The treatment of movement disorders, such as tremor, is now possible at University Hospital Vienna/Medical University of Vienna without opening the brain and without general anesthesia. The tissue lesion is guided by magnetic resonance imaging and high-intensity, focused ultrasound. Transcranial MR-guided focused ultrasound therapy (TK-MRgFUS) is a method of functional neurosurgery for the treatment of essential tremor. The procedure combines two technologies: magnetic resonance imaging (MRI) is used to identify the area in the brain that is responsible for the movement disorder. Focused ultrasound (FUS) is used to heat and thus destroy the identified tissue. The ultrasound device is integrated into a 3 Tesla MRI scanner. Patients are mechanically immobilized for the intervention using a head ring, but are awake and responsive throughout the treatment. The treatment result is checked immediately after the treatment with MR imaging sequences and clinical neurological examinations.
The treatment is performed without a skin incision, i.e. it is not necessary to open the skull bone, and also allows success to be monitored during the therapy using reversible test lesions. The treatment is carried out in three stages under permanent anaesthesiological monitoring: first, the temperature in the target tissue is raised only moderately (40-45°C) and the exact localization of the focused ultrasound is checked using MRI. The temperature in the target tissue is then increased to 46-50°C. At this temperature, only reversible effects result, which make it possible to assess the therapeutic effect and undesirable effects - through active feedback from the patient and checking the tremor - and to adjust the positioning of the ultrasound if necessary. In the final step, the maximum temperature is then increased to 56-60°C. "Only then does the actual therapy take place by means of permanently effective temperature increases over 10 - 25 seconds," explains neurosurgeon Klaus Novak.
The entire duration of this treatment, which is particularly gentle on the patient, is approx. 2-4 hours and takes place as part of an inpatient stay at the Department of Neurosurgery, headed by Karl Rössler. Seven patients have already been successfully treated at Vienna General Hospital. The technical basis for the treatment is the ExAblate 4000 ultrasound platform from Insightec, which was installed at the Division of Neuroradiology and Musculoskeletal Radiology, headed by Gregor Kasprian.
Since certification of this device in Europe and the USA, the treatment has been performed on more than 6,000 patients worldwide. In Austria, around 1% of the total population is affected by essential tremor. Before a possible treatment, a medical assessment is necessary to determine whether the prerequisites for this type of therapy are met.
Patient care in the context of this new type of therapy requires interdisciplinary collaboration between several medical disciplines (neurosurgery, neuroradiology, neurology, anesthesia) and several medical specialties (nursing, MTDG), which are also represented in the Comprehensive Center for Clinical Neurosciences and Mental Health of University Hospital Vienna and MedUni Vienna.