Pilot Study to Assess Changes in the Blink Reflex Across Age

ObjectiveThe objective was to conduct a preliminary study to access blink reflex parameters across age using the Eyestat.BackgroundThe blink reflex is a primitive brainstem response to an external stimulus is affected by multiple neurologic disorders, including those that affect the dopaminergic circuit that controls the eyelid. Our laboratory has utilized a potential objective measure to identify concussions within a college aged sport population called Eyestat, which measures changes in blink reflex parameters. Prior research cited significant differences in various blink reflex parameters between active play, concussion, and baseline. However, data with older, non-athlete populations has not defined.Design/MethodsOne hundred forty three subjects between the ages of 8–80 participated in this study. Once the subject was seated, the test sequence was initiated, in which the subject placed their face into the mask and 5 random air puffs were applied to the corner of the left or right eyes over a course of 20 seconds. High-speed videography (280 frames/sec.) captured the response of the subject's eyes before and after each stimuli.ResultsDescription statistics of the data indicated differences across age with the following parameters: Latency (ms): 46.02 (ages 8–21); 47.12 (ages 22–30); 48.96 (ages 31–40); 47.44 (ages 41–50); 55.20 (ages 51–60); and 55.39 (ages 61–80). Oscillations (qty): 14.10 (ages 8–21); 14.25 (ages 22–30); 12.19 (ages 31–40); 12.75 (ages 41–50); 9.98 (ages 51–60); and 9.78 (ages 61–80). Excursions (px): 127.57 (ages 8–21); 137.46 (ages 22–30); 135.34 (ages 31–40); 144.88 (ages 41–50); 147.72 (ages 51–60); and 148.85 (ages 61–80).ConclusionsAlthough more research is warranted to determine if these differences occur with a larger subject pool, this data substantiates the need for longitudinal assessments of the blink reflex as a potential biomarker, providing a non-invasive assessment of brain health in various populations.

Electrophysiological assessment of the cranial reflexes

Electrophysiological assessment methods play a key role in the diagnosis of various neurological disorders. Electrophysiological evaluation of cranial reflexes is particularly valuable for neurologists. This article provides an overview of electrophysiological evaluation methods for cranial reflexes, which are most commonly used in clinical practice. They provide objective assessment of the functional integrity of nervous system structures that make up the cranial reflex arc, identify the level and, in some cases, the nature of disease, as well as pathophysiological mechanisms of central and peripheral nervous system disorders. We describe the instruments and main approaches to analysing the results for the standard blink reflex, blink reflex with prepulse inhibition, blink reflex with paired stimuli and recovery curve evaluation, reflex inhibition of the levator palpebrae superioris, jaw jerk reflex, and reflex inhibition (cutaneous silent period) of the masseter muscle.

Preventive treatment with CGRP monoclonal antibodies restores brain stem habituation deficits and excitability to painful stimuli in migraine: results from a prospective case-control study

Background & Objectives Calcitonin gene-related peptide ligand/receptor (CGRP) antibodies effectively reduce headache frequency in migraine. It is understood that they act peripherally, which raises the question whether treatment merely interferes with the last stage of headache generation or, alternatively, causes secondary adaptations in the central nervous system and might thus possess disease modifying potential. This study addresses this question by investigating the nociceptive blink reflex (nBR), which is closely tied to central disease activity, before and after treatment with CGRP antibodies. Methods We enrolled 22 patients suffering episodic migraine (21 female, 46.2 ± 13.8 years of age) and 22 age-/gender-matched controls. Patients received assessments of the nBR (R2 component, 10 trials, 6 stimuli/trial) before (V0) and three months (V3) after treatment with CGRP antibodies started, controls were assessed once. The R2 area (R2a) and habituation (R2h; gradient of R2a against stimulus order) of the stimulated/non-stimulated side (_s/_ns) following repeated supraorbital stimulation provide a direct readout of brainstem excitability and habituation as key mechanisms in migraine. Results All patients showed a substantial reduction of headache days/month (V0: 12.4±3.3, V3: 6.6 ± 4.9). R2a_s (Fglobal=5.86, p<0.001; block 1: R2a_s: -28%, p<0.001) and R2a_ns (Fglobal=8.22, p<0.001, block 1: R2a_ns: -22%, p=0.003) were significantly decreased, and R2h_ns was significantly enhanced (Fglobal=3.07, p<0.001; block 6: R2h_ns: r=-1.36, p=0.007) from V0 to V3. The global test for changes of R2h_s was non-significant (Fglobal=1.46, p=0.095). Changes of R2h significantly correlated with improvement of headache frequency (R2h_s, r=0.56, p=0.010; R2h_ns: r=0.45, p=0.045). None of the nBR parameters assessed at baseline predicted treatment response. Discussion We provide evidence that three months of treatment with CGRP antibodies restores brain stem responses to painful stimuli and thus might be considered disease modifying. The nociceptive blink reflex may provide a biomarker to monitor central disease activity. Future studies should evaluate the blink reflex as a clinical biomarker to predict treatment response at baseline and to establish the risk of relapse after treatment discontinuation. Trial registration This trial was prospectively registered at clinicaltrials.gov (ID: NCT04019496, date of registration: July 15, 2019).

ASSESSMENT OF VISUAL PROGNOSIS IN PATIENTS WITH OCULAR BURNS: A CROSSSECTIONAL STUDY

Introduction: Ocular burns are ophthalmic emergencies due to their visual morbidity. The extent of ocular surface involvement at the time of presentation is critically associated with visual outcome. Comprehensive ocular examination and prompt management is needed to optimize visual outcome. Objective: This study aims to evaluate the epidemiological trends, clinical features of patients with ocular burns and to determine their relationship with visual outcome. Methods:This prospective, cross-sectional study was conducted on 96 consecutive in-patients who were admitted in the Department of Plastic surgery and Burns in our hospital and sought opinion for ocular burns, irrespective of age and sex. The main outcome measures evaluated were clinical features of ocular burns and prognostic factors associated with visual impairment. Results: In our study, the mean age (S.D.) of patients was 32.83+/- 18.70 years with both males and females equally affected. The most common mode of injury was thermal injury due to domestic accidents (88.5%). 74% of patients had bilateral ocular presentation. Lid burns (42.2%) and lid edema (41.1%) were the most common ocular findings. About 5.2% of eyes showed corneal involvement. About 14 eyes (7.3%) had severe ocular complications among which one eye developed phthisis bulbi. 20 eyes (16.1%) had visual acuity of less than 6/60 causing visual morbidity. In multivariate logistic regression analysis, corneal involvement (p<0.001) and ocular complications (p=0.011) had a significant association with visual impairment. Conclusion:Corneal involvement and ocular complications are less common in facial burns due to Bell's phenomenon and protective blink reflex. However, both factors had a significant influence on visual outcome contributing to visual prognosis. Early intervention and adequate management will lead to favorable visual outcome.

Preventive Treatment With CGRP Monoclonal Antibodies Restores Brain Stem Habituation Deficits and Excitability to Painful Stimuli in Migraineurs: Results From a Prospective Case-control Study

Background & ObjectivesCalcitonin gene-related peptide ligand/receptor (CGRP) antibodies effectively reduce headache frequency in migraineurs. It is understood that they act peripherally, which raises the question whether treatment merely interferes with the last stage of headache generation or, alternatively, causes secondary adaptations in the central nervous system and might thus possess disease modifying potential. This study addresses this question by investigating the nociceptive blink reflex (NBR), which is closely tied to central disease activity, before and after treatment with CGRP antibodies.MethodsWe enrolled 22 episodic migraineurs (21 female, 46.2 ± 13.8 years of age) and 22 age-/gender-matched controls. Patients received assessments of the NBR (R2 component, 10 trials, 6 stimuli/trial) before (V0) and three months (V3) after treatment with CGRP antibodies started, controls were assessed once. The R2 area (R2a) and habituation (R2h; gradient of R2a against stimulus order) of the stimulated/non-stimulated side (_s/_ns) following repeated supraorbital stimulation provide a direct readout of brainstem excitability and habituation as key mechanisms in migraine.ResultsAll patients showed a substantial reduction of headache days/month (V0: 12.4±3.3, V3: 6.6 ± 4.9). R2a_s (Fglobal=5.86, p<0.001; block 1: R2a_s: -28%, p<0.001) and R2a_ns (Fglobal=8.22, p<0.001, block 1: R2a_ns: -22%, p=0.003) were significantly decreased, and R2h_ns was significantly enhanced (Fglobal=3.07, p<0.001; block 6: R2h_ns: r=-1.36, p=0.007) from V0 to V3. The global test for changes of R2h_s was non-significant (Fglobal=1.46, p=0.095). Changes of R2h significantly correlated with improvement of headache frequency (R2h_s, r=0.56, p=0.010; R2h_ns: r=0.45, p=0.045). None of the NBR parameters assessed at baseline predicted treatment response.DiscussionWe provide evidence that three months of treatment with CGRP antibodies restores brain stem responses to painful stimuli and thus might be considered disease modifying. The nociceptive blink reflex may provide a biomarker to monitor central disease activity. Future studies should evaluate the blink reflex as a clinical biomarker to predict treatment response at baseline and to establish the risk of relapse after treatment discontinuation.Trial registrationThis trial was prospectively registered at clinicaltrials.gov (ID: NCT04019496, date of registration: July 15, 2019).