Frameless Deep Brain Stimulation Surgery: A Single-Center Experience and Retrospective Analysis of Placement Accuracy of 220 Electrodes in a Series of 110 Patients.

BACKGROUND: Proper lead placement is considered one of the key factors in achieving a good clinical outcome in deep brain stimulation (DBS), but there is still considerable controversy surrounding the accuracy of the frameless in comparison to the frame-based technique. OBJECTIVE: We report our single-center experience with DBS electrode placement to evaluate the accuracy of the frameless stereotactic system. METHODS: We prospectively analyzed the data of 110 patients who underwent DBS surgery for Parkinson disease, dystonia, essential tremor, or refractory epilepsy. The final targets (FTs) of the 220 leads were: subthalamic nucleus, globus pallidus pars interna, ventralis intermedius nucleus, and anterior nuclei of thalamus in thalamus. A bilateral stereotactic approach using a combined identification of target based on preoperative images (MRI and CT scan fusion) and intra-operative micro-electrode recording (MER) were done. We collected and compared the coordinates of planned target (PT), the definitive expected target (ET) during MER, and the effective final location (FT) of the lead using the postoperative CT. Accuracy was assessed by both vector error (VE) and deviation from the PT. RESULTS: The mean and SD from PTs was 0.78 ± 0.43 mm in the x direction, 0.68 ± 0.41 mm in the y direction, and 0.76 ± 0.41 mm in the z direction. Global VE was 1.43 ± 0.37. CONCLUSION: Frameless systems appear to be a reliable and accurate technique.

Monitoring cognitive functions during deep brain stimulation (DBS) interventions by Real Time Neuropsychological Testing (DBS-RTNT).

Objective: We monitored cognition during Deep brain stimulation (DBS) surgery, when the electrode is positioned at the target subthalamic nucleus (i.e., STN motor area) in 14 PD patients. Methods: We present the Real Time Neuropsychological Testing (DBS-RTNT) protocol, our preliminary experience, along with patients' performance comparing intraoperative results with baseline data. Results: Compared to baseline, DBS-RTNT in the target area showed a significantly decreased performance at some tasks belonging to memory and executive functions domains. Significantly decreased short-term memory and sequencing scores were found for right (vs. left) hemisphere DBS-RTNT. Conclusions: PD patients' performance should be monitored during DBS surgery as STN-DBS may induce changes in cognitive performance. These preliminary data contribute to improve, during DBS-surgery the anatomo-functional topography of the STN in order to identify, in future approaches, in the individual patient the best site producing positive motor effects, without causing negative cognitive and/or emotional changes. Medications (i.e., the patients underwent surgery in a levodopa off state) could in principle have influenced our results therefore future studies are needed to address possible confounding effect of levodopa use.

Globus Pallidus Internus Deep Brain Stimulation Using Frame-Based vs. Frameless Stereotaxy in Dystonia: A Single-Center Experience.

Objective: Bilateral globus pallidus internus deep brain stimulation (GPi-DBS) is an established and effective therapy for primary refractory dystonia. However, the comparison of frameless vs. frame-based DBS surgery technique is still controversial. This retrospective study aims to compare the clinical outcome of two GPi-DBS surgical techniques for patients affected by primary generalized or multi-segmental dystonia. Methods: For lead's stereotaxic placement, 10 patients underwent frame-based surgery and the other 10 subjects DBS surgery with a frameless technique. Clinical features were evaluated at baseline and 6 and 12 months after surgery by means of the Burke-Fahn-Marsden Dystonia Rating Scale. Results: Frame-based GPi-DBS and frameless stereotaxic group revealed a comparable clinical outcome with no surgical complications. Conclusions: Frameless technique is safe and well-tolerated by patients and showed similar effectiveness of the frame-based stereotaxic surgery during GPi-DBS for primary dystonia. Notably, it could be a valid alternative solution because of the great advantage in improving the patient's discomfort during awake surgery.

Incidental Low-Grade Gliomas: Single-Institution Management Based on Clinical, Surgical, and Molecular Data.

BACKGROUND: Incidentally discovered diffuse low-grade gliomas (iLGG) are poorly documented in the literature. They are diagnosed by chance during radiological examinations. OBJECTIVE: To review a cohort of patients with iLGG surgically treated in our institution, analyzing clinical, molecular, and surgical aspects. METHODS: Clinical, radiological, and treatment data of iLGG were retrieved and compared with those of symptomatic diffuse LGGs (sLGG). Histological and molecular review was carried out as well. The extent of resection was evaluated on preoperative and postoperative T2-weighted magnetic resonance imaging. RESULTS: Thirty-four iLGG cases were identified within a monoinstitutional cohort of 332 patients operated for low-grade gliomas from 2000 to 2017. Clinically, patients with iLGG had higher preoperative karnofsky performance scale (KPS) (P = .003), smaller tumor volume (P = .0001), lower frequency of eloquent areas involvement (P = .0001), and higher rate of complete resection (P = .0001) compared to those with sLGG. No differences in the molecular profile and O6-methylguanine-DNA-methyltransferase promoter methylation were detected between iLGG and sLGG. Importantly, patients with iLGG had longer overall survival than those with sLGG (P = .0001), even when a complete surgical resection was achieved (P = .001). CONCLUSION: Although the therapeutic strategy of iLGG is still a matter of debate, our data support the safety and the effectiveness of early surgical resection. The favorable prognosis of iLGG may be due to the higher practicability of extensive resection, noneloquent tumor location, and smaller tumor volume.

Brain impedance variation of directional leads implanted in subthalamic nuclei of Parkinsonian patients.

OBJECTIVE: Conventional deep brain stimulation (DBS) systems with ring-shaped leads generate spherical electrical fields. In contrast, novel directional leads use segmented electrodes. Aim of this study was to quantify the impedance variations over time in subjects with the directional Cartesia-Boston® system. METHODS: Impedance records, programming settings, and clinical data of 11 consecutive Parkinsonian patients implanted with DBS directional leads in two Italian centers (Udine and Vicenza) were retrospectively evaluated. Data were collected before starting stimulation (in the operating room and at days 5 and 40) and after switching stimulation on at the successive follow-up visits (1, 6 and 12 months). RESULTS: Directional leads have significantly higher impedance than ring leads. Stimulated contacts had always lower impedance compared to non-stimulated contacts. Before DBS-on, all contacts had higher impedance in the operating room, with an initial decrease five days post-surgery and a subsequent increase at day 40, more evident for directional contacts. The impedance of directional leads increased post-implantation at 1 and 6 months with a plateau at 12 months. CONCLUSIONS: There was a significant difference between the directional and ring leads at baseline (before activation of DBS) and during follow-up (chronic DBS). SIGNIFICANCE: Our study reveals new information about the impedance of segmented electrodes that is useful for patient management during the initial test period, as well as during long-term DBS follow-up.

Emotion recognition in Parkinson's disease after subthalamic deep brain stimulation: differential effects of microlesion and STN stimulation.

Deep brain stimulation of the subthalamic nucleus (STN-DBS) has acquired a relevant role in the treatment of Parkinson's disease (PD). Despite being a safe procedure, it may expose patients to an increased risk to experience cognitive and emotional difficulties. Impairments in emotion recognition, mediated both by facial and prosodic expressions, have been reported in PD patients treated with such procedure. However, it is still unclear whether the STN per se is responsible for such changes or whether others factors like the microlesion produced by the electrode implantation may also play a role. In this study we evaluated facial emotions discrimination and emotions recognition using both facial and prosodic expressions in 12 patients with PD and 13 matched controls. Patients' were tested in four conditions: before surgery, both in on and off medication, and after surgery, respectively few days after STN implantation before turning stimulator on and few months after with stimulation on. We observed that PD patients were impaired in discriminating and recognizing facial emotions, especially disgust, even before DBS implant. Microlesion caused by surgical procedure was found to influence patients' performance on the discrimination task and recognition of sad facial expression while, after a few months of STN stimulation, impaired disgust recognition was again prominent. No impairment in emotional prosody recognition was observed both before and after surgery. Our study confirms that PD patients may experience a deficit in disgust recognition and provides insight into the differential effect of microlesion and stimulation of STN on several tasks assessing emotion recognition.

Microsubthalamotomy improves sleep in patients affected by advanced Parkinson's disease.

BACKGROUND: Deep brain stimulation of the subthalamic nucleus (STN-DBS) improves sleep in patients affected by Parkinson's disease (PD). Since microsubthalamotomy (mSTN) shows positive effects on motor symptoms, it could improve sleep in PD patients. Our goals were: to assess the effects of mSTN on sleep in patients affected by advanced PD; and to look for a correlation between sleep and motor features after the neurosurgical procedure. METHODS: Fifteen patients who underwent bilateral STN-DBS were enrolled. Subjective sleep evaluation was assessed using the Parkinson's Disease Sleep Scale (PDSS). Data on sleep schedule and presence of restless legs syndrome (RLS) were obtained. Objective sleep features were investigated by polysomnography (PSG). To evaluate the mSTN effect, we compared motor state and sleep features before and after the neurosurgical procedure, before the programmable pulse generator was switched on. RESULTS: mSTN had beneficial effects on motor state and sleep features. After the surgery, the mean total PDSS score increased from 84.0±25.2 to 115.2±16.6 (P<0.001). PD patients reported longer total sleep time duration, decreased daytime sleepiness, and improvement in RLS symptoms. PSG data showed an increase in total sleep time and sleep efficiency with a decrease in wakefulness after sleep onset and arousal index. No correlation between motor improvements and sleep features modifications was observed after mSTN. CONCLUSIONS: mSTN improves sleep quality and ameliorates several sleep complaints, as well as motor symptoms, in advanced PD patients who have undergone STN-DBS.

To move or not to move: subthalamic deep brain stimulation effects on implicit motor simulation.

We explored implicit motor simulation processes in Parkinson's Disease (PD) patients with ON-OFF subthalamic deep brain stimulation (DBS) of the sub-thalamic nucleus (STN). Participants made lexical decisions about hand action-related verbs, abstract verbs, and pseudowords presented either within a positive (e.g., "Do …") or a negative (e.g., "Don't …") sentence context. Healthy controls showed significantly slower responses for hand-action verbs (vs. abstract verbs) in the negative (vs. positive) context, which suggests that negative contexts may suppress motor simulation or preparation processes. The STN-DBS improves cortical motor functions, thus patients are expected to perform at the same level as unimpaired subjects in the ON condition. By contrast, the 50% reduced DBS is expected to result in a reduced activation for motor information, which in turn might cause a reduced, if not absent, context modulation. PD patients exhibited the same pattern as controls when their DBS was at 100% ON; however, reducing the DBS to 50% had a deleterious outcome on the positive faster than negative context effect, suggesting that the altered inhibition mechanism in PD could be responsible for the missed effect. In addition, our results confirm the view that implicit motor simulation mechanisms behind action-related verb processing are flexible and context-dependent.

Deep brain stimulation: Subthalamic nucleus electrophysiological activity in awake and anesthetized patients.

OBJECTIVE: The purpose of this study was to evaluate changes in subthalamic nucleus (STN) neuronal activity in Parkinson's disease (PD) patients during deep brain stimulation (DBS) surgery under general anesthesia, and to compare these data with those recorded in the same subjects during previous surgery under local anesthesia. METHODS: Five patients with advanced PD, who had previously undergone bilateral STN-DBS under local anesthesia, underwent re-implantation under general anesthesia (with an anesthetic protocol based on the intravenous infusion of remifentanyl and ketamine) owing to surgical device complications. The microelectrode recording (MER) data obtained were analyzed by an off-line spike-sorting software. Neurophysiological data (number of spikes detected, mean firing rate, pause index and burst index) obtained under local and general anesthesia were then evaluated and compared by means of statistical analysis. RESULTS: We found no statistically significant difference between the first and second surgical procedures in any of the neurophysiological parameters analyzed. CONCLUSIONS: Bilateral STN-DBS for advanced PD with MER guidance is possible and reliable under a ketamine-based anesthetic protocol. SIGNIFICANCE: General anesthesia can be proposed for those patients who do not accept an "awake surgery" for clinical reasons, such as excessive fear, poor cooperation or severe "off"-medication effects.