Imaging of the upper airways during hypoglossal nerve stimulation

The upper airways were imaged in an anesthetized beagle to investigate the effect of selective stimulation of the hypoglossal nerve (HG) with a multi-contact peripheral nerve electrode. A fiberoscope lead (diam. 5 mm) was inserted transorally and positioned at various points in the upper airways while the head was fixed at either 30/spl deg/ or 90/spl deg/ from the horizontal. Images taken in the pharynx and near the base of the tongue show that stimulations delivered through the electrode contacts placed around the HG nerve trunk can generate several different patterns of tongue activation. A subset of these patterns substantially increase the size of the pharyngeal opening. These results suggest that selective stimulation of the whole HG nerve can be a useful technique to maximize the effect of the HG nerve stimulation in removing the obstructions in steep apnea patients.