Coupling between beta band and high frequency oscillations as a clinically useful biomarker for DBS.

Beta hypersynchrony was recently introduced into clinical practice in Parkinson's disease (PD) to identify the best stimulation contacts and for adaptive deep brain stimulation (aDBS) sensing. However, many other oscillopathies accompany the disease, and beta power sensing may not be optimal for all patients. The aim of this work was to study the potential clinical usefulness of beta power phase-amplitude coupling (PAC) with high frequency oscillations (HFOs). Subthalamic nucleus (STN) local field potentials (LFPs) from externalized DBS electrodes were recorded and analyzed in PD patients (n = 19). Beta power and HFOs were evaluated in a resting-state condition; PAC was then studied and compared with the electrode contact positions, structural connectivity, and medication state. Beta-HFO PAC (mainly in the 200-500 Hz range) was observed in all subjects. PAC was detectable more specifically in the motor part of the STN compared to beta power and HFOs. Moreover, the presence of PAC better corresponds to the stimulation setup based on the clinical effect. PAC is also sensitive to the laterality of symptoms and dopaminergic therapy, where the greater PAC cluster reflects the more affected side and medication "off" state. Coupling between beta power and HFOs is known to be a correlate of the PD "off" state. Beta-HFO PAC seems to be more sensitive than beta power itself and could be more helpful in the selection of the best clinical stimulation contact and probably also as a potential future input signal for aDBS.

Successful asymmetrical deep brain stimulation using right subthalamic and left pallidal electrodes in a patient with Parkinson's disease.

PURPOSE: Despite the best efforts of neurologists, the results of pharmacotherapy in the late stages of Parkinson's disease are often disappointing and accompanied by debilitating side effects. Under these circumstances, deep brain stimulation is a viable treatment option. The aim of the meticulous pre-surgical planning is not only precise electrode implantation, but also the avoidance of intraoperative vascular conflicts potentially causing intracerebral bleeding. MATERIAL AND METHODS: In this report, we present a patient with early-onset Parkinson's disease whose cerebral vascular anatomy precluded standard bilateral subthalamic nucleus electrode implantation. Initially, right subthalamic stimulation alone provided a very mild clinical benefit that was not reflected in the patient's quality of life. In this patient, an unusual configuration of intracerebral electrodes with right subthalamic and left pallidal stimulation electrodes was applied 15 months after the initial subthalamic electrode implantation. RESULTS: The procedure has had a highly beneficial long-term effect without any significant complications. The greatest improvement was noted using the setting 1.8 V, 130 Hz, 90 µs at the right side (STN) and 3.7 V, 130 Hz, 120 µs at the left side (GPi). This allowed the patient to return to his daily life activities. CONCLUSIONS: The reported case provides a new perspective of treatment possibilities in complex functional neurosurgical cases requiring exceptional individualisation of the treatment approach.

The Results of Neuroendoscopic Surgery in Patients with Posttraumatic and Posthemorrhagic Hydrocephalus.

BACKGROUND: Posttraumatic hydrocephalus (PTH) and posthemorrhagic hydrocephalus (PHH) were previously considered not suitable for neuroendoscopic treatment. New hydrocephalus theories support possible successful neuroendoscopy in such patients. METHODS: This study presents the results of neuroendoscopy in PTH and PHH with a background analysis. From 130 hydrocephalic patients after neuroendoscopic surgeries, 35 cases with PTH (n = 11) or PHH (n = 24; acute: n = 9, subacute: n = 10, chronic: n = 5) were found. The success rate (Glasgow Outcome Scale [GOS] score 4 or 5 without shunt) and clinical outcome (GOS score) of endoscopic third ventriculostomy (ETV) were analyzed. During the study period, 34 patients had ventriculoperitoneal shunts implanted, including 2 PTH and 5 PHH patients (all chronic). RESULTS: The success rate of ETV in PTH was 54.5%. In acute PHH, the success rate was 33.3%, 42.8% after excluding devastating hematomas. A post-ETV shunt was implanted in 1 patient (massive subarachnoid hemorrhage [SAH]) with final GOS score of 5. In subacute cases, the ETV success rate was 40% (no post-ETV shunts). In chronic PHH, only 1 patient with a GOS score of 5 was shunt-free (20%). The cause of ETV failure was massive SAH. Low final GOS score was caused by the extent of intracerebral bleeding or extracranial problems. The main indications for primary shunt implantation in PTH and PHH were infectious complications. The rate of good outcomes was 0% in PTH and 40% in PHH. CONCLUSIONS: The best results of neuroendoscopy were achieved in PTH and acute PHH. ETV failures were associated with massive SAH; arachnoid cistern blockage and scarring precludes ETV success.

The Role of Anterior Nuclei of the Thalamus: A Subcortical Gate in Memory Processing: An Intracerebral Recording Study.

OBJECTIVE: To study the involvement of the anterior nuclei of the thalamus (ANT) as compared to the involvement of the hippocampus in the processes of encoding and recognition during visual and verbal memory tasks. METHODS: We studied intracerebral recordings in patients with pharmacoresistent epilepsy who underwent deep brain stimulation (DBS) of the ANT with depth electrodes implanted bilaterally in the ANT and compared the results with epilepsy surgery candidates with depth electrodes implanted bilaterally in the hippocampus. We recorded the event-related potentials (ERPs) elicited by the visual and verbal memory encoding and recognition tasks. RESULTS: P300-like potentials were recorded in the hippocampus by visual and verbal memory encoding and recognition tasks and in the ANT by the visual encoding and visual and verbal recognition tasks. No significant ERPs were recorded during the verbal encoding task in the ANT. In the visual and verbal recognition tasks, the P300-like potentials in the ANT preceded the P300-like potentials in the hippocampus. CONCLUSIONS: The ANT is a structure in the memory pathway that processes memory information before the hippocampus. We suggest that the ANT has a specific role in memory processes, especially memory recognition, and that memory disturbance should be considered in patients with ANT-DBS and in patients with ANT lesions. ANT is well positioned to serve as a subcortical gate for memory processing in cortical structures.

Neurosurgical treatment of cerebrovascular complications of heart surgeries and interventions.

AIM: Intracerebral haematoma and brain ischaemia are rare life-threatening complications of cardiovascular surgery. The aim of this study is to present the experience with the neurosurgical treatment of patients with cerebrovascular complications of heart surgery. MATERIAL AND METHODS: Patients with brain ischaemia or intracerebral haematoma in the acute phase after heart surgery or invasive intervention operated on between 2002 and 2011 were reviewed. There were 3 patients with middle cerebral artery infarction requiring decompressive craniectomy (2 males, 1 female; mean age 54.3 years) and 5 patients with intracerebral haematoma (3 males, 2 females; mean age 55 years). The type of surgery for intracerebral haematoma was selected individually preferring minimally invasive techniques: stereotactic aspiration (2 patients), neuroendoscopy (1 patient), stereotactic craniotomy (1 patient) or classical craniotomy (1 patient). RESULTS: The results of decompressive craniectomy were unsatisfactory: GOS 1, 3 and 4 in 1 patient each. The results of surgery for intracerebral haematoma were GOS 5 in 1 patient, GOS 4 in 2 patients, and lethal in 2 patients. CONCLUSION: Minimally invasive neurosurgery techniques appear to be beneficial for selected patients with intracerebral haematoma after heart surgeries even when considering the limited number of patients. Decompressive craniectomy should be considered strictly individually.

Diagnostic value of brain tumor neuroendoscopic biopsy and correlation with open tumor resection.

BACKGROUND: The risks of stereotactic biopsy are increased not only in tumors located in the vicinity of vascular structures, but also in cystic, intraventricular, and periventricular lesions. The use of neuroendoscopy for cystic, intraventricular, or periventricular brain tumors is particularly advantageous because of the possibility of biopsy and immediate hemostasis under direct vision. Neuroendoscopy provides the possibility of controlling tumor-associated obstructive hydrocephalus by means of endoscopic third ventriculostomy or septostomy. The literature gives good evidence for the diagnostic benefits of neuroendoscopic biopsy. The correlation of the histology obtained by neuroendoscopic biopsy and subsequent surgical resection may allow the evaluation of the validity of diagnostic neuroendoscopic biopsy. MATERIALS AND METHODS: Between 2003 and 2010, 23 patients with suspected cystic brain tumor (12 males; age range, 21-75 years; mean age, 49.7 years; and 11 females; age range, 22-76 years; mean age, 59.1 years) and 35 patients with intraventricular or periventricular brain tumors (19 males; age range, 6-80 years; mean age, 43.9 years; and 16 females; age range, 11-78 years; mean age, 46.2 years) underwent navigated neuroendoscopic biopsy. RESULTS: Diagnostic samples were obtained in all cystic tumors and in 94.7% of intraventricular or periventricular tumors. Tumor resection after neuroendoscopic biopsy was performed in seven patients with cystic tumors. The results of the histological analysis of samples taken during endoscopic biopsy and surgical resection were identical in five of these patients (70.1%). Four patients with intraventricular or periventricular tumors underwent tumor resection after neuroendoscopic biopsy. The histological results of neuroendoscopic biopsy and tumor resection were identical in three patients (75%). Neuroendoscopic biopsy was performed in six patients with expansive pseudocyst after tumor resection and oncological therapy. The results of the neuroendoscopic biopsy matched the results of open surgery in four patients (66%). In the two remaining patients, there was a difference in tumor grading. CONCLUSION: The diagnostic accuracy of neuroendoscopic biopsy samples can be compared with the results of stereotactic biopsy. The histological results of endoscopically taken biopsy samples and the final histological results obtained during open surgery correlate in the majority of patients, and underlines the high diagnostic validity of neuroendoscopic biopsy.

The role of brain shift, patient age, and Parkinson's disease duration in the difference between anatomical and electrophysiological targets for subthalamic stimulation.

INTRODUCTION: Although microrecording is common in subthalamic stimulation, microelectrode monitoring prolongs surgical time and may increase the risk of haemorrhagic complications. The main reason for electrophysiological mapping is the discrepancy between the calculated anatomical and final electrophysiological targets. The aim of this paper is to describe the relationship between anatomical and electrophysiological targets defined as the best electrophysiological recordings from multiple parallel electrode tracts, explaining the target discrepancy with attention paid to the role of brain shift and patient- and disease-related factors. MATERIALS AND METHODS: Subthalamic electrodes were stereotactically implanted in 58 patients using microrecording by means of parallel electrodes at defined distances. The relationship between the final electrode placement to its anatomical trajectory and the relationship between the definitive electrodes implanted on the right and left sides were analysed, as was the influence of patient age, Parkinson's disease duration, and late motor complications duration. RESULTS: Final electrode placement matched the anatomical trajectory in 53.4% of patients on the right side and 43.1% of patients on the left side. Electrode positions were symmetrical in 38.3% of patients. The analysis of left and right electrode positions does not prove a statistically significant prevalence of lateral and posterior final electrode trajectories as could be expected from lateral and posterior movements of the brain caused by brain shift, although there was some tendency for a larger percentage of lateral electrodes on the left side. Age, Parkinson's disease duration, and L-DOPA effect duration were not confirmed as responsible factors. CONCLUSIONS: The difference between anatomical trajectory and final electrode placement supports the use of functional microelectrode monitoring in subthalamic deep brain stimulation. Brain shift is not the only causative factor of the difference. The possible roles of age, Parkinson's disease duration, and late motor complications duration were also not confirmed by study results.

Peripheral neuroactive steroids may be as good as the steroids in the cerebrospinal fluid for the diagnostics of CNS disturbances.

To compare the predictivity of the neuroactive steroids in the cerebrospinal fluid and peripheral blood for the diagnostics of CNS disturbances, eighteen unconjugated steroids were quantified in the cerebrospinal fluid (CSF) from the 3rd ventricle and 18 unconjugated steroids and 7 steroid polar conjugates were measured in the serum using GC-MS and RIA. Eight postmenopausal women (56-78 years of age) and 7 men (22-88 years of age) with hydrocephalus were enrolled in the study. The sensitivity of the method ranged from low femtogram to low picogram levels depending on the steroid fragmentation pattern. Using multivariate regression, a model for simultaneous prediction of the CSF steroids from the serum steroids was completed. Then, the penetrability of the individual steroids across the blood-brain-barrier was evaluated and the sources of various brain steroids were estimated. Our data show that a part of the steroids may be synthesized de novo in the CNS. However, substantial part of the steroid metabolites may be synthesized in the CNS from the steroid precursors or directly transported from the periphery. The CNS in situ synthesis and transport from periphery might be complementary in some cases, i.e. brain synthesis might provide minimum level of steroids, which are indispensable for the CNS functions.