Electrophysiology in the locked-in-syndrome

We investigated five patients with a locked-in-syndrome (LIS) and reported the clinical, electrophysiologic, neuroradiologic, and neuropathologic findings. EEG reactivity was present in two and absent in three cases. Somatosensory evoked potentials (SEP) varied from unilaterally normal to bilaterally absent. We conclude that there is no specific pattern of SEP abnormality characteristic of LIS and that EEG reactivity cannot be taken as a sole measure of consciousness.