Blink analysis and reanimation of the eyelid in facial nerve paralysis

This dissertation is both a historical review, and summary of the experimental research pertaining to reanimation of the paralyzed eyelid in facial nerve paralysis. It begins with an overview of the problem, available solutions, followed by descriptions and conclusions of the experiments that evaluate the role of electrical stimulation in the reanimation of the eyelid in facial nerve paralysis. It evaluates the role of electrical stimulation of the paralyzed eyelid and argues about the benefits of multichannel electrical stimulation. It reviews methods used to measure eyelid movement and emphasizes the need for an objective method to quantify eyelid motion. The latter part of the dissertation evaluates the role of a computerized eyelid motion analysis method and its use in objectively measuring the kinematic profile of the eyelid.; The dissertation is divided into four chapters covering eyelid anatomy and eyeblink physiology, review of the reanimation methods in facial nerve paralysis, role of electrical stimulation in restoring an eyeblink, and the development and use of a computerized eyelid motion analysis system to objectively quantify eyelid movement. Chapter One is a comprehensive review of the anatomy of the eyelid and the physiology of the eyeblink. This chapter also reviews the intimate structure-function relationship between the eyelid and the nervous control of the eyeblink. The second chapter is an experimental study where canine orbicularis oculi muscle dimensions were measured and an artificial implantable eyelid electrode was designed based on the information obtained. In particular, the anatomical and physiological basis for the design of the implantable electrode was reviewed.; Chapter Three is an experimental study that compares multichannel and single channel electrical stimulation for their ability to produce closure of the paralyzed eyelid in the canine model. Whereas chapters two and three focus on electrical stimulation of the eyelid to restore a blink, Chapter Four comprehensively describes the development and validation of a computerized eyelid motion analysis system to objectively quantify eyelid motion. This motion analysis system is evaluated in a clinical setting by measuring the displacement, velocity and acceleration of an eyeblink and the degree of synchronous movement between the left and the right eyelid both in normal subjects and in patients with facial paralysis. Next, the reliability and repeatability of this computerized eyelid motion analysis system is evaluated and the computerized eyelid motion analysis system is found to be reliable and repeatable. Finally the effect of loading the paralyzed eyelid with gold weights on the kinematics of the opposite eyelid in normal subjects and in patients with unilateral facial nerve paralysis is evaluated. It is found that, in facial paralysis, the adaptive gain mechanism was compromised compared to normal subjects.