Functional Neurosurgery, Pain, and Intraoperative Neurophysiology
Functional neurosurgery deals with a wide range of neurosurgical procedures for the treatment of functional disorders of the nervous system, such as movement, gait, and cognitive disorders, epilepsy, as well as pain syndromes and psychiatric conditions.
The principle of these treatments is, whenever possible, a non-destructive modulation of nervous system functions, aimed at curing the disease, alleviating symptoms, or slowing the progression of disease-related impairments.
Patient care is provided through broad interdisciplinary collaboration with the university clinics for neurology, pediatric and adolescent medicine, radiology and radiation therapy, psychiatry and psychotherapy, as well as anesthesiology, intensive care and pain management.
Collaboration with the University Clinic for Neurology in connection with treatment concepts for movement disorders was intensified in 2019 under the leadership of Dr. med. univ. Christof Brücke. The intensive interdisciplinary cooperation takes place in the comprehensive preoperative assessment, diagnostics, and selection of patients for deep brain stimulation (DBS), in intraoperative neurophysiological testing, as well as in the perioperative adjustment of patient therapy.
Our future projects in this area include:
- Transition of target planning to a 3T MRI system, for which a new metal-free stereotactic frame system (Vantage™ Frame, Fig. 1) is also planned.
- Enhancement of the planning software to incorporate diffusion tensor imaging (DTI) datasets into MRI planning and the use of the Brainlab planning system.
- Replacement and modernization of the intraoperative microelectrode recording system.
Advances in the technology of stimulation systems, including segmented stimulation electrodes and the recording of local field potentials via the stimulation electrodes, help us tailor therapies even more closely to the individual needs of patients with movement disorders.
Currently, lesions (thalamotomies) in patients with tremor disorders, for whom deep brain stimulation (DBS) is not an option, can be performed non-invasively using the Gamma Knife. At the University Clinic for Neurosurgery of MedUni Vienna and AKH Vienna, the only device in Austria suitable for this therapy is available for patients.
In the future: MRgFUS
MRgFUS stands for magnetic resonance-guided focused ultrasound therapy. With this novel treatment method, under clinical observation of awake patients and without the use of radioactive radiation, a target region in the thalamus can be heated using focused ultrasound energy until the symptoms of the tremor disorder are alleviated.
The procedure is guided and monitored using MRI (magnetic resonance imaging), which allows the treatment area to be fully visualized and treated safely. This is a technically complex but patient-friendly procedure.
The establishment of MRgFUS in Austria—including the logistical, structural, and economic requirements for performing targeted ultrasound lesions in the brain—is being developed in collaboration with the University Clinics for Neurology as well as Radiology and Nuclear Medicine.
The University Clinics for Neurosurgery and Neurology at the Medical University of Vienna, as part of the interdisciplinary project “Pre-surgical Evaluation and Epilepsy Surgery” decided early on to use deep brain stimulation (DBS) in the treatment of therapy-resistant epilepsy. In 2011, the first patient in Austria received DBS therapy for chronic stimulation of the anterior nucleus of the thalamus. Since 2011, eight patients have undergone surgery and have been included in an ongoing study of long-term outcomes as part of a multicenter European registry (Medtronic Registry for Epilepsy – MORE).
In the treatment of therapy-resistant epilepsies for which no curative surgical procedure is possible, vagus nerve stimulation (VNS) has already been successfully applied since 1999.
The non-destructive nature of surgical techniques in functional neurosurgery allows surgical intervention to be applied, under strict indication criteria, even in severe, treatment-resistant psychiatric disorders. In this context, in 2020, Univ.-Prof. Karl Rössler implanted two vagus nerve stimulators for the treatment of severe depression for the first time in Austria. The patients were enrolled in a multicenter study (RESTORE-LIFE), which is conducted in collaboration with the Department of Psychiatry and Psychotherapy, to evaluate the effectiveness of the therapy for the treatment of severe depression.
Similarly, patients with severe obsessive-compulsive disorders are being recruited for treatment using deep brain stimulation (DBS). Within a specialized protocol, a monocentric study (“Glucose metabolism under deep brain stimulation in obsessive-compulsive disorder”) is being conducted at the Medical University of Vienna in collaboration with the Department of Psychiatry and Psychotherapy and the Department of Radiology and Nuclear Medicine, in which the effects of the therapy are investigated through measurements of brain glucose metabolism using functional positron emission tomography (fPET).
In the treatment of normal pressure hydrocephalus, we have developed, in cooperation with the university clinic for neurology (outpatient clinic for movement disorders and clinic for memory disorders and dementias), a diagnostic protocol which, including radiological and nuclear medicine examinations, can improve the assessment of prognosis for the neurosurgical therapy performed by implantation of a ventriculoperitoneal shunt system.
An important part of functional neurosurgery at the Medical University of Vienna is the treatment of trigeminal neuralgia. In close cooperation with our partner clinics (Department of Neurology and Department of Anaesthesia, Intensive Care Medicine and Pain Medicine), the appropriate surgical therapy is indicated for patients after unsuccessful conservative treatment.
In addition to the standard surgical procedure of microvascular decompression of the trigeminal nerve according to Jannetta—performed using microneurosurgical techniques with the aid of a high-resolution microscope—we can offer patients a variety of alternative interventions when needed. Ablative procedures such as thermocoagulation and balloon compression of the Gasserian ganglion or Gamma Knife treatment of the trigeminal nerve are available. Smaller procedures such as Botox and glycerol injections or ganglionic local opioid applications are also offered and can be performed on an outpatient basis.
Intraoperative neurophysiological monitoring (IOM), as a technical method for monitoring neurological functions during surgical procedures on the brain and spine, is an integral part of neurosurgical surgical planning.
Through its potential to detect and predict neurological deficits at an early stage intraoperatively, IOM has contributed to expanding the indications for high-risk operations and to reducing permanent neurological deficits to a minimum.
The University Clinic of Neurosurgery is among the first institutions in Europe to have established routine intraoperative diagnostics using motor evoked potentials (from muscle and spinal cord) and the monitoring of corticobulbar motor evoked potentials (motor cranial nerve monitoring).
In the field of intraoperative neurophysiological monitoring, with the support of two staff members with additional training in this specialized area, we have succeeded in performing around 200 operations per year with IOM.
Movement Disorder Board
The Movement Disorder Board was established as an interdisciplinary case conference in 2011. The board consists of participants from the Department of neurology, pediatrics and adolescent medicine, Biomedical Imaging and Image-Guided Therapy, and neurosurgery.
Patients with complex movement disorders are presented after thorough neurological evaluation (medical history, neurological status, genetics, neuroradiological findings, clinical findings, and classification of the movement disorder), incorporating detailed video documentation of the condition, and a case-specific treatment strategy is established.
The Movement Disorder Board meetings are convened at intervals of 1–3 months and are held at the University Clinic of Neurosurgery.