One or more of three primitive reflexes (palmomental, snout, and corneomandible) was elicited in 50.5% of 105 normal subjects in the third through the ninth decades of life. The reflexes appeared in a patterned fashion with advancing age. The palmomental reflex appeared earliest and was the most frequent reflex elicited at all ages. The snout and corneomandibular reflexes appeared at later ages and were elicited less frequently. The palmomental and snout reflexes often occurred alone, but the corneomandibular was elicited only when one or both of the other reflexes was also present. These reflexes appear to be normal phenomena in a significant proportion of the healthy population.
Facial paralysis due to facial nerve injury results in the loss of function of the muscles of the hemiface. The most serious complication in extreme cases is the loss of vision. In this study, we compared the effectiveness of single- and multiple-channel electrical stimulation to restore a complete and cosmetically acceptable eye blink. We established bilateral orbicularis oculi muscle (OOM) paralysis in eight dogs; the OOM of one side was directly stimulated using single-channel electrical stimulation and the opposite side was stimulated using multi-channel electrical stimulation. The changes in the palpebral fissure and complete palpebral closure were measured. The difference in current intensities between the multi-channel and single-channel simulation groups was significant, while only multi-channel stimulation produced complete eyelid closure. The latest electronic stimulation circuitry with high-quality implantable electrodes will make it possible to regulate precisely OOM contractions and thus generate complete and cosmetically acceptable eye-blink motion in patients with facial paralysis.
Six subjects with profound facial paralysis were tested to determine the feasibility of restoring functional blink via electrical stimulation of the orbicularis oculi muscle (OOM) without also evoking painful sensations.Stimulation of the paretic eyelid was triggered by EMG detection of blink in contralateral healthy OOM to deliver charge during inhibition of the levator palpebrae antagonist. Transcutaneous and percutaneous stimulation electrode placements were tested during multiple stimulation trials in subjects. Stimulation was delivered via two constant voltage computer controlled channels. Sensory activation thresholds were approximately an order of magnitude lower for percutaneous stimulation (0.4 V) vs. transcutaneous stimulation (3 V). Exploration of multiple possible stimulation paradigms yielded a means by which sufficient muscle activation could be recruited to evoke complete eyelid closure without producing prohibitively painful sensation. Stimulation efficacy across subjects correlated with degree of patient neuromuscular recovery following initial paresis.
Facial paralysis is a serious neurologic disorder, particularly when it affects the eye. Loss of the protective blink reflex may lead to corneal ulceration and, possibly, visual loss. The purpose of this study was to compare different nerve-grafting techniques to reanimate the paralyzed eyelid. Sixteen adult dogs (25 kg each) were allocated into four groups. Denervation of the left hemi-face was performed in all cases. One dog served as a control animal (group I). Group II dogs (n = 5) underwent end-to-side coaptation of the nerve graft to the intact palpebral branch and end-to-end coaptation to the denervated palpebral branch. Group III dogs (n = 5) underwent end-to-end coaptation of the nerve graft to the intact palpebral branch and end-to-end coaptation to the denervated palpebral branch. Group IV dogs (n = 5) underwent end-to-side coaptation of the nerve graft to the intact and denervated palpebral branches. The animals were monitored for 9 months after the surgical procedures, to allow adequate time for reinnervation. The dogs were postoperatively monitored with clinical observation, electrophysiologic testing, video motion analysis, and histologic assessments. Clinical observation and electrophysiologic testing demonstrated the production of an eye blink in the denervated hemi-face in all experimental groups. There was a trend toward increased speed of reinnervation for group III animals (end-to-end coaptations). It was concluded that end-to-side coaptation can produce a contralateral synchronous eye blink in a clinically relevant, large-animal model.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.