Research focus

Prof. Atilla YILMAZ's principal research contribution is a double-target deep brain stimulation technique in which the ventral intermediate nucleus (VIM) and the posterior subthalamic area (PSA) are stimulated through a single electrode trajectory — an approach aimed at tremor syndromes that respond incompletely to either target alone. The series was published in Stereotactic and Functional Neurosurgery in 2024 with Prof. Patric Blomstedt of Umeå University.

Double-target VIM + PSA stimulation

Tremor is not one disease. The VIM has been the classical DBS target for tremor for decades, but a proportion of patients — particularly those with Holmes tremor, dystonic tremor and other rare syndromes — respond only partially, or lose benefit over time. The posterior subthalamic area, including the caudal zona incerta (cZi), emerged from the Umeå group's work as an alternative target with a different response profile.

The approach described by Prof. YILMAZ and colleagues places one electrode along a trajectory that passes through both regions, so that different contacts on the same lead can stimulate VIM and PSA. Stimulation can then be balanced between the two during programming, without a second trajectory and without the additional risk that a second brain pass carries.

A related asymmetric approach — one GPi and one STN electrode implanted in the same patient — has been used for tremor-dominant patients with troublesome dyskinesia, where the two targets address different components of the problem.

Device development: a fluid-tight burr hole closure

Bilateral DBS carries a well-recognised accuracy problem. Once the first burr hole is open, cerebrospinal fluid escapes, the brain shifts slightly inside the skull, and the coordinates calculated from the pre-operative images no longer describe exactly where the second target sits. The shift is usually small — but in an operation measured in millimetres, small is not nothing. The same open hole is also where an electrode can migrate, and a route for infection.

Prof. YILMAZ is a co-inventor of a device designed to seal that opening. The Turkish Patent and Trademark Office granted it as a utility model, TR 2025 000875 Y, on 21 April 2026. Its stated aims are to prevent cerebrospinal fluid leakage and the second-side targeting error that follows from it, to secure the electrode against migration, and to lower post-operative infection and complication risk — through the seal itself and through the material the device is made from.

Registration record: Türk Patent ve Marka Kurumu, application 2025/000875, published 21 February 2025 as TR 2025 000875 A2, granted 21 April 2026 as TR 2025 000875 Y.

What stimulation does beyond movement

A second research line asks a question that matters a great deal to patients and is often under-studied: what else does stimulation change? Working with speech-language pathologists, physiotherapists, neurologists and psychologists, Prof. YILMAZ has published on the effects of subthalamic nucleus stimulation and of different stimulation frequencies on:

• acoustic and articulatory features of vowels, and on voice quality;
• static balance at different stimulation frequencies;
• somatosensation;
• cerebral haemodynamics, measured by transcranial Doppler;
• gastrointestinal symptoms and quality of life;
• facial expression — a collaboration with the University of Florida group and METU.

The practical point of this work is programming. If a frequency change improves gait but degrades speech, the surgeon and the neurologist need to know that before they make it.

Selected research output

1. Deep Brain Stimulation with Double Targeting of the VIM and PSA for the Treatment of Rare Tremor SyndromesStereotact Funct Neurosurg, 2024 · doi:10.1159/000539162
2. Deep Brain Stimulation for the Abernethy Malformation Related TremorClinical Neurology and Neurosurgery, 2022 · doi:10.1016/j.clineuro.2022.107554
3. Does subthalamic nucleus deep brain stimulation affect the static balance at different frequencies?Neurocirugía, 2022 · doi:10.1016/j.neucir.2022.01.001
4. Investigating the effects of Subthalamic Nucleus Deep Brain Stimulation on the voice qualitySomatosensory & Motor Research, 2020 · doi:10.1080/08990220.2020.1761317
5. The effect of Subthalamic Nucleus Deep Brain Stimulation and different stimulation frequencies on cerebral haemodynamics in Parkinson's disease: a transcranial Doppler studyClinical Neurology and Neurosurgery, 2020 · doi:10.1016/j.clineuro.2020.105778
6. Analysis of the effects of subthalamic nucleus deep brain stimulation on somatosensation in Parkinson's disease patientsNeurological Sciences, 2019 · doi:10.1007/s10072-019-04168-9
7. Investigating the Effect of STN-DBS Stimulation and different Frequency settings on the Acoustic-Articulatory Features of VowelsNeurological Sciences, 2018 · doi:10.1007/s10072-018-3479-y

See the full publication list →