Who Developed The Foundations For Stereotactic Radiosurgery?

One of the most important developments ever made in a radiotherapy centre was the invention of stereotactic radiosurgery.

Also known as the Gamma Knife method, Lars Leksell’s pioneering innovation allowed for an unparalleled level of precision in treating and removing brain conditions, including lesions, growths and trapped nerves.

However, one of the most interesting aspects of Gamma Knife is that the two core components of it were developed largely in parallel with each other.

Radiotherapy went through a wide range of developments as the understanding of how it should and should not be used increased, whilst the stereotactic aspect of Gamma Knife was not initially intended to be used for radiotherapy doses.

In fact, it was originally a surgical method looking for a reason to exist, although it did manage to contribute a great deal to neurosurgery even at an early stage.

The Horsley-Clarke Apparatus

The first stereotactic device was developed by two English doctors as their last collaboration together as peers.

The latter part of the name, Robert H Clarke, is far less well known than the former, Sir Victor Horsley, but was just as critical to the device’s creation.

Dr Clarke believed in the importance of applying mathematical concepts to the field of neurophysiology and wanted to create a workable method for producing brain atlases using Cartesian coordinates.

His counterpart, Sir Victor, was a pioneering neurosurgeon, who innovated a range of surgical techniques to make brain surgery more effective and less risky during a time when surgery as a field was changing rapidly.

He was one of the first surgeons to develop a consistent working method for treating trigeminal neuralgia and also developed bone wax and the skin flap method, as well as making several notable breakthroughs in surgical innovations that could treat epilepsy, something that would later be attempted through radiotherapy by the start of the 20th century.

Mathematics

By 1905, he had started working with Dr Clarke, and the pair developed a mathematical method for undertaking neurosurgery, where different parts of the brain could be identified through coordinates that could be mapped consistently onto a frame.

However, its biggest achievement as described in a 1908 article by the pair was the development of their neurosurgical frame, known as the Horsley-Clark Apparatus, as a system to create an atlas of the brain and a three-dimensional map of where critical brain structures are located.

The system worked in that regard, but it was ultimately designed for cat brains rather than human ones. Despite this, it was still an incredibly important first step and would shape neurosurgery for decades to come.

Influence

The system would prove highly influential, and a decade after its invention, Aubrey T. Mussen commissioned an adaptation of the frame designed for human brains, inspired by the three working at the National Hospital in London.

However, the brass frame does not appear to have ever been used on human brains and did not receive a lot of attention at the time.

In fact, it would take another 15 years after Aubrey’s adaptation for Martin Kirschner to use a similar system to treat an actual patient.

In 1933, the German doctor used a minimally invasive surgical method to insert an electrode into the trigeminal nerve and burn it, treating a condition Sir Victor pioneered the surgical method for with a system extremely similar to stereotactic radiosurgery aside from the use of a physical electrode.

However, by the 1940s, the Horsley-Clark method would reach both its peak of importance and obsolescence within the span of three years.

Human brain atlas

In 1947, after the end of the Second World War, Henry Wycis and Ernest Spiegel used a Horsley-Clarke frame with a cartesian coordinates system to develop the first human brain atlas in history, as well as use the system as part of the now-controversial field of psychosurgery.

The later Talairach coordinates system would evolve from this, which used the brain atlas information to create a grid system more relevant to the actual structure of the human brain.

In 1949, Lars Leksell would effectively make the Horsley-Clarke method obsolete by developing his Gamma Knife system to use a system of polar coordinates as part of his stereotactic radiotherapy system.

This system, alongside a new generation of more advanced three-dimensional imaging systems that allowed brain surgeons to be more precise, led to the obsolescence of the Horsley-Clarke method.

However, without these two doctors and their pioneering system, the Gamma Knife would not have existed.