neurosurgeons of his time, comparable to both Horsley and Cushing, by eminent colleagues such as Wilder Penfield of McGill University (Montreal), his contemporary Paul C. Bucy from Chicago, or his pupil and successor at the USZ, M. Gazi Yaşargil [16, 67, 105, 109]. His tenet was “Der Neurochirurg ist ein Neurologe, der operieren kann” (“A neurosurgeon is a neurologist who knows how to operate”) [3], indicating the importance he placed on solid neurological training, as Cushing did before him [99]. This firm grounding in neurology distinguished him from many of his general and neurosurgical contemporaries, and he earned the admiration of his fellow physicians for being both a superb clinical neurologist as well as an outstanding surgeon. He would actively seek contact with the leading neurologists and neurosurgeons of his time, as indicated by his attendance at international congresses (Figs. 7 and 8). In the USZ archive, for example, we found personal correspondence between Krayenbühl and Wilder Penfield dating from 1949, in which both exchange their ideas on how the perfect neurosurgical operating theatre should be designed (with hand-made illustrations) [68]. He not only founded a Swiss school of neurosurgery, but his followers were frequently elected chiefs of departments, such as in St. Gallen (Gerhard Weber), Lausanne (Eric Zander), and Geneva (Alois Werner) [8]. Until the early 1970s, it was a requirement for all Swiss neurosurgeons to have worked under Krayenbühl before they were authorised to practice in other clinics. Moreover, Swiss neurologists that would soon qualify for a position as the head of a department [e.g. Marco Mumenthaler (Bern), Franco Regli (Mainz and Lausanne)] were asked to spend 1 year in Krayenbühl’s clinic. These directives ensured a common level of qualification across Swiss clinical neuroscience.

Krayenbühl mastered multiple languages. This enabled him to forge and maintain international relations, and attracted many renowned neurosurgeons from Europe, the USA, and Japan to train under his supervision in Zürich [113]. He made neurosurgical education a main focus of his daily work. He emphasised not only professional expertise, but patient care with respect and dignity [99, 109]. He was reported to always have the well-being of his patients as his first priority, and to guide his employees through objective criticism and stimulating encouragement [3].

Krayenbühl was active in the World Federation of Neurosurgical Societies (WFNS) and was a founding member of the First International Congress of Neurosurgery organised by the WFNS in 1955 (Brussels; Fig. 8). He represented Switzerland and acted as their honorary president. He organised and hosted the first European Congress of Neurosurgery in Zurich (1959), which eventually led to the foundation of the European Association of Neurosurgical Societies (EANS) in 1971. He was among the founding members of the Swiss Neurosurgical Society, held the position of its first president from 1955 to 1961, and became its first honorary member in 1974. He was also the president of the Societé de Neurochirurgie de Langue Française and received honorary doctorates from the Universities of Lausanne and Geneva [105, 109]. At his retirement in 1973, Krayenbühl left a soundly based department filled with young people striving for leadership at the various growing points of the expanding field of neurosurgery.

M. Gazi Yaşargil (born 6 July 1925; Fig. 9) himself has summarised his early years and the inspiring encounters he had as a child and young adult, which paved the way for his profound interest in clinical neuroscience [106]. After an internship as a nursing aid in Naumburg an der Saale (Germany), he studied Medicine in Jena (Germany) during the Second World War. When the US and Russian troops made their approach, he was forced to leave Germany and continued his studies in Basel (Switzerland), where he had his first experience with microsurgery—in frogs [106]. After his board examination, he studied the anatomy of white matter tracts in Josef Klingler’s (1888–1963) anatomy laboratory and went on to pursue a residency in psychiatry, neurology, general surgery and internal medicine, in the Berne region, i.e. Interlaken and Münsingen.

He joined Krayenbühl’s department in 1953 and found in his chairman a teacher and mentor. Although he is more remembered for other achievements (see below), Yaşargil was an active spine surgeon who developed his own surgical instruments and materials, fulfilling the needs of each individual case. In 1960, for the removal of a giant cell tumour of the 11th and 12th thoracic vertebrae, he created a “telescoping screw” that he implanted using a trans-thoracic approach [76], and which seems to have inspired the creation of today’s frequently used expandable cages for traumatic and oncological indications. After professional visits to Traugott Riechert (Freiburg, Germany) and Jean Talairach (Paris, France), Yaşargil introduced stereotaxy to treat movement disorders and epilepsy at the USZ [8]. In the field of functional neurosurgery, he performed about 800 operations between 1958 and 1965, before concentrating on his main interest: the field of neurovascular surgery.

In 1963, interest in microsurgery was on the rise, and a binocular Zeiss microscope—an OPMI-1 on a NC-1-stand—was purchased. The first operations were performed to remove herniated disks. Unsatisfied with the balancing of that microscope, Yaşargil and collaborators from the Contraves company improved upon it by adopting the neutralisation of recoiling forces applied in canons (parallelogram-levers), and adding lighting, video and still photography, which were introduced in the legendary NC-1 model. From 1965 on, Yaşargil devoted himself to the development of microneurosurgery. After returning from a 2-year microsurgery fellowship in Raymond M. P. Donaghy’s (1919–1991) department in Burlington, Vermont (USA) [56], Yaşargil developed microsurgery with enthusiasm and strengthened the role of Zürich in the expansion of the field. Important concepts largely developed by Yaşargil include the combination of microsurgical techniques with bipolar coagulation—originally invented by Leonard Malis (1919–2005) [57]—the concept of arachnoidal exploration along cisterns as natural pathways, and the concept of the segmental and compartmental occurrence of vascular and neoplastic lesions of the central nervous system (CNS) with their predilection sites. These achievements allowed microsurgery to gradually mature and progress [106]. Both junior and senior neurosurgeons from all over the world travelled to Zürich in order to see, learn and acquire microsurgical techniques, applied under 4- to 25-fold magnification, improved lighting, and using special micro-instruments. Likewise, patients from near and far sought his advice and care, as previously feared procedures became possible. Microneurosurgery was estimated to have improved the outcome of neurosurgical operations by at least a factor of three [113]. However, this development did not come without resistance by established senior neurosurgeons. Decisive in the treatment of disturbances of cerebral circulation was the development of the extracranial-intracranial (EC-IC) bypass, which is described in more detail below. Furthermore, the microsurgical technique was combined with innovative approaches to the skull base and vascular tree; namely, the pterional approach for aneurysms of the anterior circulation [111] or basilar tip [110].

In 1971, Yaşargil was offered the chair of neurosurgery at the University of Berlin in Germany, but Krayenbühl insisted that he stay in Zürich, and he succeeded his teacher as chairman [106]. He asserted that he would endeavour to maintain the high standards set by Krayenbühl [105]. When he took over the position, he could count on a well-trained 180-person staff, some with decades of experience in neurosurgical patient care, as well as a solid average number of 70 admissions per week.

His work on the operating table, as well as his articles and books, were described as legendary by world leaders in the field. Alongside Harvey Cushing, Yaşargil was labelled “Man of the century”, as one of the two most important neurosurgeons of the twentieth century, for his immense contributions to modern microneurosurgery. His awards and honours have been listed elsewhere [104]. Without a doubt, he fundamentally influenced modern cerebral and medullary neurosurgery, which is based on methodologies developed at the USZ. Even today, many neurosurgeons all over the world use instruments developed in Zürich (e.g. Leyla bar, self-retaining retractor, mouthpiece for microscope position adjustment).

Yasuhiro Yonekawa [born 12 November 1939 in Kyoto-fu (Japan); died 25 February 2017; Fig. 10] studied medicine in Japan. After receiving his medical and doctor’s degree in 1965, he was neurosurgical resident at the University Hospital of Kyoto (Japan) until 1969. He continued his neurosurgical training at USZ from 1970 onwards and was promoted attending in 1973. In this time, he was trained in microneurosurgery by M. Gazi Yaşargil until he returned to the University Hospital of Kyoto in 1977. He there wrote his habilitation on the topic, “Experimental intracranial transplantation of the omentum majus in dogs: a tentative new treatment for hydrocephalus and cerebral ischaemia”. In Kyoto, he was appointed associate professor for neurosurgery in 1981. In 1986, he was appointed Chair of the Department of Neurosurgery at the National Cardiovascular Centre in Osaka (Japan) and in January 1993 he took over the Department of Neurosurgery at USZ.

Based on the work of his predecessors, Yonekawa refined surgical treatment strategies for pathologies of the posterior part of the hippocampus [115], and the EC-IC bypass technique for moyamoya disease. He extended the pterional approach described by Yaşargil by adding extradural anterior clinoidectomy, which has become indispensable for the radical treatment of paraclinoid aneurysms [116].

He summarised the 70-year history of the department on the occasion of his retirement in 2007 [114]. The modern re-organisation of the department during his time led to a decrease in beds while maintaining the number of surgeries performed annually [114]. In his time, operating with the use of open magnetic resonance imaging (MRI) was introduced in Zürich, and congresses/workshops for intraoperative (io) imaging (held at the USZ in 2002; largely supported by René Bernays) and pituitary ademomas (held at the USZ in 1987; largely supported by Alex M. Landolt) were conducted, among others. He found great support by Hans-Georg Imhof in leading the department.

Helmut Bertalanffy had trained in Freiburg (Germany) and Tokyo (Japan) before he was Vice Chair of Neurosurgery in Aachen (Germany) and Chair of Neurosurgery in Marburg (Germany) from 1997 to 2007. Between 2007 and 2010, the USZ Department of Neurosurgery was headed by Helmut Bertalanffy, who is well known for his contributions to modern skull base surgery, and surgery on brain stem cavernomas in particular [12, 17].

Between 2010 and 2012, René Bernays led the department as interim chief. He is known for his contributions to the development of ioMRI, mainly in trans-sphenoidal pituitary surgery [6, 7].

Luca Regli trained in Lausanne. In Nicolas de Tribolet, he found not only a trainer but also a mentor. He later specialised in vascular microsurgery at the Mayo Clinic, Minnesota, with Thoralf M. Sundt (born 1930; died 1992) and Frederic B. Meyer. Visits led him to the neurovascular clinics of Robert F. Spetzler and Juha Hernesniemi. In 2008, at the retirement of Prof. C.A.F. Tulleken, he was appointed Head of Neurosurgery at the University Medical Centre of Utrecht, The Netherlands, one of the world’s leading academic neurovascular centres. In 2009, together with Karl Schaller, he held the European Lecture of the EANS on “promoting change in neurosurgery”. In October 2012, as the new Chair of the department, he brought change but also stability to USZ neurosurgery after a few turbulent years. His vast experience with minimally invasive and complex neurovascular surgery has particularly revitalised the neurovascular section at the USZ. Under his leadership, neurovascular surgery at the USZ has experienced a renaissance and the numbers of cerebrovascular procedures, particularly for the treatment of complex intracranial aneurysms, cerebrovascular bypasses [including excimer laser-assisted non-occlusive anastomosis (ELANA)] and arterio-venous malformations (AVMs), have again increased [96]. In addition, microsurgical carotid endarterectomy procedures, which he learned from the masters at the Mayo Clinic, have been added to the spectrum of USZ neurosurgical procedures. Luca Regli continues to develop microsurgical techniques for cerebrovascular indications. Under his leadership, the concept of “neurosurgery 3.0” moves the department into the next area, in which an armamentarium of sophisticated modern tools for intraoperative (io) imaging (high-definition io ultrasound, high-field 3-T ioMRI, io computed tomography [CT], three-dimensional endoscopy) as well as computer-assisted supports are ideally combined with established techniques (microsurgery, electrophysiology, etc.) to increase the precision and safety of complex neurosurgical procedures. Like Krayenbühl and Yaşargil [106, 108], Regli feels connected to and has a deep respect for the neurological specialty, perpetrating the family tradition of excellence in clinical neurosciences learned from his father, Franco Regli. Strong focus is placed on the complete and standardised assessment of patient outcome and complications for quality control [74]. This patient-centred philosophy and the on-going super-specialisation of neurosurgery within the “big fields” of cerebrovascular, neuro-oncological, functional, spine and paediatric surgery are key factors today to assert the leading position of a neurosurgical department in an increasingly competitive medico-economic environment.

Neurosurgeons have made continuous and notorious contributions to the care of patients suffering from cerebrovascular, neuro-oncological, functional and spinal disorders. Over recent decades, progress in endovascular and radiotherapeutical techniques have challenged the traditional role of microsurgery, pushing neurosurgeons to explore new avenues. In addition, an increasing number of healthcare providers competing for patients have led to a surplus of neurosurgical care in some regions, changing the referral patterns and postgraduate training models [8, 83]. Necessarily, transformations take place, but the spirit and the fundamental neurosurgical principles developed by our mentors continue to be key factors for success today and can be transferred to the present generation of neurosurgeons.

The neurosurgical department at the USZ was among the first of its kind in Europe [2], and was founded along the lines of the independent departments established in London, England, in 1886 (Victor Horsley) [70], Berlin, Germany, in 1900 (Fedor Krause), St.Petersburg, Russia, in 1910 (Pussel) [54], Breslau, former Germany, in 1911 (today’s Wrocław, Poland; Otfrid Foerster; Fig. 7) [19] and Istanbul, Turkey, in 1923 (Abdulkadir Cahit Tuner) [62]. Ludvig Puusepp (Fig. 7) was a Professor of Neurology at the University of Tartu with a strong interest in surgery, who performed the first brain tumour operation in Estonia on 30 April 1921, for a right-sided cerebello-pontine angle mass. The Tartu clinic remained the key Baltic centre for neurosurgery until 1940, but the exact time-point for the founding of a dedicated neurosurgery department in Estonia remains unknown to the authors [91]. Other early departments were established in 1930 in Dublin, Ireland (Adams Andrew McConnell) [53], and in 1933 in Socola, Romania (Moruzzi) [71]. In France, Antony Chipault (1866–1920) was destined to become the father of French neurosurgery for his important clinical and scientific contributions to the field, but he retired early due to an unknown neurological disease [4]. It was thus the general surgeons Thierry de Martel (1876–1940; Fig. 7) and Clovis Vincent (1879–1947; Fig. 7) who paved the way for neurosurgery to become a specialty in France. A specialised department at L’hôpital de la Pitié, in Paris was created in 1933 and was headed by Vincent; a university chair in neurosurgery followed in 1938 [15]. In Germany, Wilhelm Tönnis founded the department of neurosurgery in Würzburg in 1934 [19], and in 1935, departments in Stockholm, Sweden (Herbert Olivecrona), and Bucharest, Romania (Dimitrie Bagdasar) [60], followed, as well as a department in Frankfurt, Germany in 1936 (Traugott Riechert) [19]. In the Netherlands, early representatives of neurosurgery were the two US-trained physicians, Ignaz Oljenick [(1888–1981; started neurosurgical activity in Amsterdam in Bernard Brouwer’s (1881–1949) neurological department in 1929)], Ferdinand Verbeek (1902–1958; started neurosurgical activity in Groningen in 1935), as well as Cornelis Hendrikus Lenshoek (1902–1969), who established the French school of neurosurgery in Utrecht in 1936 [30, 43]. The German invasion during the Second World War disturbed the development of neurosurgery in The Netherlands considerably. Departments founded after 1937 include those in Oxford, England (Hugh Cairns, 1938) [69], Bonn, Germany (Peter Röttgen, 1938) [19], Belgrade, Serbia (Milivoje Kostić, 1938) [71], Athens, Greece (Heliades K., 1939) [71], Kolozsvar, Romania (1941) [20], Sofia, Bulgaria (Philip Philipov, 1942) [71] and Zagreb, Croatia (Danko Riessner, 1945) [71], among others. Italian neurosurgery has a long tradition, as recently reported in a comprehensive review [59], with contemporary neurosurgery evolving in parallel to the development of clinical neurology, neuropathology, neurophysiology and neuro-anaesthesiology. The most important schools were reported to be located in Florence, Bologna, Pisa, Turin and Padua–Venice; later also in Pavia, Verona, Milan, Rome and Naples [59], whereas the exact date of foundation remains unknown. In Spain, Barcia Goyannes began a neurosurgical practice in Valencia in 1957. His efforts, and those of Tolosa and A. Ley (Barcelona; Fig. 7) and Obrador and E. Ley (Madrid), led to the establishment of the first dedicated neurosurgery units on the Iberian Peninsula [117]. In Belgium, the first neurosurgical department was built by Paul Martin (1891–1968; Fig. 8) at the Institut Héger-Bordet (Université Libre de Bruxelles) in 1948, following his training in Halsted’s and Cushing’s clinics [14]. This list is not exhaustive, but it serves to demonstrate that Krayenbühl knew many of those early founders of European neurosurgery, as likewise documented by Figs. 7 and 8. They mutually influenced each other, often maintained professional and personal relationships, and built a common ground to promote modern neurosurgery in Europe.

The founding of neurosurgery at the USZ allowed the Swiss school of neurosurgery to develop and influenced the rise of modern neurosurgery in Europe. Over the decades, it has laid the grounds for important developments in the specialty; in particular, in the areas of vascular, skull base, epilepsy and neuro-oncological surgery. As such, it continues to be among the top teaching institutions not only in Switzerland, but also in Europe, and is visited by many students, postdocs and surgical fellows. Looking back, one realises that to go forward, neurosurgery today needs to integrate both the characteristics of success of yesterday and modern visionary concepts.