Chapter 12 - Consciousness in the Locked-In Syndrome

Abstract

Patients in a locked-in syndrome (LIS) are selectively de-efferented (i.e., they have no means of producing speech, limb, or face movements). Usually the anatomy of the responsible lesion in the brainstem is such that locked-in patients are left with the capacity to use vertical eye movements and blinking to communicate with the external world. The syndrome is subdivided as: (i) classical LIS, which is characterized by total immobility except for vertical eye movements or blinking; (ii) incomplete LIS, which allows remnants of voluntary motion such as head or finger movements; and (iii) total LIS, which is a complete immobility including all eye movements. In all three cases, consciousness is usually fully preserved. Eye-controlled computer-based communication and brain-computer interface technology currently allows these patients to control their environment, use a word processor coupled to a speech synthesizer and access the world wide net. Available literature raises important ethical considerations in terms of quality of life and end-of-life decisions in such challenging patients.