Deniz Tuna Edizer1, Zehra Dönmez1, Mehmet Gül2, Özgür Yiğit1, Birgül Yiğitcan2, Turgut Adatepe3, Nurten Uzun4. 1. Department of Otorhinolaryngology, İstanbul Training and Research Hospital, İstanbul, Turkey. 2. Department of Histology and Embryology, İnönü University School of Medicine, Malatya, Turkey. 3. Department of Electrophysiology, İstanbul Training and Research Hospital, İstanbul, Turkey. 4. Department of Neurology, İstanbul University-Cerrahpaşa, Cerrahpaşa School of Medicine, İstanbul, Turkey.
Abstract
OBJECTIVES: To investigate the effects of topical and systemic administrations of melatonin and dexamethasone on facial nerve regeneration. MATERIALS AND METHODS: In total, 50 male albino Wistar rats underwent facial nerve axotomy and neurorrhaphy. The animals were divided into 5 groups: control, topical melatonin, systemic melatonin, topical dexamethasone, and systemic dexamethasone. Nerve conduction studies were performed preoperatively and at 3, 6, 9, and 12 weeks after drug administrations. Amplitude and latency of the compound muscle action potentials were recorded. Coapted facial nerves were investigated under light and electron microscopy. Nerve diameter, axon diameter, and myelin thickness were recorded quantitatively. RESULTS: Amplitudes decreased and latencies increased in both the melatonin and dexamethasone groups. At the final examination, the electrophysiological evidence of facial nerve degeneration was not significantly different between the groups. Histopathological examinations revealed the largest nerve diameter in the melatonin groups, followed by the dexamethasone and control groups (p<0.05). Axon diameter of the control group was smaller than those of the melatonin (topical and systemic) and topical dexamethasone groups (p<0.05). The melatonin groups had almost normal myelin ultrastructure. CONCLUSION: Electrophysiological evaluation did not reveal any potential benefit of dexamethasone and melatonin in contrast to histopathological examination, which revealed beneficial effects of melatonin in particular. These agents may increase the regeneration of facial nerves, but electrophysiological evidence of regeneration may appear later.
OBJECTIVES: To investigate the effects of topical and systemic administrations of melatonin and dexamethasone on facial nerve regeneration. MATERIALS AND METHODS: In total, 50 male albino Wistar rats underwent facial nerve axotomy and neurorrhaphy. The animals were divided into 5 groups: control, topical melatonin, systemic melatonin, topical dexamethasone, and systemic dexamethasone. Nerve conduction studies were performed preoperatively and at 3, 6, 9, and 12 weeks after drug administrations. Amplitude and latency of the compound muscle action potentials were recorded. Coapted facial nerves were investigated under light and electron microscopy. Nerve diameter, axon diameter, and myelin thickness were recorded quantitatively. RESULTS: Amplitudes decreased and latencies increased in both the melatonin and dexamethasone groups. At the final examination, the electrophysiological evidence of facial nerve degeneration was not significantly different between the groups. Histopathological examinations revealed the largest nerve diameter in the melatonin groups, followed by the dexamethasone and control groups (p<0.05). Axon diameter of the control group was smaller than those of the melatonin (topical and systemic) and topical dexamethasone groups (p<0.05). The melatonin groups had almost normal myelin ultrastructure. CONCLUSION: Electrophysiological evaluation did not reveal any potential benefit of dexamethasone and melatonin in contrast to histopathological examination, which revealed beneficial effects of melatonin in particular. These agents may increase the regeneration of facial nerves, but electrophysiological evidence of regeneration may appear later.
Authors: Caroline A Banks; Christopher Knox; Daniel A Hunter; Susan E Mackinnon; Marc H Hohman; Tessa A Hadlock Journal: J Reconstr Microsurg Date: 2015-01-28 Impact factor: 2.873