Abstracts

Rationale: Electroencephalographic reactivity (EEG-R) has been defined in the 2021 American Clinical Neurophysiology Society (ACNS) guidelines as a change in cerebral EEG activity to stimulation. Such changes may consist of increases or decreases in frequency or amplitude following the stimulation. Methods of stimulation are highly variable among institutions and even vary within a single institution. Clinical and logistical limitations as well as risks to patient and technologist often determine whether or how effectively stimulation can be performed. Utility of assessing reactivity is well-established, however, in prognostication of encephalopathic patients. The primary objective of this study was to identify our predominantly used methods of stimulation, or combinations of modalities for such patients. We sought also to identify if some modalities were more consistent in yielding EEG reactivity.

Methods: We conducted a retrospective chart review of adult patients with long term monitoring (LTM) performed while clinically reported to be encephalopathic between August 2021 and February 2021 at Wake Forest Medical Center. Baseline EEG data at the beginning of the LTMs was assessed to identify which modalities of stimuli were performed, and whether associated reactivity could be identified on the EEG. Patients with active seizures, status epilepticus or medically induced anesthetic patterns were excluded from analysis. Studies were reviewed by the epilepsy fellow, then reviewed by a clinical neurophysiology attending, and correlated with the previously reported result.

Results: Thirty adult patients between the ages of 61-70 met criteria for analysis.The most common stimulus used was visual activation by passive or active eye opening. Both auditory and painful stimulation were performed second most frequently (30% of patients for each). Double stimuli (visual with auditory or visual with painful) were performed in more than half of the records. Utilization of at least three modalities was less consistent, but when at least three stimuli were performed, always included visual and auditory, with either tactile or painful stimulation as the third modality. In several cases, stimulation could not be accurately assessed due to difficulty visualizing on camera.

Conclusions: There is variability in stimulation during encephalopathic EEGs, which is sometimes unavoidable due to patient circumstances. This preliminary study is limited due to retrospective analysis and small numbers of subjects. Our data, however, provides some insight into initial implementation for a prospective optimization and standardization of stimulation. We propose observing EEG reactivity to two modalities as an efficient initial testing protocol. In the absence of reactivity to initial two modalities, additional testing with two different modalities should be employed. Additional goals for future quality improvement planned include technologist training of effective and systematic stimulation techniques, optimization of camera view of stimulation process, and templates for specific documentation of modality and response on EEG by reporting physician.

Funding: Please list any funding that was received in support of this abstract.: none.