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This thesis investigated the underlying physiology of the human facial nerve in health and disease. This involved the translation and optimisation of techniques for determining axonal excitability measures in the human facial nerve. The techniques have proven to be valuable in determining pathophysiology in neuropathies and it was hypothesised that the information they provide may be helpful in understanding facial nerve disorders. The initial studies developed the technique in healthy controls and established normative data (Chapter 1). The initial study in a disease group (Chapter 2) was targeted at a broad cross-section of facial palsy patients to explore the utility of the technique. Findings consistent with membrane hyperpolarisation were demonstrated. Subsequent studies examined specific disease groups including Bell’s palsy (Chapter 3), facial synkinesis (Chapter 4), and assessment of facial nerve function of the contralateral face to facial palsy (Chapter 5). Changes consistent with reduced inward sodium conductances were noted in Bell’s palsy and these occurred in a pattern that has been noted with tetrodotoxin ingestion. In patients with facial synkinesis, changes in excitability were observed that would be consistent with axonal membrane depolarisation and which may predispose to ectopic motor activity. Altered facial nerve function was also noted in recordings from the contralateral face in patients who had experienced facial palsy and the pattern of change varied according to the severity of facial palsy. These changes provide physiological support for treatment of the contralateral face with chemodenervation in patients with facial palsy.

La Neurofisiología Clínica es una especialidad médica cuyo objeto es el estudio del sistema nervioso y muscular con fines diagnósticos, pronósticos y terapéuticos. En este artículo se analiza el objetivo básico que pretende esta disciplina, las técnicas que utiliza y su reconocimiento como especialidad médica. Se hace un pequeño recorrido por su definición y alcance de la misma, cómo se estructura hoy día y las posibilidades de futuro que ofrece.