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Published on: October 13, 2016
Contralateral R1 response in blink reflex in patients with amyotrophic lateral sclerosis
Julian Theuriet1, Adrien Bohic1,2, Maxime Bonjour3,4
1Service d'ENMG et de Pathologies Neuromusculaires, Centre de Référence des Maladies Neuromusculaires PACA-Réunion-Rhône-Alpes, Hôpital Neurologique Pierre Wertheimer, Hospices Civils de Lyon, Groupement Est, 69500 Bron, France.
Objective:
This study aimed to compare the frequency of blink reflex's contralateral R1 responses (R1') between patients with amyotrophic lateral sclerosis (ALS), non-ALS motor deficit patients, and healthy volunteers.
Methods:
A total of 120 participants were prospectively recruited: 40 with ALS, 40 with a non-ALS motor deficit, and 40 healthy volunteers. Blink reflexes were recorded from orbicularis oculi muscles following supraorbital nerve stimulation.
Results:
R1' was more frequent in the ALS group (42.5 %) compared to healthy volunteers (12.5 %, p = 0.00588), and compared to non-ALS patients (7.5 %, p = 0.000789). Bilateral R1' was observed only in ALS patients (22.5 %). No clinically significant difference was found in the latencies or amplitudes of the R1, R2, or R1' responses among groups. R1' was more frequent in ALS patients with pseudobulbar affect (71.4 %) compared to those without (36.4 %).
Conclusions:
The higher frequency of R1' in ALS highlights its potential role in distinguishing ALS from other motor disorders. Its sensitivity was low, but bilateral R1' was specific to ALS. The higher frequency of R1' among ALS patients with pseudobulbar affect potentially reflects corticobulbar neuron degeneration.
Significance:
The R1', especially when bilateral, could serve as an additional diagnostic biomarker for ALS, although its clinical relevance should be considered within the broader diagnostic context.
