Blink Restoration in Patients With Facial Nerve Palsy

Overview

This study is a non-blinded single armed pilot study aiming to apply a newly created medical device in patients with seventh nerve palsy suffering from lagophthalmus in order to determine the best way for neuromuscular stimulation of the orbicularis oculi muscle and facial nerve in order to enable eyelid closure (blink). Initially, a tailored external neurostimulation prototype will be created in collaboration with the ETH for patients with facial nerve palsy and lagophthalmos. Aim of this study is to create an efficient, safe and comfortable medical device that can achieve an effective blinking through external electrical neuromuscular stimulation of the orbicularis oculi in patients with facial palsy and lagophthalmos. Such a device can become an essential part of facial palsy treatment.

Facial paralysis rates are reported to be 4/10,000 per annum leading to facial asymmetry and impairs essential facial functions, including blinking, protection of the cornea, lip competence, mastication, speaking, but also has psychosocial penalties. Facial animation is orchestrated by the facial muscles directed by the facial nucleus through a network of the facial nerve and its branches. The facial nerve (CNVII) plays a critical role in multiple complex functions of human life including mastication, speech, and successful social communication through expression of mood and emotion. The absence of facial nerve's function can be a result of a developmental anomaly, of a stroke leading to a damage to the central segment of this nerve (facial nucleus in the pons, motor cortex, or connections between the two), an iatrogenic or traumatic injury, a neoplastic infiltration or an infectious (e.g., borreliosis and herpes zoster), or idiopathic inflammation of the extratemporal segments of the facial nerve. The peripheral facial paralysis (PFP), resulting from affection of the seventh nerve is the most common pathology of the cranial pairs. The facial nerve normally emits electrical impulses to give muscles their tone and shape. Therefore, when it is damaged, the muscles become weak and floppy. External electrical stimulation can mimic the electrical nerve impulses and help restore muscle tone in patients with facial palsy. Applications involving nerve stimulation can be divided into three separate categories: therapeutic electrical stimulation (TES), neuromodulatory stimulation (NMS), and functional electrical stimulation (FES). By FES standards, neural prosthetic reanimation of the eyelids for blink restoration is a relatively simple and low-risk application. Restoration of blinking involves a single muscle, the orbicularis oculi. The presence of the nerve is not required for external electrical stimulation to be used. External electrical neuromuscular stimulation can try to mimic the electrical nerve impulses in patients with facial palsy. However, no device has yet been proven appropriate for daily use. The research question the investigators aim to answer is whether an efficient, safe and comfortable medical device that can achieve an effective blinking through external electrical neuromuscular stimulation of the orbicularis oculi in patients with facial palsy and lagophthalmos can be created. The stimulation will be provided in the form of charge balanced biphasic square pulses as shown in the image below at a frequency of 100Hz. The investigators mainly want to determine the functionality of a constant external electrostimulation for the patients. Blinking sufficiency will be evaluated qualitatively and quantitatively through surveys and observations. The investigators aim to recruit initially 10 patients suffering from lagophthalmos due to facial nerve palsy, who will be invited to wear the device. The exact parameters needed for the neurostimulation and symptoms of patients or any adverse events will be documented on the case report form (CRF).