Authors :
Presenting Author: Paul Wilkerson, DO – University of Kentucky
Meriem Bensalem Owen, MD, FANA, FACNS, FAES – University of Kentucky; Gulam Khan, MD – University of Kentucky; Zahra Haghighat, MD – University of Kentucky
Rationale:
The use of Deep Brain Stimulation (DBS) has expanded from the treatment of movement disorders to the treatment of refractory focal epilepsy. DBS therapy can cause a distinct artifact on the electroencephalogram (EEG) resulting from the electrical stimulation. The DBS stimulation settings used for movement disorders are different from those used for epilepsy. When the DBS artifact is recognized and if it obscured the EEG recording, the device can be momentarily paused to record an artifact-free study. Certain artifacts are important contributors to misdiagnosis and mismanagement. We present the case of a patient with refractory epilepsy, alerted sensorium, and an unusual DBS artifact that was misinterpreted for an ictal pattern which significantly impacted management.
Methods:
A 53 year old woman with drug resistant epilepsy requiring polytherapy and management with a vagus nerve stimulator and a DBS was admitted due to altered mental status.
The initial EEG (Figure 1) was concerning for recurrent focal subclinical electrographic seizures (red box) that spread to adjacent electrodes (orange box) and showed some evolution in frequency. These findings prompted initiation of video-EEG monitoring while the patient’s home medications were optimized. Lorazepam was administered as well as fosphenytoin which had no effect on the EEG pattern. The patient required subsequently mechanical ventilation. A burst suppression pattern was eventually observed on the EEG due the use of propofol, midazolam and eventually pentobarbital. None of these anesthetics altered the electrographic pattern that was interpreted as very frequent recurrent seizures in the bursts.
Results:
As treatment was being escalated with anesthetics, the patient’s primary epileptologist was consulted. The unusual field and the lack of clear evolution in morphology and frequency of this activity, as well as the perfectly cyclic pattern of this activity (one minute on and five minutes off) corresponding to the DBS stimulation cycle were recognized. The DBS was paused and the pattern subsided during that time. The current of the left lead was turned back on and the pattern recurred on the EEG’s left electrodes (Figure 2- Blue box). A similar pattern was noted when the current was turned back on the right lead. Following these findings, the patient’s management was changed accordingly.
Conclusions:
When interpreting EEGs, it is essential to recognize artifact to prevent misdiagnosis and mismanagement that may adversely impact patient care. The recognition of unusual device artifacts, such as DBS artifact especially in patients with altered mental status as exemplified in this case, can create a management conundrum.
Funding: None