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Neurostimulation for chronic noncancer pain

Kim J. Burchiel

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Incidence of silent hemorrhage and delayed deterioration after stereotactic brain biopsy

Abhaya V. Kulkarni, Abhijit Guha, Andres Lozano, and Mark Bernstein

Object. Many neurosurgeons routinely obtain computerized tomography (CT) scans to rule out hemorrhage in patients after stereotactic procedures. In the present prospective study, the authors investigated the rate of silent hemorrhage and delayed deterioration after stereotactic biopsy sampling and the role of postbiopsy CT scanning.

Methods. A subset of patients (the last 102 of approximately 800 patients) who underwent stereotactic brain biopsies at the Toronto Hospital prospectively underwent routine postoperative CT scanning within hours of the biopsy procedure. Their medical charts and CT scans were then reviewed.

A postoperative CT scan was obtained in 102 patients (aged 17–87 years) who underwent stereotactic biopsy between June 1994 and September 1996. Sixty-one patients (59.8%) exhibited hemorrhages, mostly intracerebral (54.9%), on the immediate postoperative scan. Only six of these patients were clinically suspected to have suffered a hemorrhage based on immediate postoperative neurological deficit; in the remaining 55 (53.9%) of 102 patients, the hemorrhage was clinically silent and unsuspected. Among the clinically silent intracerebral hemorrhages, 22 measured less than 5 mm, 20 between 5 and 10 mm, five between 10 and 30 mm, and four between 30 and 40 mm. Of the 55 patients with clinically silent hemorrhages, only three demonstrated a delayed neurological deficit (one case of seizure and two cases of progressive loss of consciousness) and these all occurred within the first 2 postoperative days. Of the neurologically well patients in whom no hemorrhage was demonstrated on initial postoperative CT scan, none experienced delayed deterioration.

Conclusions. Clinically silent hemorrhage after stereotactic biopsy is very common. However, the authors did not find that knowledge of its existence ultimately affected individual patient management or outcome. The authors, therefore, suggest that the most important role of postoperative CT scanning is to screen for those neurologically well patients with no hemorrhage. These patients could safely be discharged on the same day they underwent biopsy.

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Deep brain stimulation: current and future perspectives

Nasir Raza Awan, Andres Lozano, and Clement Hamani

Deep brain stimulation (DBS) has been used to treat various neurological and psychiatric disorders. Over the years, the most suitable surgical candidates and targets for some of these conditions have been characterized and the benefits of DBS well demonstrated in double-blinded randomized trials. This review will discuss some of the areas of current investigation and potential new applications of DBS.

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Deep brain stimulation in the treatment of dyskinesia and dystonia

Hiroki Toda, Clement Hamani, and Andres Lozano

Deep brain stimulation (DBS) has become a mainstay of treatment for patients with movement disorders. This modality is directed at modulating pathological activity within basal ganglia output structures by stimulating some of their nuclei, such as the subthalamic nucleus (STN) and the globus pallidus internus (GPi), without making permanent lesions. With the accumulation of experience, indications for the use of DBS have become clearer and the effectiveness and limitations of this form of therapy in different clinical conditions have been better appreciated. In this review the authors discuss the efficacy of DBS in the treatment of dystonia and levodopa-induced dyskinesias. The use of DBS of the STN and GPi is very effective for the treatment of movement disorders induced by levodopa. The relative benefits of using the GPi as opposed to the STN as a target are still being investigated. Bilateral GPi stimulation is gaining importance in the therapeutic armamentarium for the treatment of dystonia. The DYT1 forms of generalized dystonia and cervical dystonias respond to DBS better than secondary dystonia does. Discrimination between the diverse forms of dystonia and a better understanding of the pathophysiological features of this condition will serve as a platform for improved outcomes.

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Introduction. Deep brain stimulation in 2018

Francisco A. Ponce, Kelly D. Foote, and Andres M. Lozano

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Deep brain stimulation for depression

Jonathan P. Miller and Warren R. Selman

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Efficacy and safety of motor cortex stimulation for chronic neuropathic pain: critical review of the literature

Clinical article

Denys Fontaine, Clement Hamani, and Andres Lozano


The authors systematically reviewed the published literature to evaluate the efficacy of and adverse effects after motor cortex stimulation (MCS) for chronic neuropathic pain.


A search of the PubMed database (1991–2006) using the key words “motor cortex,” “stimulation,” and “pain” yielded 244 articles. Only original nonduplicated articles were selected for further analysis; 14 studies were identified for critical review. All were series of cases and none was controlled. The outcomes in 210 patients were assessed and expressed as the percentage of patients that improved with the procedure.


A good response to MCS (pain relief ≥ 40–50%) was observed in ~ 55% of patients who underwent surgery and in 45% of the 152 patients with a postoperative follow-up ≥ 1 year. Visual analog scale scores were provided in 76 patients, revealing an average 57% improvement in the 41 responders. A good response was achieved in 54% of the 117 patients with central pain and 68% of the 44 patients with trigeminal neuropathic pain. Adverse effects were reported in 10 studies, including 157 patients. Infections (5.7%) and hardware-related problems (5.1%) were relatively common complications. Seizures occurred in 19 patients (12%) in the early postoperative period, but no chronic epilepsy was reported.


The results of the authors' review of the literature suggest that MCS is safe and effective in the treatment of chronic neuropathic pain. Results must be considered with caution, however, as none of the trials were blinded or controlled. Studies with a better design are mandatory to confirm the efficacy of MCS for chronic neuropathic pain.

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Imaging alone versus microelectrode recording–guided targeting of the STN in patients with Parkinson’s disease

Christopher S. Lozano, Manish Ranjan, Alexandre Boutet, David S. Xu, Walter Kucharczyk, Alfonso Fasano, and Andres M. Lozano


The clinical results of deep brain stimulation (DBS) of the subthalamic nucleus (STN) are highly dependent on accurate targeting and target implantation. Several targeting tactics are in current use, including image-only and/or electrophysiologically guided approaches using microelectrode recordings (MERs). The purpose of the present study was to make an appraisal of imaging only–based versus imaging with the addition of intraoperative MER-guided STN electrode targeting.


The authors evaluated 100 consecutive patients undergoing STN DBS. The position of the STN target was estimated from preoperative MR images (direct target) or in relation to the position of the anterior and posterior commissures (indirect target). MERs were obtained for each trajectory. The authors tracked which targets were adjusted intraoperatively as a consequence of MER data. The final placement of 182 total STN electrodes was validated by intraoperative macrostimulation through the implanted DBS electrodes. The authors compared the image-based direct, indirect, MER-guided target adjustments and the final coordinates of the electrodes as seen on postoperative MRI.


In approximately 80% of the trajectories, there was a good correspondence between the imaging-based and the MER-guided localization of the STN target. In approximately 20% of image-based targeting trajectories, however, the electrophysiological data revealed that the trajectory was suboptimal, missing the important anatomical structures to a significant extent. The greatest mismatch was in the superior-inferior axis, but this had little impact because it could be corrected without changing trajectories. Of more concern were mismatches of 2 mm or more in the mediolateral (x) or anteroposterior (y) planes, discrepancies that necessitated a new targeting trajectory to correct for the mis-targeting. The incidence of mis-targetting requiring a second MER trajectory on the first and second sides was similar (18% and 22%).


According to the present analysis, approximately 80% of electrodes were appropriately targeted using imaging alone. In the other 20%, imaging alone led to suboptimal targeting that could be corrected by a trajectory course correction guided by the acquired MER data. The authors’ results suggest that preoperative imaging is insufficient to obtain optimal results in all patients undergoing STN DBS.

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Current and future directions of deep brain stimulation for neurological and psychiatric disorders

JNSPG 75th Anniversary Invited Review Article

Darrin J. Lee, Christopher S. Lozano, Robert F. Dallapiazza, and Andres M. Lozano

Deep brain stimulation (DBS) has evolved considerably over the past 4 decades. Although it has primarily been used to treat movement disorders such as Parkinson’s disease, essential tremor, and dystonia, recently it has been approved to treat obsessive-compulsive disorder and epilepsy. Novel potential indications in both neurological and psychiatric disorders are undergoing active study. There have been significant advances in DBS technology, including preoperative and intraoperative imaging, surgical approaches and techniques, and device improvements. In addition to providing significant clinical benefits and improving quality of life, DBS has also increased the understanding of human electrophysiology and network interactions. Despite the value of DBS, future developments should be aimed at developing less invasive techniques and attaining not just symptom improvement but curative disease modification.

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Editorial: Right hemisphere language

Tejas Sankar and Andres M. Lozano