Central modulation in cluster headache patients treated with occipital nerve stimulation: an FDG-PET study
MAGIS, Delphine ; Bruno, Marie-Aurélie ; FUMAL, Arnaud et al
in BMC Neurology (2011), 11Detailed reference viewed: 31 (10 ULg)
Supraorbital transcutaneous neurostimulation has sedative effects in healthy subjects.
; ; SAVA, Simona Liliana et al
in BMC Neurology (2011), 11
BACKGROUND: Transcutaneous neurostimulation (TNS) at extracephalic sites is a well known treatment of pain. Thanks to recent technical progress, the Cefaly(R) device now also allows supraorbital TNS ... [more ▼]
BACKGROUND: Transcutaneous neurostimulation (TNS) at extracephalic sites is a well known treatment of pain. Thanks to recent technical progress, the Cefaly(R) device now also allows supraorbital TNS. During observational clinical studies, several patients reported decreased vigilance or even sleepiness during a session of supraorbital TNS. We decided therefore to explore in more detail the potential sedative effect of supraorbital TNS, using standardized psychophysical tests in healthy volunteers. METHODS: We performed a double-blind cross-over sham-controlled study on 30 healthy subjects. They underwent a series of 4 vigilance tests (Psychomotor Vigilance Task, Critical Flicker Fusion Frequency, Fatigue Visual Numeric Scale, d2 test). Each subject was tested under 4 different experimental conditions: without the neurostimulation device, with sham supraorbital TNS, with low frequency supraorbital TNS and with high frequency supraorbital TNS. RESULTS: As judged by the results of three tests (Psychomotor Vigilance Task, Critical Flicker Fusion Frequency, Fatigue Visual Numeric Scale) there was a statistically significant (p < 0.001) decrease in vigilance and attention during high frequency TNS, while there were no changes during the other experimental conditions. Similarly, performance on the d2 test was impaired during high frequency TNS, but this change was not statistically significant. CONCLUSION: Supraorbital high frequency TNS applied with the Cefaly(R) device decreases vigilance in healthy volunteers. Additional studies are needed to determine the duration of this effect, the underlying mechanisms and the possible relation with the stimulation parameters. Meanwhile, this effect opens interesting perspectives for the treatment of hyperarousal states and, possibly, insomnia. [less ▲]Detailed reference viewed: 13 (0 ULg)
Effects of light deprivation on visual evoked potentials in migraine without aura.
; Cremers, Julien ; GERARD, Pascale et al
in BMC Neurology (2011), 11
BACKGROUND: The mechanisms underlying the interictal habituation deficit of cortical visual evoked potentials (VEP) in migraine are not well understood. Abnormal long-term functional plasticity of the ... [more ▼]
BACKGROUND: The mechanisms underlying the interictal habituation deficit of cortical visual evoked potentials (VEP) in migraine are not well understood. Abnormal long-term functional plasticity of the visual cortex may play a role and it can be assessed experimentally by light deprivation (LD). METHODS: We have compared the effects of LD on VEP in migraine patients without aura between attacks (MO, n = 17) and in healthy volunteers (HV, n = 17). Six sequential blocks of 100 averaged VEP at 3.1 Hz were recorded before and after 1 hour of LD. We measured VEP P100 amplitude of the 1st block of 100 sweeps and its change over 5 sequential blocks of 100 responses. RESULTS: In HV, the consequence of LD was a reduction of 1st block VEP amplitude and of the normal habituation pattern. By contrast, in MO patients, the interictal habituation deficit was not significantly modified, although 1st block VEP amplitude, already lower than in HV before LD, further decreased after LD. CONCLUSIONS: Light deprivation is thought to decrease both excitatory and subsequent inhibitory processes in visual cortex, which is in line with our findings in healthy volunteers. The VEP results in migraine patients suggest that early excitation was adequately suppressed, but not the inhibitory mechanisms occurring during long term stimulation and habituation. Accordingly, deficient intracortical inhibition is unlikely to be a primary factor in migraine pathophysiology and the habituation deficit. [less ▲]Detailed reference viewed: 23 (7 ULg)
Visual fixation in the vegetative state: an observational case series PET study.
Bruno, Marie-Aurélie ; Vanhaudenhuyse, Audrey ; Schnakers, Caroline et al
in BMC Neurology (2010), 10
BACKGROUND: Assessment of visual fixation is commonly used in the clinical examination of patients with disorders of consciousness. However, different international guidelines seem to disagree whether ... [more ▼]
BACKGROUND: Assessment of visual fixation is commonly used in the clinical examination of patients with disorders of consciousness. However, different international guidelines seem to disagree whether fixation is compatible with the diagnosis of the vegetative state (i.e., represents "automatic" subcortical processing) or is a sufficient sign of consciousness and higher order cortical processing. METHODS: We here studied cerebral metabolism in ten patients with chronic post-anoxic encephalopathy and 39 age-matched healthy controls. Five patients were in a vegetative state (without fixation) and five presented visual fixation but otherwise showed all criteria typical of the vegetative state. Patients were matched for age, etiology and time since insult and were followed by repeated Coma Recovery Scale-Revised (CRS-R) assessments for at least 1 year. Sustained visual fixation was considered as present when the eyes refixated a moving target for more than 2 seconds as defined by CRS-R criteria. RESULTS: Patients without fixation showed metabolic dysfunction in a widespread fronto-parietal cortical network (with only sparing of the brainstem and cerebellum) which was not different from the brain function seen in patients with visual fixation. Cortico-cortical functional connectivity with visual cortex showed no difference between both patient groups. Recovery rates did not differ between patients without or with fixation (none of the patients showed good outcome). CONCLUSIONS: Our findings suggest that sustained visual fixation in (non-traumatic) disorders of consciousness does not necessarily reflect consciousness and higher order cortical brain function. [less ▲]Detailed reference viewed: 26 (4 ULg)
Abnormal cortical responses to somatosensory stimulation in medication-overuse headache.
; ; et al
in BMC neurology (2010), 10
BACKGROUND: Medication-overuse headache (MOH) is a frequent, disabling disorder. Despite a controversial pathophysiology convincing evidence attributes a pivotal role to central sensitization. Most ... [more ▼]
BACKGROUND: Medication-overuse headache (MOH) is a frequent, disabling disorder. Despite a controversial pathophysiology convincing evidence attributes a pivotal role to central sensitization. Most patients with MOH initially have episodic migraine without aura (MOA) characterized interictally by an absent amplitude decrease in cortical evoked potentials to repetitive stimuli (habituation deficit), despite a normal initial amplitude (lack of sensitization). Whether central sensitization alters this electrophysiological profile is unknown. We therefore sought differences in somatosensory evoked potential (SEP) sensitization and habituation in patients with MOH and episodic MOA. METHODS: We recorded median-nerve SEPs (3 blocks of 100 sweeps) in 29 patients with MOH, 64 with MOA and 42 controls. Episodic migraineurs were studied during and between attacks. We measured N20-P25 amplitudes from 3 blocks of 100 sweeps, and assessed sensitization from block 1 amplitude, and habituation from amplitude changes between the 3 sequential blocks. RESULTS: In episodic migraineurs, interictal SEP amplitudes were normal in block 1, but thereafter failed to habituate. Ictal SEP amplitudes increased in block 1, then habituated normally. Patients with MOH had larger-amplitude block 1 SEPs than controls, and also lacked SEP habituation. SEP amplitudes were smaller in triptan overusers than in patients overusing nonsteroidal anti-inflammatory drugs (NSAIDs) or both medications combined, lowest in patients with the longest migraine history, and highest in those with the longest-lasting headache chronification. CONCLUSIONS: In patients with MOH, especially those overusing NSAIDs, the somatosensory cortex becomes increasingly sensitized. Sensory sensitization might add to the behavioral sensitization that favors compulsive drug intake, and may reflect drug-induced changes in central serotoninergic transmission. [less ▲]Detailed reference viewed: 18 (1 ULg)
Diagnostic accuracy of the vegetative and minimally conscious state: clinical consensus versus standardized neurobehavioral assessment.
Schnakers, Caroline ; Vanhaudenhuyse, Audrey ; et al
in BMC Neurology (2009), 9
BACKGROUND: Previously published studies have reported that up to 43% of patients with disorders of consciousness are erroneously assigned a diagnosis of vegetative state (VS). However, no recent studies ... [more ▼]
BACKGROUND: Previously published studies have reported that up to 43% of patients with disorders of consciousness are erroneously assigned a diagnosis of vegetative state (VS). However, no recent studies have investigated the accuracy of this grave clinical diagnosis. In this study, we compared consensus-based diagnoses of VS and MCS to those based on a well-established standardized neurobehavioral rating scale, the JFK Coma Recovery Scale-Revised (CRS-R). METHODS: We prospectively followed 103 patients (55 +/- 19 years) with mixed etiologies and compared the clinical consensus diagnosis provided by the physician on the basis of the medical staff's daily observations to diagnoses derived from CRS-R assessments performed by research staff. All patients were assigned a diagnosis of 'VS', 'MCS' or 'uncertain diagnosis.' RESULTS: Of the 44 patients diagnosed with VS based on the clinical consensus of the medical team, 18 (41%) were found to be in MCS following standardized assessment with the CRS-R. In the 41 patients with a consensus diagnosis of MCS, 4 (10%) had emerged from MCS, according to the CRS-R. We also found that the majority of patients assigned an uncertain diagnosis by clinical consensus (89%) were in MCS based on CRS-R findings. CONCLUSION: Despite the importance of diagnostic accuracy, the rate of misdiagnosis of VS has not substantially changed in the past 15 years. Standardized neurobehavioral assessment is a more sensitive means of establishing differential diagnosis in patients with disorders of consciousness when compared to diagnoses determined by clinical consensus. [less ▲]Detailed reference viewed: 36 (4 ULg)
NG2 and phosphacan are present in the astroglial scar after human traumatic spinal cord injury.
; ; et al
in BMC Neurology (2009), 9
BACKGROUND: A major class of axon growth-repulsive molecules associated with CNS scar tissue is the family of chondroitin sulphate proteoglycans (CSPGs). Experimental spinal cord injury (SCI) has ... [more ▼]
BACKGROUND: A major class of axon growth-repulsive molecules associated with CNS scar tissue is the family of chondroitin sulphate proteoglycans (CSPGs). Experimental spinal cord injury (SCI) has demonstrated rapid re-expression of CSPGs at and around the lesion site. The pharmacological digestion of CSPGs in such lesion models results in substantially enhanced axonal regeneration and a significant functional recovery. The potential therapeutic relevance of interfering with CSPG expression or function following experimental injuries seems clear, however, the spatio-temporal pattern of expression of individual members of the CSPG family following human spinal cord injury is only poorly defined. In the present correlative investigation, the expression pattern of CSPG family members NG2, neurocan, versican and phosphacan was studied in the human spinal cord. METHODS: An immunohistochemical investigation in post mortem samples of control and lesioned human spinal cords was performed. All patients with traumatic SCI had been clinically diagnosed as having "complete" injuries and presented lesions of the maceration type. RESULTS: In sections from control spinal cord, NG2 immunoreactivity was restricted to stellate-shaped cells corresponding to oligodendrocyte precursor cells. The distribution patterns of phosphacan, neurocan and versican in control human spinal cord parenchyma were similar, with a fine reticular pattern being observed in white matter (but also located in gray matter for phosphacan). Neurocan staining was also associated with blood vessel walls. Furthermore, phosphacan, neurocan and versican were present in the myelin sheaths of ventral and dorsal nerve roots axons. After human SCI, NG2 and phosphacan were both detected in the evolving astroglial scar. Neurocan and versican were detected exclusively in the lesion epicentre, being associated with infiltrating Schwann cells in the myelin sheaths of invading peripheral nerve fibres from lesioned dorsal roots. CONCLUSION: NG2 and phosphacan were both present in the evolving astroglial scar and, therefore, might play an important role in the blockade of successful CNS regeneration. Neurocan and versican, however, were located at the lesion epicentre, associated with Schwann cell myelin on regenerating peripheral nerve fibres, a distribution that was unlikely to contribute to failed CNS axon regeneration. The present data points to the importance of such correlative investigations for demonstrating the clinical relevance of experimental data. [less ▲]Detailed reference viewed: 16 (1 ULg)
Matrix metalloproteinases and their inhibitors in human traumatic spinal cord injury.
; ; et al
in BMC Neurology (2007), 7
BACKGROUND: Matrix metalloproteinases (MMPs) are a family of extracellular endopeptidases that degrade the extracellular matrix and other extracellular proteins. Studies in experimental animals ... [more ▼]
BACKGROUND: Matrix metalloproteinases (MMPs) are a family of extracellular endopeptidases that degrade the extracellular matrix and other extracellular proteins. Studies in experimental animals demonstrate that MMPs play a number of roles in the detrimental as well as in the beneficial events after spinal cord injury (SCI). In the present correlative investigation, the expression pattern of several MMPs and their inhibitors has been investigated in the human spinal cord. METHODS: An immunohistochemical investigation in post mortem samples of control and lesioned human spinal cords was performed. All patients with traumatic SCI had been clinically diagnosed as having "complete" injuries and presented lesions of the maceration type. RESULTS: In the unlesioned human spinal cord, MMP and TIMP immunoreactivity was scarce. After traumatic SCI, a lesion-induced bi-phasic pattern of raised MMP-1 levels could be found with an early up-regulation in macrophages within the lesion epicentre and a later induction in peri-lesional activated astrocytes. There was an early and brief induction of MMP-2 at the lesion core in macrophages. MMP-9 and -12 expression peaked at 24 days after injury and both molecules were mostly expressed in macrophages at the lesion epicentre. Whereas MMP-9 levels rose progressively from 1 week to 3 weeks, there was an isolated peak of MMP-12 expression at 24 days. The post-traumatic distribution of the MMP inhibitors TIMP-1, -2 and -3 was limited. Only occasional TIMP immuno-positive macrophages could be detected at short survival times. The only clear induction was detected for TIMP-3 at survival times of 8 months and 1 year in peri-lesional activated astrocytes. CONCLUSION: The involvement of MMP-1, -2, -9 and -12 has been demonstrated in the post-traumatic events after human SCI. With an expression pattern corresponding largely to prior experimental studies, they were mainly expressed during the first weeks after injury and were most likely involved in the destructive inflammatory events of protein breakdown and phagocytosis carried out by infiltrating neutrophils and macrophages, as well as being involved in enhanced permeability of the blood spinal cord barrier. Similar to animal investigations, the strong induction of MMPs was not accompanied by an expression of their inhibitors, allowing these proteins to exert their effects in the lesioned spinal cord. [less ▲]Detailed reference viewed: 16 (2 ULg)