[Paradoxical dynamics in the values of bispectral index for bilateral registration in a patient during parastem tumor removal (a clinical case)].

The paper describes an unusual clinical case. During a neurosurgical operation (removal of parastem tumor (neuroma) on the right side), bilateral registration of the bispectal index (BSI) in order to monitor a hypnotic component of anesthesia showed that the tumor removal stage was marked by a paradoxical reaction of the BSI as an increase in its values up to 70-80% (corresponds to the patient's emergence) on the right, ipsilaterally, with the preserved low BSI values on the left--30-40%. Possible explanations of the observed are considered.