Objective—To investigate the value of nasopharyngeal
and tracheal recordings of somatosensory
evoked potentials (SSEP) in anesthetized dogs.
Animals—10 healthy mixed-breed dogs (5 males and
Procedure—Square-ware electrical stimuli (50
microseconds duration, 4Hz) were delivered through
bipolar surface electrodes to the median nerve of the
right forelimb with 7 to 12 mA constant current. The
SSEP were recorded with soft electrodes placed on
the epipharynx and dorsal wall of the trachea, respectively.
Traditional scalp and neck recordings of SSEP
were also performed, using SC-inserted needle electrodes.
The potentials recorded dorsally and ventrally
from the neuraxis were compared to assess the application
of these signals for intraoperative neurophysiologic
Results—Electrical stimulation of the median nerve
resulted in multiphasic potentials recorded from all 4
recording sites. Latency and phase shifts were
observed between the far-field potentials placed ventrally
and dorsally from the neuraxis.
Conclusions and Clinical Relevance—Potentials
recorded with nasopharyngeal and tracheal electrodes
are regarded suitable for intraoperative neurophysiologic
monitoring in anesthized dogs. (Am J Vet
Res 2002; 63:669–672)