Lars Leksell

Clarke came up with the concept in 1895, and the original device was constructed in 1905 and first used in 1906.

Lars Leksell (1907–1986) was a Swedish physician and Professor of Neurosurgery at the Karolinska Institute in Stockholm, Sweden.

He was the inventor of radiosurgery.

Lars Leksell was born in Fässberg Parish, Sweden on November 24, 1907.

He completed medical studies at the Karolinska Institute and began his neurosurgical training in 1935 under Herbert Olivecrona.

Development of electronystagmography and his thesis on muscular control and gamma motor neurons were his early scientific achievements.

Leksell started his neurosurgical training with Herbert Olivecrona in 1935 at the Serafimer Hospital, one of the oldest hospitals in Sweden founded in 1752.

The Olivecrona neurosurgical service enjoyed a solid international reputation and attracted a large number of trainees from all over the world.

For a short period Leksell served as a volunteer medical doctor in Finland when it was attacked by the Soviet Union in November 1939.

Later he told that during that war, he often speculated on the possibility of extracting bullets from the brain with minimal damage to the surrounding brain tissue using a mechanically guided instrument.

In the early 1940s Leksell joined Ragnar Granit, Nobel Laureate 1967, for experimental studies in neurophysiology.

In 1945 he presented a PhD dissertation, a monograph on the motor gamma system titled ‘‘The action potential and excitatory effects of the small ventral root fibers to skeletal muscle.’’ This was a major milestone in the understanding of muscle control and has now become part of basic neurophysiology.

During these years he, together with Granit and Skoglund, made another major contribution by describing the phenomenon of ephapsis, ‘‘artificial synapses,’’ caused by local pressure on a nerve, as a possible mechanism involved in trigeminal neuralgia.

After resuming clinical work, he started work on the development of a stereotactic instrument.

The stereotactic method is the product of Robert Clarke, an engineer, physiologist and surgeon, who, together with neurosurgeon Victor Horsley, devised an instrument for simulating and making lesions at exact locations within the brains of experimental animals: the Horsley–Clarke apparatus.

The first successful cranial application of stereotactic surgery in humans is credited to the team of Ernest Spiegel and Henry Wycis in the Department of Experimental Neurology at Temple University in Philadelphia (Spiegel et al. 1947).

Their original frame, using a Cartesian coordinate systems and similar in design and operation to the Clarke-Horsley device, was fixed to a patient's head by means of a plaster cast.

The frame and cast were removable, allowing separate imaging and surgery sessions.

Contrast radiography, ventriculography and later pneumoencephalography permitted the visualization of intracranial reference points from which the location of target structures of interest could be determined.

Initial applications were for psychosurgery.

In 1947 Leksell visited Wycis in Philadelphia and then developed and described his instrument in a publication in 1949.

This was the first example of a stereotactic system based on the principle of ‘‘center-of-arc’’.

In contrast to the Cartesian coordinate system of the Spiegel-Wycis device, Leksell's frame utilized three polar coordinates (angle, depth and anterior–posterior location).

This ‘‘arc-quadrant’’ device provided maximum flexibility in choosing probe entry point and trajectory, and was therefore much easier to use.

In 1949, he developed his arc centered stereotactic frame based on A polar coordinate system.

The frame has been modified over the ensuing years, but remains remarkably similar in function and appearance to the original 1949 device.

The use of a movable semi-arc with an electrode carrier implies that the tip of a probe can reach the target regardless of the position of the carrier or the angling of the arc relative to the skull fixation device, a frame or base plate with bars for bone fixation screws.

In 1951, using the Uppsala University cyclotron, Leksell and the physicist and radiobiologist Borje Larsson, developed the concept of radiosurgery.

Leksell and Larsson first employed proton beams coming from several directions into a small area into the brain, in experiments in animals and in the first treatments of human patients.

Thus, he achieved a new non-invasive method of destroying discrete anatomical regions within the brain while minimizing the effect on the surrounding tissues.

He became a professor of surgery at University of Lund in 1958.

From 1960 until his retirement, in 1974, he was Professor & Chairman of neurosurgery at the Karolinska Institute in Stockholm, succeeding Herbert Olivecrona, who was the department's founder in 1920.

During this time Leksell pursued his work on stereotactic radiosurgery and refinement of stereotactic methods.

The first prototype of the gamma knife was installed in Sophiahemmet in 1968.

Over the rest of his career, Leksell treated 762 patients with it.

Throughout this time he would propose improving radiosurgery with modern imaging modalities including CT, MRI and angiography, as is currently used.

Today, Leksell's technique is used as an effective treatment for many conditions such as arteriovenous malformations, pituitary tumors, acoustic neuromas, craniopharyngiomas, meningioma, metastatic and skull base tumors, and primary brain tumors.

The device is manufactured by Elekta Instruments, Inc., a Swedish company which manufactures stereotactic surgery and radiosurgery equipment, based on the inventions of Leksell.

It was founded by him in 1972.

He died peacefully at age of 78 in 1986 while taking a brisk walk in Swiss alps.