The blink reflex in "chronic migraine".

OBJECTIVES: Activation of the trigeminovascular system and sensitisation of brainstem trigeminal nuclei are thought to play an important role in migraine. The aim of this study was to investigate the blink reflex and its habituation in patients with "chronic migraine". METHODS: We studied 35 patients suffering from "chronic migraine" (IHS classification criteria) outside and during a spontaneous attack, and 35 control subjects. An EMG device with a specific habituation test program was used to elicit and record blink reflex responses and to randomly repeat stimulations at different time intervals so as to induce habituation. RESULTS: The R(1) and R(2) latencies, amplitudes and areas of the basal blink reflex were similar in patients studied both outside and during an attack as well as in control subjects, whereas the blink reflex habituation responses were markedly reduced in patients studied outside an attack. The percent changes in the R(2) areas from the baseline values, obtained when stimuli were delivered at time intervals of 10, 5, 4, 3, 2 and 1s, were statistically different (p<0.01-p<0.001) from those of the same patients studied during a migraine attack and of those of control subjects. There was a significant correlation between decreased habituation of the blink reflex and a higher frequency of attacks. The stimulus intensities of the blink reflex (multiples of the detection threshold intensities) were significantly lower (p<0.001) on the side affected, or more severely affected, by headache in patients studied during a migraine attack. CONCLUSIONS: The decreased habituation of the blink reflex outside an attack reflects abnormal excitability in "chronic migraine", which normalizes during the attacks. The inverse correlation between the frequency of attacks and habituation responses confirms the abnormal excitability induced by the high frequency of attacks. Central sensitisation mechanisms (allodynia) may explain the lower detection thresholds observed on the side affected by headache in patients during the attacks. SIGNIFICANCE: The blink reflex and its habituation may help shed light on the subtle neurophysiological changes that occur in migraine patients between and during attacks.     

Variability of the blink reflex in patients with migraine

Background and purposeSensitization of brainstem trigeminal nuclei and activation of the trigeminovascular system are thought to play an important role in migraine. The blink reflex has become a valuable tool for investigating trigeminal nerve function. The aim of the study was to assess the differences in electrophysiological examinations of the trigeminal nerve (blink reflex) in a group of patients with migraine in comparison with a healthy control group.Material and methodsThe examination was conducted among 58 patients. Patients were diagnosed in the Polyclinic or hospitalized in the Department of Neurology of Warsaw Medical University in Bielański Hospital. The study group included 29 patients suffering from migraine (diagnosed according to the International Classification of Headache Disorders, 2^nd edition) and 29 patients without headaches served as controls. All patients underwent neurological examination and magnetic resonance imaging to identify organic disorders. The blink reflex was tested among all patients in accordance with electrophysiological laboratory standards.ResultsThe latency of the R1 response was significantly shorter among patients with migraine. The latency of R2 and R2’ responses was similar in patients and controls. A significant inverse correlation was observed between latency of R2 and R2’ responses and frequency of migraine attacks.ConclusionsThe inverse correlation between the frequency of attacks and the latency of R2 and R2’ responses of the blink reflex confirms the abnormal eaxcitability induced by the high frequency of migraine attacks.     

Pupillary responses and blink reflex in myotonic dystrophy

Research Paper We have studied pupillary responses to parasympathetic and sympathomimetic agents, pupillary cycle time and the electrophysiology of the blink reflex in 18 patients with myotonic dystrophy. The response of the iris to dilute pilocarpine and phenylephrine did not indicate pharmacologic supersensitivity. Pupillary cycle time was prolonged in nine of the 18 patients. Ipsilateral R₁ blink reflex latencies were normal in all cases, and bilateral R₂ were normal in 16 of the 18 patients. These results do not support either autonomic or brainstem dysfunction in the majority of patients with myotonic dystrophy. In 50% of the patients the results are compatible with smooth muscle involvement of the iris.     

The human blink reflex

A detailed study of the human blink reflex in the different parts of the orbicularis oculi muscle has been carried out. The first component of the blink reflex has been demonstrated in patients with Friedreich's ataxia, who have selective loss of large sensory fibres resulting in loss of proprioceptive input. It has been established that both components of the blink reflex are cutaneous reflexes which represent a highly organized and purposeful mechanism in man. Afferent fibres for the blink reflex have been identified in the human supraorbital nerve and their conduction velocity has been estimated for the first time in man. It has been demonstrated that both components of the blink reflex are mediated by the same group of afferent fibres.     

Decreased habituation of the R2 component of the blink reflex in migraine patients.

OBJECTIVE: Activation of the trigemino-vascular system as well as of brainstem trigeminal nuclei are thought to play an important role in migraine. The aim of this study was to investigate the habituation phenomenon of the blink reflex in 30 headache-free migraine patients and 30 control subjects. METHODS: An electromyographic device with a specific habituation test program was used to elicit and record blink reflex responses on both the right and left sides, and to randomly repeat the stimulations at different time intervals in order to induce habituation. RESULTS: Whereas the R1 and R2 latencies, amplitudes and areas in the basal assessment were similar in patients and control subjects, the blink reflex habituation responses were markedly reduced in migraine patients who had a migraine attack within 72 h after testing (group A). In these patients, the differences between the R2 areas, obtained when stimuli were delivered at subsequent time intervals ranging between 10-5, 5-4, 4-3 and 3-2 s, were statistically different (P<0.001) from those of the patients who had a migraine attack after a longer time interval (group B) and control subjects. CONCLUSIONS: Our data suggest that the brainstem pathways involved in the blink reflex may be activated in the premonitory phase of migraine attacks, probably through mechanisms that involve dopaminergic function.     

The corneal reflex and the R2 component of the blink reflex

A reflex contraction of the human orbicularis oculi muscles can be evoked by stimulation of either the supraorbital region ("blink reflex") or the cornea ("corneal reflex"). We found that the latency of the corneal reflex was longer, and the duration was longer than the R2 component of the blink reflex. The absolute refractory period of the R2 component of the blink reflex was longer after supraorbital than after corneal conditioning stimulation. When the R2 component of the blink reflex was habituated by repetitive stimuli, stimulation of the cornea still evoked a reflex, but supraorbital stimulation produced only a depressed R2 response. These findings suggest that the two reflexes do not have identical neural connections.     

Comparative study of pain perception and polysynaptic blink reflex responses in man

Stimulation of the first trigeminal branch using a 10 ms train of 5 pulses of 0.1 ms duration is performed on 17 healthy subjects (19-65 years of age) in order to assess the relationship between polysynaptic components of the blink reflex and perceptive and pain thresholds (ths). The mean value of tactile ths (Pth) is 2.22 +/- 0.86 mA; while R2, R3 and pain threshold values are 1.25 +/- 0.34, 3.52 +/- 1.94 and 4.78 +/- 2.77 times the Pth respectively. The pain ths average is 1.47 +/- 0.92 with regard to the R3 threshold. The R2 ths are very close to those of tactile perception, while those of R3 appear significantly related to the pain ths.     

The blink reflex in chronic renal failure

Summary The components of the electrically elicited blink reflex were investigated in 15 patients who were admitted to a chronic dialysis program because of chronic renal insufficiency with serum creatinine concentrations from 6.0 to 14.2 mg/dl. In addition, the conduction time in the facial nerve, the motor conduction velocities, and the distal motor latencies of the median and peroneal nerves were measured.In 13 of 15 patients (87%) there was at least one component of the blink reflex pathologically delayed. Bilateral prolongation of the latency of the component R₁ was seen most frequently. In all pathological cases the distribution pattern of the responses revealed dysfunction in the brainstem. Correlating the values of blink reflex latencies, the period of dialysis, the values of serum creatinine and urea nitrogen, and the results of peripheral neurography, there was a significant relationship between the motor conduction velocity of the peroneal nerve and the latency of the early component R₁. The value of these findings in reference to the known neurological symptomatology in chronic renal failure is discussed.

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Zusammenfassung Bei 15 Patienten, die wegen einer chronischen Niereninsuffizienz in einem Dauerdialyseprogramm standen und Serumkreatininwerte zwischen 6,0 und 14,2 mg/dl aufwiesen, wurden die Komponenten des elektrisch ausgelösten Blinkreflexes untersucht. Zusätzlich erfolgte die Bestimmung der Leitungszeit des N. facialis sowie der motorischen Nervenleitgeschwindigkeit und der distalen motorischen Latenz des N. medianus und N. peronaeus.Bei 13 von 15 Patienten (87%) ließen eine oder mehrere Komponenten des Blinkreflexes eine pathologische Verzögerung erkennen. Am häufigsten zeigte sich eine beidseitige Latenzverlängerung der Komponente R₁. In sämtlichen pathologischen Fällen konnte aufgrund des Verteilungsmusters der Reflexantworten eine Funktionsstörung im Bereich des Hirnstammes angenommen werden. Korrelationsberechnungen zwischen den Latenzwerten des Blinkreflexes, der bisherigen Dialysedauer, den Serumwerten von Kreatinin und Harnstoff sowie den Ergebnissen der peripheren Neurographie ergaben einen bedeutsamen Zusammenhang zwischen der motorischen Leitgeschwindigkeit des N. peronaeus und der Latenz der frühen Komponente R₁. Die Wertigkeit dieser Befunde im Rahmen der bekannten neurologischen Symptomatik bei der chronischen Niereninsuffizienz wird diskutiert.

     

The blink reflex: maturation and modification in the neonate

The onset and development of the delayed blink response, elicited by a tap to the glabella, and its modification by an acoustic stimulus (tone), were studied longitudinally in 36 healthy preterm and 43 term infants. Blink amplitude increased with gestational age. By term postconceptional age, the responses of the preterm infants to tap alone, and to both tap and tone, were not significantly different from those of the term infants. These results suggest that neurological development, as reflected by the blink reflex and its modification, proceeds in an orderly, sequential fashion and that the mechanisms affecting these brainstem processes are not altered by environmental influences.     

精神分裂症瞬目反射诱发电位研究

目的:探讨精神分裂症患者瞬目反射特征性变化。方法:对48例精神分裂症患者及41例正常对照组运用KEYPOINT2000型肌电诱发电位仪进行BR检测。结果:精神分裂症患者的左侧R2、R2′潜伏期以及右侧R2、R2′,潜伏期指标显著高于对照组(P<0.05或P<0.01),左右R1潜伏期指标两组无差异。精神分裂症患者组和对照组左右两侧R1、R2、R2′波幅指标无差异。19例精神分裂症患者治疗前后的左右两侧R1、R2、R2′潜伏期及波幅均无显著性差异。结论:精神分裂症患者可能存在脑干功能如脊髓束核、网状结构的异常改变,瞬目反射可为精神分裂症诊断提供有益补充。     

Maturation of the blink reflex in infants

The blink reflex was elicited in 50 children from birth to 3 years of age. In the awake state, the R1 response was always obtained; R2 responses, especially contralateral ones, were more difficult to elicit under 9 months of age. R1 latency and VIIth motor nerve conduction variations were a good witness of the peripheral nervous system maturation. The influence of the different states of waking and sleeping on these reflex responses was studied. These results and some of the mechanisms that underlie these changes are discussed.     

Hand blink reflex in virtual reality: The role of vision and proprioception in modulating defensive responses

Our research focused on the role of vision and proprioception in modulating a defensive reflex (hand blink reflex, HBR) whose magnitude is enhanced when the threatened hand is inside the peripersonal space of the face. We capitalized on virtual reality, which allows dissociating vision and proprioception by presenting a virtual limb in congruent/incongruent positions with respect to the participants' limb. In experiment 1, participants placed their own stimulated hand in far/near positions with respect to their face (postural manipulation task), while observing a virtual empty scenario. Vision was not informative, but the HBR was significantly enhanced in near compared with far position, suggesting that proprioception is sufficient for the HBR modulation to occur. In experiment 2, participants did not perform the postural manipulation but they (passively) observed the avatar's virtual limb performing it. Proprioceptive signals were not informative, but the HBR was significantly enhanced when the observed virtual limb was near to the face, suggesting that visual information plays a role in modulating the HBR. In experiment 3, both participants and avatar performed the postural manipulation, either congruently (both of them far/near) or incongruently (one of them far, the other near). The HBR modulation was present only in congruent conditions. In incongruent conditions, the conflict between vision and proprioception confounded the system, abolishing the difference between far and near positions. Taken together, these findings promote the view that observing a virtual limb modulates the HBR, providing also new evidence on the role of vision and proprioception in modulating this subcortical reflex.     

Masseter reflex and blink reflex abnormalities in Chiari II malformation

Masseter reflex and blink reflex were evaluated in 64 patients with a myelomeningocele and Chiari II malformation. In 46 patients, no brainstem signs or symptoms were present. Brainstem dysfunction related to Chiari II malformation occurred in 18 patients. The masseter reflex was more frequently abnormal in the symptomatic than asymptomatic patients (P = 0.02). Although the blink reflex was similarly affected in the two groups of patients (P > 0.1), it was very sensitive, being abnormal in 83% of symptomatic and 65% of asymptomatic patients. Concomitant abnormality of masseter reflex and the late contralateral blink reflex component (R2c) was almost exclusively found in symptomatic patients and reached the highest significance in separating the two groups (P = 0.002).