The SSEP on the ICU: Current applications and pitfalls

Clinical neurological evaluation of patients in the intensive care unit (ICU) is often limited. Registration of the somatosensory evoked potential (SSEP) can assist in the neurological evaluation in these patients. In this paper, we discuss the principles, applications and limitations of the SSEPs in the ICU with a focus on prognostication in comatose patients. Registration of the SSEP is a very reliable and reproducible method, if it is performed and interpreted correctly. A bilateral absent cortical SSEP response is a reliable predictor for poor neurological outcome in patients with a post-anoxic coma, but not in patients with traumatic brain injury or subarachnoid haemorrhage. During SSEP recordings, great care should be taken in improving the signal to noise ratio. Since the interpreting clinician is often not present during the actual SSEP registration itself, the role of the lab technician is crucial in obtaining reliable SSEP results. If the noise level is too high, the peripheral responses are abnormal, or the response is not reproducible in a second set of stimuli, interpretation of the SSEP cannot be done reliably.