Comparison of two segmentation software tools for deep brain stimulation of the subthalamic and ventro-intermedius nuclei.

PURPOSE: Deep brain stimulation (DBS) relies on precise targeting of key structures such as the subthalamic nucleus (STN) for Parkinson's disease (PD) and the ventro-intermedius nucleus of the thalamus (Vim) for essential tremor (ET). Segmentation software, such as GuideXT© and Suretune©, are commercially available for atlas-based identification of deep brain structures. However, no study has compared the concordance of the segmentation results between the two software. METHODS: We retrospectively compared the concordance of segmentation of GuideXT© and Suretune© software by comparing the position of the segmented key structures with clinically predicted targets obtained using the newly developed RebrAIn© software as a reference. RESULTS: We targeted the STN in 44 MRI from PD patients (88 hemispheres) and the Vim in 31 MRI from ET patients (62 hemispheres) who were elected for DBS. In 22 STN targeting (25%), the target positioning was not correlating between GuideXT© and Suretune©. Regarding the Vim, targets were located in the segmented Vim in 37%, the posterior subthalamic area (PSA) in 60%, and the STN in 3% of the cases using GuideXT©; the proportions were 34%, 60%, and 6%, respectively, using Suretune©. The mean distance from the centre of the RebrAIn© targeting to the segmented Vim by Suretune© was closer (0.64 mm) than with GuideXT© (0.96 mm; p = 0.0004). CONCLUSION: While there is some level of concordance in the segmentation results of key structures for DBS treatment among software models, differences persist. Therefore, such software should still be considered as tools and should not replace clinician experience in DBS planning.

Multicolumn spinal cord stimulation for significant low back pain in failed back surgery syndrome: design of a national, multicentre, randomized, controlled health economics trial (ESTIMET Study).

BACKGROUND: Many studies have demonstrated the efficacy of spinal cord stimulation (SCS) for chronic neuropathic radicular pain over recent decades, but despite global favourable outcomes in failed back surgery syndrome (FBSS) with leg pain, the back pain component remains poorly controlled by neurostimulation. Technological and scientific progress has led to the development of new SCS leads, comprising a multicolumn design and a greater number of contacts. The efficacy of multicolumn SCS lead configurations for the treatment of the back pain component of FBSS has recently been suggested by pilot studies. However, a randomized controlled trial must be conducted to confirm the efficacy of new generation multicolumn SCS. Évaluation médico-économique de la STImulation MEdullaire mulTi-colonnes (ESTIMET) is a multicentre, randomized study designed to compare the clinical efficacy and health economics aspects of mono- vs. multicolumn SCS lead programming in FBSS patients with radicular pain and significant back pain. MATERIALS AND METHODS: FBSS patients with a radicular pain VAS score≥50mm, associated with a significant back pain component were recruited in 14 centres in France and implanted with multicolumn SCS. Before the lead implantation procedure, they were 1:1 randomized to monocolumn SCS (group 1) or multicolumn SCS (group 2). Programming was performed using only one column for group 1 and full use of the 3 columns for group 2. Outcome assessment was performed at baseline (pre-implantation), and 1, 3, 6 and 12months post-implantation. The primary outcome measure was a reduction of the severity of low back pain (bVAS reduction≥50%) at the 6-month visit. Additional outcome measures were changes in global pain, leg pain, paraesthesia coverage mapping, functional capacities, quality of life, neuropsychological aspects, patient satisfaction and healthcare resource consumption. TRIAL STATUS: Trial recruitment started in May 2012. As of September 2013, all 14 study centres have been initiated and 112/115 patients have been enrolled. Preliminary results are expected to be published in 2015. TRIAL REGISTRATION: Clinical trial registration information-URL: www.clinicaltrials.gov. Unique identifier NCT01628237.

Intraoperative 3D imaging control during subthalamic Deep Brain Stimulation procedures using O-arm® technology: Experience in 15 patients.

OBJECTIVE: O-arm(®) now gives us the opportunity not only to perform 2D but also 3D scans during deep brain stimulation (DBS) procedures. We present our experience with the intraoperative use of this device. Our objective was to measure the geometrical accuracy of electrode placement during surgical procedures driven under O-arm(®) control. METHODS: Fifteen patients underwent STN-DBS. For the first 4 patients, 3D scans were performed at the end of the procedure. We calculated the accuracy of electrode positioning, i.e. the distance between final electrode positioning and the planned trajectory. For the next 11 patients, who underwent both intraoperative and final 3D scan, we also calculated the accuracy of the microelectrode positioning. RESULTS: Average stimulation-induced improvement of UPDRS-III score was 52.5±15%. For the first 4 patients, the mean electrode positioning accuracy was 1.46±0.56mm. For the 11 patients who underwent intraoperative 3D scan, the mean microelectrodes positioning accuracy was 1.59±1.1mm. Aberrant positioning was detected in two cases, and was analyzed by fusing 3D scan with preoperative MR images. The definite electrodes positioning accuracy was 1.05±0.54mm. CONCLUSION: Intraoperative 3D scan is feasible, and can help us detect and correct early aberrant trajectories.

A long-term follow-up of weight changes in subthalamic nucleus stimulated Parkinson's disease patients.

Deep brain stimulation of the subthalamic nucleus (STN-DBS) constitutes the mainstay treatment in advanced Parkinson's disease (PD) with motor fluctuations. Despite its efficacy on motor signs and quality of life, emergent adverse events have been recently reported. Among them, weight gain (WG) is a recognized adverse event of subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson's disease (PD). Also, WG is poorly known at the long-term and predisposing factors have not yet been identified. We conducted a cross-sectional study of WG in 47 STN-DBS PD patients between 1999-2006. Data on disease history, motor status and dopaminergic drug treatment were retrospectively collected at surgery and 1 year post-surgery. Weight at disease diagnosis and at surgery, as well as the current weight and height were gathered by an autoquestionnaire. Moreover, the weight before surgery was obtained and verified in medical files in more than 90% of our patients. Sixty-six patients who underwent surgery between 1999-2006 were included, but six were deceased, four refused to participate and nine were lost for follow-up. So, 47 (71%) were retained in our analysis. A total of 78.7% of patients gained weight. On average 4.7 years follow up after surgery, the mean weight gain was +7.2±8.1kg compared to the preoperative assessment (p<0.001) and the mean BMI gain was +2.7±3.0kg/m(2) compared to pre-surgery values (p<0.001). The patients gained more weight after surgery than they had lost during disease evolution before surgery. Women and patients with a more severe UPDRS-III "off" drug score before surgery significantly gained more weight. Our study provides further evidence that the WG is a problem after STN-DBS and concerns a majority of patients at the long term. It may expose them to complications that should be considered for prevention and the patient's information before surgery.

[Cranial nerve functional neurosurgery: evaluation of surgical practice]. / La neurochirurgie fonctionnelle des nerfs crâniens Evaluation de l'activité

We report the results of an investigation carried out on the activity of functional neurosurgery of the cranial nerves in the French-speaking countries, based on the analysis of a questionnaire addressed to all the members of the SNCLF. Eighteen centers responded to this questionnaire, which showed that activities and indications varied greatly from one unit to another. The results appear homogeneous and comparable with those reported in the literature. The questionnaire sought to provide a global perspective, open to the comments and questions of all responders on the various techniques raised, with the objective of establishing a common decisional tree for these pathologies and providing if possible to a consensus for better dissemination of these therapies.

Sensory motor mismatch within the supplementary motor area in the dystonic monkey.

Dystonia, a movement disorder characterized by abnormal postures, is associated in primary forms of the disease with subtle proprioceptive troubles and aberrant somatotopic representation in the somatosensory cortex (SC). However, it is unclear whether these sensory features are a causal phenomenon or a consequence of dystonia. The supplementary motor area proper (SMAp), a premotor cortical region, receives strong inputs from both the SC and basal ganglia. We hypothesized that disruption in sensory-motor integration within the SMAp may play a part in the pathophysiology of dystonia. Using a model of secondary dystonia obtained by 3-nitropropionic acid intoxication in rhesus monkeys, we first provide evidence that the SMAp was overexcitable in dystonic animals. Second, we show that proprioceptive inputs processed by SMAp neurons were dramatically increased with wider sensory receptive fields and a mismatch between sensory inputs and motor outputs. These findings suggest that abnormal sensory inputs impinging upon SMAp neurons play a critical role in the pathophysiology of dystonia.

[Intrathecal baclofen in hereditary spastic paraparesis: benefits and limitations]. / Intérêts et limites du baclofène intrathécal dans les paraparésies spastiques héréditaires.

BACKGROUND: Chronic intrathecal delivery of baclofen has been introduced for treatment of severe spinal spasticity. Very little is known about this treatment in hereditary spastic paraparesis. Here we review the benefits and limitations of pump implantation for baclofen delivery in this population. METHODS: Consecutive patients presenting with hereditary spastic paraparesis were assessed for spasticity (Ashworth and Penn scores), muscular strength and walking (speed, comfort and perimeter length). The effect of intrathecal delivery of baclofen was judged after progressive bolus injections or chronic administration by electrical syringe. The pump implantation was proposed when spasticity scores decreased by 2 or more points, with muscular strength preserved and walking area increased. RESULTS: We investigated 6 patients (3 males; mean age 48 years) with hereditary spastic paraparesis. The mean follow-up was 19 years; for 4 patients who received pump implantation, the mean follow-up was 6.2 years. The mean baclofen daily dose was 75 mug. Satisfaction was high for patients who received implantation early instead of waiting for the natural course of the disease. DISCUSSION: Some patients with hereditary spastic paraparesis have good functional improvement with chronic intrathecal delivery of baclofen if walking is still possible. Despite the natural history of the disease, functional results are stable during the first 5 years of treatment. The data indicate a possible compromise between decreased spasticity and muscular strengthening with the treatment.

Use of intraoperative monitoring of somatosensory evoked potentials to prevent ischaemic stroke after surgical exclusion of middle cerebral artery aneurysms.

OBJECTIVE: The aim of this study was to assess the value of monitoring somatosensory evoked potentials (SEP) in the prevention of ischaemic stroke occurring during surgical exclusion of middle cerebral artery aneurysms. METHODS: SEP monitoring was performed during the surgical exclusion of 131 aneurysms in 122 patients. All SEP variations over 30% were notified to the surgeon and those over 50% were considered as highly significant. If this happened, and in concert with the conduct of the operation, a return to the basal level was systematically sought. RESULTS: Post-operative ischemic stroke was observed after 15 (11.4%) operations, leading to a permanent neurological deficit in 12 (9.2%). During nine (6.9%) operations there was a highly significant SEP change that persisted, or was only partially reversed, after corrective procedure. Nine of these patients had a post-operative ischaemic stroke. In 25 (19%), operations there was a highly significant SEP change followed by complete recovery. Of these 25 patients, 2 suffered a post-operative ischemic stroke. Following 49 operations (37.4%) with less significant SEP modifications, 4 patients suffered a post-operative stroke (8%). A stroke did not occur in the 48 (36.6%) operations during which there was not a variation in SEP. The strokes were related to temporary clipping in 9 patients to definitive clipping in 3 to sylvian fissure opening in 1 to brain retraction in and to dissection of the aneurysm in 1 (1 case). CONCLUSION: Changes in the SEP correlated well with the occurrence of post-operative stroke. This early detection of ischemia directs attention to the need for measures such as withdrawal of temporary clipping or identification of another factor (e.g. release of brain retraction or repositioning of an occlusive clip) so that the risk of post-operative is reduced.

Side-effects of subthalamic stimulation in Parkinson's disease: clinical evolution and predictive factors.

Chronic bilateral high-frequency stimulation of the subthalamic nucleus (STN) is an alternative treatment for disabling forms of Parkinson's disease when on-off fluctuations and levodopa-induced dyskinesias compromise patients' quality of life. The aim of this study was to assess the evolution of side-effects during the first year of follow-up and search for clinical predictive factors accounting for their occurrence. We compared the frequency of side-effects at 3 and 12 months after surgery in a cohort of 44 patients. The off-medication scores of Unified Parkinson's Disease Rating Scale (UPDRS) II, III, axial symptoms, disease duration and age at surgery were retained for correlation analysis. Dysarthria/hypophonia, weight gain and postural instability were the most frequent chronic side-effects. Whereas dysarthria/hypophonia remained stable over time, weight gain and postural instability increased during the first year post-op. High axial and UPDRS II scores at surgery were predictive of dysarthria/hypophonia. Age and axial score at surgery were positively correlated with postural instability. Despite the occurrence of side-effects, the benefit/side-effects ratio of STN stimulation was largely positive during the first year of follow-up. Age, intensity of axial symptoms and UDPRS II off-medication score before surgery are predictive factors of dysarthria/hypophonia and postural instability after surgery.

Evolution of postural stability after subthalamic nucleus stimulation in Parkinson's disease: a combined clinical and posturometric study.

OBJECTIVES: The occurrence of postural and balance disorders is a frequent feature in advanced forms of Parkinson's disease (PD). However, the pathological substrate of these disturbances is poorly understood. METHODS: In the present work, we investigated the evolution of posturometric parameters [center of pressure (CoP) displacement and CoP area] and axial scores between the pre-operative period and 3 months post-operative in seven PD patients who underwent bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN). RESULTS: After surgery, the patients leaned backwards much more regardless of the STN stimulation, suggesting that surgery could have a deleterious effect on postural adaptation. During the post-operative period, the improvement in axial and postural scores was similar under levodopatherapy and DBS. On the other hand, DBS of the STN significantly reduced the CoP displacement and the CoP area, whereas levodopatherapy tended only to reduce the CoP displacement and to increase the CoP area significantly. CONCLUSIONS: These data suggest that DBS of the STN and levodopa do not act on the same neurological systems involved in posture regulation. DBS of the STN could improve posture via a direct effect on the pedunculopontine nucleus, which is known to be involved in posture regulation.

[Botulinum toxin and traumatic brain injury]. / Toxine botulique et traumatisme crânien.

Botulinum toxin is a successful focal spasticity therapy. The aim of this article is to study the data of the literature concerning its utilisation in traumatic brain injured patients, whom motor and tonus disturbances are polymorphic, in their clinical presentation as well as in their evolution. Although there are few studies concerning its utilisation in such patients, none of them being controlled, its use seems interesting in focal spasticity treatment. It can contribute to improve functional abilities and comfort for these patients.

[Intrathecal baclofen and traumatic brain injury. A review]. / Le traitement par baclofène intrathécal chez le traumatise crânien grave. Revue de la littérature.

Severe head injury can induce hypertonia. There are two kinds of hypertonia related to severe injury. The most common one is a spasticity that occurs a long time after the head injury; the second is hypertonia that occurs during the early stage of the post-trauma recovery. Hypertonia is associated with other symptoms and defines post-trauma dysautonomia. Intrathecal baclofen can alleviate spasticity in severe head injury with improvement of the Ashworth score, spasm score or reflex score. But it also improves the number of paroxymal dysautonomic episodes. Real functional improvement is more difficult to show. To be effective, intrathecal baclofen therapy in brain injured patients needs high doses per day, through a spinal catheter in the mediothoracic region, and delivered at least continuously for a few hours to achieve a functional improvement.

[How can we define the modalities and clinical levels of coma to wakefulness?]. / Comment définir les modalités et les niveaux cliniques de passage du coma à l'éveil ?

OBJECTIVE: The starting point of the French conference of consensus concerning arousal after coma was to answer the following question: "How can we define the ways of going from coma to arousal and their clinical levels? MATERIALS AND METHOD: A team of readers have picked up in the literature one hundred and fifty papers, out of which fifty six have been analysed. RESULTS: From this analysis, three points emerged: The concepts of coma and arousal; The conditions of evolution from coma to arousal; Various groups of patients depending on their expressing arousal. One could not find any consensual model concerning the different ways of going from coma to arousal. The variability of the technics and the changing validity of all scores did not allow the conditions of arousal to reach a satisfactory level of proof. The Glasgow Coma Scale (GCS) is the recognised standard for severe wakefulness' impairment, but it is not sensitive enough while patients' arousing. The Glasgow Outcome Scale (GOS) takes into account the patients' situations far later and does not include situations such as Minimally Conscious States (MCS). That's why we face multiple scores, either ordinal, or categorial, all tending to evaluate the slow levels of arousal. CONCLUSION: Clinical findings concerning arousal are to be completed by non-clinical data. This would be greatly helpful to define appropriate management concerning individualized groups of patients. At this stage, another challenge for clinicians is to make the difference between emerging wakefulness and growing conscious activity.