Methohexital - Induced lateralized periodic discharges during Wada test

Omar A Danoun; Nicholas Beimer; Henry Buchtel; Simon Glynn; David Harris

doi:10.1016/j.cnp.2021.07.002

Methohexital - Induced lateralized periodic discharges during Wada test

Clin Neurophysiol Pract. 2021 Jul 24:6:225-228. doi: 10.1016/j.cnp.2021.07.002. eCollection 2021.

Authors

Omar A Danoun^{1

2}, Nicholas Beimer³, Henry Buchtel⁴, Simon Glynn³, David Harris³

Affiliations

¹ Comprehensive Epilepsy Program, Department of Neurology, Henry Ford Hospital, Detroit, MI, USA.
² Palestinian Neuroscience Initiative, Al-Quds University, Abu Dis, Jerusalem, Palestine.
³ Comprehensive Epilepsy Program, Department of Neurology, University of Michigan, Ann Arbor, MI, USA.
⁴ Neuropsychology Section, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA.

Abstract

Objective: The Wada test is used to evaluate language lateralization and memory performance after inactivation of an isolated cerebral hemisphere. Methohexital a short-acting barbiturate has a history of use to induce interictal discharges during intraoperative corticography. We report a new finding of activation of lateralized periodic discharges (LPDs) after Methohexital injection.

Methods: We retrospectively reviewed 174 consecutive adult patients who underwent Wada testing in preparation for epilepsy surgery (N = 129, 74%) or brain tumor resection (N = 45, 26%) at the University of Michigan to determine the frequency of induced periodic discharges by methohexital.

Results: Four epilepsy patients (2.29%) had methohexital-induced LPDs within a median of 2 s (1-99 s) of the injection and lasting a median of 4 min (3-10 min) after a total of 7 injections. All LPDs occurred ipsilateral to the injection hemisphere in the known region of interictal epileptiform discharges. LPDs were not induced in brain tumor patients. In one patient, LPDs occurred during memory testing, and this patient's memory performance was below expectation based on pre-test neuropsychological testing.

Conclusions: Methohexital can induce LPDs in ipsilateral hemisphere and that can potentially affect memory performance.

Significance: This observation indicates that concurrent EEG monitoring during the Wada test is important and that induced discharges should be considered when interpreting Wada test results.

Keywords: Brain tumors; Epilepsy surgery; Interictal discharges; Language lateralization; Neuropsychology.