From the Massachusetts Eye and Ear Infirmary, Harvard Medical School, the Department of Otolaryngology, Surgical Photonics & Engineering Laboratory; and the Department of Biomedical Engineering, McGill University.
Plast Reconstr Surg. 2019 Jan;143(1):62e-76e. doi: 10.1097/PRS.0000000000005164.
Facial palsy is a devastating condition potentially amenable to rehabilitation by functional electrical stimulation. Herein, a novel paradigm for unilateral facial reanimation using an implantable neuroprosthetic device is proposed and its feasibility demonstrated in a live rodent model. The paradigm comprises use of healthy-side electromyographic activity as control inputs to a system whose outputs are neural stimuli to effect symmetric facial displacements. The vexing issue of suppressing undesirable activity resulting from aberrant neural regeneration (synkinesis) or nerve transfer procedures is addressed using proximal neural blockade.
Epimysial and nerve cuff electrode arrays were implanted in the faces of Wistar rats. Stimuli were delivered to evoke blinks and whisks of various durations and amplitudes. The dynamic relation between electromyographic signals and facial displacements was modeled, and model predictions were compared against measured displacements. Optimal parameters to achieve facial nerve blockade by means of high-frequency alternating current were determined, and the safety of continuous delivery was assessed.
Electrode implantation was well tolerated. Blinks and whisks of tunable amplitudes and durations were evoked by controlled variation of neural stimuli parameters. Facial displacements predicted from electromyographic input modelling matched those observed with a variance-accounted-for exceeding 96 percent. Effective and reversible facial nerve blockade in awake behaving animals was achieved, without detrimental effect noted from long-term continual use.
Proof-of-principle of rehabilitation of hemifacial palsy by means of a neuroprosthetic device has been demonstrated. The use of proximal neural blockade coupled with distal functional electrical stimulation may have relevance to rehabilitation of other peripheral motor nerve deficits.
面瘫是一种可能通过功能性电刺激进行康复的破坏性疾病。在此，提出了一种使用可植入神经假体设备对面部进行单侧重新激活的新范例，并在活体啮齿动物模型中证明了其可行性。该范例包括使用健康侧肌电图活动作为系统的控制输入，该系统的输出是对实现对称面部位移的神经刺激。通过近端神经阻断来解决由于异常神经再生（联带运动）或神经转移手术而产生的不良活动的棘手问题。
在 Wistar 大鼠的面部植入肌膜和神经袖电极阵列。施加刺激以引发各种持续时间和幅度的眨眼和拂动。对肌电图信号和面部位移之间的动态关系进行建模，并将模型预测与测量位移进行比较。确定通过高频交流实现面神经阻断的最佳参数，并评估连续传递的安全性。
电极植入耐受性良好。通过控制神经刺激参数的变化，可以诱发可调节幅度和持续时间的眨眼和拂动。从肌电图输入建模预测的面部位移与观察到的位移相匹配，方差解释超过 96%。在清醒行为动物中实现了有效且可逆的面神经阻断，并且没有观察到长期连续使用的不利影响。
通过神经假体设备对面瘫进行康复的原理已经得到证明。近端神经阻断与远端功能性电刺激的结合可能与其他周围运动神经缺陷的康复有关。
