Accuracy of cerebral monitoring in detecting cerebral ischemia during carotid endarterectomy: a comparison of transcranial Doppler sonography, near-infrared spectroscopy, stump pressure, and somatosensory evoked potentials - Moritz, S; Kasprzak, P; Arlt, M; Taeger, K; Metz, C (Anesthesiology, 2007)