Intraoperative monitoring during surgery for XXXX : benefits of an extratympanic intrameatal electrode.

@entity5 @entity1 @entity5513
OBJECTIVES: To assess the utility of an extratympanic intrameatal electrode for intraoperative monitoring during @entity5513 and other @entity5 surgery and to define the neurophysiological and surgical factors which influence hearing preservation. METHODS: Twenty two @entity1 , 18 with @entity5513 and four with @entity5 , underwent intraoperative monitoring during @entity5 excision. The extratympanic intrameatal electrode (IME) was used to record the electrocochleogram (ECoG) and surface electrodes to record the brainstem auditory evoked response (ABR). RESULTS: The compound action potential (CAP) of the ECoG was two and a half times greater in amplitude than wave I of the ABR and was easily monitored. Virtually instant information was available as minimal averaging was required. Continuous monitoring was possible from the commencement of anaesthesia to skin closure. The IME was easy to place, non-invasive, and did not interfere with the operative field. Operative procedures which affected CAP or wave V latency or amplitude were drilling around the internal auditory meatus, @entity5 dissection, nerve section, and brainstem and cerebellar retraction. Hearing was achieved in 59% of @entity1 . CONCLUSIONS: The IME had significant benefits in comparison with other methods of monitoring. The technique provided information beneficial to preservation of hearing.
