Andreas Nowacki

Inselspital, Universitätsspital Bern · Department of Neurosurgery

Ictal SPECT is an informative seizure imaging technique to tailor epilepsy surgery. However, capturing the onset of unpredictable seizures is a medical and logistic challenge. Here, we sought to image planned seizures triggered by direct stimulation of epileptic networks via stereotactic electroencephalography (sEEG) electrodes. Methods: In this ca...

Background Subthalamic nucleus deep brain stimulation (STN-DBS) is a well-established treatment for motor complications in Parkinson’s disease (PD). However, its effects on neuropsychiatric symptoms remain disputed. The aim of this study was to evaluate the effects of STN-DBS on neuropsychiatric symptoms in PD. Methods We retrospectively assessed...

Treatment-resistant depression is a severe form of major depressive disorder and deep brain stimulation is currently an investigational treatment. The stimulation’s therapeutic effect may be explained through the functional and structural connectivities between the stimulated area and other brain regions, or to depression-associated networks. In th...

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for advanced Parkinson's disease. Stimulation of the hyperdirect pathway (HDP) may mediate the beneficial effects, whereas stimulation of the corticospinal tract (CST) mediates capsular side effects. The study's objective was to suggest stimulation parameters ba...

Introduction: Decompressive hemicraniectomy (DCE) is routinely performed for intracranial pressure control after malignant middle cerebral artery (MCA) infarction. Decompressed patients are at risk of traumatic brain injury and the syndrome of the trephined until cranioplasty. Cranioplasty after DCE is itself associated with high complication rate...

Objective: The aim of this feasibility study was to investigate the properties of median nerve somatosensory evoked potential (SEPs) recorded from segmented Deep Brain Stimulation (DBS) leads in the sensory thalamus (VP) and how they relate to clinical and anatomical findings. Methods: We analyzed four patients with central post-stroke pain and...

Background: The landscape of neurophysiological symptoms and behavioral biomarkers in basal ganglia signals for movement disorders is expanding. The clinical translation of sensing-based deep brain stimulation (DBS) also requires a thorough understanding of the anatomical organization of spectral biomarkers within the subthalamic nucleus (STN). O...

Background: Directional deep brain stimulation (DBS) allows for steering of the stimulation field, but extensive and time-consuming testing of all segmented contacts is necessary to identify the possible benefit of steering. It is therefore important to determine under which circumstances directional current steering is advantageous. Methods: Fi...

Deep Brain Stimulation (DBS) is an effective treatment for advanced Parkinson’s disease. However, identifying stimulation parameters, such as contact and current amplitudes, is time-consuming based on trial and error. Directional leads add more stimulation options and render this process more challenging with a higher workload for neurologists and...

Objective: The beneficial effects of thalamic deep brain stimulation (DBS) at various target sites in treating chronic central neuropathic pain (CPSP) remain unclear. This study aimed to evaluate the effectiveness of DBS at a previously untested target site in the central lateral (CL) thalamus, together with classical sensory thalamic stimulation...

OBJECTIVE Decompressive hemicraniectomy (DCE) is the standard of care for space-occupying malignant infarction of the medial cerebral artery in suitable patients. After DCE, the brain is susceptible to trauma and at risk for the syndrome of the trephined. This study aimed to assess the feasibility of using temporary space-expanding flaps, implanted...

Objective We aimed to demonstrate the feasibility of using motor evoked responses to intraoperative double-train stimulation to guide lead placement and matching of intraoperative contacts with postoperative electrode programming in spinal cord stimulation for pain performed under general anesthesia. Materials and Methods The study included a seri...

Objective: To obtain individual clinical and neuroimaging data of patients undergoing Deep Brain Stimulation for essential tremor from five different European centers to identify predictors of outcome and to identify an optimal stimulation site. Methods: We analysed retrospectively baseline covariates, pre- and postoperative clinical tremor scor...

Background Deep brain stimulation (DBS) programming of multicontact DBS leads relies on a very time-consuming manual screening procedure, and strategies to speed up this process are needed. Beta activity in subthalamic nucleus (STN) local field potentials (LFP) has been suggested as a promising marker to index optimal stimulation contacts in patien...

Objectives Subthalamic nucleus (STN) deep brain stimulation (DBS) programming in patients with Parkinson disease (PD) may be challenging, especially when using segmented leads. In this study, we integrated a previously validated probabilistic STN sweet spot into a commercially available software to evaluate its predictive value for clinically effec...

Deep brain stimulation is an effective neurosurgical intervention for movement disorders such as Parkinson's disease. Despite its success, the underlying mechanisms are still debated. One tool to better understand them is the Volume of Tissue Activated (VTA), that estimates the region activated by electrical stimulation. Different estimation approa...

Although deep brain stimulation (DBS) of the globus pallidus internus (GPi) and the subthalamic nucleus (STN) has become an established treatment for Parkinson's disease (PD), a recent meta-analysis of outcomes is lacking. To address this gap, we performed a meta-analysis of bilateral STN-and GPi-DBS studies published from 1990-08/2019. Studies wit...

Background Open and stereotactic transfrontal or transcerebellar approaches have been used to biopsy brainstem lesions. Method In this report, a stereotactic posterior and midline approach to the distal medulla oblongata under microscopic view is described. The potential advantages and limitations are discussed, especially bilateral damage of the...

Background Stereotactic biopsies for brainstem lesions are frequently performed to yield an accurate diagnosis and help guide subsequent management. In this study, we summarize our experience with different stereotactic approaches to brainstem lesions of different locations and discuss possible implications for safety and diagnostic yield. Methods...

Background Different deep brain stimulation (DBS) targets have been suggested as treatment for patients with pharmacologically refractory Holmes tremor (HT). We report the clinical and quality of life (QoL) long‐term (up to nine years) outcome in four patients with HT treated with DBS (in thalamic ventral intermediate nucleus‐VIM or in dentato‐rubr...

Background/Objective In order to monitor tissue oxygenation in patients with acute neurological disorders, probes for measurement of brain tissue oxygen tension (ptO 2 ) are often placed non-specifically in a right frontal lobe location. To improve the value of ptO 2 monitoring, placement of the probe into a specific area of interest is desirable....

Deep Brain Stimulation of the posterior subthalamic area is an emergent target for the treatment of Essential Tremor. Due to the heterogeneous and complex anatomy of the posterior subthalamic area, it remains unclear which specific structures mediate tremor suppression and different side effects. The objective of the current work was to yield a bet...

Objective Deep brain stimulation (DBS) is a treatment alternative for refractory chronic Cluster headache (CCH). Despite several recent prospective case series reporting on good outcome, the effectiveness and the optimal stimulation target of DBS for CCH remain unclear. We aimed to obtain precise estimates and predictors of long‐term pain relief in...

Whilst exaggerated bursts of beta frequency band oscillatory synchronization in the subthalamic nucleus have been associated with motor impairment in Parkinson's disease, a plausible mechanism linking the two phenomena has been lacking. Here we test the hypothesis that increased synchronization denoted by beta bursting might compromise information...

Indirect targeting of the Ventralis Intermedius Nucleus (Vim) is widely used for functional neurosurgical procedures to treat essential tremor (ET). Here, we review if the laterality of the Vim depends on the diameter of the third ventricle and if a targeting approach that incorporates this correlation can facilitate targeting and yields accurate l...

Objective Segmented deep brain stimulation leads in the subthalamic nucleus have shown to increase therapeutic window using directional stimulation. However, it is not fully understood how these segmented leads with reduced electrode size modify the volume of tissue activated (VTA) and how this in turn relates with clinically observed therapeutic a...

Background: Directional deep brain stimulation (dDBS) of the subthalamic nucleus for Parkinson's disease (PD) increases the therapeutic window. However, empirical programming of the neurostimulator becomes more complex given the increasing number of stimulation parameters. A better understanding of dDBS is needed to improve therapy and help guide...

In a single-center, randomized trial involving 361 patients, the use of routine computed tomography after the removal of a chronic hematoma had no advantage over CT performed only in patients with clinical deterioration.

Objective: We present long-term follow-up results and analysis of stimulation sites of a prospective cohort study of six patients with chronic cluster headaches undergoing deep brain stimulation of the ipsilateral posterior hypothalamic region. Methods: The primary endpoint was the postoperative change in the composite headache severity score "h...

Objective: Functional processes in the brain are segregated in both the spatial and spectral domain. Motivated by findings reported at the cortical level in healthy participants we test the hypothesis in the basal ganglia of Parkinson's disease patients that lower frequency beta band activity relates to motor circuits associated with the upper lim...

OBJECTIVE Deep brain stimulation (DBS) of the posterior subthalamic area (PSA) is an alternative to thalamic DBS for the treatment of essential tremor (ET). The dentato-rubro-thalamic tract (DRTT) has recently been proposed as the anatomical substrate underlying effective stimulation. For clinical purposes, depiction of the DRTT mainly depends on d...

INTRODUCTION Chronic subdural hematoma has a high recurrence rate after surgery and postoperative scans often show substantial residuals, eventually leading to a higher rate of reoperation. However, the benefit of postsurgical imaging for patient outcome remains unknown. METHODS We randomly assigned 368 patients with newly diagnosed chronic subdur...

The pedunculopontine nucleus (PPN) is a reticular nucleus located in the mesencephalic and upper pontine tegmentum. Initially, characterized by its predominant cholinergic projection neurons, it was associated with the "mesencephalic locomotor region" and "reticular activating system". Furthermore, based on histopathological studies, the PPN was hy...

Background: Accurate interindividual comparability of deep brain stimulation (DBS) lead locations in relation to the surrounding anatomical structures is of eminent importance to define and understand effective stimulation areas. The objective of the current work is to compare the accuracy of the DBS lead localisation relative to the STN in native...

Background: External ventricular drainage (EVD) catheter placement is one of the most commonly performed neurosurgical procedures. The study's objective was to compare a computed tomography (CT) bolt scan-guided approach for the placement of EVDs with conventional landmark-based insertion. Methods: In this retrospective case-control study, we an...

OBJECTIVE The dentatorubrothalamic tract (DRTT) has been suggested as the anatomical substrate for deep brain stimulation (DBS)–induced tremor alleviation. So far, little is known about how accurately and reliably tracking results correspond to the anatomical DRTT. The objective of this study was to systematically investigate and validate the resul...

Background: Although recently introduced directional DBS leads provide control of the stimulation field, programing is time-consuming. Objectives: Here, we validate local field potentials recorded from directional contacts as a predictor of the most efficient contacts for stimulation in patients with PD. Methods: Intraoperative local field pot...

Background: Subthalamic nucleus (STN) stimulation has been recognized to control resting tremor in Parkinson disease. Similarly, thalamic stimulation (ventral intermediate nucleus; VIM) has shown tremor control in Parkinson disease, essential, and intention tremors. Recently, stimulation of the posterior subthalamic area (PSA) has been associated...

BACKGROUND: Targeting accuracy in deep brain stimulation (DBS) surgery can be defined as the level of accordance between selected and anatomic real target reflected by characteristic electrophysiological results of microelectrode recording (MER). OBJECTIVE: To determine the correspondence between the preoperative predicted target based on modern 3-...

Objective: Recent advances in different MRI sequences have enabled direct visualization and targeting of the Globus pallidus internus (GPi) for DBS surgery. Modified Driven Equilibrium Fourier Transform (MDEFT) MRI sequences provide high spatial resolution and an excellent contrast of the basal ganglia with low distortion. In this study, we invest...

Case presentation and systematic review of the literature to update our current knowledge of induction of fear by cortical stimulation. We present a case of refractory epilepsy associated with a lesion where fear could be induced by intraoperative electrical stimulation of the posterior inner part of the superior temporal gyrus. We performed a syst...