Complications of deep brain stimulation surgery

New-Onset Stutter After Electrode Insertion in the Ventrocaudalis Nucleus for Face Pain

BACKGROUND

Deep brain stimulation (DBS) of the ventrocaudalis nucleus of the thalamus is a last resort treatment for chronic refractory pain. DBS is generally a safe procedure, although it can result in functional disturbances depending on the site of stimulation. There has been 1 previous report of stuttering induced by microlesioning of the thalamus, as well as several reports of stuttering induced by stimulation of the thalamus and other related structures in the brain.

CASE DESCRIPTION

We describe the case of a patient with trigeminal deafferentation face pain who was treated with DBS of the ventrocaudalis nucleus thalamus and developed a reversible stutter immediately on insertion of the electrode. The stutter improved significantly over 12 days after implant; however, the device was not effective in relieving the patient's pain and was removed.

CONCLUSIONS

Stuttering is a rare complication of deep brain exploration of the sensory thalamus. Our coordinates are near to but in a distinct anatomic region compared with cases previously described as having similar effects on speech.

Revision Surgery of Deep Brain Stimulation Leads

INTRODUCTION

Deep brain stimulation (DBS) is widely used for various movement disorders. DBS lead revisions are becoming more common as the indications and number of cases increases.

METHODS

Patients undergoing DBS lead revisions at a single institution were retrospectively analyzed based on diagnosis, reason for revision, where the lead was relocated, and surgical technique.

RESULTS

We reviewed 497 consecutive DBS lead placements and found that there was need for 25 DBS lead revisions with at least six months of follow-up. Loss of efficacy and development of adverse effects over time were the most common reasons for lead revision across all diagnosis. Lead malfunction was the least common. Ten patients requiring 19 DBS lead revisions that underwent their original surgery at another institution were also analyzed. Surgical technique dictated replacing with a new lead while maintaining brain position and tract with the old lead until final placement. Methods to seal exposed wire were developed.

CONCLUSION

Surgical technique, as well as variable options are important in lead revision and can be dictated based on reason for revision. Over time patients who have had adequate relief with DBS placement may experience loss of efficacy and development of adverse effects requiring revision of the DBS lead to maintain its effects.

Deep brain stimulation in mental health: Review of evidence for clinical efficacy

OBJECTIVE

There is increasing interest in the use of deep brain stimulation as a treatment for psychiatric disorders. In this review, we consider the evidence for the effectiveness of deep brain stimulation for psychiatric indications, with a primary focus on obsessive compulsive disorder and major depressive disorder.

METHODS

Case reports, case series and clinical trials where deep brain stimulation was primarily utilised in the treatment of a psychiatric disorder, including obsessive compulsive disorder, major depressive disorder, anorexia nervosa or an addictive disorder were identified. The evidence for the effectiveness of deep brain stimulation in the treatment of obsessive compulsive disorder and major depressive disorder was reviewed with studies clustered by the site of implantation.

RESULTS

The majority of identified manuscripts report small case series or single cases. A limited number of studies have reported some form of randomised or blinded stimulation comparison. All of these comparative reports have included small samples of subjects (less than 20 per study in total) compromising the feasibility of making statistical comparison between outcomes in the comparison phases. The two exceptions to this have been industry-sponsored studies conducted in the treatment of major depressive disorder. However, both were stopped prematurely due to concerns about poor efficacy.

CONCLUSIONS

There is insufficient evidence at this point in time to support the use of deep brain stimulation as a clinical treatment for any psychiatric disorder outside of research and programmes where formal outcome data are being systematically collated. While some promising initial data exist to support its potential efficacy for a number of psychiatric conditions, further research is required to establish optimal implantation targets, patient characteristics associated with positive therapeutic outcomes and optimal deep brain stimulation parameters and parameter-programming methods.

Factors associated with successful magnetic resonance-guided focused ultrasound treatment: efficiency of acoustic energy delivery through the skull

OBJECTIVE

Magnetic resonance-guided focused ultrasound surgery (MRgFUS) was recently introduced as treatment for movement disorders such as essential tremor and advanced Parkinson's disease (PD). Although deep brain target lesions are successfully generated in most patients, the target area temperature fails to increase in some cases. The skull is one of the greatest barriers to ultrasonic energy transmission. The authors analyzed the skull-related factors that may have prevented an increase in target area temperatures in patients who underwent MRgFUS.

METHODS

The authors retrospectively reviewed data from clinical trials that involved MRgFUS for essential tremor, idiopathic PD, and obsessive-compulsive disorder. Data from 25 patients were included. The relationships between the maximal temperature during treatment and other factors, including sex, age, skull area of the sonication field, number of elements used, skull volume of the sonication field, and skull density ratio (SDR), were determined.

RESULTS

Among the various factors, skull volume and SDR exhibited relationships with the maximum temperature. Skull volume was negatively correlated with maximal temperature (p = 0.023, r(2) = 0.206, y = 64.156 - 0.028x, whereas SDR was positively correlated with maximal temperature (p = 0.009, r(2) = 0.263, y = 49.643 + 11.832x). The other factors correlate with the maximal temperature, although some factors showed a tendency to correlate.

CONCLUSIONS

Some skull-related factors correlated with the maximal target area temperature. Although the number of patients in the present study was relatively small, the results offer information that could guide the selection of MRgFUS candidates.

The Feasibility of Using Acoustic Markers of Speech for Optimizing Patient Outcomes during Randomized Amplitude Variation in Deep Brain Stimulation: A Proof of Principle Methods Study

Background

Deep brain stimulation (DBS) is an effective treatment for reducing symptoms of tremor. A common and typically subjectively determined adverse effect of DBS is dysarthria. Current assessment protocols are driven by the qualitative judgments of treating clinicians and lack the sensitivity and objectivity required to optimize patient outcomes where multiple stimulation parameters are trialed.

Objective

To examine the effect of DBS on speech in patients receiving stimulation to the posterior sub-thalamic area (PSA) via randomized manipulation of amplitude parameters.

Methods

Six patients diagnosed with tremor receiving treatment via DBS of the PSA were assessed in a double-blinded, within-subjects experimental protocol. Amplitude (i.e., voltage or current) was randomly adjusted across 10 settings, while speech samples (e.g., sustained vowel, counting to 10) were recorded to identify the patient-specific settings required for optimal therapeutic benefit (reduced tremor) with minimal adverse effects (altered speech). Speech production between stimulation parameters was quantified using acoustic analysis.

Results

Speech changed as a response to DBS but those changes were not uniform across patients nor were they generally in line with changes in amplitude with the exception of reduced vocal control and increased mean silence length in two patients. Speech outcomes did not correlate with changes in tremor.

Conclusion

Intra-individual changes in speech were detected as a response to modified amplitude; however, no clear pattern was observed across patients as a group. The use of objective acoustic measures allows for quantification of speech changes during DBS optimization protocols, even when those changes are subtle and potentially difficult to detect perceptually.

Neuroimaging and neuromodulation approaches to study eating behavior and prevent and treat eating disorders and obesity

Functional, molecular and genetic neuroimaging has highlighted the existence of brain anomalies and neural vulnerability factors related to obesity and eating disorders such as binge eating or anorexia nervosa. In particular, decreased basal metabolism in the prefrontal cortex and striatum as well as dopaminergic alterations have been described in obese subjects, in parallel with increased activation of reward brain areas in response to palatable food cues. Elevated reward region responsivity may trigger food craving and predict future weight gain. This opens the way to prevention studies using functional and molecular neuroimaging to perform early diagnostics and to phenotype subjects at risk by exploring different neurobehavioral dimensions of the food choices and motivation processes. In the first part of this review, advantages and limitations of neuroimaging techniques, such as functional magnetic resonance imaging (fMRI), positron emission tomography (PET), single photon emission computed tomography (SPECT), pharmacogenetic fMRI and functional near-infrared spectroscopy (fNIRS) will be discussed in the context of recent work dealing with eating behavior, with a particular focus on obesity. In the second part of the review, non-invasive strategies to modulate food-related brain processes and functions will be presented. At the leading edge of non-invasive brain-based technologies is real-time fMRI (rtfMRI) neurofeedback, which is a powerful tool to better understand the complexity of human brain-behavior relationships. rtfMRI, alone or when combined with other techniques and tools such as EEG and cognitive therapy, could be used to alter neural plasticity and learned behavior to optimize and/or restore healthy cognition and eating behavior. Other promising non-invasive neuromodulation approaches being explored are repetitive transcranial magnetic stimulation (rTMS) and transcranial direct-current stimulation (tDCS). Converging evidence points at the value of these non-invasive neuromodulation strategies to study basic mechanisms underlying eating behavior and to treat its disorders. Both of these approaches will be compared in light of recent work in this field, while addressing technical and practical questions. The third part of this review will be dedicated to invasive neuromodulation strategies, such as vagus nerve stimulation (VNS) and deep brain stimulation (DBS). In combination with neuroimaging approaches, these techniques are promising experimental tools to unravel the intricate relationships between homeostatic and hedonic brain circuits. Their potential as additional therapeutic tools to combat pharmacorefractory morbid obesity or acute eating disorders will be discussed, in terms of technical challenges, applicability and ethics. In a general discussion, we will put the brain at the core of fundamental research, prevention and therapy in the context of obesity and eating disorders. First, we will discuss the possibility to identify new biological markers of brain functions. Second, we will highlight the potential of neuroimaging and neuromodulation in individualized medicine. Third, we will introduce the ethical questions that are concomitant to the emergence of new neuromodulation therapies.

Impact of advancing age on post-operative complications of deep brain stimulation surgery for essential tremor

Essential tremor (ET) was the original indication for deep brain stimulation (DBS), with USA Food and Drug Administration approval since 1997. Despite the efficacy of DBS, it is associated with surgical complications that cause sub-optimal clinical outcomes. Given that ET is a progressive disease with increase in symptom severity with increasing age, this study evaluated the impact of increasing age on short-term complications following DBS surgery for ET. The Thomson-Reuters MarketScan database was utilized (New York, NY, USA). Patients selected were over age 18 and underwent DBS for ET between the years 2000 and 2009. Multivariable logistic regression analysis was used to calculate complication odds ratios (OR) for a 5 year increase in age, after controlling for other covariates. Six hundred sixty-one patients were included in the analysis. The mean (standard deviation) age was 61.9 (14.3) years, with 17% of individuals aged ⩾75 years. Overall 56.9% of patients were male, and 44.6% had a Charlson Comorbidity Score of ⩾1. Additionally, 7.1% of patients experienced at least one complication within 90 days, including wound infections (3.0%), pneumonia (2.4%), hemorrhage or hematoma (1.5%), or pulmonary embolism (0.6%). Increasing age was not significantly associated with the overall 90 day complication rates (OR 0.89; 95% confidence interval [CI] 0.77-1.02; p=0.102). The risk of the two most common procedure-related complications, hemorrhage and infection, did not significantly increase with age (hemorrhage: OR 1.02; 95%CI 0.77-1.37; p=0.873; and infection: OR 0.88; 95%CI 0.72-1.07; p=0.203). Our findings suggest that age should not be a primary exclusion factor for determining candidacy for DBS and also suggest a possible expansion of the traditional therapeutic window since post-operative complications remained relatively stable.

Functional recordings from awake, behaving rodents through a microchannel based regenerative neural interface

OBJECTIVE

Neural interface technologies could provide controlling connections between the nervous system and external technologies, such as limb prosthetics. The recording of efferent, motor potentials is a critical requirement for a peripheral neural interface, as these signals represent the user-generated neural output intended to drive external devices. Our objective was to evaluate structural and functional neural regeneration through a microchannel neural interface and to characterize potentials recorded from electrodes placed within the microchannels in awake and behaving animals.

APPROACH

Female rats were implanted with muscle EMG electrodes and, following unilateral sciatic nerve transection, the cut nerve was repaired either across a microchannel neural interface or with end-to-end surgical repair. During a 13 week recovery period, direct muscle responses to nerve stimulation proximal to the transection were monitored weekly. In two rats repaired with the neural interface, four wire electrodes were embedded in the microchannels and recordings were obtained within microchannels during proximal stimulation experiments and treadmill locomotion.

MAIN RESULTS

In these proof-of-principle experiments, we found that axons from cut nerves were capable of functional reinnervation of distal muscle targets, whether regenerating through a microchannel device or after direct end-to-end repair. Discrete stimulation-evoked and volitional potentials were recorded within interface microchannels in a small group of awake and behaving animals and their firing patterns correlated directly with intramuscular recordings during locomotion. Of 38 potentials extracted, 19 were identified as motor axons reinnervating tibialis anterior or soleus muscles using spike triggered averaging.

SIGNIFICANCE

These results are evidence for motor axon regeneration through microchannels and are the first report of in vivo recordings from regenerated motor axons within microchannels in a small group of awake and behaving animals. These unique findings provide preliminary evidence that efferent, volitional motor potentials can be recorded from the microchannel-based peripheral neural interface; a critical requirement for any neural interface intended to facilitate direct neural control of external technologies.

Suppression of subthalamic nucleus activity by micromagnetic stimulation

Magnetic stimulation delivered via 0.5-mm diameter coils was recently shown to activate retinal neurons; the small coil size raises the possibility that micromagnetic stimulation ( μMS) could underlie a new generation of implanted neural prosthetics. Such an approach has several inherent advantages over conventional electric stimulation, including the potential for selective activation of neuronal targets as well as less susceptibility to inflammatory responses. The viability of μMS for some applications, e.g., deep brain stimulation (DBS), may require suppression (rather than creation) of neuronal activity, however, and therefore we explore here whether (μMS) could, in fact, suppress activity. While single pulses elicited weak and inconsistent spiking in neurons of the mouse subthalamic nucleus (in vitro), repetitive stimulation effectively suppressed activity in ∼ 70% of targeted neurons. This is the same percentage suppressed by conventional electric stimulation; with both modalities, suppression occurred only after an initial increase in spiking. The latency to the onset of suppression was inversely correlated to the energy of the stimulus waveform: larger amplitudes and lower frequencies had the fastest onset of suppression. These findings continue to support the viability of μMS as a next-generation implantable neural prosthetic.

A groove technique for securing an electrode connector on the cranial bone: case analysis of efficacy

Objective

A groove technique for securing an electrode connector was described as an alternative surgical technique in deep brain stimulation (DBS) surgery to avoid electrode connector-related complications, such as skin erosion, infection, and migration.

Methods

We retrospectively reviewed 109 patients undergoing one of two techniques; the standard technique (52 patients using 104 electrodes) and the groove technique (57 patients using 109 electrodes) for securing the electrode connector in DBS surgery, regardless of patient disease. In the standard percutaneous tunneling technique, the connector was placed on the vertex of the cranial surface. The other technique, so called the groove technique, created a groove (about 4 cm long, 8 mm wide) in the cranial bone at the posterior parietal area. Wound erosion and migration related to the connectors were compared between the two techniques.

Results

The mean follow-up period was 73 months for the standard method and 46 months for the groove technique. Connector-related complications were observed in three patients with the groove technique and in seven patients with the standard technique. Wound erosion at the connector sites per electrode was one (0.9%) with the groove technique and six (5.8%) with the standard technique. This difference was statistically significant. The electrode connector was migrated in two patients with the groove technique and in one patient with the standard technique.

Conclusions

The groove technique, which involves securing an electrode using a groove in the cranial bone at the posterior parietal area, offers an effective and safe method to avoid electrode connector-related complications during DBS surgery.

Deep brain stimulation macroelectrodes compared to multiple microelectrodes in rat hippocampus

Microelectrode arrays (wire diameter <50 μm) were compared to traditional macroelectrodes for deep brain stimulation (DBS). Understanding the neuronal activation volume may help solve some of the mysteries associated with DBS, e.g., its mechanisms of action. We used c-fos immunohistochemistry to investigate neuronal activation in the rat hippocampus caused by multi-micro- and macroelectrode stimulation. At ± 1V stimulation at 25 Hz, microelectrodes (33 μm diameter) had a radius of activation of 100 μm, which is 50% of that seen with 150 μm diameter macroelectrode stimulation. Macroelectrodes activated about 5.8 times more neurons than a single microelectrode, but displaced ~20 times more neural tissue. The sphere of influence of stimulating electrodes can be significantly increased by reducing their impedance. By ultrasonic electroplating (sonicoplating) the microelectrodes with platinum to increase their surface area and reduce their impedance by an order of magnitude, the radius of activation increased by 50 μm and more than twice the number of neurons were activated within this increased radius compared to unplated microelectrodes. We suggest that a new approach to DBS, one that uses multiple high-surface area microelectrodes, may be more therapeutically effective due to increased neuronal activation.

Deep brain stimulation for dystonia

Dystonia is a movement disorder characterized by involuntary muscular contractions that generate twisting and repetitive movements and/or abnormal postures. It can affect a few muscle groups (focal dystonia) or spread to most muscles in the body (generalized dystonia). While botulinum toxin injections can be successfully used to treat focal dystonias, medical options for generalized dystonia are very limited. Surgical therapies--and in particular deep brain stimulation (DBS)--are becoming the standard of care for medically intractable, disabling dystonias. Advantages of DBS include reversibility, adjustability and continued access to the therapeutic target. Initial reports describing the use of DBS in generalized dystonia have been very encouraging and experience in the use of DBS to treat various forms of dystonia is continuously growing. This article reviews the issues related to DBS treatment of dystonia, including proper patient selection, surgical approaches to target choice and device implant, a description of the stimulating device and its programming principles, clinical results - with a focus on different outcomes for primary versus secondary and generalized versus cervical dystonia - and complications.

Unchanged safety outcomes in deep brain stimulation surgery for Parkinson disease despite a decentralization of care

OBJECT

Early work on deep brain stimulation (DBS) surgery, when procedures were mostly carried out in a small number of high-volume centers, demonstrated a relationship between surgical volume and procedural safety. However, over the past decade, DBS has become more widely available in the community rather than solely at academic medical centers. The authors examined the Nationwide Inpatient Sample (NIS) to study the safety of DBS surgery for Parkinson disease (PD) in association with this change in practice patterns.

METHODS

The NIS is a stratified sample of 20% of all patient discharges from nonfederal hospitals in the United States. The authors identified patients with a primary diagnosis of PD (332.0) and a primary procedure code for implantation/replacement of intracranial neurostimulator leads (02.93) who underwent surgery between 2002 and 2009. They analyzed outcomes using univariate and hierarchical, logistic regression analyses.

RESULTS

The total number of DBS cases remained stable from 2002 through 2009. Despite older and sicker patients undergoing DBS, procedural safety (rates of non-home discharges, complications) remained stable. Patients at low-volume hospitals were virtually indistinguishable from those at high-volume hospitals, except that patients at low-volume hospitals had slightly higher comorbidity scores (0.90 vs 0.75, p < 0.01). Complications, non-home discharges, length of hospital stay, and mortality rates did not significantly differ between low- and high-volume hospitals when accounting for hospital-related variables (caseload, teaching status, location).

CONCLUSIONS

Prior investigations have demonstrated a robust volume-outcome relationship for a variety of surgical procedures. However, the present study supports safety of DBS at smaller-volume centers. Prospective studies are required to determine whether low-volume centers and higher-volume centers have similar DBS efficacy, a critical factor in determining whether DBS is comparable between centers.

A comparison between stereotactic targeting methods of the subthalamic nucleus in cases with Parkinson's disease

BACKGROUND

Several methods are used for targeting of the subthalamic nucleus (STN) for the surgical treatment of Parkinson's disease (PD). The goal of this study is to determine the most suitable morphological method for localizing the STN in order to perform deep brain stimulation (DBS) in the treatment of PD.

METHODS

Twelve cases with PD underwent bilateral STN-DBS and followed up for 5 years. Indirect calculation of the STN using AC-PC coordinates, and direct targeting of the STN using stereotactic CT/MRI fusion, were used for targeting. A microelectrode recording method was used to localize the STN.

RESULTS

Direct targeting of the STN using CT/MRI fusion was very precise in every case, based upon evaluation of the intraoperative microelectrode recordings, postoperative MRI scans, and clinical follow-up of the cases. The coordinate differences obtained from these two methods were statistically significant.

CONCLUSION

Direct targeting method of the STN using CT/MRI fusion provided higher precision than the indirect calculation method. This method may be used as a standard targeting technique, and may obviate the need for using complicated technologies such as microelectrode recording, which may sometimes be risky and counterproductive.

Deep brain stimulation for refractory epilepsy

Deep brain stimulation (DBS) is a method of treatment utilized to control medically refractory epilepsy (RE). Patients with medically refractory epilepsy who do not achieve satisfactory control of seizures with pharmacological treatment or surgical resection of the epileptic focus and those who do not qualify for surgery could benefit from DBS. The most frequently used stereotactic targets for DBS are the anterior thalamic nucleus, subthalamic nucleus, central-medial thalamic nucleus, hippocampus, amygdala and cerebellum. The DBS is believed to be an effective method of treatment for various types of epilepsy among adults and adolescents. Side effects may be associated with implantation of electrodes and with the stimulation itself. An increasing number of publications and growing interest in DBS application for RE may result in standardization of the qualification and treatment protocol for RE with DBS.

Displacement of a deep brain stimulator lead during placement of an additional ipsilateral lead

OBJECTIVE

The use of Deep Brain Stimulation (DBS) has been increasing. It follows the premise of neuromodulation in that it is reversible, as compared to previous lesioning procedures.

MATERIALS AND METHODS

Complications with DBS are inherently low and range from short-term complications during surgery such as hemorrhage to long-term complications that include lead fractures and infection. Over time, the authors have experienced indications for additional lead placements or change in position of the lead on the ipsilateral side. There is the inherent possibility of direct contact between leads or the microelectrode. This can lead to malpositioning, displacement of a lead placed previously, and malfunctioning.

RESULT

We report a case in which a lead placed previously becomes displaced during microelectrode recording on the ipsilateral side.

CONCLUSION

This scenario was corrected and had no clinical or functional complication. Placement of an additional ipsilateral DBS lead can be a safe and effective treatment option.

Microscopic magnetic stimulation of neural tissue

Electrical stimulation is currently used to treat a wide range of cardiovascular, sensory and neurological diseases. Despite its success, there are significant limitations to its application, including incompatibility with magnetic resonance imaging, limited control of electric fields and decreased performance associated with tissue inflammation. Magnetic stimulation overcomes these limitations but existing devices (that is, transcranial magnetic stimulation) are large, reducing their translation to chronic applications. In addition, existing devices are not effective for deeper, sub-cortical targets. Here we demonstrate that sub-millimeter coils can activate neuronal tissue. Interestingly, the results of both modelling and physiological experiments suggest that different spatial orientations of the coils relative to the neuronal tissue can be used to generate specific neural responses. These results raise the possibility that micro-magnetic stimulation coils, small enough to be implanted within the brain parenchyma, may prove to be an effective alternative to existing stimulation devices.

Electrical stimulation is used to treat a range of neurological diseases, but there are limitations that reduce its benefits. Bonmassar and colleagues show that magnetic stimulation delivered by small coils, close to the targeted neural tissue, can also be used to activate neurons and with fewer limitations.

An evaluation of hardware and surgical complications with deep brain stimulation based on diagnosis and lead location

INTRODUCTION

Deep brain stimulation is the most frequently performed neurosurgical procedure for movement disorders. This procedure is well tolerated, but not free of complications. Analysis of hardware complications based on patient diagnosis and lead location could prove valuable in recognizing potential pitfalls and patients at higher risk.

METHODS

This review analyzes the most common surgery-related complications that may occur based on diagnosis and lead location. Patients were categorized based on diagnosis - Parkinson's disease (PD), dystonia, and essential tremor (ET) - as well as by lead location - subthalamic nucleus (STN), globus pallidus interna (GPi), and ventral intermediate nucleus of the thalamus (Vim). It is a retrospective review of 326 patients undergoing 949 procedures over a 10-year period by one surgeon. Fisher's exact test and χ(2) test were employed and multivariate logistic regression analysis was performed to identify the significant variables of correlation.

RESULTS

Overall lead revision was observed at 5.7%, but was observed at 11.9% of GPi lead placements, and 10.7% of dystonia patients with only 4.6% of STN lead placements. Total extension revision was at 2.5%, but observed at 5.3% for dystonia patients and at only 1.4% for ET patients. Overall infection rate was at 1.9% with the highest rate observed in dystonia and ET patients. Postoperative complications with hardware, erosion, infection, and delayed stimulation failure were observed more often with ET and dystonia than with PD. This difference was statistically significant between dystonia and PD (p < 0.03) but not between the other disease entities (p > 0.05). On multivariate analysis, age and gender had no correlation with these complications. PD had significantly fewer complications on forward selection regression analysis (p = 0.004). Asymptomatic intracerebral hemorrhage was at 2.5% with the majority in Vim and none observed in GPi placements. There was only one symptomatic hemorrhage with a permanent deficit. Infarcts were observed at 0.8%. There were no mortalities.

CONCLUSION

This large series of patients and long-term follow-up demonstrate that risks of complications are not universal among movement disorder patients. Diagnosis and lead location are important risk stratification factors in determining complications.

Surgical treatment of dystonia

Dystonia is a neurological condition characterised by abnormal muscle contractions, often causing repetitive twisting movements or abnormal postures. Varying forms of surgical intervention, for dystonia unresponsive to medical therapy, have evolved over the years and have often been associated with poor outcomes and high morbidity. The advent of stereotactic neurosurgery and the success of Deep Brain Stimulation (DBS) in treating a number of movement disorders has revolutionized the surgical treatment for dystonia. This chapter reviews the literature concerning the surgical treatment dystonic conditions, from historical origins to the current use of modern functional neurosurgical techniques.

A forward-imaging needle-type OCT probe for image guided stereotactic procedures

A forward-imaging needle-type optical coherence tomography (OCT) probe with Doppler OCT (DOCT) capability has the potential to solve critical challenges in interventional procedures. A case in point is stereotactic neurosurgery where probes are advanced into the brain based on predetermined coordinates. Laceration of blood vessels in front of the advancing probe is an unavoidable complication with current methods. Moreover, cerebrospinal fluid (CSF) leakage during surgery can shift the brain rendering the predetermined coordinates unreliable. In order to address these challenges, we developed a forward-imaging OCT probe (740 μm O.D.) using a gradient-index (GRIN) rod lens that can provide real-time imaging feedback for avoiding at-risk vessels (8 frames/s with 1024 A-scans per frame for OCT/DOCT dual imaging) and guiding the instrument to specific targets with 12 μm axial resolution (100 frames/s with 160 A-scans per frame for OCT imaging only). The high signal-to-background characteristic of DOCT provides exceptional sensitivity in detecting and quantifying the blood flow within the sheep brain parenchyma in real time. The OCT/DOCT dual imaging also demonstrated its capability to differentiate the vessel type (artery/vein) on rat's femoral vessels. We also demonstrated in ex vivo human brain that the location of the tip of the OCT probe can be inferred from micro-anatomical landmarks in OCT images. These findings demonstrate the suitability of OCT guidance during stereotactic procedures in the brain and its potential for reducing the risk of cerebral hemorrhage.

Subthalamic deep brain stimulation for the treatment of Parkinson disease

BACKGROUND AND PURPOSE

The role of subthalamic nucleus deep brain stimulation (STN DBS) in the treatment of Parkinson disease (PD) is well established. The authors present a group of patients diagnosed with PD who were treated with STN DBS.

MATERIAL AND METHODS

Between 2008 and 2009, 32 female and 34 male patients with PD were treated with STN DBS. Mean age at implantation was 57 ± 12 years. PD lasted from 6 to 21 years (mean 10 years). Patients were qualified for the surgery according to the CAPSIT-PD criteria. The STN was identified with direct and indirect methods. Macrostimulation and microrecording for STN identification were used in all cases. A unilateral STN DBS system was implanted in two cases and bilateral implantation was performed among rest of the group. Outcome was assessed six months after implantation. Results : The mean reduction of UPDRS III score among 51 patients who underwent follow-up was 45% (5-89%). Reduction of levodopa consumption varied from 15 to 100%. Infection forced the authors to remove the DBS system in one case four months after implantation. Skin erosion above the internal pulse generator was noted in four cases.

CONCLUSIONS

Cardinal symptoms of Parkinson's disease can be safely and effectively treated with STN DBS in selected group of patients.

Diagnosis and treatment of complications related to deep brain stimulation hardware

Deep brain stimulation is a therapeutic technique increasingly used in the treatment of a variety of neurological, psychiatric, and pain disorders. Although beneficial, it carries the immediate and long-term risks associated with implanted hardware in the brain parenchyma and subcutaneous tissue. The most common hardware complications include electrode migrations or misplacements, wire fractures, skin erosion, infections, and device malfunction. We systematically reviewed the literature on deep brain stimulation-related complications and propose a diagnostic and therapeutic algorithm. Our aim is to provide a guide for clinicians and medical staff involved in the treatment of patients with deep brain stimulation for rapid recognition and efficient management of these complications.

Infected internal pulse generator: Treatment without removal

Background:

One of the rare but devastating complications of deep brain stimulation (DBS) is internal pulse generator (IPG) infection. In the majority of the cases, removal of the device is required, despite appropriate antibiotic therapy. We demonstrate that eradication of an IPG infection is feasible without removal of the IPG device.

Case Description:

This article reports the authors’ experience on two patients who underwent DBS for advanced Parkinson's disease (PD) and, subsequently, suffered from infection and skin breakdown over the IPG. The patients were treated with antibiotic therapy, surgical revision of the wound, intraoperative disinfection of the IPG and relocation of the subcutaneous pocket. In both cases, the infection was eradicated and DBS therapy was continued uninterrupted.

Conclusion:

Although not generally recommended, DBS IPG may be salvaged in selected cases of superficial device infection. Our experience suggests that it is possible to treat the infection without removing the device. Such an approach decreases the morbidity, duration of hospital stay and health care costs.

High frequency deep brain stimulation of the subthalamic nucleus versus continuous subcutaneous apomorphine infusion therapy: a review

In advanced Parkinson's disease, several therapeutical option including not only lesional surgery (VIM, GPi) and deep brain stimulation (STN, GPi, VIM) but also continuous subcutaneous apomorphine infusion therapy can be proposed to the patient. The choice depends on the hope of the patient, patient's general health condition and the experience and choice of the neurosurgical and neurologist team. Here we report our experience based on 400 STN-DBS cases and we discuss, on the basis of our experience and on the literature, the advantage and disadvantage of DBS strategy as compared with non-surgical option such as continuous subcutaneous apomorphine infusion therapy.

Molecular photovoltaic structures for optical activation of excitable cells: current advances and perspectives

Current neural stimulation devices for the treatment of sensory and motor disorders are based on electrical stimulation. Using this technique, neural activity is triggered by electrical stimuli applied through electrodes in contact with the cells. Due to physical constraints of the electrodes the spatial control of stimulation is limited, which in some cases generates unwanted side effects. In addition, adverse tissue reactions occur after long term contact with the electrodes. A potential solution is the application of methods based on light instead of electrical energy, in which the electrical stimulator and the electrode are replaced by a light source and an optical fiber. Although optical stimulation approaches that allow spatially selective, highly specific and contact-free control of the neural activity have been developed in recent years, their implementation requires genetic manipulation, limiting the perspectives for clinical applications. A molecular photovoltaic structure potentially able to mediate light-induced cellular responses without involving genetic modification is the photosynthetic pigment-protein complex Photosystem I (PSI). In this work, the recent advances on the application of PSI reaction centers for optical control of cellular activity are presented. Perspectives of application of PSI reaction centers in the development of future methods for clinical neural stimulation are also presented.

Deep brain stimulation compared with bariatric surgery for the treatment of morbid obesity: a decision analysis study

Object

Roux-en-Y gastric bypass is the gold standard treatment for morbid obesity, although failure rates may be high, particularly in patients with a BMI > 50 kg/m2. With improved understanding of the neuropsychiatric basis of obesity, deep brain stimulation (DBS) offers a less invasive and reversible alternative to available surgical treatments. In this decision analysis, the authors determined the success rate at which DBS would be equivalent to the two most common bariatric surgeries.

Methods

Medline searches were performed for studies of laparoscopic adjustable gastric banding (LAGB), laparoscopic Roux-en-Y gastric bypass (LRYGB), and DBS for movement disorders. Bariatric surgery was considered successful if postoperative excess weight loss exceeded 45% at 1-year follow-up. Using complication and success rates from the literature, the authors constructed a decision analysis model for treatment by LAGB, LRYGB, DBS, or no surgical treatment. A sensitivity analysis in which major parameters were systematically varied within their 95% CIs was used.

Results

Fifteen studies involving 3489 and 3306 cases of LAGB and LRYGB, respectively, and 45 studies involving 2937 cases treated with DBS were included. The operative successes were 0.30 (95% CI 0.247–0.358) for LAGB and 0.968 (95% CI 0.967–0.969) for LRYGB. Sensitivity analysis revealed utility of surgical complications in LRYGB, probability of surgical complications in DBS, and success rate of DBS as having the greatest influence on outcomes. At no values did LAGB result in superior outcomes compared with other treatments.

Conclusions

Deep brain stimulation must achieve a success rate of 83% to be equivalent to bariatric surgery. This high-threshold success rate is probably due to the reported success rate of LRYGB, despite its higher complication rate (33.4%) compared with DBS (19.4%). The results support further research into the role of DBS for the treatment of obesity.

Relationship between higher rates of adverse events in deep brain stimulation using standardized prospective recording and patient outcomes

Object

Adverse event (AE) rates for deep brain stimulation (DBS) are variable, due to various methodologies used for identifying, collecting, and reporting AEs. This lack of a prospective, standardized AE collection method is a shortcoming in the advancement of DBS. In this paper the authors disclose the standardized and prospectively recorded AE data from their institution, correlated with clinical outcome and quality of life (QOL) measures.

Methods

All patients who underwent operations at the authors' institution for Parkinson disease (PD), essential tremor, dystonia, other tremor, and obsessive-compulsive disorder were included. Complications occurring intraoperatively or within the first 180 days following surgery were recorded, analyzed, and classified as mild, moderate, or severe, regardless of their perceived relationship to the procedure. The presence, frequency, and severity of AEs were compared with the following outcome measurements: postoperative change in the QOL scales (Medical Outcomes Study 36-Item Short-Form Survey, 39-Item PD Questionnaire); motor scales (Tremor Rating Scale, Unified Dystonia Rating Scale, Unified PD Rating Scale); and Patient Global Impression Scale (PGIS).

Results

Two hundred seventy DBS procedures were performed in 198 patients. Three hundred AEs were recorded in 146 (54.1%) of the 270 procedures, and the AEs were recorded in 119 (60.1%) of 198 patients. Of the 198 patients, the maximum severity of AEs was mild in 28 (14.1%), moderate in 35 (17.7%), and severe in 56 (28.3%). Of the 300 AEs, 102 (34.1%) of 299 were mild, 106 (35.5%) were moderate, and 91 (30.4%) were severe. The AEs were classified as probably not stimulation induced in 10 (3.4%) of 297, probably in 44 (14.9%), unclear for 89 (30%), and not applicable to stimulation in 154 (51.9%). Adverse events were also classified as probably related to surgery in 111 (37.2%) of 298, possibly related in 96 (32.2%), and probably not related to surgery in 91 (30.5%). There was no significant difference (p = 0.22) in QOL outcomes among patients who had no AEs compared with those who experienced mild, moderate, or severe AEs. There was no significant difference in QOL outcomes between patients who did not experience an AE compared with those who experienced any AE. There was no significant difference in the mean General PGIS score between patients without an AE versus those with any AE, as well as on the Symptom-Specific PGIS. Motor function outcomes did not vary between patients with or without AEs. For patients with PD with or without AEs, there was no significant difference in preoperative off-medicine Unified PD Rating Scale score and postoperative 6-month on-medication/on-stimulation change scores (p = 0.59). For patients with tremor there were no differences between those with or without AEs on the Tremor Rating Scale for motor function or activities of daily living. Patients with dystonia with and without AEs showed no differences in the Unified Dystonia Rating Scale.

Conclusions

Prospectively and systematically recording AEs may result in higher AE rates, but this does not correlate with poorer QOL, motor function, or patient-oriented outcome scores.

Identification and management of deep brain stimulation intra- and postoperative urgencies and emergencies

Deep brain stimulation (DBS) has been increasingly utilized for the therapeutic treatment of movement disorders, and with the advent of this therapy more postoperative urgencies and emergencies have emerged. In this paper, we will review, identify, and suggest management strategies for both intra- and postoperative urgencies and emergencies. We have separated the scenarios into 1--surgery/procedure related, 2--hardware related, 3--stimulation-induced difficulties, and 4--others. We have included ten illustrative (and actual) case vignettes to augment the discussion of each issue.

Oral and infusion levodopa-based strategies for managing motor complications in patients with Parkinson's disease

Levodopa is the most effective treatment for Parkinson's disease (PD) signs and symptoms, and patients invariably will require it during the course of the disease. It also provides benefits in activities of daily living, quality of life and life expectancy. However, after a few years of levodopa treatment the majority of patients will experience motor fluctuations and dyskinesia. Initial use of a dopamine receptor agonist may delay the emergence of motor fluctuations but at the cost of reduced symptomatic control compared with the use of levodopa in some cases. Adequate management of motor fluctuations and dyskinesia is essential to maintaining satisfactory quality of life at the advanced stage of disease. Various levodopa-based strategies are currently available that aim to control motor complications (wearing-off and dyskinesia) in PD and each approach has its own unique benefit and risk profile. Strategies such as dose fragmentation (smaller, more frequent dosing) or the use of orally administered, liquid levodopa formulations or melevodopa can reduce off-time intervals or facilitate absorption. More recently introduced, continuous delivery of dopaminergic medications may represent a more effective approach to treat motor complications in advanced PD and its effect can be perceived from improvement in clinical scales, as well as in health-related items. Indeed, continuous levodopa delivery by duodenal infusion may stabilize and significantly improve motor function as well as patients' quality of life. We propose a treatment algorithm that takes into account all currently available levodopa-based treatment strategies for motor complications in patients with PD.

Neurosurgical treatment for Gilles de la Tourette syndrome: the Italian perspective

Despite the availability of both pharmacological and behavioral therapies for Gilles de la Tourette Syndrome (GTS), a subgroup of patients suffer intractable disease and require treatment through non-conservative means. Since 1955, various neurosurgical procedures have been considered as a potential resort for this severely affected sub-group; this article reviews the neurosurgical treatment for GTS, with in-depth discussion on deep brain stimulation (DBS). Internationally, 39 cases of GTS undergoing DBS treatment have been published. Yet, despite the small numbers of patients assessed in centers involved and the inconsistency of postoperative assessment between centres, DBS has been considered the most promising neurosurgical procedure. Patients resorting to surgical measures often carry the additional burden of a diverse range of behavioral disturbances found to significantly impair health-related quality of life; comorbid psychopathologies must be considered when postoperatively evaluating the benefits of DBS. The authors acknowledge that out of the 39 documented cases of GTS treated with DBS, 18 cases originate from Italy; thus, it seems both relevant and pertinent to recount and present the lived Italian experience of that subgroup of GTS treated by DBS, for the first time. Recommendations from such experience are presented.

Integrated device for optical stimulation and spatiotemporal electrical recording of neural activity in light-sensitized brain tissue

Neural stimulation with high spatial and temporal precision is desirable both for studying the real-time dynamics of neural networks and for prospective clinical treatment of neurological diseases. Optical stimulation of genetically targeted neurons expressing the light sensitive channel protein Channelrhodopsin (ChR2) has recently been reported as a means for millisecond temporal control of neuronal spiking activities with cell-type selectivity. This offers the prospect of enabling local delivery of optical stimulation and the simultaneous monitoring of the neural activity by electrophysiological means, both in the vicinity of and distant to the stimulation site. We report here a novel dual-modality hybrid device, which consists of a tapered coaxial optical waveguide ('optrode') integrated into a 100 element intra-cortical multi-electrode recording array. We first demonstrate the dual optical delivery and electrical recording capability of the single optrode in in vitro preparations of mouse retina, photo-stimulating the native retinal photoreceptors while recording light-responsive activities from ganglion cells. The dual-modality array device was then used in ChR2 transfected mouse brain slices. Specifically, epileptiform events were reliably optically triggered by the optrode and their spatiotemporal patterns were simultaneously recorded by the multi-electrode array.