Localization of motor and verbal fluency effects in subthalamic DBS for Parkinson's disease

IntroductionSubthalamic nucleus deep brain stimulation (STN DBS) improves cardinal motor symptoms of Parkinson's disease (PD) but can worsen verbal fluency (VF). An optimal site of stimulation for overall motor improvement has been previously identified using an atlas-independent, fully individualized, field-modeling approach. This study examines if cardinal motor components (bradykinesia, tremor, and rigidity) share this identified optimal improvement site and if there is co-localization with a site that worsens VF.MethodsAn atlas-independent, field-modeling approach was used to identify sites of maximal STN DBS effect on overall and cardinal motor symptoms and VF in 60 patients. Anatomic coordinates were referenced to the STN midpoint. Symptom severity was assessed with the MDS-UPDRS part III and established VF scales.ResultsSites for improved bradykinesia and rigidity co-localized with each other and the overall part III site (0.09 mm lateral, 0.93 mm posterior, 1.75 mm dorsal). The optimal site for tremor was posterior to this site (0.10 mm lateral, 1.40 mm posterior, 1.93 mm dorsal). Semantic and phonemic VF sites were indistinguishable and co-localized medial to the motor sites (0.32 mm medial, 1.18 mm posterior, 1.74 mm dorsal).ConclusionThis study identifies statistically distinct, maximally effective stimulation sites for tremor improvement, VF worsening, and overall and other cardinal motor improvements in STN DBS. Current electrode sizes and voltage settings stimulate all of these sites simultaneously. However, future targeted lead placement and focused directional stimulation may avoid VF worsening while maintaining motor improvements in STN DBS.     

Intraoperative cerebral blood flow monitoring in neurosurgery: A review of contemporary technologies and emerging perspectives

Intraoperative monitoring of cerebral blood flow (CBF) has become an invaluable adjunct to vascular and oncological neurosurgery, reducing the risk of postoperative morbidity and mortality. Several technologies have been developed during the last two decades, including laser-based techniques, videomicroscopy, intraoperative MRI, indocyanine green angiography, and thermography. Although these technologies have been thoroughly studied and clinically applied outside the operative room, current practice lacks an optimal technology that perfectly fits the workflow within the neurosurgical operative room. The different available technologies have specific strengths but suffer several drawbacks, mainly including limited spatial and/or temporal resolution. An optimal CBF monitoring technology should meet particular criteria for intraoperative use: excellent spatial and temporal resolution, integration in the operative workflow, real-time quantitative monitoring, ease of use, and non-contact technique. We here review the main contemporary technologies for intraoperative CBF monitoring and their current and potential future applications in neurosurgery.     

Simulation of transcranial magnetic stimulation in head model with morphologically-realistic cortical neurons

BackgroundTranscranial magnetic stimulation (TMS) enables non-invasive modulation of brain activity with both clinical and research applications, but fundamental questions remain about the neural types and elements TMS activates and how stimulation parameters affect the neural response.ObjectiveTo develop a multi-scale computational model to quantify the effect of TMS parameters on the direct response of individual neurons.MethodsWe integrated morphologically-realistic neuronal models with TMS-induced electric fields computed in a finite element model of a human head to quantify the cortical response to TMS with several combinations of pulse waveforms and current directions.ResultsTMS activated with lowest intensity intracortical axonal terminations in the superficial gyral crown and lip regions. Layer 5 pyramidal cells had the lowest thresholds, but layer 2/3 pyramidal cells and inhibitory basket cells were also activated at most intensities. Direct activation of layers 1 and 6 was unlikely. Neural activation was largely driven by the field magnitude, rather than the field component normal to the cortical surface. Varying the induced current direction caused a waveform-dependent shift in the activation site and provided a potential mechanism for experimentally observed differences in thresholds and latencies of muscle responses.ConclusionsThis biophysically-based simulation provides a novel method to elucidate mechanisms and inform parameter selection of TMS and other cortical stimulation modalities. It also serves as a foundation for more detailed network models of the response to TMS, which may include endogenous activity, synaptic connectivity, inputs from intrinsic and extrinsic axonal projections, and corticofugal axons in white matter.     

听神经瘤术后面神经功能损伤危险因素分析

目的分析影响听神经瘤患者术后短期及长期面神经功能的危险因素。 方法回顾性分析厦门大学附属第一医院神经外科自2015年1月至2018年6月收治的62例听神经瘤患者的临床资料。于术后7 d及术后6个月对所有患者的面神经功能进行评估。收集可能与患者术后早期及长期面神经功能障碍存在相关性的因素，采用Logistic单因素与多因素回归对相关因素与患者术后短期及长期面神经功能的关系进行分析。 结果术后7 d，21例（33.9%）患者面神经功能正常，41例（66.1%）患者出现面神经功能损伤；术后6个月，49例（79.0%）患者面神经功能为正常，13例（21.0%）患者面神经功能损伤。Logistic单因素回归分析结果显示：肿瘤最大直径越大、肿瘤与面神经黏连越紧密，患者术后7 d发生面神经功能损伤的可能性越大（P=0.002、0.002）；术前临床症状持续时间为患者术后6个月面神经功能障碍的危险因素（P=0.035）。Logistic多因素回归分析结果显示：肿瘤与面神经的黏连程度、肿瘤最大直径为患者术后7 d面神经功能障碍的独立危险因素（P=0.003、0.014）；术前临床症状持续时间、肿瘤最大直径为患者术后6个月面神经功能障碍的独立危险因素（P=0.010、0.030）。 结论肿瘤与面神经的黏连越紧密、肿瘤最大直径越大，患者术后7 d发生面神经功能损伤的可能性越大。患者术前临床症状持续时间越长、肿瘤最大直径越大，术后6个月发生面神经功能损伤的可能性越大。     

Relationship between Neurological Deterioration and Blood Pressure/Heart Rate Variability in Patients with Acute Cerebral Infarction

ObjectivesNeurological deterioration (ND) during hospitalization is an independent predictor of poor prognosis after stroke. Risk factors affecting early ND within 48 h post stroke have been intensively investigated, while few data are available on those for late ND after transfer to a wheelchair. Therefore, it was investigated whether hemodynamic factors may affect the late ND during hospitalization.Materials and methodsA retrospective study was conducted on 135 patients with atherothrombotic or cardiogenic cerebral infarction who were admitted to our hospital between April 1st, 2014 and July 31st, 2017. During hospitalization, average, maximum, and minimum values were determined for systolic blood pressure (sBP), diastolic BP (dBP), and heart rate (HR), respectively.135 patients were classified into two groups; ND (+) group, in which modified Barthel index score at the time of transfer to a wheelchair showed five points or more decrease between wheelchair transfer and discharge, and ND (?) group, which did not. Vital indices were compared between the two groups and subjected to ROC-curve analysis.ResultsThe ND (+) group included 32 patients, and the ND (?) 103. Significant differences were found between the groups in four items; sBPmin (p = 0.029), dBPmin (p = 0.019), HRave (p = 0.028), and HRmax (p < 0.01). The ND (+) group showed lower sBPmin and dBPmin, and higher HRave and HRmax than the ND (?) group.ConclusionsLate ND after transfer to a wheelchair is related to the vital indices during hospitalization and should be cautiously managed to prevent late ND