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At least 433 records · Page 24Linked to original sources
PubMed1993

Hemifacial spasm: early postoperative normalization of blink reflex latency.

Electrophysiological improvement in the blink reflex latency after neurovascular decompression of the facial nerve in patients with hemifacial spasm is believed to be related to remyelination and occurs 2-8 months after surgery. We report a patient with hemifacial spasms for 3 years, in whom the increased blink reflex latency returned to normal within a week after surgery. This suggests that compression without demyelination may be responsible for increased blink reflex latency in some of the patients with hemifacial spasms.

Adult↗
PubMed1997

Electrophysiological investigation of hemifacial spasm after microvascular decompression: F waves of the facial muscles, blink reflexes, and abnormal muscle responses.

In patients with hemifacial spasm, it has been said that the spasm is due to cross compression of the facial nerve by a blood vessel and that microvascular decompression (MVD) of the facial nerve is an effective treatment. The F waves, which result from backfiring of antidromically activated motor neurons of the facial motor nucleus, are indices of the excitability of the facial motor nucleus and are enhanced in patients with hemifacial spasm. Measuring blink reflexes and abnormal muscle responses (lateral spread), a characteristic sign of hemifacial spasm, has been used to investigate the mechanism of hemifacial spasm pathophysiologically. Thus the authors measured F waves of the facial muscle, blink reflexes, and abnormal muscle responses before and after MVD in patients suffering from hemifacial spasm to investigate the excitability of the facial motor nucleus and the course of the cure of hemifacial spasm after MVD. The authors obtained facial nerve-evoked electromyograms in 20 patients with hemifacial spasm before and after the MVD procedure. On the spasm side, the F waves and blink reflexes were enhanced preoperatively compared to those on the normal side and abnormal muscle responses were recorded in all patients. In 12 patients whose hemifacial spasm had not disappeared completely for 5.1 +/- 1.7 (mean +/- standard error) months following the MVD procedure, F waves were still enhanced significantly and abnormal muscle responses were still recordable, albeit at lower amplitude. Within 1 month after the hemifacial spasm had disappeared completely. F waves were still significantly enhanced in 17 patients and abnormal muscle responses were recorded in seven of 15 patients. Subsequently, the enhanced F waves and abnormal muscle responses disappeared completely. The authors' study supports the hypothesis that the cause of hemifacial spasm is hyperexcitability of the facial motor nucleus and suggests that additional surgery should not be performed for at least 2 years after MVD, because that period is necessary for the disappearance of the hyperexcitability of the facial motor nucleus.

Adult↗
PubMed2005

Attentional and perceptual sources of the auditory attentional blink.

When a rapid succession of auditory stimuli is listened to, processing of the second of two successive targets among fillers is often impaired, a phenomenon known as the attentional blink (AB). Three experiments were conducted to examine the role of filler items in modulating the size of the auditory AB, using a two-alternative forced choice discrimination paradigm. In the first experiment, dual-stream presentations in which low- and high-pitch items were separated by six semitones were tested. A transient deficit in reporting the probe was observed in the presence of fillers that was greater when fillers were in the same stream as the probe. In the absence of a filler, there was a residual deficit, but this was not related to the time lag between the target and the probe. In the second and third experiments, in which single-stream presentations were used, a typical AB was found in the presence of homogeneous fillers, but heterogeneous fillers tended to produce a greater deficit. In the absence of a filler, there was little or no evidence of a blink. The pattern of results suggests that other attentional and perceptual factors contribute to the blink.

Attention↗
PubMed2001

Modification of the human blink reflex by transient and sustained features of acoustic prestimulation.

The effects of acoustic stimuli whose onsets and durations were controlled to vary their transient and sustained features on the size of a subsequently elicited blink reflex were examined in humans. Prestimuli both with and without transient features inhibited the reflex when they preceded the eliciting stimulus by brief lead intervals, showing that acoustic transients are sufficient, but not necessary, for reflex inhibition. Inhibition evoked by transient and sustained stimulus features showed partial summation, and inhibition evoked by stimuli with only transient and with transient and sustained features showed similar decay functions with increasing lead intervals. Blink augmentation was found at longer lead intervals early but not late in a session, and was more evident in women than men. Prestimuli with only transient features were more effective than those with both transient and sustained features, showing that sustained stimulus energy at the time of reflex elicitation is not only not necessary for blink augmentation, but also diminishes it.

Acoustic Stimulation↗
PubMed2000

The effects of change in lead stimulus modality on the modulation of acoustic blink startle.

In two experiments we investigated the effect of generalized orienting induced by changing the modality of the lead stimulus on the modulation of blink reflexes elicited by acoustic stimuli. In Experiment 1 (n = 32), participants were presented with acoustic or visual change stimuli after habituation training with tactile lead stimuli. In Experiment 2 (n = 64), modality of the lead stimulus (acoustic vs. visual) was crossed with experimental condition (change vs. no change). Lead stimulus change resulted in increased electrodermal orienting in both experiments. Blink latency shortening and blink magnitude facilitation increased from habituation to change trials regardless of whether the change stimulus was presented in the same or in a different modality as the reflex-eliciting stimulus. These results are not consistent with modality-specific accounts of attentional startle modulation.

Acoustic Stimulation↗
PubMedDate not supplied

Blink reflex in hyperthyroidism.

Although there are studies regarding the effects of thyroid hormones on some neurologic reflexes, literature lacks knowledge of the effects of thyroid hormones on blink reflex circuits. To understand the behaviour of excess thyroid hormone on this circuit that involves synapses in brainstem, we studied electrically elicited blink reflexes of 7 patients with hyperthyroidism, 8 patients with hyperthyroidism who were under therapy and 14 volunteers as control by electroneuromyograph. Mean values of the latencies and amplitudes of the R1 and R2 responses were not statistically different between groups, while the duration of R2 response and controlateral R2 response were found shorter in patients with hyperthyroidism comparing to the patients under therapy and controls. We have thought that these findings might reflect the inhibitor effect of the excess thyroid hormone on polysynaptic reflex arc of the blink response.

Antithyroid Agents↗
PubMed2001

[Evaluation of peripheral facial nerve palsy with R 2 wave latency in blink reflex].

Electrically elicited blink reflexes were investigated in 60 patients with peripheral facial nerve palsy. The purpose of this study was to evaluate the utility of analysis of R 2 wave in blink reflex as a prognostic indicator for the patients with facial palsy. The patients treated by stellate ganglion block were classified into three groups: Group I scored more than 90 points (full score is 100 points) within 2 weeks, Group II scored more than 90 points over 2 weeks, and Group III scored less than 90 points. The examinations were performed at the first visit, and 2, 4, 6 weeks after the onset of facial palsy. Latencies of ipsilateral and contralateral R 2 wave were measured by electrical stimulation on both side. There were significant differences of R 2 latency between ipsilateral and contralateral side in each of the three groups at the first visit. In Group II, contralateral R 2 latency obtained by stimulation of the paralytic side was prolonged significantly. In Group III, the ipsilateral R 2 wave was not observed. The results of this study indicate that measurement of the R 2 latency of blink reflex is useful in judging the severity of the peripheral facial nerve palsy. The R 2 latencies obtained by stimulation of ipsilateral and contralateral side should be used as one of the parameters for evaluation of the prognosis of patients with peripheral facial nerve palsy.

Adult↗
PubMedDate not supplied

[The intercentral relations of the biopotentials in the rabbit brain during the creation of a blinking dominant].

On rabbits in chronic experiment intercentral relations were studied of biopotentials of the sensorimotor cortical zone (blinking presentation in the cortex), VPM of the thalamus and motor nucleus of the oculomotor nerve at formation of blinking dominant created by serial stimulation of one eye by air jet. By the method of spectral-correlation analysis an increase was revealed of spectrum power and increase of COG of the potentials in delta-range in the structures connected with blinking function of the stimulated eye. At transition of the dominant focus to the inhibitory state and activation of the symmetrical centre of the other eye, in centers constellation of this induced focus a reconstruction of the electrical processes took place typical for the dominant.

Animals↗
PubMed2004

Hyperexcitable blink reflex preceding the diagnosis of neuroblastoma.

The diagnosis of neuroblastoma is sometimes preceded by development of a paraneoplastic syndrome, most commonly opsoclonus-myoclonus-ataxia (OMA). The authors describe a patient who developed a hyperexcitable blink reflex, without symptoms of OMA, prior to his oncologic diagnosis. The authors believe this may represent a distinct paraneoplastic process caused by increased dopaminergic stimulation of the blink reflex and suggest that children manifesting an unexplained hyperexcitable blink reflex should be screened for occult neuroblastoma.

Abdominal Injuries↗
PubMed1992

[Excitability of the blink reflex during self-elicitation or elicitation by others].

Electrically evoked blink reflexes were studied in 24 healthy subjects in different conditions of elicitation. In one condition the electrical shock was delivered by the experimenter; in a second condition the subject triggered the stimulus himself by manually operating a switch. The different conditions were investigated relaxed or clenching the fist with left hand. Moreover, in 3 subjects the stimulus was given in various delays after the occurrence of the EMG activity of the forearm flexor muscles due to a ballistic wrist flexion. The latencies and peak to peak amplitudes of the ipsi- and contralateral early and late responses were analysed. Voluntary sustained contraction of the left hand (fist) caused no significant modification of the blink reflex. Self-triggering of the stimulus had a facilitating influence on the early components (R1, R1') and an inhibitory effect on the late components (R2, R2'). In EMG triggered self-stimulation the R2-inhibition could already be seen at a delay of 0 ms. From a delay of 10 ms on the suppression was still more pronounced and recovered over the following 500-1000 ms. We conclude, that the reflex alterations are not due to the outflow of the motor cortex, but to the conditioning effect of self-elicitation. The influence on the excitability of the blink reflex resemble that described in the literature for the conditioning effect of an acoustic or visual stimulus. We suggest involvement of the same interneuron network on the condition of self-eliciting.

Adult↗
PubMed2006

Blink reflex, H-reflex and nerve-conduction alterations in leprosy patients.

Peripheral nerve lesions are the most important cause of disability in leprosy patients. Electrophysiological studies are used in the diagnosis and prognosis of neuropathy. Nerve conduction is the most frequently used electrophysiological test method to detect neuropathy, although it evaluates only a part of the peripheral nervous system. Blink reflex and H-reflex are electrophysiological tests which evaluate facial and trigeminal nerve function. This study determined the frequencies of blink reflex, H-reflex and motor and sensory nerve conduction alterations in twenty five heterogeneous, clinic patients with lepromatous leprosy and a control group of 20 healthy subjects. Study results showed a decrease in motor and sensory nerve conduction in 40% and 30%, respectively. In blink reflex (BR), right R1 was altered in latency in 20% of patients, left R1 in 20%, right ipsilateral R2 in 16%, left ipsilateral R2 in 20%, and right and left contralateral R2 were altered in 32% of patients. There was an absence of H-reflex in 16% (n = 4) and prolonged latency in 4% (n = 1).

Adult↗
PubMed1990

Unilateral enhancement of early and late blink reflex components in hemidystonia.

The side-to-side differences in the EMG activity of the early and late components of blink reflex, regarded as revealing the state of excitability of the brain stem reflex centers, have been analyzed in patients with unilateral dystonia without demonstrable brain lesions. It has been observed that both early and late responses of direct blink reflex were higher on the side affected by hemidystonia than on the contralateral one, while the latency values were in the normal range. Possibility that an abnormal output from the striatum towards the brainstem structures involved in blink reflex appears on the affected side of hemidystonic patients is discussed.

Adult↗
PubMed1989

Functional blinking in childhood.

At the Department of Pediatric Ophthalmology, Wills Eye Hospital, 17 children, 18 months to 10 years of age, were seen with a chief complaint of intermittent excessive blinking. Eight (47%) of the patients had been referred for ophthalmologic examination by their pediatrician for evaluation of this symptom. All were in excellent health with no associated symptoms or signs of systemic or ocular disease. None of the children were taking topical ocular or systemic medications. The parents of seven (41%) of these children were able to identify a temporally related stressful event that coincided with the onset of blinking. Durations of the symptom prior to examination ranged from 1 week to 4 months. Spontaneous resolution occurred from one day to 5 months after the first ophthalmologic examination. Recurrence occurred in only one child, but resolution was still completed within 5 months. Excessive eye blinking unassociated with other systemic or ocular findings appears to be a medically benign, self-limited functional disorder.

Blinking↗
PubMedDate not supplied

[The blink reflex and stimulus detection by the facial nerve in 50 cases of Guillain-Barré polyradiculitis].

The blink reflex combined with stimulo-detection of the facial nerve was studied in 50 patients presenting Guillain-Barré polyradiculoneuritis. The reflex was normal in more than half the cases. The most frequent electrological picture consisted in bilateral lengthening of the early and late reflex responses of the blink reflex with unilateral or bilateral increase of motor facial latency. The blink reflex showed various abnormalities in slightly more than one third of the cases of polyradiculoneuritis presenting no clinical signs of facial involvement, thus constituting subclinical lesional evidence of the reflex arc.

Adolescent↗
PubMed1986

[Influence of hemisphere lesions on the contralateral blink reflex].

Electrically elicited blink reflexes were investigated in 28 patients with unilateral hemispheral lesion. The reflex evoked by electrical stimulation of the supraorbital nerve contralateral to the side of the hemispheral lesion was absent or depressed in 14 out of 28 cases. The abnormal patterns of the blink reflexes were devided into four different types (Type AB, Type AD, Type EB, and Type AB-EB). The Type AB, recorded in 4 cases, consisted of bilateral absence of late component (R2) when the supraorbital nerve on the non-lesion side was stimulated. In contrast, the reflex responses were almost normal bilatarally when the stimulus was applied to the nerve on the lesion side. The Type AD was observed in 2 cases. When the stimulus applied on the non-lesion side, both ipsilateral and consensual R2 were markedly delayed in latency. The Type EB was seen in one case. In this type the absence of the late component (R2) was confined to the clinically affected side independent of the side of stimulation. The Type AB-EB was observed in 4 cases. This type consisted of bilateral absence of R2 component after stimulation on the non-lesion side as seen in Type AB. However, when the stimulus applied on the lesion side, R2 component was only elicited on the ipsilateral side of stimulation. Based on our results, the authors emphasize that abnormality of the contralateral blink reflex in the patients with unilateral hemispheral lesion showed not only Type AB or Type AD but also Type AB-EB which may indicate lowered excitability of bulbar lateral reticular formation of the lower brain stem as well as spinal trigeminal system. This type was presumably due to loss of facilitatory influences associated with the contralateral hemispheral lesion, closely correlated with the lower postcentral region advocated by Ongerboer de Visser.

Adult↗
PubMed1983

[Evaluation of blink reflexes in cerebellopontine angle tumors].

Blink reflexes were analysed in 28 cases with cerebello-pontine angle tumors (22 cases of acoustic neurinoma and 6 cases of meningioma). In patients with acoustic neurinoma, delay or absence of R1 was found in all but two cases (91%) and abnormality of R2 was in 11 (50%). Estimating the mean latency difference of R1 on both sides it was found useful for establishing early diagnosis of small acoustic neurinomas, which had no apparent clinical signs of facial or trigeminal nerve involvement. In patient with obsolete hemorrhage (5 cases) or large cyst (6 cases) within the acoustic neurinomas, which were proven at operation, abnormality of blink reflexes was more prominent than in patient with solid tumors (11 cases). In patients with meningioma, although all were huge tumors, abnormality of R1 was less conspicuous in comparison with acoustic neurinoma. Bilateral delay of R2 was found in 3 of 6 patients. In 13 patients who underwent spinal accessory-facial anastomosis for facial palsy after removal of the tumors, R1-like response were recorded in all but one on the affected side and R2-like response was recorded in only one patient. Observing alteration of blink reflexes in patients with cerebello-pontine angle tumor was useful for establishing early diagnosis and evaluating function of trigeminal nerve, facial nerve and brainstem.

Accessory Nerve↗
PubMed1983

A physiological study of acoustic blinking reflex in the cat.

Blinking reflex was elicited by acoustic stimulus to investigate the reflex pathway in the encéphalo isolé cat. Reflex responses were recorded using electromyography (EMG) of the orbicularis oculi. The investigation was as follows: After stimulation by a loud click sound, the EMGs of the orbicularis oculi were elicited bilaterally. Latencies were 17-20 msec on the ipsilateral side, and 19-21 msec on the contralateral side. By electrical stimulation of the peripheral nerve in the cochlea and the acoustic nerve EMGs were also obtained. The latencies of the electrical stimulation responses correlated well with the latencies in the EMGs obtained through sound stimulation. The evoked potentials after auditory and electrical stimulation were obtained in several nuclei in the brainstem. The conduction time between two nuclei was calculated by measuring the latency of discharges in each nucleus. The alteration of the evoked discharge was observed through surgical transection of the brainstem. After each successive surgery the EMG showed differences in responses. Thus, the location of the neural connections of the pathways were differentiated in the brainstem. From this, we concluded that the reflex arc has the following pathway: The acoustic input to the ventral cochlear nucleus (VCN) is relayed to the acoustic route of the superior olivary complex and to the lateral lemniscus. Then, the impulse reaches the VIIth nucleus via the pontine reticular formation in the ipsilateral side. On the other hand, the input to the VCN crosses over the trapezoid body to the superior olivary complex. Then, the impulse uses the same pathway as described for the contralateral side. Finally, the pathway of the acoustic blinking reflex is located more caudally than that of the tactual blinking reflex. The comparison of the recordings of both reflexes is useful clinically, as a diagnostic method to study the function of the brainstem.

Acoustic Stimulation↗
PubMed1995

[Utility of electrophysiologic study using the blink reflex and brainstem evoked potentials for the evaluation of the course of uremic polyneuropathy].

On the present study the authors evaluate the utility of electrophysiologic examination in uraemic polyneuropathy. A group of 19 uraemic patients in chronic dialysis underwent the Blink reflex and BAEPSs study to evaluate the alterations of nervous pathways. The results obtained were compared with those of a group of 10 healthy patients comparable for age and sex. The electrophysiologic parameters have been statistically compared with the plasma levels of vit. B12. folic acid, PTH and beta-2-microglobulin. The results show a significant difference of uremic patients compared with the healthy ones for the Blink reflex (ipsilateral and contralateral R2 responses). Also BAEPSs show significant alterations in the uraemic group (latencies of the III, V components). A statistically significantly inverse correlation is present between folic acid values and blink reflex R1 and R2 responses. Therefore our study shows the existence of a combined degeneration of central and peripheral nervous pathways in chronic uraemic patients. We believe that the decrease in folic acid concentration found in our study may be one of the causes of the beginning and then of the worsening of neurologic damage.

Adult↗