 The hallmark of C-sonostagmus are that one eye elevates as the other eye depresses the elevating eye in torts while the depressing eye extorts. Here for example, it's difficult to see the torsional movements of the eye, but the vertical movements can be clearly seen. The waveforms are pendular, continuous, and in this patient seen best in eccentric positions of gaze as opposed to forward positions of gaze. C-sonostagmus is one of the localizing the stagmus and when seen should suggest a large structural lesion in the paracella region. These lesions are often associated with bi-temporal field defects.