Abstract
Objectives:
The purpose of this study was to assess 1) the degree of motoneuron cell loss and 2) the combinatorial effects of electrical stimulation (ES) and testosterone propionate (TP) on cell survival following an intracranial facial nerve crush injury and 3) to compare these results to distal injuries.
Methods:
Study Design: Prospective, randomized, controlled animal study. Sprague-Dawley rats were randomly divided into three groups: intracranial sham surgery or intracranial crush injury with or without ES and TP treatments. The intracranial sham group underwent exposure of the meatal segment of the right facial nerve. The intracranial crush groups underwent a crush of the meatal segment following exposure with or without ES and TP treatment immediately following the injury and were followed for 8 weeks. Brain sections were thionin-stained, and facial motoneurons were counted using light microscopy. Results were compared to intratemporal and extracranial facial nerve crush injuries.
Results:
Intracranial crush injury resulted in a significant decrease in cell survival of 65.6% as compared to the sham group (99.4%). The treatments increased cell survival to 93.8%. The cell loss in the intracranial facial nerve injury is more substantial than the intratemporal (85.8%) and extracranial (103.3%) injuries.
Conclusions:
Intracranial injury results in a more profound cell loss compared to the distal injuries; however, combinatory treatments improve facial motoneuron survivability regardless of injury location. These data suggest the important clinical implication that this combinatorial treatment may significantly improve cell survival and therefore facial nerve function following even the most severe facial nerve injuries.
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