Transparent graphene-based neural electrode arrays provide unique opportunities for simultaneous investigation of electrophysiology, various neural imaging modalities, and optogenetics. Graphene electrodes have previously demonstrated greater broad-wavelength transmittance (∼90%) than other transparent materials such as indium tin oxide (∼80%) and ultrathin metals (∼60%). This protocol describes how to fabricate and implant a graphene-based microelectrocorticography (μECoG) electrode array and subsequently use this alongside electrophysiology, fluorescence microscopy, optical coherence tomography (OCT), and optogenetics. Further applications, such as transparent penetrating electrode arrays, multi-electrode electroretinography, and electromyography, are also viable with this technology. The procedures described herein, from the material characterization methods to the optogenetic experiments, can be completed within 3-4 weeks by an experienced graduate student. These protocols should help to expand the boundaries of neurophysiological experimentation, enabling analytical methods that were previously unachievable using opaque metal-based electrode arrays.

Background Primary central nervous system post-transplant lymphoproliferative disorder (PCNS-PTLD) is a rare complication following solid organ transplantation (SOT). With increasing rates of SOT, PCNS-PTLD incidence is increasing. Objective Describe the characteristics of PCNS-PTLD patients requiring neurosurgical intervention. Methods From 2000-2011 ten patients with prior SOT underwent biopsy for evaluation of brain lesions and were diagnosed with PCNS-PTLD. Data collected included imaging characteristics, pathology, treatments administered, and survival outcomes. Results All patients had kidney transplantation, and 3 had concurrent pancreas transplantation. Median age at diagnosis was 49 years, with a median of 4.5 years from SOT to diagnosis (range 1.8-11.4 years). Presenting symptoms most often included focal neurologic deficits (n=6), although several patients had non-specific symptoms of headache and altered mental status. Brain lesions were generally multiple (n=7), supratentorial (n=8), and lobar or periventricular in distribution with ring-enhancement. Diagnosis was established by stereotactic (n=4) and open surgical biopsy (n=6). Treatments most frequently administered included reduction of immunosuppression (n=10), dexamethasone (n=10), rituximab (n=8), high-dose methotrexate (n=3), and whole-brain radiotherapy (n=6). Six patients remain alive without PCNS-PTLD relapse, including 4 patients who have sustained remissions beyond 2 years from diagnosis of PCNS-PTLD. Of 4 observed deaths, 1 was related to progressive PCNS-PTLD. Conclusion PCNS-PTLD must be considered in the differential diagnosis of any patient with prior SOT presenting with an intracranial lesion. Histologic diagnosis with brain biopsy is imperative given the risk for opportunistic infections that may have similar imaging findings and presentation. Prognosis is variable, although long-term survival has been reported.

Background: Deep brain stimulation (DBS) for Parkinson's disease (PD) has traditionally been performed in awake patients. Some patients are unable to tolerate awake surgery or extensive time off their medication to allow for neurophysiological testing during traditional DBS implantation, which has previously limited surgical options for these patients. Recently, asleep image-guided lead placement using intraoperative MRI or CT for verification has been proposed as an alternative for patients unable or unwilling to undergo awake DBS surgery. Methods: We conducted a retrospective chart review comparing PD patients who underwent asleep MRI-guided subthalamic nucleus (STN) DBS lead placement (n = 14) and awake neurophysiologically guided STN DBS lead placement (n = 23) at our institution. Both groups' levodopa equivalent daily doses (LEDDs) and complications at approximately 6 months of follow-up were compared, along with operative times. Results: Both groups showed statistically similar reductions in LEDD at 6 months of therapy (38.27% for awake, 49.27% for asleep; p = 0.4447), and similar complications. Operative times were initially longer for MRI-guided DBS but improved with surgical experience. Conclusion: Asleep MRI-guided DBS is a viable option for PD patients unable or unwilling to undergo awake placement, with similar results in terms of LEDD reduction and complications.

Background Finding the optimal location for the implantation of the electrode in Deep Brain Stimulation (DBS) surgery is crucial for maximizing therapeutic benefit to the patient. Such targeting is challenging for several reasons including anatomical variability between patients as well as lack of consensus about the location of the optimal target. Objective To compare the performance of popular manual targeting methods against a fully automatic non-rigid image registration based approach. Methods In 71 Parkinson's disease STN-DBS implantations, an experienced functional neurosurgeon selected the target manually using three different approaches; indirect targeting using standard stereotactic coordinates, direct targeting based on the patient MRI, and indirect targeting relative to the red nucleus. Targets were also automatically predicted using a leave-one-out approach to populate the CranialVault atlas using non-rigid image registration. The different targeting methods were compared against the location of the final active contact, determined through iterative clinical programming in each individual patient. Results Targeting using standard stereotactic coordinates corresponding to the center of the motor territory of the STN had the largest targeting error (3.69 mm), followed by direct targeting (3.44 mm), average stereotactic coordinates of active contacts from this study (3.02 mm), red nucleus based targeting (2.75 mm), and non-rigid image registration based automatic predictions using the CranialVault atlas (2.70 mm). The CranialVault atlas method had statistically smaller variance than all manual approaches. Conclusions Fully automatic targeting based on non-rigid image registration using the CranialVault atlas is as accurate and more precise than popular manual methods for STN-DBS.