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Blink Reflex (blink + reflex)
Selected AbstractsSupraspinal Modulation of Trigeminal Nociception and PainHEADACHE, Issue 5 2009Amy E. Williams MA Objective., This study examined modulation of trigeminal pain/nociception by 2 supraspinal mechanisms: emotional controls of nociception and diffuse noxious inhibitory controls. Background., Prior research suggests emotional picture viewing (emotional controls) and tonic noxious stimuli (diffuse noxious inhibitory controls) engage supraspinal mechanisms to modulate pain and nociceptive processes. It is currently unknown, however, whether emotional controls modulate trigeminal pain and nociception. Additionally, the influences of emotional controls and diffuse noxious inhibitory controls have not been compared in the same group of participants. Methods., Noxious electrodermal stimuli were delivered to the trigeminal nerve using a concentric electrode designed to selectively activate nociceptive fibers. Trigeminal nociception and pain were assessed (34 participants) from the nociceptive blink reflex and pain ratings, respectively. Emotional controls were engaged by presentation of standardized picture stimuli (pleasant, neutral, and unpleasant) shown to reliably evoke pleasure-induced inhibition and displeasure-induced facilitation of pain and nociception. Diffuse noxious inhibitory controls were engaged with a forearm ischemia task. Results., Trigeminal pain (self-report ratings) and nociception (blinks) were facilitated by unpleasant pictures and inhibited by pleasant pictures. Emotion induction (as assessed from trend analysis) explained 51% of the variance in trigeminal pain and 25% of the variance in trigeminal nociception. Additionally, forearm ischemia inhibited trigeminal pain but not nociception. The baseline vs ischemia comparison explained 17% of the variance in pain report and 0.1% of the variance in blinks. Supraspinal modulation by emotional controls and diffuse noxious inhibitory controls were uncorrelated. Conclusions., Emotional controls and diffuse noxious inhibitory controls modulated trigeminal pain and emotional controls modulated trigeminal nociception. These procedures can be used to study supraspinal modulation of nociceptive processing in disorders of the trigeminal pain system, including headache. [source] Change of Excitability in Brainstem and Cortical Visual Processing in Migraine Exhibiting AllodyniaHEADACHE, Issue 10 2006Koichi Shibata MD Background.,Clinical and neurophysiological manifestations of information processing associated with central sensitization are little known. Allodynic migraine (AM) can be caused by the sensitization of trigeminal neuron, but no study has reported on AM between attacks using blink reflex (BR) and pattern-reversal visual evoked potentials (PVEPs). Objective.,We explored the characteristics of AM between attacks associated with central sensitization using BR and PVEP. Methods.,We recruited 13 patients with interictal AM and 15 patients with nonallodynic migraine (NA), and 30 healthy subjects (HS). BRs were obtained using paired pulses delivered at the interstimulus interval (ISI) of 150, 300, and 500 ms. The ratio of the area in the R2 of the second to R2 of the first shock was measured for each ISI. PVEP were recorded with 2 spatial frequencies (0.5 and 4.0 cpd) and 2 low and high contrasts (29% and 98%, respectively). Amplitudes of P100 were measured. Results.,For BR, there were no significant differences in the ratio of the area of the R2 between the sides of stimulation, and the sides of headache. AM patients had less suppression of the R2 at the ISI of 150 and 300 ms when compared with the NA patients and HS. For PVEP, at 0.5, there were significant differences of amplitude between AM patients and HS, and between NA patients and HS in low and high contrast. At 4.0 cpd, there were significant differences of amplitude between AM patients and HS in low contrast, and between AM patients and HS, and NA patients and HS in high contrast. In AM patients, there was a significant difference of amplitude ratio between 0.5 and 4.0 cpd. Conclusions.,Our BR and PVEP study showed that migraine patients exhibiting allodynia may show central sensitization of brainstem trigeminal neuron and have contrast modulating dysfunction during the cortical visual processing of striate and extrastriate on visual cortex in-between attacks. [source] Changes in blink reflex excitability after globus pallidus internus stimulation for dystoniaMOVEMENT DISORDERS, Issue 10 2006Stephen Tisch MBBS Abstract A pathophysiological feature of dystonia is reduced inhibition at various levels of the nervous system, which may be detected in clinically unaffected body parts. Chronic deep brain stimulation (DBS) of the globus pallidus internus (GPi) has emerged as an effective treatment for primary torsion dystonia (PTD), although its mechanism of action and impact on inhibitory abnormalities in dystonia are unknown. We sought to understand the effect of GPi DBS on brainstem excitability in patients with PTD. We measured the blink reflex from orbicularis oculi in response to paired electrical stimulation of the supraorbital nerve at interstimulus intervals of 500 and 1,000 milliseconds in 10 patients with PTD before and at intervals of 1, 3, and 6 months after bilateral GPi DBS and in 10 healthy subjects. Patients were clinically evaluated using the Burke,Fahn,Marsden dystonia rating scale. We found R2 inhibition was significantly decreased in PTD patients compared with control subjects and progressively increased after GPi DBS, which correlated with clinical improvement in dystonia. We conclude that GPi DBS for PTD results in functional reorganization of the nervous system, which includes a long-term increase in brainstem inhibition. © 2006 Movement Disorder Society [source] Features of the blink reflex in individuals at risk for Huntington's diseaseMUSCLE AND NERVE, Issue 11 2001Marina de Tommaso MD Abstract The aim of the study was to correlate the features of the blink reflex (BR) with the genetic abnormalities and the clinical findings in patients with Huntington's disease (HD) and asymptomatic gene carriers. Twenty patients with HD and 20 relatives were studied. Mutation analysis was performed for the CAG expansion within the HD gene using HD 333,HD 447 as oligonucleotide primers. The BR was elicited transcutaneously by electrical stimulation of the right supraorbital nerve. The recovery curve of the R2 and R3 responses after a conditioning stimulus was evaluated. R2 latency and duration and R3 duration were significantly increased in HD patients and in presymptomatic carriers in comparison with controls; reduced R2 recovery was also clear in both HD and gene-carrier relatives. In HD patients, the R2 latency increase correlated significantly with the severity of facial chorea. The R2 abnormalities are probably caused by impaired suprasegmental control by the basal ganglia over brainstem interneurons, which may precede the onset of involuntary movements, probably conditioning the severity of facial chorea during development of the disease. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1520,1525, 2001 [source] Startle potentiation in aversive anticipation: Evidence for state but not trait effectsPSYCHOPHYSIOLOGY, Issue 2 2002Jack B. Nitschke The present study was undertaken to determine whether aversiveness contributes to startle potentiation in anticipation of affective pictures above and beyond the effects of emotional arousal. Further, participants high in trait anxious apprehension, which is characterized by worry about the future, were expected to show especially pronounced anticipatory startle responses. Startle blink reflex was measured during warning stimuli that predicted the valence of ensuing aversive/unpleasant, pleasant, or neutral pictures. Startle magnitude was larger in anticipation of aversive than of pleasant pictures and smallest in anticipation of neutral pictures. Enhanced startle potentiation was not found in anxious apprehension subjects. These data suggest that the aversive nature of stimuli contribute to the potentiation of startle above and beyond the effects of emotional arousal, which may be a universal phenomenon not modulated by individual differences. [source] 1322: History of disease, facial nerve grading systems & clinical evaluationACTA OPHTHALMOLOGICA, Issue 2010I MAVRIKAKIS Obtaining an accurate history of the onset, progress and associated symptoms of newly acquired facial nerve palsy is extremely helpful in determining the potential cause of the palsy. More importantly it serves as a guide for prognosis and timing of any necessary surgical intervention. Acute versus chronic facial nerve palsy, complete versus incomplete facial nerve palsy, recovery and recurrence of the disease will be discussed. The gold standard for grading facial nerve function is the House-Brackmann grading scale. Due to the limitations and subjectivity of this scale, several new scales of various degrees of objectivity and ease of use have been introduced. These include the Nottingham system, the Sunnybrook scale, the Yanagihara and the Sydney system, all with their advantages and disadvantages. Clinical evaluation of a patient with facial nerve palsy include evaluation of upper eyelid retraction, blink reflex, lagophthalmos, brow ptosis, paralytic ectropion, midface ptosis, mouth symmetry, platysma muscle strength, hearing, corneal sensation, Bell's phenomenon, tear function and synkinesis. [source] Visual signs and symptoms of Parkinson's diseaseCLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 2 2008Richard A Armstrong DPhil Parkinson's disease (PD) is a common disorder of middle-aged and elderly people, in which there is degeneration of the extra-pyramidal motor system. In some patients, the disease is associated with a range of visual signs and symptoms, including defects in visual acuity, colour vision, the blink reflex, pupil reactivity, saccadic and smooth pursuit movements and visual evoked potentials. In addition, there may be psychophysical changes, disturbances of complex visual functions such as visuospatial orientation and facial recognition, and chronic visual hallucinations. Some of the treatments associated with PD may have adverse ocular reactions. If visual problems are present, they can have an important effect on overall motor function, and quality of life of patients can be improved by accurate diagnosis and correction of such defects. Moreover, visual testing is useful in separating PD from other movement disorders with visual symptoms, such as dementia with Lewy bodies (DLB), multiple system atrophy (MSA) and progressive supranuclear palsy (PSP). Although not central to PD, visual signs and symptoms can be an important though obscure aspect of the disease and should not be overlooked. [source] Clinical relevance of electrophysiological tests in the assessment of patients with Huntington's diseaseMOVEMENT DISORDERS, Issue 6 2002Jean-Pascal Lefaucheur MD Abstract Assessment programs recently designed to follow-up patients with Huntington's disease (HD) in therapeutic trials have not included electrophysiological testing in the list of mandatory examinations. This omission is likely due to the current lack of data establishing a clear correlation between the electrophysiological results and those of clinical assessment. We address this issue in a cohort of 36 patients at relatively early stages of the disease (I and II). Electrophysiological studies comprised the recording of palmar sympathetic skin responses (SSRs), blink reflexes (BRs), thenar long latency reflexes (LLRs), cortical somatosensory evoked potentials (SEPs), and electromyographic silent periods evoked by transcranial magnetic stimulation (SPs). Results were analyzed with reference to disease duration and staging and to specific cognitive, psychiatric, and motor alteration. SEPs were the most and very sensitive markers, because they were abnormal in 94% of patients. Except for LLRs, alteration of electrophysiological results increased in parallel to the evolution of the disease. Except for LLRs and SSR latency, electrophysiological results correlated with those of specific clinical examinations. In particular, an increased BR latency or a reduced amplitude of the N20 component of SEPs correlated with the extent of bradykinesia, whereas a reduced amplitude of SSRs or of the N30 component of SEPs correlated with hyperkinesia. Overall, electrophysiological tests, in particular SEPs and BRs, appeared sensitive and interesting in the follow-up of HD patients and correlated with various clinical parameters, suggesting that these easy to perform and noninvasive repeatable examinations could be added fruitfully to the assessment programs for HD. © 2002 Movement Disorder Society [source] Blepharoclonus and Arnold,Chiari malformationACTA NEUROLOGICA SCANDINAVICA, Issue 2 2001M.D. Daniel E. Jacome Objective, Blepharoclonus (BLC) denotes a large amplitude, involuntary tremors of the orbicularis oculi muscles, observed during gentle closure of the eyelids. BLC may follow major head trauma. Four patients with Arnold,Chiari malformation (ACM) and BLC are described. Materials and methods, The first patient had facial numbness for 5 months; the remaining patients had headaches following minor head or cervical spinal injuries. Brain magnetic resonance imaging (MRI), electroencephalogram (EEG) blink reflexes, mental and facial nerve responses and facial electromyogram (EMG) were performed. Results, All patients exhibited ACM on brain MRI. The first patient had coincidental dural venous malformation, empty-sella turcica and familial digital dysplasia. She exhibited oculopterygoid synkinesis. The last 3 patients had posttraumatic headache; the second and third patients had limited features of Ehlers,Danlos syndrome (EDS). The second patient had cervical spinal fusion and the fourth a cervical syrinx. All the patients had BLC on gentle eyelid closure. Conclusion, BLC is an underdiagnosed neuro-ophthalmological sign of ACM. [source] | ||||||||||