Blink reflex: comparison of latency measurements in different human races

Blink reflex: A practical test to evaluate the trigeminal nerve injury following percutaneous balloon compression for the treatment of trigeminal neuralgia

OBJECTIVE

To evaluate the blink reflex (BR) in estimating the potential injury of trigeminal nerve following percutaneous balloon compression (PBC) surgery, and to determine the association between BR alterations and early surgical outcomes.

METHODS

In this single-center, prospective before-and-after study, a total of 74 patients who had primary trigeminal neuralgia and scheduled for PBC between October 2020 and June 2021 were prospectively included. BR testing and facial sensory assessment were performed pre- and post-PBC. The latency and the area under the curve (AUC) of pre- and postoperative R1 (R1_pre /R1_post ) and R2 (R2_pre /R2_post ) were measured.

RESULTS

The BR components were noticeably delayed or diminished following PBC. R1_post was elicited in only 26 patients, and absent in 48 patients. The residual R1_post had markedly reduced AUC (median difference [Hodges-Lehmann]: -59.5, 95% confidence interval [CI]: -217.5 to -6.9, p = 0.023). Compared with R2_pre , the latency of R2_post was considerably delayed (mean difference: 4.3, 95% CI: 2.9 to 5.7, p < 0.001) and the AUC was greatly suppressed (median difference [Hodges-Lehmann]: -388.4, 95% CI: -548.4 to -259.5, p < 0.001). After PBC, 58 patients had immediate total pain relief, and 16 had partial relief. The absence of R1_post was found in 46 of 58 (79.3%) patients with complete remission, whereas in only 2 of 16 (12.5%) patients with partial relief. Association analysis showed that the absence of R1_post was strongly associated with total pain relief (46/58 [79.3%] vs. 2/16 [12.5%], odds ratio [OR]: 26.8, 95% CI: 5.4 to 134.5, Cramér's V: 0.6, p < 0.001). The latency of R2_post in patients with total relief was significantly delayed (mean difference: 2.5, 95% CI: 0.3 to 4.6, p = 0.028). Patients experienced graded facial numbness after PBC, of whom 31 reported mild numbness (Grades I-II) and 43 reported more severe numbness (Grades III-IV). The absence of R1_post was significantly associated with facial numbness severity, 33/43 (76.7%) in Grades III-IV vs. 15/31 (48.4%) in Grades I-II (OR: 0.284, 95% CI: 0.105 to 0.771, Cramér's V: 0.3, p = 0.012). In patients with more severe numbness, the latency of R2_post was significantly delayed (mean difference: 2.7, 95% CI: 0.1 to 5.3, p = 0.043), and the reduction of AUC was much greater (median difference [Hodges-Lehmann]: 17.2, 95% CI: 0.5 to 35.4, p = 0.041).

CONCLUSION

Both R1 and R2 were significantly diminished after PBC and these alterations were associated with early surgical outcomes, suggesting that the BR is useful in evaluating trigeminal injury following PBC and could provide objective information about early prognosis.

Differences in startle reflex and prepulse inhibition in European-Americans and African-Americans

The acoustic startle reflex and its modulation by a prepulse are psychophysiological phenomena that are commonly studied to evaluate various aspects of information processing. Recent reports in human populations suggest that subjects from disparate racial backgrounds may have significant differences in the startle response. To determine if this pattern could be observed in our subject population and whether it extended to prepulse inhibition (PPI), we evaluated baseline startle parameters and PPI in 53 African-Americans (AA) and 38 European-Americans (EA). In AA compared to EA, mean startle magnitude and probability of blink response were lower, with no difference in habituation. PPI was greater in AA than EA when groups were matched on baseline startle magnitude. These findings support the idea of racial differences in startle response. Implications for study design are highlighted, and possible environmental and genetic influences are considered.

Aspectos neurofisiológicos da musculatura facial visando a reabilitação na paralisia facial

OBJETIVO: revisão teórica dos aspectos e particularidades neurofisiológicas relevantes da musculatura orofacial, visando a reabilitação na paralisia facial periférica. MÉTODOS: revisão da literatura sobre neuro-anatomofisiologia da musculatura orofacial mediante pesquisa dos artigos dos periódicos nacionais e internacionais e nos livros científicos sobre o tema, no período entre 1995 a 2005. RESULTADOS: foram revistas 50 referências neste trabalho. Destas, 20 sobre neurofisiologia, 14 sobre neuroanatomia. As demais sobre fonoaudiologia e paralisia facial. Os artigos de neurofisiologia e neuroanatomia estudados foram divididos em três grupos: I - Aspectos do complexo neuromuscular; II - Características morfológicas e histoquímicas dos músculos da face e III - Denervação e atrofia muscular. CONCLUSÃO: a partir dos achados, procurou-se sistematizar didaticamente as particularidades da neuro-anatomofisiologia, cujo conhecimento, na impressão dos autores, são relevantes para o sucesso na reabilitação da paralisia facial.