| 소속 |
Department of Rehabilitation Medicine, Gangnam Severance Hospital, Rehabilitation Institute of Neuromuscular Disease, Yonsei University College of Medicine, Seoul, Republic of Korea1, Department and Research Institute of Rehabilitation Medicine, Severance Hospital, Yonsei University College of Medicine2 |
Objective: The blink reflex is usually identified in response to electrical stimulation of the trigeminal nerve, which is used for the functional analysis of the trigeminal and facial nerves and brainstem connections. Two components (R1 and R2) have been established as meaningful parameters in diagnosing and predicting the prognosis in patients with facial palsy. A few researchers recognized the presence of R3 response, and reported presumed clinical significance. However, the definition, neural route or the clinical role of the R3 is not yet clearly established. Hereby, we retrospectively analyzed the responses of the blink reflex in patients with facial palsy to reveal the neural route of the R3.
Methods: By retrospective medical chart review, we screened 340 cases of the electrodiagnostic study (EDx) including the blink reflex between January 2017 and December 2018. The inclusion criteria were (a) unilateral facial palsy with House-Brackmann Scale > 1, (b) age > 15. The exclusion criteria were (a) central nervous system lesion (brain or brainstem) which was confirmed by imaging study, (b) trigeminal nerve lesion, (c) history of systemic peripheral neuropathy, facial spasm, or (d) history of botulinum toxin injection in facial muscles. Identification of R3 component was based on the normative parameters of the Medvedeva study (latency, 73-90 ms; duration, 15-20 ms; amplitude, 50-79 uV). The electrodiagnostic technique for blink reflex followed the Aramideh study (sweep speed, 10 ms/division; sensitivity, 200 uV/division; stimulation, 15-25 mA; Figure 1) with Cadwell Sierra® Summit™ EMG.
Results: A total of 97 cases was satisfied with the inclusion criteria, and four cases did not show ipsilateral and contralateral R3. The 93 cases were enrolled for analysis. The characteristics of subjects are presented in Table 1. In all 97 cases, every R3 response followed the R2 component. There was no case that the R3 component sorely exists without the R2. Most of the R3 was identified in contralateral side when stimulating the lesion side (81.4 %), and identified in ipsilateral side (85.6 %) when stimulating the normal side (Table 2). Additionally, the R3 wave was identified as either a single separate wave form from R2 (52.6 %) or as a mixed wave form following R2 (47.4 %).
Conclusion: The presence of the single wave form of the R3 represents that the R3 is not only the prolonged response of the R2, but a response from a separate neural route which is longer than that of R2. It can be deduced that some of the neural routes of R2 and R3 overlap in that R3 is always observed with R2. Additionally, the result that the R3 is scarcely observed in the lesion side in patients with facial palsy support that the R3 would share the final neural route of the R2. To clarify the R3 component of the blink reflex, further data accumulation from various clinical condition is required. |
