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Christian Wirtz prefers a navigation system when operating on the brain

One job but two workplaces: Christian Rainer Wirtz has for some time now been commuting regularly along the Danube river between the Bavarian city of Günzburg and the Baden-Württemberg city of Ulm. The new medical director and professor for neurosurgery at the Ulm University Hospital runs a hospital on two sites, i.e. the Günzburg District Hospital and the Safranberg Hospital in Ulm.

Prof. Christian Wirtz; Medical Director of the Department of Neurosurgery at Ulm University Hospital © Pytlik

The 47-year-old neurosurgeon and former vice-director of the Department of Neurosurgery at the Heidelberg University Hospital, had good reason to move to Ulm.

Wirtz, born in Stuttgart, is a specialist in computer-assisted neuronavigation, combined with intraoperative imaging. The hospital in Günzburg has one of the most modern operating theatres in the world and is equipped with state-of-the art devices.

Computer-based neuronavigation is an effective brain surgery tool as it provides the operating surgeon with information about the position of the instruments inside the skull.

Neurosurgeons use neuronavigation to plan actual surgery and to be better able to orient the position of the instruments inside the skull during surgery.

First surgery in the Günzburg Brain Suite in October 2008

In October 2008, Wirtz conducted the first open brain surgery in the Günzburg ‘Brain Suite’ using the new navigation tool. The digitally integrated workflow-optimised neurosurgical operating room has a magnetic resonance imager (MRI), which, combined with a neurosurgical navigation system, enables difficult interventions to be carried out with high levels of efficiency and safety.

Found “his subject” very early

The researcher and neurosurgeon-to-be Wirtz found “his chosen subject” very early on during his period as assistant doctor. The original subject was neuronavigation to be later followed by intraoperative imaging, which became another major priority of his work. In 2001, Wirtz habilitated in Heidelberg on neuronavigation and intraoperative magnetic resonance imaging.

Convinced about surgical navigation right from the start

A great deal of state-of-the-art technology, including imaging methods, is required to provide brain surgeons with a good view of the brain. Without such methods, this is difficult to achieve.
A great deal of state-of-the-art technology, including imaging methods, is required to provide brain surgeons with a good view of the brain. Without such methods, this is difficult to achieve. © University Hospital Ulm

During his doctorate at the University of Aachen (RWTH), Wirtz, who, in common with all other neurosurgeons, is enthusiastic about technology, studied neurosurgical pain therapy. In 1989, he moved on to the University Hospital of Heidelberg, where he immediately established a neuronavigation workgroup. Prior to this, Wirtz and a colleague from the Department of Oral and Maxillofacial Surgery, had managed to convince their bosses of the necessity of using computer-assisted navigation systems.

In 1993, the ‘Kopfklinik’ Heidelberg acquired the first commercially available navigation system. Wirtz investigated the system in great detail, carried out many experiments and compared the system with other navigation systems. He thus succeeded in establishing and comprehensively evaluating the hospital’s computer-assisted work method.

Close interdisciplinary cooperation

Before the computer-assisted method became an integral part of the hospital, a lot of clinical research was required. The efficiency of the navigation system was initially tested by using it in surgical interventions where it was not strictly speaking required. The questions that were asked included: Does it prolong the intervention? How can it be integrated into daily routine? How does it fit into the surgeon’s ergonomic workspace? How is the information presented? It was only possible to answer these questions in close cooperation with the engineering sciences and other disciplines such as the Karlsruhe Institute of Process Control and Robotics.

Three-dimensional representation of the operating area

Three-dimensional representation of the human brain © Wirtz

Prof. Wirtz explains that neuronavigation provides the surgeon with a three-dimensional picture of the operating area. This was made possible by progress in information and computer technology which led to imaging methods such as CT, MRI or SPECT.

The position of the surgical instruments during surgery is monitored by an infrared camera and integrated into slice or three-dimensional images recorded prior to surgery with X-ray technology (CT, MRI).

Brain shift problem solved

During the operation, the operating surgeon faces a problem that Christian Rainer Wirtz has now managed to solve. Experts refer to this problem as “brain shift”, meaning that the brain’s anatomy alters during the surgical removal of brain tissue.

The more tumour tissue that is removed the greater the difficulty to actually discern healthy from malignant tissue. The “map” of the operating area becomes increasingly inaccurate, especially towards the end of surgery, when the brain tumour has been removed and care has to be taken to remove the tiny tumour tissue pieces that can only be differentiated from normal tissue with great difficulty.

Upgraded navigation system for neurosurgeons

In close cooperation with Siemens, Wirtz initiated a project to integrate a magnetic resonance imager into the operating theatre in order to be able to carry out what is known as intraoperative imaging. Towards the end of neurosurgical interventions, another image of the patient is taken, thereby providing the surgeon with a new, up-to-date map.

Wirtz greatly contributed to this technology, which was developed by an interdisciplinary team of researchers. Basically, said Wirtz, this technology is continuously being optimised for clinical application. One of the first intraoperative MRI images was taken during the neurosurgical removal of a brain tumour in Heidelberg.

The benefit is considerable rather than comprehensive

Rough schematic of a brain operation involving a neurosurgical navigation system.
Rough schematic of a brain operation involving a neurosurgical navigation system. © Wirtz

Neuronavigational surgery means that more tumours can be removed than would be possible without such systems, but surgeons are a long way from being able to remove all tumours. Tumours that originate in the brain cannot be treated surgically because their cells spread into the surrounding tissue where they lead to a new tumour, even in cases where the surgeon has removed the tumour he saw on the images.

Wirtz believes that successful surgery improves the subsequent treatment of the tumour patient. Glioma can not usually be completely removed because the tumours are very often close to sensitive regions such as motor and speech centres, which therefore prohibits surgery.

Using neuronavigation and intraoperative imaging, surgeons are able to completely remove between 60 and 70 percent of all gliomas. If only neuronavigation is used, the success rate drops to fifty percent. Wirtz also explains that some centres that do not have access to intraoperative imaging use ultrasound and, to a growing extent, dyes to remove gliomas.

Brain Suite is suitable for gliomas and pituitary gland tumours

The complex technology used by the Günzburg District Hospital’s Brain Suite is only suitable for a certain range of neurosurgical interventions, mainly gliomas and larger pituitary gland tumours. Wirtz also believes that the technology can be applied in functional neurosurgery (epilepsy surgery) and vascular surgery using MR angiography.

Research requires “extended reality”

Brain surgery not only involves surgical microscopes (top left), but also allows the surgeon to receive anticipation data blended into his eye. © Wirtz

Thanks to modern medical technology, brain surgeons are now able to visualise the operating area to an increasing extent. This is something that was impossible for many centuries. Wirtz likes to compare this visualisation to "a kind of eye amplifier" and he hints at the latest research direction known as "extended reality", which is an attempt to visualise things that the human eye does not see: for example,  it will be possible for the surgeon to  look at the operating area through the surgical microscope at the same time as having additional anticipation data blended into his eye.

Neurosurgeons thus see the tumour before the first cut has been made. This method is also used when only the outline of a tumour is visible.

Wirtz intends to continue his close cooperation with engineers and medical device companies in Günzburg and Ulm. He hopes to further develop navigation systems in order to make them suitable for surgery planning and the training of surgeons (in the operation of the system and in simulated surgery on virtual patients) before difficult surgeries are undertaken with professional guidance.

Wirtz also intends to improve the systems' visualisation capabilities and ergonomics as well as optimising the Brain Suite technology in cooperation with the companies involved. Wirtz envisages another new research priority, i.e. basic research in tumour biology and genetics, aimed at developing further therapies.

Commuting between Ulm and Günzburg

Following his inaugural lecture and the official opening of the Brain Suite, Prof. Christian Rainer Wirtz will now be able to bring out the best in his two workplaces. Wirtz has already turned the theoretical disadvantage of two workplaces into a practical advantage in terms of increased scope for research and patient care. He hopes to broaden the catchment area of the two hospitals and establish different priorities in each. Günzburg’s principal focus will be the surgery of brain tumours in children and adults, and Ulm, due to its close vicinity to the university’s department of paediatrics, will focus mainly on paediatric neurosurgery.

Further information:
Professor Dr. Christian Rainer Wirtz
Director of the Hospital of Neurosurgery
at the University of Ulm

Centre of Surgery
Hospital of Neurosurgery
Steinhövelstraße 9
89075 Ulm
E-mail: rainer.wirtz(at)uniklinik-ulm.de

and

Günzburg District Hospital
Neurochirurgische Klinik
Ludwig-Heilmeyer-Straße 2
89312 Günzburg
E-mail: rainer.wirtz(at)bkh-guenzburg.de

 

 

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