Unusual complications of deep brain stimulation

Optimized Deep Brain Stimulation Surgery to Avoid Vascular Damage: A Single-Center Retrospective Analysis of Path Planning for Various Deep Targets by MRI Image Fusion

Co-registration of stereotactic and preoperative magnetic resonance imaging (MRI) images can serve as an alternative for trajectory planning. However, the role of this strategy has not yet been proven by any control studies, and the trajectories of commonly used targets have not been systematically studied. The purpose of this study was to analyze the trajectories for various targets, and to assess the role of trajectories realized on fused images in preventing intracranial hemorrhage (ICH). Data from 1019 patients who underwent electrode placement for deep brain stimulation were acquired. Electrode trajectories were not planned for 396 patients, whereas trajectories were planned for 623 patients. Preoperative various MRI sequences and frame-placed MRI images were fused for trajectory planning. The patients’ clinical characteristics, the stereotactic systems, intracranial hemorrhage cases, and trajectory angles were recorded and analyzed. No statistically significant differences in the proportions of male patients, patients receiving local anesthesia, and diseases or target distributions (p > 0.05) were found between the trajectory planning group and the non-trajectory planning group, but statistically significant differences were observed in the numbers of both patients and leads associated with symptomatic ICH (p < 0.05). Regarding the ring and arc angle values, statistically significant differences were found among various target groups (p < 0.05). The anatomic structures through which leads passed were found to be diverse. Trajectory planning based on MRI fusion is a safe technique for lead placement. The electrode for each given target has its own relatively constant trajectory.

Peri-Lead Edema After Deep Brain Stimulation Surgery: A Poorly Understood but Frequent Complication

OBJECTIVE

Postoperative peri-lead edema (PLE) is a poorly understood complication of deep brain stimulation (DBS), which has been described sporadically in patients presenting with profound and often delayed symptoms. We performed a prospective evaluation of patients undergoing DBS to determine the frequency of and identify risk factors for PLE.

METHODS

Patients underwent DBS electrode placement by a single physician. Postoperative magnetic resonance imaging (MRI) was performed approximately 6 weeks after the operation in asymptomatic subjects and analyzed for presence of PLE. All symptomatic subjects underwent MRI at the time of presentation. Data regarding index disease, preoperative medical issues, operative technique, and intraoperative variables were collected and statistically analyzed.

RESULTS

A total of 191 leads were placed in 102 subjects; 15 patients (14.7%) demonstrated PLE. Seven patients (6.9%) presented with symptoms related to PLE, most often altered mental status or neurologic deficit. Many of the MRI findings were profound, with PLE sometimes several centimeters in diameter. No statistically significant difference was found between PLE-positive and normal subjects when analyzing multiple variables, including presence of vascular disease, hypertension, anticoagulant/antiplatelet use, electrode target, index disease, unilateral versus bilateral lead placement, number of brain penetrations, and presence or absence of microelectrode recording.

CONCLUSIONS

Patients with postoperative PLE can present with severe symptoms or can be asymptomatic and go undiagnosed. Because of the delayed-onset potential, PLE may be more common than previously reported. No clear risk factors have been identified; therefore, further studies and increased clinical vigilance are paramount for improving comprehension and possible prevention of PLE.

Delayed complications of deep brain stimulation: 16-year experience in 249 patients

BACKGROUND

Over the years, most of the deep brain stimulation (DBS) complications described have been mainly related to the surgery itself or the stimulation. Only a few authors have dealt with chronic complications or complications due to implanted material.

METHODS

We retrospectively analyzed complications beyond the 1st month after surgery in 249 patients undergoing DBS at our site for 16 years, with 321 interventions overall.

RESULTS

Our results show that infection is the most frequent delayed complication (12.5%), the pulse generator being the most common location. Lead breaks (9.3%) are the second most frequent complication. Symptomatic peri-lead edema and cyst formation were exceptional.

CONCLUSIONS

The best knowledge about DBS complications allows for better solutions. In case of infection, conservative treatment or partial removal of the DBS system appears to be safe and reasonable. Intracranial complications related to DBS material such as peri-lead edema and cyst formation have a good prognosis. They may appear long after DBS implantation.

Pocket Pain and Neuromodulation: Negligible or Neglected?

OBJECTIVES

Pain encountered at the site of the implantable pulse generator (IPG) after invasive neuromodulation is a well-known and important complication. The reported incidence of implant site pain is variable, ranging between 0.4 and 35%. Implant site pain has never been systematically studied and no treatment guidelines are available.

MATERIAL AND METHODS

We performed an observational study (study registration number mp05728) on the incidence and the determining factors of implant site pain, the subjective rating of intensity by sending questionnaires (n = 554) to our cohort of neuromodulation patients with IPGs. The number of revision surgeries and explants due to implant site pain were also analyzed.

RESULTS

Total response rate was 50% (n = 278). Pain patients suffered significantly (p < 0.05) more often from IPG site pain than other patients undergoing neuromodulation therapies. Up to 64% of patients undergoing spinal cord stimulation reported IPG site discomfort or pain. Severe pocket pain was found in up to 8% of patients. No association was found between other variables (age, BMI, duration of follow-up, gender, smoking, number of pocket surgeries) and implant site pain.

CONCLUSION

Pocket pain represents an important problem after invasive neuromodulation and is more prevalent in pain patients. We believe further technological improvements with miniaturized IPGs will impact the incidence of pocket pain and could even obviate the need for an IPG pocket.

Changing of the guard: reducing infection when replacing neural pacemakers

OBJECTIVE

Infection of deep brain stimulation (DBS) hardware has a significant impact on patient morbidity. Previous experience suggests that infection rates appear to be higher after implantable pulse generator (IPG) replacement surgery than after the de novo DBS procedure. In this study the authors examine the effect of a change in practice during DBS IPG replacements at their institution.

METHODS

Starting in January 2012, patient screening for methicillin-resistant Staphylococcus aureus (MRSA) and, and where necessary, eradication was performed prior to elective DBS IPG change. Moreover, topical vancomycin was placed in the IPG pocket during surgery. The authors then prospectively examined the infection rate in patients undergoing DBS IPG replacement at their center over a 3-year period with at least 9 months of follow-up.

RESULTS

The total incidence of infection in this prospective consecutive series of 101 IPG replacement procedures was 0%, with a mean follow-up duration of 24 ± 11 months. This was significantly lower than the authors' previously published historical control group, prior to implementing the change in practice, where the infection rate for IPG replacement was 8.5% (8/94 procedures; p = 0.003).

CONCLUSIONS

This study suggests that a change in clinical practice can significantly lower infection rates in patients undergoing DBS IPG replacement. These simple measures can minimize unnecessary surgery, loss of benefit from chronic stimulation, and costly hardware replacement, further improving the cost efficacy of DBS therapies.

Thalamotomy-Like Effects From Partial Removal of a Ventral Intermediate Nucleus Deep Brain Stimulator Lead in a Patient With Essential Tremor: Case Report

BACKGROUND AND IMPORTANCE

The ventral intermediate nucleus of the thalamus is a primary target of deep brain stimulation (DBS) in patients with essential tremor. Despite reliable control of contralateral tremor, there is sometimes a need for lead revision in cases of infection, hardware malfunction, or failure to relieve symptoms. Here, we present the case of a patient undergoing revision after ventral intermediate nucleus (Vim) DBS failed to control his tremor. During the electrode removal, the distal portion of the lead was found to be tightly adherent to tissue within the deep brain. Partial removal of the electrode in turn caused weakness, paresthesias, and tremor control similar to the effects produced by thalamotomy or thalamic injury.

CLINICAL PRESENTATION

A 48-year-old man with essential tremor had bilateral Vim DBS leads implanted 10 years earlier but had poor control of his tremor and ultimately opted for surgical revision with lead placement in the zona incerta. During attempted removal of his right lead, the patient became somnolent with contralateral weakness and paresthesias. The procedure was aborted, and postoperative neuroimaging was immediately obtained, showing no signs of stroke or hemorrhage. The patient had almost complete control of his left arm tremor postoperatively, and his weakness soon resolved.

CONCLUSION

To the best of our knowledge, this is the first reported case of cerebral injury after DBS revision and offers insights into the mechanism of high-frequency electric stimulation compared with lesions. That is, although high-frequency stimulation failed to control this patient's tremor, thalamotomy-like injury was completely effective.

Cystic Lesions as a Rare Complication of Deep Brain Stimulation

DBS is a typically well-tolerated operation for treatment of Parkinson's disease, dystonia, and essential tremor (ET). Complications related to the surgical procedure and implanted hardware may occur. More commonly reported complications include hemorrhage, seizure, confusion, and infection. In this article, we report on a rare, but important, complication of DBS surgery, a brain cyst formation at the tip of the implanted ventralis intermedius nucleus (VIM) DBS lead in 2 patients who underwent the procedure at 2 different centers. The indication for surgery was debilitating ET, and in both cases, there was development of a delayed-onset neurological deficit associated with an internal capsule/thalamic cystic lesion formation located at the tip of the DBS lead. Case 1 presented within a few months post-DBS, whereas case 2 had a 10-mo delay to onset of symptoms. No clinical and radiological signs of infection were observed and both DBS systems were explanted with uneventful recovery.