Assessment of facial nerve function in acoustic tumor disease by nasal muscle F waves and transcranial magnetic stimulation

Standard transcranial magnetic stimulation and nasal muscle F-wave recordin gs were used to assess proximal facial nerve function in 27 patients with u nilateral acoustic tumors (mean diameter, 29 mm) and clinically intact faci al nerve function. Latency measurements for F waves and cortical magnetic s timulation were abnormal. Moreover, F ratios, central motor conduction time , and the ratio of response latency to cortical and cisternal magnetic stim ulation were significantly increased. Amplitudes were unchanged. Correlatio n analysis with tumor diameter as dependent variable yielded maximum r valu es for F-wave latencies (0.57) and F ratios (0.41), whereas for magnetic st imulation, a significant correlation could be found (0.4) only for cortical stimulation. Nasal muscle F-wave recording can reveal clinically inapparen t facial nerve dysfunction. its efficacy in predicting tumor diameter seems to be superior to that of standard magnetic stimulation. (C) 2000 John Wil ey & Sons, Inc.