A Single-Center Experience with the NeuroPace RNS System: A Review of Techniques and Potential Problems.

INTRODUCTION: The clinical results for the RNS System (NeuroPace, Mountain View, California, USA) closed-loop responsive neurostimulator for the treatment of medically intractable partial-onset seizures have been encouraging. The University of Southern California (USC) Neurorestoration Center and the Keck Hospital of USC have become the world's first institutions to implant an RNS System post U.S. Food and Drug Administration (FDA) approval. As one of the study centers, we review our experience with our group of patients who have been implanted with the RNS System. METHODS: A total of 40 surgeries by a single surgeon were performed on 10 patients (7 male and 3 female) with an average age of 39.2 years (24-66 years) and were followed for an average of 45 months (30-54 months). The average age at seizure onset was 14 years (birth-37 years) with an average of 4.7 (3-12) failed antiepileptic drugs. We reviewed the patients' charts for complications from the surgeries including infections requiring surgical intervention, hematomas, hardware failures, and death. RESULTS: Of the 40 surgeries, there were 10 initial implantations of the neurostimulator and leads, 24 neurostimulator replacements for expected end of neurostimulator service, 2 incision and drainage procedures (I & Ds) for soft tissue infection followed by 1 explantation and 1 reimplantation (same patient), and 2 revisions because of one lead that was damaged at the exit point between the skull and a titanium mesh and the second lead that was damaged at an acute bend over the skull (same patient). Eight of the patients had no complications and underwent an average of 2.7 neurostimulator replacements over 7 consecutive years to date. Each patient underwent routine postoperative computed tomography imaging of the brain, and none had any intracranial hematomas or misplaced leads requiring revision surgery. Finally, there were no deaths in our patient population. CONCLUSIONS: Our experience with the NeuroPace RNS System over an average follow-up of 45 months suggests that the surgery and device are safe when placed by an experienced surgeon. Although there were no clinically significant hematomas or patient deaths, we did have 1 patient each with infection and lead damage at the point of exit from the skull. We compare the results of this study with other neuromodulation procedures for epilepsy to evaluate the safety and complications associated with the RNS System. Our initial experience suggests that the RNS System can be readily incorporated into an active epilepsy surgical center.

Resection of a cystic brainstem hemangioblastoma via a retrosigmoid approach.

Lesions of the brainstem pose a technical challenge due to their close proximity to critical vascular structures, neural pathways, and nuclei. Hemangioblastomas are rare lesions of the central nervous system and can cause significant neurological dysfunction, primarily due to enlargement of the cystic component. This is especially relevant when hemangioblastomas occur in eloquent brainstem regions. However, the outcomes after hemangioblastoma resection are good if complete surgical resection of the tumor of the mural nodule, can be achieved. This video demonstrates the excision of a brainstem hemangioblastoma via a left retrosigmoid craniotomy under Stealth guidance. The video can be found here: http://youtu.be/bCkuaPwMV20 .

Cellular signaling in neural stem cells: implications for restorative neurosurgery.

Over the course of the past few decades, it has become apparent that in contrast to previously held beliefs, the adult central nervous system (CNS) may have the capability of regeneration and repair. This greatly expands the possibilities for the future treatment of CNS disorders, with the potential strategies of treatment targeting the entire scope of neurological diseases. Indeed, there is now ample evidence that stem cells exist in the CNS throughout life, and the progeny of these stem cells may have the ability to assume the functional role of neural cells that have been lost. The existence of stem cells is no longer in dispute. In addition, once transplanted, stem cells have been shown to survive, migrate, and differentiate. Nevertheless, the clinical utility of stem cell therapy for neurorestoration remains elusive. Without question, the control of the behavior of stem cells for therapeutic advantage poses considerable challenges. In this paper, the authors discuss the cellular signaling processes that influence the behavior of stem cells. These signaling processes take place in the microenvironment of the stem cell known as the niche. Also considered are the implications attending the replication and manipulation of elements of the stem cell niche to restore function in the CNS by using stem cell therapy.