GABAergic pathway in a rat model of chronic neuropathic pain: modulation after intrathecal transplantation of a human neuronal cell line.

Current understanding of chronic pain points a decrease in level of the inhibitory neurotransmitter GABA, in the spinal dorsal horn, leading to an imbalance between excitatory and inhibitory pathways. A subcloned derivative of the human NT2 cell line (hNT2.17) which, after neuronal differentiation, secretes different inhibitory neurotransmitters such as GABA and glycine has been recently isolated. In this study, we have investigated the effect of this new cell line on peripheral nerve injury induced by chronic constriction (CCI) and notably the effect on the cellular GABAergic pathway. Our data show that the decrease in GABA expression in the spinal dorsal horn of injured animals is concomitant with a decline of its synthetic enzyme GAD67-Ir and mRNA but not GAD65. Interestingly, in transplanted animals we observed a strong induction of GAD67 mRNA with one week after graft, which is followed by a recovery of GAD67 and GABA Ir. This effect paralleled a reduction of hindpaw hypersensitivity and thermal hyperalgesia induced by CCI. These results suggest that hNT2.17 GABA cells can modulate neuropathic pain after CCI certainly by minimizing the imbalance and restoring the cellular GABAergic pathway.

[Dosimetric stereotactic radiosurgical accident: Study of 33 patients treated for brain metastases]. / Traitement des métastases cérébrales par radiochirurgie stéréotaxique : étude de 33 cas liés à un accident de "surexposition".

The consequences of a dosimetric radiosurgery accident are not the same as a conventional radiotherapy accident. The objective of this study was to estimate the clinical and radiological outcome of patients treated by radiosurgery for metastasis during the period of the overexposure accident that occurred in the Toulouse Radiosurgery Unit. Between April 2006 and March 2007, 33 patients with 57 metastases were treated in the Toulouse Radiosurgery Unit (Novalis(®), BrainLab). An initial error in the estimation of the scatter factors led to an overexposure to radiation. The median age was 55 years [range, 35-85]. Twenty-one patients (64%) harbored a single metastasis. The primary tumor location was lung (16 cases), kidney (nine cases), breast (four cases), and others (four cases). The mean tumoral volume was 3.2cm(3) [0.04-14.07]. The mean prescribed dose at the isocenter was 20 Gy [range, 10-23], the mean delivered dose was 31.5 Gy [range, 13-52], and the mean overdose was 61.2% [range, 5.6-226.8]. In order to evaluate the consequences of the overdose, three parameters were analyzed: a risk index using dose and volume, the volume of parenchyma that received more than 12 Gy, and the mean dose in a sphere of 20cm(3) surrounding the target volume. Median actuarial survival was 14.1 months, the survival rate was 79.4 % at six months, 59.1% at 12 months, and 27.2% at 24 months. The rate of tumor control was 80.7%. No morbidity was observed. There was no correlation between death and the parameters studied. The survival rates and times observed in our study of the patients treated for brain metastases by radiosurgery and overexposed were among the good results of the international literature. Deaths were not related to the overdose and no side effect was noted. This dosimetric accident has not had worse consequences in this population.

Motor cortex stimulation for neuropathic pain.

Since the initial publication of Tsubokawa in 1991, epidural motor cortex stimulation (MCS) is increasingly reported as an effective surgical option for the treatment of refractory neuropathic pain although its mechanism of action remains poorly understood. The authors review the extensive literature published over the last 15 years on central and neuropathic pain. Optimal patient selection remains difficult and the value of pharmacological tests or transcranial magnetic stimulation in predicting the efficacy of MCS has not been established. Pre-operative functional magnetic resonance imaging (fMRI), 3-dimensional volume MRI, neuronavigation and intra-operative neurophysiological monitoring have contributed to improvements in the technique for identifying the precise location of the targeted motor cortical area and the correct placement of the electrode array. MCS should be considered as the treatment of choice in post-stroke pain, thalamic pain or facial anesthesia dolorosa. In brachial plexus avulsion pain, it is preferable to propose initially dorsal root entry zone (DREZ)-tomy; MCS may be offered after DREZotomy has failed to control the pain. In our experience, the results of MCS on phantom limb pain are promising. In general, the efficacy of MCS depends on: a) the accurate placement of the stimulation electrode over the appropriate area of the motor cortex, and b) on sophisticated programming of the stimulation parameters. A better understanding of the MCS mechanism of action will probably make it possible to adjust better the stimulation parameters. The conclusions of multicentered randomised studies, now in progress, will be very useful and are likely to promote further research and clinical applications in this field.

Viability and functionality of bovine chromaffin cells encapsulated into alginate-PLL microcapsules with a liquefied inner core.

Implantation of adrenal medullary bovine chromaffin cells (BCC), which synthesize and secrete a combination of pain-reducing neuroactive compounds including catecholamines and opioid peptides, has been proposed for the treatment of intractable cancer pain. Macro- or microencapsulation of such cells within semipermeable membranes is expected to protect the transplant from the host's immune system. In the present study, we report the viability and functionality of BCC encapsulated into microcapsules of alginate-poly-L-lysine (PLL) with a liquefied inner core. The experiment was carried out during 44 days. Empty microcapsules were characterized in terms of morphology, permeability, and mechanical resistance. At the same time, the viability and functionality of both encapsulated and nonencapsulated BCC were evaluated in vitro. We obtained viable BCC with excellent functionality: immunocytochemical analysis revealed robust survival of chromaffin cells 30 days after isolation and microencapsulation. HPLC assay showed that encapsulated BCC released catecholamines basally during the time course study. Taken together, these results demonstrate that viable BCC can be successfully encapsulated into alginate-PLL microcapsules with a liquefied inner core.

Cell therapy of pain: Characterization of human fetal chromaffin cells at early adrenal medulla development.

Adult adrenal chromaffin cells are being utilized for therapeutic transplantation. With the prospect of using fetal chromaffin cells in pain therapy, we studied their phenotype, proliferative power, function, and growth in vitro and in situ in order to determine the optimal time for implantation. Between 7 and 10 gestational weeks (GW), we isolated, in vitro, two types of chromaffin cells with a noradrenergic phenotype akin to that observed, in situ. Among the adherent chromaffin cells first observed in vitro, only a few samples expressed met-enkephalin, whereas almost all the neurosphere-like colonies, which appeared later, expressed it. However, neither of the two types of populations expressed an adrenergic phenotype in line with that observed in situ. At the upper limits of the voluntary abortion period authorized in France, this phenotype (12 GW) and met-enkephalin expression (13 GW) were evidenced in situ. For the first time in man, we demonstrate the secretion of noradrenaline in vitro by the two populations of cells. Consistent with this result, we also noted dopamine beta hydroxylase (DbetaH) mRNA expression in vitro and in situ within this period. These observations on the expression of these biological factors indicate that 9-10 GW would be the best stage for sampling these cells for preclinical transplantation experiments.

Intrathecal grafting of porcine chromaffin cells reduces formalin-evoked c-Fos expression in the rat spinal cord.

Chromaffin cells from the adrenal gland secrete a combination of neuroactive compounds including catecholamines, opioid peptides, and growth factors that have strong analgesic effects, especially when administered intrathecally. Preclinical studies of intrathecal implantation with xenogeneic bovine chromaffin cells in rats have provided conflicting data with regard to analgesic effects, and recent concern over risk of prion transmission has precluded their use in human clinical trials. We previously developed a new, safer source of adult adrenal chromaffin cells of porcine origin and demonstrated an in vivo antinociceptive effect in the formalin test, a rodent model of tonic pain. The goal of the present study was to confirm porcine chromaffin cell analgesic effects at the molecular level by evaluating neural activity as reflected by spinal cord c-Fos protein expression. To this end, the expression of c-Fos in response to intraplantar formalin injection was evaluated in animals following intrathecal grafting of 10(6) porcine or bovine chromaffin cells. For the two species, adrenal chromaffin cells significantly reduced the tonic phases of the formalin response. Similarly, c-Fos-like immunoreactive neurons were markedly reduced in the dorsal horns of animals that had received injections of xenogeneic chromaffin cells. This reduction was observed in both the superficial (I-II) and deep (V-VI) lamina of the dorsal horn. The present study demonstrates that both xenogeneic porcine and bovine chromaffin cells transplanted into the spinal subarachnoid space of the rat can suppress formalin-evoked c-Fos expression equally, in parallel with suppression of nociceptive behaviors in the tonic phase of the test. These findings confirm previous reports that adrenal chromaffin cells may produce antinociception by inhibiting activation of nociceptive neurons in the spinal dorsal horn. Taken together these results support the concept that porcine chromaffin cells may offer an alternative xenogeneic cell source for transplants delivering pain-reducing neuroactive substances.

[Cost-benefit evaluation of spinal cord stimulation treatment for failed-back surgery syndrome patients]. / Evaluation coût/bénéfice du traitement des lombosciatalgies post-operatoires par stimulation médullaire.

BACKGROUND AND PURPOSE: Spinal cord stimulation is a well-known treatment of rigorously selected failed-back surgery syndrome patients. Efficacy levels over 50% of pain relief have been reported in long-term studies. The objective of this multicenter prospective evaluation was to analyze the cost to benefit ratio of spinal cord stimulation treatment for failed back surgery syndrome patients. METHODS: Nine hospitals (pain evaluation and treatment centers) were involved in the study. Forty-three patients were selected and implanted between January 1999 and January 2000. For each patient, pre- and post-operative evaluations (6, 12 and 24 months after implantation) were performed to assess pain relief and economical impact on pain treatment costs. RESULTS: After 24 months, mean 60% pain relief was achieved as assessed with the neuropathic pain score using a Visual Analog Scale (success rate=70%), whereas low-back pain was moderately reduced (29%). The Oswestry Disability questionnaire score was improved by a mean 39%. Costs of pain treatment (medication, consultation, other) are reduced by a mean 64% (1705 Euro) per patient per year. CONCLUSIONS: This study confirms a clear analgesic effect on neuropathic sciatalgia, and moderate attenuation of low-back pain. One particular interest of this study is the medico-economic prospective evaluation showing that the initial cost of the implanted device is compensated by a significant, early, and stable reduction in the cost of associated pain therapies.

Grafts of immortalized chromaffin cells bio-engineered to improve met-enkephalin release also reduce formalin-evoked c-fos expression in rat spinal cord.

Transplantation of adrenal medullary tissue for terminal cancer pain has been tested clinically, but this approach is not practical for routine use because of the shortage of organ donors and lack of tissue homogeneity. As a first alternative step, we have generated immortalized chromaffin cells over-expressing opioid peptides, namely met-enkephalin. Rat chromaffin cells have been genetically modified with vectors containing expression cassettes with either synthetic met-enkephalin or pro-enkephalin gene coding regions, fused with the nerve growth factor signal peptide for secretion. After stable transfection and differentiation in vitro, met-enkephalin and pro-enkephalin cells had higher met-enkephalin immunoreactivity and secreted met-enkephalin levels, compared to control cells containing the expression vector only. In the formalin hindpaw-injection model, 15 days after subarachnoid transplant of cells, grafts of met-enkephalin and pro-enkephalin cells significantly reduced the number of formalin-evoked c-fos immunoreactive spinal neurons in the spinal cord, compared to grafts of vector-alone chromaffin cells. The use of such expandable cell lines, for chronic spinal delivery of opiates, could offer an attractive and safe alternative strategy based on ex vivo gene therapy for the control of opioid-sensitive chronic pain.

Intrathecal xenogeneic chromaffin cell grafts reduce nociceptive behavior in a rodent tonic pain model.

Adrenal medullary chromaffin cells synthetize and secrete a combination of pain-reducing neuroactive compounds including catecholamines and opioid peptides. Previous reports have shown that implantation of chromaffin cells into the spinal subarachnoid space can reduce both acute and chronic pain in several animal models. We recently demonstrated that human chromaffin cell grafts in the cerebrospinal fluid (CSF) could alleviate intractable cancer pain after failure of systemic opiates. However, wider application of this approach was limited by the limited availability of allogeneic donor material. Alternatively, chromaffin cells from xenogeneic sources such as bovine adrenal medulla were successful in the experimental treatment of pain, but recent concern over risk of prion transmission precluded use of bovine grafts in human clinical trials. The objective of the present study was to investigate the possibility of developing a new xenogeneic porcine source of therapeutic chromaffin cells because this strategy is currently considered the safest for transplantation in man. In the present study, we report the isolation and the characterization of primary porcine chromaffin cells (PCC) compared to bovine cells. We show, for the first time, that these cells grafted in the rat subarachnoid space can attenuate pain-related behaviors as assessed by the formalin test, a model of tonic pain. Moreover, in addition to behavioral studies, immunohistochemical analysis revealed robust survival of chromaffin cells 35 days after transplantation. Taken together, these results support the concept that porcine chromaffin cells may offer an alternative xenogeneic cell source for transplants delivering pain-reducing neuroactive substances.

[Intrathecal baclofen. Experimental and pharmacokinetic studies]. / Baclofène intrathecal. Historique, preuves expérimentales, et données pharmacocinétiques.

Baclofen, the most effective drug to treat spasticity, is a specific agonist of gamma-aminobutyric acid-B receptors, and is very abondant in the superficial layers of the spinal cord. Given orally, baclofen does not easily penetrate the blood-barrier, and is distributed equally to the brain and spinal cord. After oral administration of baclofen, the drug is resorbed by more than 80-90% in the stomach and bowel and is eliminated by urinary excretion. Failure of oral medication to produce sufficient relief of spasticity is due to the poor passage of the drug across the blood-brain barrier. In animals the concentration in brain is less than 1/10 of the blood levels. The problem of insufficient anti-spastic efficacy (in relation to the rate of side-effects) after systemic medication may be overcome by local application in spinal CSF. Direct intrathecal administration of baclofen in the treatment of severe spasticity was proposed in 1984 by Richard Penn with the objective to carry out a selective spinal distribution of the active principle thus avoiding supraspinal side effects. The pharmacokinetics of baclofen in animal and man after intrathecal administration have been investigated to determine the CSF pharmacokinetic parameters.

Deep brain stimulation for parkinson's disease: correlation between intraoperative subthalamic nucleus neurophysiology and most effective contacts.

Though intraoperative neurophysiology is essential to precisely define the definitive target, little is known regarding its predictive value in defining the most effective contact for chronic deep brain stimulation. In this retrospective study, we reviewed the correlation between intraoperative neurophysiology and contacts selected for chronic stimulation. Twenty consecutive patients implanted for subthalamic nucleus (STN) stimulation were reviewed. There was no significant correlation between the electrophysiologically defined STN and the most effective contact for chronic stimulation at 3 months or at 6 months. Furthermore, there was a discrepancy between the most effective contact for rigidity versus akinesia or tremor at 3 months. Interestingly, at 3 months, the same electrode contact was maximally efficient for rigidity, akinesia and tremor in only 13 of the 39 cases. This lack of correlation did not affect the global improvement.

[Feasability of a back school assessment programme]. / Etude de faisabilité dun programme dévaluation de lécole du dos.

OBJECTIVES: Testing the feasability of a back school assessment programme in two populations of people suffering with chronic low back pain. MATERIAL: Twenty-nine patients were randomly included in a chronic low back pain assessment programme (15 patients waiting for back school and 14 patients after back school). METHODS: The programme was made of the measure of the age, the sex, the body mass index, the pain (VAS, St Antoine Hospitals Pain Questionnaire - SAPQ), the anxiety, the depression, the RIII nociceptive reflex, the fingertip-floor distance, the strength of the flexors and of the extensors of the lumbar spine (CybexR 6000 isocinetic dynamometer), the lumbar function (EIFEL, Dougados), the Dallas self-questionnaire. The Back School Education programme was made of five sessions (information, ergonomics, extension exercises). RESULTS: Comparing the two populations we did not observe significant differences concerning the age, the body mass index, the anxiety and depression levels, the pain (VAS, SAPA, RIII nociceptive reflex), the lumbar stiffness, the lumbar disability, the quality of life; the patients who had achieved back school had a peak torque of the flexors and a ratio flexors/extensors significantly lower. Comparing men and women we observed significant differences in the SAPQ and the muscles strength. The SAPQ was correlated with the depression and anxiety levels, the lumbar disability, the peak torque of the flexors. The VAS was correlated with the age, the lumbar stiffness, the depression level, the peak torque of the flexors. The RIII nociceptive reflex was correlated with the ratio flexors/extensors. CONCLUSION: This study present some biases but this objective assessment of chronic low back pain appeared as feasible. The pain must be investigated in term of intensity, expression, alleviation. The impairment of the flexors muscles in women and after back school has to be confirmed. The different tests are relevant to determinate the efficiency of the back school programmes.

The surgical management of spasticity.

Neurosurgery is only considered for severe spasticity following the failure of noninvasive management (adequate medical and physical therapy). The patients are carefully selected, based on rigorous multidisciplinary clinical assessment. In this we evaluate the contribution of the spasticity to the disability and any residual voluntary motor function. The goals for each patient are: (a) improvement of function and autonomy; (b) control of pain; and (c) prevention of orthopaedic disorders. To achieve these objectives, the surgical procedure must be selective and reduce the excessive hypertonia without suppressing useful muscle tone and limb functions. The surgical procedures are: (1) Classical neuro-ablative techniques (peripheral neurotomies, dorsal rhizotomies) and their modern modifications using microsurgery and intra-operative neural stimulation (dorsal root entry zone: DREZotomy). These techniques are destructive and irreversible, with the reduced muscle tone reflecting the nerve topography. It is mainly indicated when patients have localized spasticity without useful mobility. (2) Conservative techniques based on a neurophysiological control mechanism. These procedures are totally reversible. The methods involve chronic neurostimulation of the spinal cord or the cerebellum. There are only a few patients for whom this is indicated. Conversely, chronic intrathecal administration of baclofen, using an implantable pump, is well established in the treatment of diffuse spasticity of spinal origin. From reports in the literature, we critically review the respective indications in terms of function, clinical progression and the topographic extent of the spasticity.

[Use of auditory brain stem implant in a patient with bilateral vestibular schwannoma (type 2 neurofibromatosis]. / Ispol'zovanie slukhovogo implanta stvola golovnogo mozga u bol'nogo s bilateral'noi vestibuliarnoi shvannomoi (neirofibromatoz 2-go tipa).

Surgical technique and functional results of implantation of the acoustic implant of the brain stem (BS) are described for a 16-year-old patient with bilateral vestibular shvannoma (neurofibromatosis of type 2). Initially, a large (IV degree) tumor was removed from the left cerebellopontile angle using the translabyrinthine-transcochlear approach. The function of the facial nerve recovered completely. The BS implant was implanted a year later in the course of removing shvannoma from the right cerebellopontile angle using the above approach. The patient received 22-channel implant Nucleus-CI22M. Speech intelligibility improved by 90-100%. BS implantation is today the only effective method of reestablishment of acoustic sensations in patients with bilateral destruction of the acoustic nerves due to bilateral vestibular shvannoma.

Virtual movements activate primary sensorimotor areas in amputees: report of three cases.

OBJECTIVE: In our multidisciplinary pain clinic, three patients with amputated limbs and with surgical indications for chronic motor cortex stimulation for phantom limb pain were selected for their ability to voluntarily move the missing limb. The sensation of being able to move a missing limb at will occurs quite frequently among traumatic amputees, but the ability to control it sufficiently to perform a functional magnetic resonance imaging (fMRI) examination is more rarely encountered. We used motor fMRI to study these virtual movements. METHODS: In two patients with upper-limb amputations, movements of the stump, the normal hand, and the missing arm were studied. In a third patient with both legs amputated, movements of the stumps and of the missing feet were studied. The fMRI data were analyzed with the Statistical Parametric Map 96 software and reformatted for integration into anatomic slices. RESULTS: Virtual movements of the missing limbs produced contralateral primary sensorimotor cortex and central sulcus activations in the patients with upper-limb amputation. Interhemispheric and bilateral activations were found in the patient with both legs amputated. These activation areas were different from the stump activation areas. Additionally, the significance thresholds chosen to generate the activation maps in virtual movements (although individual) were globally the same as those used to detect motor activation in the normal side of the patients. CONCLUSION: Cortical areas devoted to the missing limb seem to persist for several years after amputation. The precentral activations found in our patients are in agreement with the statement that the neural mechanisms involved in the mental representation of an action and in its execution are the same. Data from fMRI can be used to evaluate phantom limb virtual movements and to study cortical reorganization phenomena that can appear with time or as a result of some therapies. In these patients, fMRI data may be useful in assisting the neurosurgeon in the placement of chronic motor cortex electrodes.

A new method for encapsulation of living cells: preliminary results with PC12 cell line.

A new method is described for encapsulation of living cells. PC12 rat adrenal pheochromocytoma cells, which have been shown to synthesize, store and release dopamine were employed. The particles are made first and the cells then incorporated in a gentle mechanical procedure. The morphology (by light and electron microscopic observation), stability, rheology, texture and permeability of these microcapsules provided by Kappa Biotech were investigated. Membrane permeability studies demonstrated exclusion of 69,000 Da human serum albumin, but equilibrium of D-glucose and inulin was within 24h, indicating a molecular weight cut-off in the 5000-70,000 Da range. The viability and the function of the encapsulated cells were evaluated by measuring the spontaneous release of dopamine by high performance liquid chromatography with electrochemical detection. The results show that dopamine-secreting cells can be sequestered in a semi-permeable capsule and still display good viability and proliferation for at least 1 month.

Chronic motor cortex stimulation for phantom limb pain: a functional magnetic resonance imaging study: technical case report.

OBJECTIVE AND IMPORTANCE: Chronic motor cortex stimulation has provided satisfactory control of pain in patients with central or neuropathic trigeminal pain. We used this technique in a patient who experienced phantom limb pain. Functional magnetic resonance imaging (fMRI) was used to guide electrode placement and to assist in understanding the control mechanisms involved in phantom limb pain. CLINICAL PRESENTATION: A 45-year-old man whose right arm had been amputated 2 years previously experienced phantom limb pain and phantom limb phenomena, described as the apparent possibility of moving the amputated hand voluntarily. He was treated with chronic motor cortex stimulation. INTERVENTION: Data from fMRI were used pre- and postoperatively to detect shoulder and stump cortical activated areas and the "virtual" amputated hand cortical area. These sites of preoperative fMRI activation were integrated in an infrared-based frameless stereotactic device for surgical planning. Phantom limb virtual finger movement caused contralateral primary motor cortex activation. Satisfactory pain control was obtained; a 70% reduction in the phantom limb pain was achieved on a visual analog scale. Postoperatively and under chronic stimulation, inhibiting effects on the primary sensorimotor cortex as well as on the contralateral primary motor and sensitive cortices were detected by fMRI studies. CONCLUSION: Chronic motor cortex stimulation can be used to relieve phantom limb pain and phantom limb phenomena. Integrated by an infrared-based frameless stereotactic device, fMRI data are useful in assisting the neurosurgeon in electrode placement for this indication. Pain control mechanisms and cortical reorganization phenomena can be studied by the use of fMRI.

Chronic motor cortex stimulation for phantom limb pain: correlations between pain relief and functional imaging studies.

Chronic motor cortex stimulation (CMCS) has provided satisfactory control of pain in patients with central or trigeminal neuropathic pain. We used this technique in 3 patients with intractable phantom limb pain after upper limb amputation. Functional magnetic resonance imaging (fMRI) correlated to anatomical MRI permitted frameless image guidance for electrode placement. Pain control was obtained for all the patients initially and the relief was stable in 2 of the 3 patients at 2 year follow-up. CMCS can be used to relieve phantom limb pain. fMRI data are useful in assisting the neurosurgeon in electrode placement for this indication.