Robot-Guided Neuronavigated Repetitive Transcranial Magnetic Stimulation (rTMS) in Central Neuropathic Pain.

OBJECTIVES: To confirm and extend previous results involving repetitive transcranial magnetic stimulation (rTMS) aimed at alleviating refractory central neuropathic pain (CNP). To evaluate pain relief in detail and to assess ongoing benefits after one year of treatment. DESIGN: Prospective observational study. SETTING: University hospital. Outpatient settings. PARTICIPANTS: Patients (N=80) with chronic central pain after brain or spinal cord injuries. INTERVENTIONS: High-frequency (20Hz) neuronavigated-rTMS sessions were applied on the primary motor cortex using a figure-of-eight coil positioned by a robotized arm. Patients received a minimum of 4 consecutive sessions, each separated by 3-4 weeks. MAIN OUTCOME MEASURES: Percentage of pain relief (%R), duration of pain relief (DPR), numeric rating scale (NRS), neuropathic pain symptom inventory (NPSI), and pain relief score (PRS). RESULTS: Seventy-one patients completed the study. On average, after the first 4 sessions, %R was 28% and DPR was 11 days. Fifty-four patients (76%) were responders with a permissive threshold of ≥10%R and 61% (43 patients) with a stringent threshold ≥30%R. After 12 months of treatment (15 sessions) we observed a cumulative effect on %R (48%), DPR (20d), and on the prevailing NPSI sub-score (-28%). This effect reached significance after 4 sessions and was further maintained over 12 months. Across participants, more than 1000 rTMS sessions were delivered over 6 years without any adverse effect. CONCLUSION: These results confirm that multiple rTMS sessions are both safe and have potential as a treatment for CNP. An ongoing randomized controlled trial will allow teasing out of this effect from placebo analgesia.

Thalamic pain: anatomical and physiological indices of prediction.

Thalamic pain is a severe and treatment-resistant type of central pain that may develop after thalamic stroke. Lesions within the ventrocaudal regions of the thalamus carry the highest risk to develop pain, but its emergence in individual patients remains impossible to predict. Because damage to the spino-thalamo-cortical system is a crucial factor in the development of central pain, in this study we combined detailed anatomical atlas-based mapping of thalamic lesions and assessment of spinothalamic integrity using quantitative sensory analysis and laser-evoked potentials in 42 thalamic stroke patients, of whom 31 had developed thalamic pain. More than 97% of lesions involved an area between 2 and 7 mm above the anterior-posterior commissural plane. Although most thalamic lesions affected several nuclei, patients with central pain showed maximal lesion convergence on the anterior pulvinar nucleus (a major spinothalamic target) while the convergence area lay within the ventral posterior lateral nucleus in pain-free patients. Both involvement of the anterior pulvinar nucleus and spinothalamic dysfunction (nociceptive thresholds, laser-evoked potentials) were significantly associated with the development of thalamic pain, whereas involvement of ventral posterior lateral nucleus and lemniscal dysfunction (position sense, graphaesthesia, pallaesthesia, stereognosis, standard somatosensory potentials) were similarly distributed in patients with or without pain. A logistic regression model combining spinothalamic dysfunction and anterior pulvinar nucleus involvement as regressors had 93% sensitivity and 87% positive predictive value for thalamic pain. Lesion of spinothalamic afferents to the posterior thalamus appears therefore determinant to the development of central pain after thalamic stroke. Sorting out of patients at different risks of developing thalamic pain may be achievable at the individual level by combining lesion localization and functional investigation of the spinothalamic system. As the methods proposed here do not need complex manipulations, they can be added to routine patients' work up, and the results replicated by other investigators in the field.

Effects of aging on laser evoked potentials.

INTRODUCTION: Aging has been reported to reduce the amplitude of laser evoked potentials. However, it is unknown whether this effect depends on the length of the sensory fibers. This is an important issue, because most painful neuropathies are length-dependent. METHODS: We conducted a study of 40 healthy subjects, half of whom were older than age 50 years. Nociceptive stimuli were delivered to the feet and thighs using a CO2 laser stimulator. RESULTS: Detection and pain perception thresholds did not correlate with age. Latencies of N1, N2, and P2 correlated positively with age on the feet but not on the thighs, whereas the amplitude of N2-P2 decreased with age for both areas. CONCLUSIONS: The effects of aging on latencies may reflect a distal loss of peripheral inputs and a length-dependent de-synchronization of the ascending nociceptive volley. Additional changes in peripheral and central processes may explain the diffuse decrease of N2-P2 amplitudes observed with aging.

Screening and management of sleep disorders in patients with fibromyalgia syndrome: a French multicentred, prospective, observational study protocol (FIBOBS).

INTRODUCTION: Sleep disorders are still often underestimated in patient care management even though they are present in the criteria of the American College of Rheumatology for the diagnosis of fibromyalgia syndrome (FMS). The objective of this study will be to assess the current situation of sleep disorders in patients with FMS in France and to estimate its prevalence. METHODS AND ANALYSIS: The FIBOBS study is a multicentred, prospective, observational trial performed by 46 specialised chronic pain structures in France. Patients with FMS visiting for a first consultation or follow-up (if they have already been followed up for less than a year with a pain management service) will be included after giving their informed consent. Data will be collected through the physician questionnaire filled during the inclusion visit. Patient self-questionnaires will be completed from home. The primary outcome of the study will be to estimate the prevalence of sleep disorders classified into three categories: (a) poor sleep quality in general, (b) sleep apnoea syndrome and (c) restless legs syndrome, using self-administered questionnaires. ETHICS AND DISSEMINATION: This protocol is approved by the ethics committee Comité de Protection des Personnes 'Ile de France II' in accordance with French regulations. The results will be disseminated through peer-reviewed journals and conferences. TRIAL REGISTRATION NUMBER: NCT04775368.

Ketamine in chronic pain: A Delphi survey.

BACKGROUND: There is no recommendation in Europe for the use of ketamine in patients with chronic pain. The heterogeneity of practice highlights the need to seek the advice of experts in order to establish a national consensus. This Delphi survey aimed to reach a national consensus on the use of ketamine in chronic pain in Pain clinics. METHODS: A collaborative four-round internet-based questionnaire was used. It was created after literature search on ketamine administration in chronic pain and included about 96 items. It discussed utility and advantages, adverse events and deleterious aspects, methods of administration, concomitant treatments and assessment of results. RESULTS: Twenty-eight experts completed all rounds of the survey with a total of 81.3% items reaching a consensual answer. Neuropathic pain represents the first indication to use ketamine, followed, with a good to moderate utility, by other situations (fibromyalgia, complex regional pain syndrome, central neuropathic pain, peripheral neuropathic pain, nociceptive pain, sensitization, opioid withdrawal, palliative care, depression). Experts agreed on the rare occurrence of adverse events. Concerning routes of administration, intravenous infusion with doses of 0.5-0.9 mg/kg/d for 4 days of treatment is preferred. Place of care is hospital, as in- or out-patient, with a quarterly administration of ketamine. Finally, ketamine effectiveness is assessed 1 month after infusion, and experts encourage combination with non-pharmacological treatment. CONCLUSIONS: This Delphi survey established a consensus of pain specialists on the use of ketamine in refractory chronic pain, thus providing a basis for future comparative trials. SIGNIFICANCE: This Delphi survey in chronic pain reached agreement on four main aspects: (1) Priority to treat neuropathic pain with evaluation of effectiveness at 1 month; (2) No deleterious effects in the majority of listed diseases/situations with the absence or <3% of suggested adverse events; (3) 0.5-0.9 mg/kg/d IV infusion; (4) Combination with non-pharmacological treatment.

Operculo-insular pain (parasylvian pain): a distinct central pain syndrome.

Central pain with dissociated thermoalgesic sensory loss is common in spinal and brainstem syndromes but not in cortical lesions. Out of a series of 270 patients investigated because of somatosensory abnormalities, we identified five subjects presenting with central pain and pure thermoalgesic sensory loss contralateral to cortical stroke. All of the patients had involvement of the posterior insula and inner parietal operculum. Lemniscal sensory modalities (position sense, graphaestesia, stereognosis) and somatosensory evoked potentials to non-noxious inputs were always preserved, while thermal and pain sensations were profoundly altered, and laser-evoked potentials to thermo-nocoiceptive stimuli were always abnormal. Central pain resulting from posterior parasylvian lesions appears to be a distinct entity that can be identified unambiguously on the basis of clinical, radiological and electrophysiological data. It presents with predominant or isolated deficits for pain and temperature sensations, and is paradoxically closer to pain syndromes from brainstem lesions affecting selectively the spinothalamic pathways than to those caused by focal lesions of the posterior thalamus. The term 'pseudo-thalamic' is therefore inappropriate to describe it, and we propose parasylvian or operculo-insular pain as appropriate labels. Parasylvian pain may be extremely difficult to treat; the magnitude of pain-temperature sensory disturbances may be prognostic for its development, hence the importance of early sensory assessment with quantitative methods.

Efficiency of an Optimized Care Organization in Fibromyalgia Patients: The From Intent to Move (FIMOUV) Study Protocol of a Randomized Controlled Trial.

Introduction: Fibromyalgia (FM) is characterized by multiple symptoms including pain, fatigue, and sleep disorders, altering patient's quality of life. In the absence of effective pharmacological therapy, the last European guidelines recommend a multidisciplinary management based on exercise and education. Thus, our main objective was to measure the effectiveness of a healthcare organization offering a specific program of adapted physical activity combined with a therapeutic education program for FM patients. Methods and Analysis: The From Intent To Move (FIMOUV) study will recruit 330 FM patients randomized into two groups: test and control. The test group will benefit from a 1-month mixed exercise training program supervised at the hospital, followed by 2 months in a community-based relay in a health-sport structure. In addition, each of the two groups will benefit from therapeutic patient education sessions. The main endpoint is the measurement of the level of physical activity by accelerometry at 1 year. The secondary endpoints concern adherence to the practice of physical activity, impact on lifestyle, state of health, and physical capacity, as well as an estimate of the budgetary impact of this management strategy. Discussion: This interventional research will allow us to assess the evolution of behaviors in physical activity after an FM syndrome management based solely on patient education or based on a supervised and adapted practice of physical activity associated with this same therapeutic education program. It seems to be the first study evaluating the impact of its intervention on objective data for measuring physical activity and sedentary behavior via accelerometry among FM patients. Trial registration: ClinicalTrials.gov NCT04107948.

Positional cluster-like headache. A case report of a neurovascular compression between the third cervical root and the vertebral artery.

Symptomatic cluster-like headaches have been described with lesions of the trigeminal and parasympathetic systems. Here, we report the case of a 44-year-old woman with continuous auricular pain and a positional cluster-like headache associated with red ear syndrome. Clinical data and morphological investigations raised the hypothesis of a neurovascular compression between the C3 root and vertebral artery. Neurosurgical exploration found a fibrosis surrounding both the C3 root and the vertebral artery. The excellent outcome after microvascular cervical decompression suggests a causal relationship between the cluster-like headache and the vertebral constraint on the C3 root.

A hidden mesencephalic variant of central pain.

BACKGROUND: Central post-stroke pain (CPSP) can arise after lesions anywhere in the central somatosensory pathways, essentially within the spinothalamic system (STS). Although the STS can be selectively injured in the mesencephalon, CPSP has not been described in pure midbrain infarcts. METHODS: Of more than 300 CPSP consecutive cases, we describe five patients who developed definite neuropathic pain following lesions circumscribed to the postero-lateral mesencephalon. RESULTS: The mesencephalic lesion responsible for pain was always haemorrhagic and always involved the spinothalamic tract (STT), as demonstrated by suppressed laser-evoked potentials in every case, with or without preserved lemniscal function. In three cases the midbrain injury could be ascribed to trauma, presumably from the cerebellar tentorium. As a result of the paucity of sensory symptoms, the pain was considered as 'psychogenic' in two of the patients until electrophysiological testing confirmed STT involvement. CONCLUSION: Postero-lateral midbrain lesions should be added to potential causes of CPSP. Because pain and spinothalamic deficits may be the only clinical sign, and because small lateral midbrain lesions may be difficult to trail with MRI, mesencephalic CPSP can be misdiagnosed as malingering or psychogenic pain for years. SIGNIFICANCE: Selective spinothalamic injury caused by small lateral midbrain lesions is a very rare cause of central post-stroke pain that can remain undiagnosed for years. It appears to obey to haemorrhagic, sometimes post-traumatic lesions. Sudden development of contralateral burning pain with isolated spinothalamic deficits may be the only localizing sign, which can be easily objectively detected with electrophysiological testing.

New procedure of high-frequency repetitive transcranial magnetic stimulation for central neuropathic pain: a placebo-controlled randomized crossover study.

Repetitive transcranial magnetic stimulation (rTMS) is a procedure increasingly used to treat patients with central neuropathic pain, but its efficacy is still under debate. Patients with medically refractory chronic central neuropathic pain were included in 2 randomized phases (active/sham), separated by a wash-out period of 8 weeks. Each phase consisted of 4 consecutive rTMS sessions and a final evaluation session, all separated from one another by 3 weeks. High-frequency (20 Hz) rTMS was delivered over the primary motor cortex (M1) contralateral to the patient's pain using a neuronavigated robotic system. Patients and clinicians assessing outcomes were blinded to treatment allocation during the trial. The primary outcome measured the percentage of pain relief (%R) from baseline. Secondary outcomes were VAS score, Neuropathic Pain Symptom Inventory, analgesic drug consumption, and quality of life (EQ-5D). Thirty-six patients performed the entire study with no adverse effects. The analgesic effect for the main criterion (%R) was significantly higher in the active (33.8% confidence interval [CI]: [23.88-43.74]) than in the sham phase (13.02% CI: [6.64-19.76]). This was also the case for the secondary outcome VAS (-19.34% CI: [14.31-25.27] vs -4.83% CI: [1.96-8.18]). No difference was observed for quality of life or analgesic drug consumption. Seventeen patients (47%) were identified as responders, but no significant interaction was found between clinical and technical factors considered here and the analgesic response. These results provide strong evidence that 3 weeks spaced high-frequency rTMS of M1 results in a sustained analgesic effect and support the clinical interest of this stimulation paradigm to treat refractory chronic pain.

One or several types of triptan overuse headaches?

BACKGROUND: Whereas the clinical features of pure triptan overuse headache (TOH) are well known, there are insufficient data regarding the semiological pattern of headaches when triptan overuse is associated with other types of medication overuse. OBJECTIVE: To investigate and compare the clinical characteristics of patients with pure TOH and those with medication overuse headaches associating triptan and other medication overuses (combined TOH). METHODS: This cross-sectional, observational study was conducted in 7 tertiary-care headache centers participating in the French Observatory of Migraine and Headaches. From 2004 to 2006, data from 163 patients with TOH were collected in face-to-face structured interviews (according to the International Classification of Headache Disorders, 2nd edition criteria). RESULTS: Eighty-two patients fulfilled criteria for pure TOH (pTOH patients) and 81 for combined TOH (cTOH) patients. Continuous headaches were reported in 76% of cTOH patients compared with 32% of pTOH patients. Significantly more frequent and severe headaches and more intense phono-/photophobia between attacks were noted in cTOH patients. More cTOH than pTOH patients reported a history of tension-type headaches and a long-standing history of chronic headaches. Finally, compared with pTOH patients, cTOH patients were characterized by stronger dependence on acute treatments of headaches according to the DSM-IV criteria. CONCLUSIONS: Combined therapy with analgesics and/or the total number of drug units taken per day may cause a shift from a pattern of clear-cut headache attacks in patients with pTOH toward more severe clinical presentation in patients with cTOH. These patients should receive more intensive prophylactic therapy and specific behavioral management.

Behavioral dependence in patients with medication overuse headache: a cross-sectional study in consulting patients using the DSM-IV criteria.

OBJECTIVE: The aim of this study was to assess behavioral dependence on migraine abortive drugs in medication-overuse headache (MOH) patients and identify the predisposing factors. BACKGROUND: It is common occurrence that MOH patients relapse after medication withdrawal. Behavioral determinants of medication overuse should therefore be identified in MOH patients. METHODS: This was a cross-sectional, multicenter study that included 247 MOH patients (according to International Classification of Headache Disorders, 2nd edition criteria) consulting in French headache specialty centers. Face-to-face interviews were conducted by senior neurologists using a structured questionnaire including the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) criteria for the evaluation of dependence, Hospital Anxiety and Depression Scale for the evaluation of anxiety and depression, and 6-item short-form Headache Impact Test scale for the determination of functional impact. RESULTS: Most MOH patients had pre-existing primary migraine (87.4%) and current migraine-type headaches (83.0%). Treatments overused included triptans (45.8%), opioid analgesics alone or in combination (43.3% of patients), and analgesics (27.9%). Nonmigraine abortive substances (tobacco, caffeine, sedatives/anxiolytics) were overused by 13.8% of patients. Two-thirds of MOH patients (66.8%) were considered dependent on acute treatments of headaches according to the DSM-IV criteria. Most dependent MOH patients had migraine as pre-existing primary headache (85.7%) and current migraine-type headaches (87.9%), and most of them overused opioid analgesics. More dependent than nondependent MOH patients were dependent on psychoactive substances (17.6% vs 6.1%). Multivariate logistic analysis indicated that risk factors of dependence on acute treatments of headaches pertained both to the underlying disease (history of migraine, unilateral headaches) and to drug addiction (opioid overuse, previous withdrawal). Affective symptoms did not appear among the predictive factors of dependence. CONCLUSION: In some cases, MOH thus appears to belong to the spectrum of addictive behaviors. In clinical practice, behavioral management of MOH should be undertaken besides pharmacological management.

Elderly Patients with Ongoing Migraine Show Reduced Gray Matter Volume in Second Somatosensory Cortex.

AIMS: To identify structural changes in gray matter in suspected migraine generators (the hypothalamus and/or brainstem nuclei) and pain pathways and to evaluate whether structural changes in migraine are definitive or resolve with age. METHODS: Voxel-based morphometry (VBM) was used to assess differences in gray matter between 39 healthy controls (HC), 25 episodic migraine (EM) subjects, and 37 subjects with a history of migraine (HM). In addition, morphometric changes were specifically investigated in suspected migraine generators and/or pain pathways. For statistical analyses, t tests between the groups were performed, and a correction for multiple comparisons was used. RESULTS: Whole-brain analysis did not reveal any gray or white matter changes. However, when the analysis was limited to the pain matrix, a lower gray matter volume was observed in the left second somatosensory (SII) cortex in EM subjects compared to HC subjects. This volume was significantly reduced in the EM group compared to the HC group and to the HM group, but not in the HM group compared to the HC group. CONCLUSION: Morphometric abnormalities in the SII in subjects with ongoing migraine but not in subjects with a resolved migrainous disease are likely to characterize a migrainous state rather than be a marker of brain susceptibility to migraine.

How a clock can change your pain? The illusion of duration and pain perception.

The intensity of experimental pain is known to be dependent on stimulation duration. However, it remains unknown whether this effect arises largely from the actual stimulus duration or is substantially influenced by the subject's perception of the stimulus duration. In the present study, we questioned this issue by misleading the perception of the duration of pain in a population of 36 healthy volunteers stimulated with a thermode. To this aim, time was signified by a clock with rotating hands in which imperceptible differences in speed rotation had been introduced. Subjects were therefore immersed in 2 comparative conditions in which time was manipulated to provide the illusion of either long or short duration of the painful stimulus. In a first condition ("full-length" clock), participants were instructed that pain would last for a complete revolution of the clock's hands, whereas in the second condition ("shortened" clock), revolution was reduced by 25%. Although the intensity and the real duration of stimulation were identical in both conditions, the intensity of pain was significantly reduced when the perception of time was misleadingly shortened by the manipulated clock. This study suggests that the perceived duration of a noxious stimulation may influence the perceived intensity of pain. The perceived duration of the length of a noxious stimulation influences (decreases) the intensity of perceived pain.

Sensory and motor neuronopathy in a patient with the A382P TDP-43 mutation.

Patients with TARDBP mutations have so far been classified as ALS, sometimes with frontal lobe dysfunction. A 66-year-old patient progressively developed a severe sensory disorder, followed by a motor disorder, which evolved over nine years. Symptoms started in the left hand and slowly involved the four limbs. Investigations were consistent with a mixed sensory and motor neuronopathy. A heterozygous change from an alanine to a proline at amino acid 382 was identified in exon 6 of the TARDPB gene (p.A382P). This case expands the phenotypic spectrum associated with mutations in the TARDBP gene and shows that sensory neurons can be severely damaged early in the course of the disease, following a propagating process, with an orderly progression from a focal starting point. A combination of severe sensory and motor neuronopathy is rarely encountered in clinical practice. The possibility of an A382P TDP-43 mutation should be considered in patients with such an association.

De novo artistic activity following insular-SII ischemia.

We report here the case of a female patient who developed the following behavioural changes after a brain lesion involving the left posterior insula and SII cortices. She discovered de novo artistic capabilities for painting, with an episodic and compulsive need to paint ("hyperpainting"), but also exhibited changes in her ability to feel emotions. In addition, she had a typical neuropathic pain syndrome, including provoked pain and spontaneous pain, whose intensity was worsened when she painted with cold colours. This case-report suggests some kind of synaesthesiae, which has previously been reported for other sensory modalities. These findings suggest that a cross-talk between emotional, thermosensory, pain, and motivational functions may take place during recovery, at the level of the left insular-SII cortices.

Construction of a medication dependence questionnaire in headache patients (MDQ-H) validation of the French version.

OBJECTIVES: To construct and validate a questionnaire measuring dependence on analgesics and on migraine attack treatments in headache patients. METHOD: The items were obtained using the Diagnostic and Statistic Manual of Mental Disorders (4th ed.) (DSM-IV) diagnostic criteria for dependence. The construct validity of the scale was investigated by confirmatory analysis in a sample of 156 patients. Regression analysis was used to explore predictive validity. RESULTS: The 21 items of the scale were grouped into seven first-order factors corresponding to seven dependence items described in the DSM-IV. There was a second-order factor that may be considered as a general dependence factor. The global questionnaire score predicted the number of units of treatment taken per week, the number of days of headache, the number of days medications were taken, and emotional distress. Patients with headache associated with chronic substance use had a significantly higher score (P < .000) than migraine and tension headache patients. CONCLUSION: It is a practical and valid tool for measuring medication dependence, including the behavioral dimension of dependence, in patients with headache associated with chronic substance use. It can prevent patients and clinicians from only focusing on pharmacological dependence.