Electroencephalographic monitoring during sevoflurane anaesthesia in an amyotrophic lateral sclerosis patient with locked-in state.

Recently, the cognitive abilities of patients with amyotrophic lateral sclerosis (ALS) have been found to be impaired along with the neurodegeneration of motor neurons. Electroencephalography (EEG) of end-stage ALS patients has reportedly shown specific features based on neuronal network modulations, differing from EEG of other patients with cognitive failure and dementia. However, EEG of end-stage ALS patients during anaesthesia has not yet been reported. A 64-year-old male ALS patient with locked-in state (LIS), supported by tracheostomy positive-pressure ventilation (TPPV) and enteral nourishment for 9years, underwent scheduled general anaesthesia for repair of a fractured mandible. He could blink and open his eyes, but seldom opened or closed his eyes on instruction. Sevoflurane anaesthesia was induced under continuous EEG monitoring with bispectral index (BIS), which is commonly used to examine the level of anaesthesia. Prominent alpha oscillations with lower peak frequency and high amplitude appeared during anaesthesia, differing from the characteristics of EEG seen in patients with general cognitive failure. Conversely, BIS reflected the sevoflurane concentration in this ALS patient, similar to healthy individuals, and BIS monitoring was useful for estimating the depth of anaesthesia. The prominent alpha oscillation revealed in this rare case report may suggest modulation of the functional neuronal network system during anaesthesia in patients with progressive ALS, in a manner quite different from typical dementia patients. EEG abnormalities in the present ALS patient did not influence the availability of BIS monitoring.