Acute peripheral facial palsy: Is there a trigeminal nerve involvement?

The aim of this study was to investigate trigeminal nerve involvement in patients with peripheral facial palsy. In total, 25 patients with facial nerve palsy and 19 controls were tested by electrophysiological methods regarding their facial and trigeminal nerve functions within 1 month after disease onset. The presence of an abnormal blink reflex was determined in patients with peripheral facial palsy by comparing paralytic and non-paralytic sides (12.3 ± 1.1 and 10.8 ± 1.3, respectively; p = 0.001). However, the average masseter inhibitory reflex difference between the paretic and non-paralytic sides of patients compared with the corresponding side-to-side comparison for controls was not statistically significant. The masseter inhibitory reflex response was abnormal in some cases. These findings suggest that the masseter inhibitory reflex, a trigemino–trigeminal reflex, was normal in most of our patients with peripheral facial palsy, but may be abnormal in individual cases. Our study showed that subclinical disorders affecting the trigeminal pathways occur in individual patients with idiopathic facial palsy, while the majority of patients have no trigeminal nerve involvement.     

The usefulness of the blink reflex in the early diagnosis of cranial nerve neuropathy associated with diabetes mellitus

BACKGROUND: Electrophysiological testing can be of value in early diagnosis of diabetic neuropathy. Limited data is available in the use of the blink reflex (BR) in diabetes mellitus (MD). AIM: is to evaluate the efficacy of BR in early diagnosis of cranial nerve neuropathy in DM. MATERIALS AND METHODS: 67 diabetes and 32 healthy controls-age and sex matched- were chosen. The diabetes were of type I and type II and of more than or less than 10 years duration. The BR was elicited by stimulation the supraorbital nerve using the Dantec Neuromatic 2000M machine. The latency of the components response recorded as R1, R2y (ipsilateral) and R2c (contralateral). A direct response was achieved by the stimulation of the facial nerve; a square wave of 200 msec. was used. RESULTS: No differences were noted when the two sides were compared in diabetic patients, while the difference was highly significant in the increased latency of R1, R2y and R2c each type of diabetes as compared to the control. Comparison of the types and duration of diabetes between each other showed no significant difference. Direct measurement of the latency response of the facial nerve gave a response in diabetics of both types and duration. CONCLUSION: the BR can be useful in the early diagnosis of diabetic neuropathy.     

Auditory-evoked masseter inhibitory reflex

We aimed to investigate auditory-evoked masseter inhibitory reflex and discuss possible auditory-trigeminal pathways in brainstem. Our study population consisted of 21 healthy volunteers (age-matched 7 males and 14 females). Bilateral electrical blink reflex (BR), auditory blink reflexes (ABR) and electrical MIR (MIR) were studied. After obtaining normal potentials, auditory MIR (AMIR) was studied. Electrical blink reflexes had two components as R1 and R2, and ABR had one evoked potential in all volunteers. There was no significant difference between gender, nor between right- and left-sided BR and ABR. The mean latency of ABR responses were shorter than latencies of R2 phase of BR (p = 0.013 for left-sided responses, p = 0.035 for right-sided responses). Electrical stimulation revealed two suppression periods (SP1 and SP2) in MIR responses bilaterally in all volunteers. Auditory stimulation evoked typical two suppression periods only in 11 subjects (5 males, 6 females). The mean latency of SP1 component of AMIR was significantly longer than those of MIR bilaterally in both males and females, while the SP2 component had a shorter onset. The durations of SP1, SP2 and total SP were always shorter than those obtained in MIR with smaller degree of suppressions. None of the MIR or AMIR responses showed significance difference between sexes. We assume that auditory-evoked MIR might share the similar interneurons as with other electrical or nociceptive stimulation, which connects cochlear-trigeminal neurons via pontine reticular system to premotor area for masseter muscle.     

特发性面神经麻痹病变部位与神经电生理检测关系探讨

目的：探讨特发性面神经麻痹病变部位与电生理检测结果的关系。方法：对发病20d内的109例特发性面神经麻痹患者,根据临床表现进行面神经病变定位,分为4个组：膝状神经节病变组、面神经管镫骨神经以上病变组、面神经管镫骨神经以下病变组、茎乳孔以外病变组,并行面神经电生理检查,各组数据进行统计学处理。结果：109例患者中膝状神经节病变组15例,面神经管镫骨神经以上病变组21例,面神经管镫骨神经以下病变组38例,茎乳孔以外病变组35例;患侧瞬目反射、面神经复合肌肉动作电位（CMAP）潜伏期、波幅及患侧波幅下降比、F波消失率各组比较差异有统计学意义。结论：面神经麻痹电生理指标波幅下降比、瞬目反射、F波与其病变部位有关。     

正常学龄儿童瞬目反射的初步研究

应用电刺激法研究４０例正常学龄儿童的瞬目反射。通常能诱发出刺激侧快反应（Ｒ１）、迟反应（Ｒ２）及对侧迟反应（Ｒ２＇）。分析Ｒ１的形态、各波的潜伏期、时程、波幅，制定出正常值。瞬目反对的检查结果可作为诊断多种脑干障碍和三叉神经、面神经病变的方法。     

Somatosensory eye blink reflex in peripheral facial palsy

To investigate the association between somatosensory blink reflex (SBR) and peripheral facial palsy (PFP) severity and trigeminal blink reflex (BR) changes in cases with PFP and subsequent postparalytic facial syndrome development (PFS). One hundred and twenty subjects with peripheral facial palsy and post-facial syndrome and 44 age and gender matched healthy volunteers were enrolled to this study. Blink reflexes and somatosensory blink reflex were studied in all. The association between R1 and R2 responses of the BR and SBR positivity was investigated. SBR was elicited in 36.3% of normal subjects, in 18.3% of PFP and in 65.3% of PFS patients. In the paralytic side, the frequency of SBR positivity was significantly lower in PFP group compared to controls and SBR was most frequently observed in patients with PFS. Compared to PFP and control groups, SBR positivity on the non-paralytic side significantly revealed a higher rate in PFS patients. SBR positivity of patients in whom R1 or R2 were absent, was significantly lower than those subjects with prolonged or normal R1 or R2 responses. PFP and successive PFS are good models for the sensory motor gate mechanisms and/or excitability enhancement of brainstem neurons responsible for SBR.     

Clinical and medial temporal features in a family with mood disorders

It is debated whether non-affected relatives of patients with affective disorders share a specific brain structure endophenotype. Aim of this work is to explore the medial temporal morphology in affected and non-affected members of a family with mood disorders. Hippocampi and amygdalae were manually traced from the 3D magnetic resonance imaging of five affected family members, 10 non-affected relatives, and 15 unrelated matched controls. Affected and non-affected relatives were characterized by larger left amygdalae (18%, p = 0.030), smaller right hippocampus (up to 18%, p < 0.0005), and reduced hippocampal asymmetry (p < 0.001) than controls. Abnormal, albeit non significant, positive correlations of MTL volumes with age were observed, with the exception of smaller volume of the left hippocampus with advancing age (r = −0.76) in the affected relatives. These data add to the evidence that abnormal medial temporal structures may constitute an endophenotype for affective disorders.     

Presurgical electrophysiological findings in acoustic nerve tumours.

The clinical involvement of the facial nerve is a rare finding among the initial symptoms of acoustic neurinomas. However, compression of the facial nerve is a common intraoperative finding. Blink reflex was recorded in 20 patients affected by cerebellar-pontine angle tumor confirmed at surgery. Recordings were also made of the M-response of the facial nerve from the naso-labial folds. In 6 cases jaw reflex was also recorded. In summary, these electrophysiological studies revealed a facial nerve damage in 13 and a trigeminal nerve dysfunction in 2 out of 18 clinically unaffected patients. The combined study of the 3 tests proved to be useful when the blink reflex showed an isolated R1 delay, that is, in cases in which the level of damage along the trigemino-facial reflex arc cannot be defined by the recording of the blink reflex alone.     

Acoustic startle response in patients with orthostatic tremor

Background and aim

Orthostatic tremor is a high frequency tremor predominantly on calf muscles during standing. Brainstem is the most probable generator in the pathogenesis since it comprises bilaterally projecting centers regulating stance or tone. We aimed to investigate the functional role of brainstem through the evaluation of acoustic startle response in primary orthostatic tremor patients.

Patients and method

We included 7 (2 males) consecutive patients and 13 (5 males) healthy volunteers. Diagnosis was confirmed by polymyographic surface electromyography. All subjects underwent acoustic startle response and blink reflex investigations.

Results

Presence rate (71.4% vs. 100%, p = 0.042) and response rate (27.5% vs. 40.5%, p = 0.047) of total acoustic startle response were lower in patient group. Similarly, probability over orbicularis oculi was lower among patients (p = 0.003). However, blink reflex was observed in all patients and healthy volunteers and latencies of startle and blink reflexes were similar between groups.

Conclusions

In our patient group, normal response rate and latencies of R1 and R2 show structural integrity of at least blink reflex circuit at brainstem. On the other hand, suppressed response rates probably reflect decreased excitability of auditory startle reflex pathway.     

面瘫患者面神经电图和瞬目反射的应用比较

目的:比较面瘫患者瞬目反射和面神经电图的应用价值。方法:这些面瘫患者经过四周基础治疗和(或)针灸治疗后,进行健、患侧瞬目反射(207例)和面神经电图(205例)检查比较。结果:瞬目反射治疗前健、患侧R1值的差异有极显著意义(P<0．01);治疗后健、患侧R1值的差异无显著意义 (P>0．05)。面神经电图患侧潜伏期延长者于治疗后均有所好转(P<0．05),波幅降低者治疗后无明显改善(P>0．05)。结论:面瘫患者治疗后瞬目反射改善非常明显,而面神经电图恢复存在明显的滞后现象,早期诊断(发病第一周)瞬目反射检查优于面神经电图,中后期面神经电图检查优于瞬目反射。     

Methods for Studying the Blink Reflex and Its Normative Parameters

Investigation of the blink reflex represents a contemporary and highly informative method in electroneurophysiological diagnosis. Contradictory data from clinical studies of the blink reflex show the relevance of the problem and dictate the need for forming universal approaches to methods of studying and interpreting the results obtained. The characteristics of the formation of the reflex electromyographic (EMG) components of the blink reflex of the orbicularis oculi muscle were studied during electrical stimulation of the supraorbital nerve in 31 healthy subjects. The latencies of the R1 and R2 components, the amplitude of the R1 component, and the area of the total power spectrum of the EMG discharges constituting the R2 component, the duration of the R2 component, and the latency of the R3 component were studied during the blink reflex.     

A pharmacological distinction between the long and short latency pathways of the human blink reflex revealed with tobacco

Summary In three, normal, human subjects, tobacco smoking was used as a pharmacological probe to modify differentially the direct and indirect pathways underlying the blink reflex. The latency of the indirect R2 component of the orbicularis oculis electromyogram evoked by electrical stimulation of the trigeminal supraorbital nerve transiently increased 20–80% after smoking, while the latency of the shorter latency, direct R1 component remained constant. The magnitude of both components of the blink reflex transiently decreased. The data demonstrate that tobacco smoking can differentially alter the long and short latency components of the blink reflex, and suggest that these effects result from modifications of central pathways sensitive to nicotine.     

Blink reflex in motor neuron disease

The aim of the study was to analyse the diagnostic value of blink reflex (BR) in motor neuron disease (MND). We studied 25 patients with MND including amyotrophic lateral sclerosis (ALS) in 18 patients, primary muscular atrophy (PMA) in 4 patients, and primary lateral sclerosis (PLS) in 3 patients and 12 healthy volunteers. The blink reflex was obtained in typical way. In ALS group, statistically significant increase in latency and decreased amplitude of R2 responses were found compared to the control group (p < 0.05), whereas BR in patients with PLS and PMA was within normal limits. The presence of low amplitude of R2 responses in patients with ALS may suggest loss of lower brainstem neurons connecting trigeminal and facial system, and probably also decreased facilitator effect of central nervous system on reticular formation in the brainstem.     

Excitability recovery curves of blink reflexes in patients with athetotic cerebral palsy

We evaluated the brainstem function or its excitability by the blink reflex evoked with the electrical stimulation to the supraorbital nerve in 10 patients with athetotic cerebral palsy compared with 10 normal subjects and 7 spastic type patients. There were no differences in stimulus intensity, latency of R1 and R2 components, and duration and area of EMG activity of the R2 component of the blink reflex elicited by single stimulation among the two patients' groups and normal subjects. R1 recovery cycle to paired stimuli in the athetotic group showed a facilitation of the test responses by the conditioning stimuli at 100 and 200 ms intervals, but were not significantly different from those in the normals. On the other hand, the R2 recovery curve in the athetotic group showed a significant hyperexcitability at all intervals from 100 to 600 ms compared to the normals. Our results from the R2 hyperexcitable recovery to paired stimuli are indicative of increased brainstem interneuronal excitability in athetotic patients and similar to the results reported in the disorders of the basal ganglia, i.e. Parkinson's disease, dystonia and blepharospasm. We suggest that this hyperexcitability might be caused by abnormal input possibly from the basal ganglia upon these brainstem interneurons.     

Increased cutaneous NGF and CGRP-labelled trkA-positive intra-epidermal nerve fibres in rat diabetic skin

In this study we have determined the amount of Nerve Growth Factor (NGF) and the innervation density of the glabrous hindpaw skin of diabetic rats (n = 4) and controls (n = 3). The proportion of intra-epidermal nerve fibres (IENF) expressing the high affinity NGF receptor (trkA) and calcitonin gene-related peptide (CGRP) were also determined. Four weeks after induction of diabetes by intraperitoneal streptozotocin injection skin was analyzed for: (i) NGF content using ELISA and (ii) the innervation density of peptidergic afferents that also expressed trkA using immunocytochemistry. NGF levels were approximately three-fold higher in diabetic skin compared to controls (diabetic: 134.7 ± 24.0 (SD) pg ml⁻¹, control: 42.7 ± 21.5 pg ml⁻¹, p = 0.002). As expected there was a significant reduction in IENF density in diabetic skin (2.7 ± 1.3 fibres mm⁻¹) compared to controls (6.9 ± 1.5 fibres mm⁻¹; p = 0.01). In diabetic rats there was no significant difference in the proportion of trkA-labelled IENF (diabetic 74 ± 21%; control 83 ± 15%, p = 0.6), but significantly more trkA-positive IENF were also labelled by CGRP antibodies in diabetic skin compared to controls (diabetic 89 ± 22%; control 38 ± 2%, p = 0.03). These data suggest that in diabetes the upregulation of cutaneous NGF may ‘over-troph’ the surviving axons, increasing CGRP labelling, which may be important in the aetiology of painful diabetic neuropathy.     

A central neuropathic pain model by DSP-4 induced lesion of noradrenergic neurons: Preliminary report

Neuropathic pain models are classified as central and peripheral pain models. Although various peripheral neuropathic pain models are established, central pain models are based only on spinal cord injury. DSP-4 is a competitive inhibitor of norepinephrine uptake that selectively degenerates the locus coeruleus (LC)-noradrenergic neurons projection to the cerebral cortex and hippocampus. In the present study, we have tested whether lesion of LC-noradrenergic neurons by ip DSP-4 (0, 10, 30, 50 mg/kg, n = 7 each) could provide a new central neuropathic pain model in rats using a hot-plate and tail-flick tests. DSP-4 significantly reduced the hot-plate latency and norepinephrine contents especially in the coerulean regions. However, DSP-4 did not change tail-flick latency. There are significant correlations of the latency in the hot-plate test with norepinephrine contents in the cerebral cortex (r = 0.432, p = 0.022), the hippocampus (r = 0.465, p = 0.013) and the pons (r = 0.400, p = 0.035) but not with those in the hypothalamus and the spinal cord. As response to hot-plate and tail-flick implies supra-spinal process and spinal reflex, respectively, central neuropathic pain may be facilitated by DSP-4 depleting LC-noradrenergic neurons although the present data are preliminary.     

Narcolepsy-cataplexy: deficient prepulse inhibition of blink reflex suggests pedunculopontine involvement

Hypocretin (orexin) deficiency plays a major role in the pathophysiology of narcolepsy–cataplexy. In animal models, hypocretinergic projections to the pedunculopontine nucleus are directly involved in muscle tone regulation mediating muscle atonia – a hallmark of cataplexy. We hypothesized that pedunculopontine nucleus function, tested with prepulse inhibition of the blink reflex, is altered in human narcolepsy–cataplexy. Twenty patients with narcolepsy–cataplexy and 20 healthy controls underwent a neurophysiological study of pedunculopontine nucleus function. Blink reflex, prepulse inhibition of the blink reflex and blink reflex excitability recovery were measured. Blink reflex characteristics (R1 latency and amplitude, and R2 and R2c latency and area under the curve) did not differ between patients and controls (P > 0.05). Prepulse stimulation significantly increased R2 and R2c latencies and reduced R2 and R2c areas in patients and controls. However, the R2 and R2c area suppression was significantly less in patients than in controls (to 69.8 ± 14.4 and 74.9 ± 12.6%, respectively, versus 34.5 ± 28.6 and 43.3 ± 29.5%, respectively; each P < 0.001). Blink reflex excitability recovery, as measured by paired‐pulse stimulation, which is not mediated via the pedunculopontine nucleus, did not differ between patients and controls (P > 0.05). Our data showed that prepulse inhibition is reduced in narcolepsy–cataplexy, whereas unconditioned blink reflex and its excitability recovery are normal. Because the pedunculopontine nucleus is important for prepulse inhibition, these results suggest its functional involvement in narcolepsy–cataplexy.     

Peroxisome proliferator-activated receptor-γ2 Pro12Ala polymorphism is associated with reduced risk for ischemic stroke with type 2 diabetes

Peroxisome proliferator-activated receptor (PPAR)-γ2 has important effects to insulin sensitivity, atherosclerosis, inflammation and endothelial cell function. Through these effects, PPAR-γ2 might be involved with the ischemic stroke in type 2 diabetes. To determine the role of PPAR-γ2 in genetic susceptibility to ischemic stroke in type 2 diabetes, we genotyped 302 ischemic stroke patients, 283 healthy controls and 141 type 2 diabetic patients without ischemic stroke (diabetes duration >10 years) for PPAR-γ2 Pro12Ala polymorphism by polymerase chain reaction-restriction fragment length polymorphism methods. PPAR-γ2 Pro/Ala genotype were lower in ischemic stroke patients than those observed in the control group (4.0% vs. 9.9%, OR = 0.38, P = 0.0046), and it were associated with the incidence of ischemic stroke in the multivariate analysis (OR = 0.43, P = 0.025). Genotypic analysis revealed that ischemic stroke patients with type 2 diabetes displayed a great lower prevalence of the Pro/Ala genotype (2.3%) than controls (9.9%) (OR = 0.21, P = 0.0047). And Pro/Ala genotype of type 2 diabetes patients with ischemic stroke were lower than type 2 diabetes patients without ischemic stroke (2.3% vs. 8.5%, OR = 0.25, P = 0.0321), however the significant association with ischemic stroke was not detected in the multivariate analysis (OR = 0.27, P = 0.051). These results suggest that the Pro/Ala genotype of PPAR-γ2 Pro12Ala polymorphism may be associated with reduced risk for ischemic stroke, and the possibility that it might have a protective effect for ischemic stroke with type 2 diabetes.     

Serotonergic receptor upregulation in cerebral cortex and down regulation in brainstem of streptozotocin induced diabetic rats: Antagonism by pyridoxine and insulin

Insulin secretion and glucose homeostasis is implicated through serotonergic function. Pyridoxine is involved in decarboxylation step in synthesis of serotonin. The present study was carried out to find the role of insulin in combination with pyridoxine on the concentrations of 5-HT and 5-HIAA, 5-HT receptor binding, 5-HTT gene expression and immunohistochemistry studies in the cerebral cortex and brainstem of streptozotocin induced diabetic rats. 5-HT content showed a significant decrease with a significant increase in 5-HIAA in cerebral cortex (p < 0.01) and brain stem (p < 0.001) in diabetic rats. 5-HT receptor binding parameters, B_max and K_d, showed a significant decrease (p < 0.001) in diabetic rats in cerebral cortex whereas in brainstem it showed a significant increase (p < 0.001) compared to control. Gene expression studies of 5-HTT in cerebral cortex showed a significant down regulation (p < 0.001) and in brainstem an upregulation (p < 0.001) in diabetic rats compared to control. Insulin and pyridoxine treatment to diabetic rats reversed the 5-HT content, B_max, K_d and gene expression of 5-HTT confirmed by immunohistochemistry studies in cerebral cortex and brainstem to near control. Thus our results suggest that pyridoxine along with insulin has a role in the regulation of insulin synthesis and release through serotonergic function which has clinical significance in the management of diabetes.     

Startle modulation by affective faces

Startle reflex modulation by affective pictures is a well-established effect in human emotion research. However, much less is known about startle modulation by affective faces, despite the growing evidence that facial expressions robustly activate emotion-related brain circuits. In this study, acoustic startle probes were administered to 37 young adult participants (20 women) during the viewing of slides from the Pictures of Facial Affect set including neutral, happy, angry, and fearful faces. The effect of expression valence (happy, neutral, and negative) on startle magnitude was highly significant (p < .001). Startle reflex was strongly potentiated by negative expressions (fearful and angry), however, no attenuation by happy faces was observed. A significant valence by gender interaction suggests stronger startle potentiation effects in females. These results demonstrate that affective facial expressions can produce significant modulation of the startle reflex.