Eye Blink Rate as a biological marker of Mild Cognitive Impairment

We investigated the relationship between dopamine activity (DA), as measured by Eye Blink Rate (EBR), and cognitive function in old adults with Mild Cognitive Impairment (MCI) and healthy controls. Research has been inconclusive so far about the factors responsible for the transition from MCI to dementia. However, some studies suggest that cortical hyperexcitability in very early stages of pathological aging may progressively lead to cell death, and thus to Alzheimer's disease. Hence, we speculated that a dysfunction of DA activity, as measured by EBR, may characterize people with MCI, and account for their poor cognitive function. Thirty three (33) healthy and thirty six (36) old adults with MCI (Mean age = 67.52 y.o.) participated in this study. The EBR was recorded under resting conditions, using two gold skin electrodes above and below the left eye. Cognitive function was assessed with a battery of neuropsychological tests. Participants with MCI showed significantly higher EBR than the healthy controls. Also, EBR was negatively related to scores on the Montreal Cognitive Assessment test (MoCA) test. We propose that abnormally increased dopamine activity, as indexed by relatively high EBR, may be partially responsible for the neurotransmitter imbalance in the central nervous system of people with MCI, and the overall impaired cognitive performance. In addition, this finding suggests that an abnormally high EBR may be a potential biomarker of the transition from healthy aging to dementia.     

Bilateral coupling in learned blinking: effects of lesion aimed at callosal disconnection of the cat motor cortex

The effects of selective transection of the rostralmost portion of the corpus callosum, which contains fibers interconnecting the motor cortices of the two hemispheres, on interocular temporal coupling in the initiation of learned symmetrical blinking were examined in 5 cats trained to blink in response to a 500-ms tone paired with 100-ms airpuffs randomly delivered to either eye (alternate airpuff; 3 animals) or simultaneously directed to both eyes (bilateral airpuff; 2 animals) 400 ms after tone onset. Lesioning had no effect on ability to respond, but did cause a significant increase in the mean conditioned response (CR) latencies of both eyes in all subjects. In the intact cats, a statistically significant difference between the mean CR latencies of the two eyes (hereafter called side superiority) was found in three animals, two of which exhibited superiority of the left eye. After lesioning, it was found that the right eye proved superior to the left eye in four subjects. Both before and after lesioning, side superiority was not due to the ability of one eye to give CRs consistently shorter than those of the other eye, but it crucially depended on the higher proportion of trials in which the superior eye led. A linear correlation between CR latencies of the right and left eye was found in all animals both before and after lesioning. It is suggested that subsequent to lesioning aimed at callosal disconnection of the motor cortex, the effects on initiation of learned symmetrical blinking are the consequences of withdrawal of both bilaterally balanced modulatory influences to both eyes and lateralized modulatory influences to the left eye.     

The blink reflex in migraine

The blink reflex is an objective and useful method to study the trigeminal system. It was recorded in 43 migraine patients and the findings compared with those of 31 healthy controls. The latencies of the R1 component were in the normal range in both groups. The R2 latencies ranged between 30 and 32 ms in the control group. In contrast, more than half of the patients with migraine had R2 latencies between 32 and 35 ms in the migraine group. Some migraine patients had latencies above 35 ms. The R2 latency was statistically significantly different between controls and migraineurs (p < 0.0001). Our findings indicate that trigeminal afferents and/or polysynaptic pathway in brainstem may be altered in migraine.     

Influences of dopaminergic systems on the blink reflex

The effect of the anti-dopaminergic drug haloperidol (6 mg/day i.m. for 2 days) on the blink reflex elicited by electric stimulation of supraorbital nerves was investigated in 12 adult volunteers. A significant increase in amplitude of the early component (R1) of the reflex was observed. This increase disappeared within 5 days of stopping the drug. Possible neural systems which might be involved in these effects are considered.

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Sommario Su 12 volontari adulti, neurologicamente indenni, sono stati studiati gli effetti indotti dalla somministrazione di un farmaco dopaminolitico (aloperidolo, 6 mg/die × 2 giorni) sul riflesso di ammiccamento (blink reflex). Si è osservato un significativo aumento dell'ampiezza della componente precoce (R1) del riflesso, con un ritorno alla norma entro 5 giorni dalla cessazione della somministrazione del farmaco. Vengono discussi i possibili circuiti nervosi coinvolti negli effetti osservati.

     

瞬目反射的正常值及其在周围性面瘫所见

本文对５０例健康人及２３例周围性面瘫患者作了瞬目反射（ＢＲ）的检测。刺激一侧眶上神经，于两侧下眼轮匝肌记录。同侧的两个波为Ｒ１、Ｒ２，对侧的一个波为Ｒ＇２。结果各成份的正常值在左右侧、性别以及各年龄组之间的差异均无显著性。Ｒ１的平均潜伏时为１０ｍｓ，Ｒ２Ｒ２为２９ｍｓ，波幅绝对值变异大、意义相对较小，但两侧的比率有一定的价值。刺激频率不能过快，以减少晚成份的适应并保持波形的重复性。病人的ＢＲ均表现为典型的传出性异常，即无论哪侧刺激，均表现为病侧所记录的ＢＲ的异常，或阻滞、延迟、或波幅异常。结论：（１）ＢＲ可为临床上评价面肌麻痹提供另外一种客观和无创的检查手段。（２）结合临床，ＢＲ可客观判断面肌麻痹的病变部位，提示病变范围和异常程度；（３）ＢＲ可反映面瘫病人的预后情况。     

Multimodality evoked potentials and electrically elicited blink reflex in optic neuritis

Summary Pattern shift visual evoked potentials, brain stem auditory evoked potentials, spinal and scalp recorded somatosensory evoked potentials, and electrically elicited blink reflexes were investigated in 32 patients with isolated optic neuritis. Eleven patients were shown to have one additional lesion in the central nervous system outside the optic nerve. Therefore, cases with optic neuritis of unknown origin should be considered as possible cases of multiple sclerosis.

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Zusammenfassung Visuelle, durch Musterumkehr evozierte Potentiale, akustisch evozierte Hirnstammpotentiale, somatosensorisch evozierte Potentiale mit Ableitung über dem unteren Cervicalmark und über dem kontralateralen Handfeld sowie elektrisch ausgelöste Blinkreflexe wurden bei 32 Patienten mit einer isolierten Opticusneuritis untersucht.Bei 11 Patienten konnten mit Hilfe dieser elektrophysiologischen Untersuchungen eine oder mehrere, weitere Läsionen im Bereich des Zentralnervensystems nachgewiesen werden. Es wird vorgeschlagen, Fälle mit einer isolierten Opticusneuritis unklarer Ursache deshalb in die Kategorie mögliche MS einzureihen.

     

Brain-stem auditory evoked potentials and blink reflex in friedreich's ataxia

Summary The brain-stem involvement in Friedreich's ataxia (FA) was studied by using brain-stem auditory evoked potentials (BAEPs) and the blink reflex. Ten out of 18 patients had abnormal BAEPs, the main abnormality being complete absence of responses and disappearance of wave V. Combined degeneration of the peripheral and central acoustic pathways probably accounts for these findings. The blink reflex was abnormal in 50% of the cases. The outstanding abnormality was bilateral delay of late responses with normal early response, which could be correlated with the known pallor of the descending trigeminal tracts. In contrast with BAEP findings, blink reflex abnormalities did not correlate with either the age of patients or the severity and duration of the disease. These data suggest a difference in susceptibility to degeneration between the auditory system and neuronal system subserving the blink reflex. We conclude that systematic BAEP and blink reflex recording is useful in the electrophysiological evaluation of FA patients.     

Hemifacial spasm in a child

Hemifacial spasm in a 10-year-old child is herein reported. Computed tomography and angiography were normal. Magnetic resonance imaging showed an anomalous vascular structure, probably a redundant loop arising from AICA or PICA, which was identified at surgery. The spasm, presumably due to vascular compression at the root entry zone of the right facial nerve, promptly and completely remitted after surgical decompression, without functional deficits. Atypical clinical features, as well as pre- and postoperative neurophysiological findings supporting the microvascular compression theory, are discussed.     

针刺联合柴胡桂枝汤治疗对难治性面瘫患者面神经肌电图和瞬目反射的影响

目的:探讨针刺联合柴胡桂枝汤治疗对难治性面瘫患者面神经肌电图和瞬目反射的影响。方法:选取122例难治型面瘫患者为研究对象,采用随机数字表法将患者分为对照组(n=62)和试验组(n=60)。对照组给予针刺治疗,试验组在针刺治疗的基础上口服柴胡桂枝汤,连续治疗4周。比较两组患者治疗前后Sunnybrook评分、House-Brackmann(H-B)评分、面神经肌电图指标、瞬目反射引出情况及临床总有效率以及不良反应发生情况。结果:试验组临床总有效率为96.67%,高于对照组的85.48%。治疗4周后,试验组鼻肌、眼轮匝与口轮匝肌的传导潜伏期均低于对照组,患健侧波幅比值则高于对照组(P<0.05)。治疗2、4周后,试验组Sunnybrook评分高于对照组,而H-B评分低于对照组(P<0.05)。治疗后,试验组患侧R1、R2检出情况优于对照组,患侧瞬目反射R1、R2潜伏期低于对照组(P<0.05)。结论:针刺联合柴胡桂枝汤治疗难治性面瘫疗效较好,可疏通经络,调整气血,有效缓解临床症状,改善面部神经功能、肌电图、瞬目反射指标,安全性较好。     

瞬目反射和面神经传导检测在Bell麻痹中的运用价值

目的:探讨瞬目反射和面神经传导检测在Bell麻痹患者的早期诊断和预后评估中的价值。方法:对39例Bell麻痹患者在病程为3 d(A组)和4～10 d(B组)时分别进行BR(Blink Reflex)、FNC(Facial Nerve Conduction)检测,3个月(C组)后复查。结果:R1﹑R2﹑R2'波缺失者24例预后较差,仅15例患侧较健侧各波延长者预后较好,其中R1/M潜伏期比值提示27例表现为茎乳孔内段损害,7例为外段损害,5例较大范围受累。结论:BR、FNC检测可客观地评价面神经损害的程度及部位,对临床诊断及预后有指导意义。