Neurostimulation methods in the treatment of chronic pain.

The goal of this narrative review was to give an up-to-date overview of the peripheral and central neurostimulation methods that can be used to treat chronic pain. Special focus has been given to three pain conditions: neuropathic pain, nociplastic pain and primary headaches. Both non-invasive and invasive techniques are briefly presented together with their pain relief potentials. For non-invasive stimulation techniques, data concerning transcutaneous electrical nerve stimulation (TENS), transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), remote electrical neuromodulation (REN) and vagus nerve stimulation (VNS) are provided. Concerning invasive stimulation techniques, occipital nerve stimulation (ONS), vagus nerve stimulation (VNS), epidural motor cortex stimulation (EMCS), spinal cord stimulation (SCS) and deep brain stimulation (DBS) are presented. The action mode of all these techniques is only partly understood but can be very different from one technique to the other. Patients' selection is still a challenge. Recent consensus-based guidelines for clinical practice are presented when available. The development of closed-loop devices could be of interest in the future, although the clinical benefit over open loop is not proven yet.

Resection of cavernous angioma located in eloquent areas using functional cortical and subcortical mapping under awake conditions. Outcomes in a 50-case multicentre series.

INTRODUCTION: Surgical resection of supratentorial cavernous angiomas located in eloquent areas poses a significant risk to the patient of postoperative neurological impairment and justifies intraoperative functional monitoring. METHODS: Multicentre retrospective series of adult patients with cavernous angiomas located within eloquent areas and treated with functional-based surgical resection according to functional boundaries under intraoperative functional cortico-subcortical monitoring under awake conditions. RESULTS: Fifty patients (18 males, mean 36.3±10.8 year-old) underwent surgical resection with intraoperative cortico-subcortical functional mapping using direct electrostimulation under awake conditions for a cavernous angioma located in eloquent areas with a mean postoperative follow-up of 21.0±21.2 months. At presentation, the cavernous angioma had previously resulted in severe impairment (neurological deficit in 34%, seizures in 70%, uncontrolled seizures in 34%, reduced Karnofsky Performance Status score of 70 or less in 24%, inability to work in 52%). Functional-based surgical resection allowed complete removal of the cavernous angioma in 98% and of the haemosiderin rim in 82%. Postoperative seizures and other complications were rare, and similarly so across all centres included in this series. Postoperatively, we found functional improvement in 84% of patients (reduced Karnofsky Performance Status score of 70 or less in 6%, uncontrolled seizures in 16%, and inability to work in 11%). CONCLUSION: Functional-based surgical resection aids the safe and complete resection of cavernous angiomas located in eloquent areas while minimizing the surgical risks. Functional mapping has to be considered in such challenging cases.

[Neurosurgical treatment of chronic pain]. / Traitement neurochirurgical de la douleur chronique.

Neurosurgical treatment of pain used two kind of techniques: 1) Lesional techniques interrupt the transmission of nociceptive neural input by lesionning the nociceptive pathways (drezotomy, cordotomy, tractotomy…). They are indicated to treat morphine-resistant cancer pain and few cases of selected neuropathic pain. 2) Neuromodulation techniques try to decrease pain by reinforcing inhibitory and/or to limit activatory mechanisms. Chronic electrical stimulation of the nervous system (peripheral nerve stimulation, spinal cord stimulation, motor cortex stimulation…) is used to treat chronic neuropathic pain. Intrathecal infusion of analgesics (morphine, ziconotide…), using implantable pumps, allows to increase their efficacy and to reduce their side effects. These techniques can improve, sometimes dramatically, selected patients with severe and chronic pain, refractory to all other treatments. The quality of the analgesic outcome depends on the relevance of the indications.

Electrical modulation of neuronal networks in brain-injured patients with disorders of consciousness: a systematic review.

Six clinical studies of chronic electrical modulation of deep brain circuits published between 1968 and 2010 have reported effects in 55 vegetative or minimally conscious patients. The rationale stimulation was to activate the cortex through the reticular-thalamic complex, comprising the tegmental ascending reticular activating system and its thalamic targets. The most frequent intended target was the central intralaminar zone and adjacent nuclei. Hassler et al. also proposed to modulate the pallidum as part of the arousal and wakefulness system. Stimulation frequency varied from 8Hz to 250Hz. Most patients improved, although in a limited way. Schiff et al. found correlations between central thalamus stimulation and arousal and conscious behaviours. Other treatments that have offered some clinical benefit include drugs, repetitive magnetic transcranial stimulation, median nerve stimulation, stimulation of dorsal column of the upper cervical spinal cord, and stimulation of the fronto-parietal cortex. No one treatment has emerged as a gold standard for practice, which is why clinical trials are still on-going. Further clinical studies are needed to decipher the altered dynamics of neuronal network circuits in patients suffering from severe disorders of consciousness as a step towards novel therapeutic strategies.

[Subthalamic nucleus stimulation using a Fisher ZD stereotactic frame, MR-CT fusion guidance and peroperative orthogonal radiographs, in Parkinson disease]. / Evaluation de la stimulation du noyau sous-thalamique utilisant un cadre de Fischer adapté, un guidage par fusion IRM-scanner et un contrôle radiographique stéréotaxique peropératoire, dans la maladie de Parkinson.

BACKGROUND: We present the method and results of an original technique to implant electrodes in the subthalamic nucleus (STN) to treat Parkinson's disease, based on adaptations of the Fisher ZD stereotactic frame. METHODS: Targets coordinates were calculated after fusion of stereotactic CT-scan and MRI images. STN was localized by its theoretical coordinates according to AC-PC and by its direct visualization on T2 images. Electrodes were implanted after local anesthesia, using peroperative multicanal microrecordings and test stimulation. Electrodes location was checked by peroperative perpendicular radiographs. To avoid projection of the frame arm on the area of interest on anteroposterior and lateral radiographs, the arm was fixed at 45 degrees from the usual 90 degrees position. This original fixation needed a trigonometric transformation of the X and Y stereotactic coordinates. Radiopaque markers, fixed on the frame, were identified on the radiographs, allowing the calculation of the stereotactic coordinates of the electrode tip, which were then entered in the stereotactic MRI, to check its location from the defined target. RESULTS: No problem due to adaptations of the frame occurred in the 60 patients. In all cases, peroperative radiographs allowed to confirm the correct location of electrodes. Six months after surgery, UPDRS III score without medication was decreased by 52% with stimulation "on". UPDRS IV items 32, 33 and 39 scores were decreased by 75,7, 79,5 and 72%. Daily dopa-equivalent dose was decreased by 71%. One asymptomatic thalamic hematoma and two wound infections occurred. CONCLUSION: This method was efficient and safe to implant deep electrodes.

[Evaluation of measles, mumps and rubella vaccine coverage in 3 year old children in twelve French counties. Time-trends and related factors]. / Evaluation de la couverture vaccinale rougeole-oreillons-rubéole chez les enfants de trois ans dans douze départements français. Evolution temporelle et facteur associés.

BACKGROUND: The aims of our study were to estimate the measle-mumps-rubella (MMR) vaccine coverage in 3 years old children in 12 French countees, to document the evolution between 1997 and 1999 in two groups of 6 countees (pilot group and control group) before and after the implementation of promotion programmes in the pilot group, and to identify factors related to measle-mumps-rubella vaccination. METHODS: Two telephone surveys were carried out in 1997 and 1999 among children randomly selected in the birth rolls of 12 French countees. Parents of 3 years old children were interviewed on measle-mumps-rubella vaccination, knowledge and opinions on vaccinations, utilisation of health care and socio-demographic characteristics. RESULTS: The participation rate was 97% in both surveys. Among the 7382 respondent parents, 98% had immediate access to the child's medical file and could document the vaccine status. The vaccine coverage did not increase significantly between 1997 and 1999 (86.7% versus 87.2%), both in control (89.3% vs. 90.2%) and pilot groups (84.3% vs. 84.3%). A logistic regression model showed that several factors were independently and significantly related to measle-mumps-rubella vaccination (utilisation of homeopathic medicines, mother's age, number of children, physician speciality (general practitioner or pediatrician) and opinion on vaccinations). CONCLUSION: Our study shows that there is a stagnation of vaccine coverage in several French countees, which makes unlikely the national objective of viruses eradication. This epidemiological situation makes very likely outbreaks of measles, mumps and rubella in these countees. National and local pilot programmes did not succeed to promote vaccination in countees with a low measle-mumps-rubella vaccine coverage. Our study identified sub-groups of parents who should be targeted by promotion programmes.

[Treatment of central and neuropathic facial pain by chronic stimulation of the motor cortex: value of neuronavigation guidance systems for the localization of the motor cortex]. / Traitement des douleurs centrales et neuropathiques faciales par stimulation chronique du cortex moteur. Intêret des systèmes de neuronavigation pour le repérage du cortex moteur]

Thirty two patients with refractory central and neuropathic pain of peripheral origin were treated by chronic stimulation of the motor cortex between May 1993 and January 1997. The mean follow-up was 27. 3 months. The first 24 patients were operated according to the technique described by Tsubokawa. The last 13 cases (8 new patients and 5 reinterventions) were operated by a technique including localization by superficial CT reconstruction of the central region and neuronavigator guidance. The position of the central sulcus was confirmed by the use of intraoperative somatosensory evoked potentials. The somatotopic organisation of the motor cortex was established peroperatively by studying the motor responses at stimulation of the motor cortex through the dura. Ten of the 13 patients with central pain (77%) and nine of the 12 patients with neuropathic facial pain had experienced substantial pain relief (75%). One of the 3 patients with post-paraplegia pain was clearly improved. A satisfactory result was obtained in one patient with pain related to plexus avulsion and in one patient with pain related to intercostal herpes zoster. None of the patients developed epileptic seizures. The position of the stimulating poles effective on pain corresponded to the somatotopic representation of the motor cortex. The neuronavigator localization and guidance technique proved to be most useful identifying the appropriate portion of the motor gyrus. It also allowed the establishment of reliable correlations between electrophysiological-clinical and anatomical data which may be used to improve the clinical results and possibly to extend the indications of this technique.

Nonpharmacologic management of patient distress during mechanical ventilation.

Patients on mechanical ventilators experience distress related to the endotracheal tube, the critical care environment, and the critical illness. The strategies suggested here to limit distress--therapeutic relationship building and communication, cognitive-behavioral therapies, and contracted family visiting--all can be implemented by critical care providers. A growing research base documents the success of these interventions in intubated patients.