Objective: We reported a generalized dystonia patient with eukaryotic translation initiation factor 2 alpha kinase 2 (EIF2AK2) gene mutation who underwent bilateral Globus pallidus interna (GPi) deep brain stimulation (DBS). The local field potential (LFP) recorded from GPi and clinical efficacy of the surgery were demonstrated.

Background: GPi DBS is an effective treatment for patients with dystonia. The therapeutic efficacy is reported to be more significant in primary dystonia but the efficacy of GPi DBS for patients with EIF2AK2 is less clear. In addition, little is known whether peri-operative LFP recordings are helpful for targeting the GPi and the selection of the stimulation contact.
We reported a 24-year-old man with heterozygous c.388G>A missense mutation in EIF2AK2 gene [1], who developed right leg dystonia since the age of 8. The dystonia gradually involved neck, trunk and four proximal limbs that he presented severe torticollis, retrocollis, opisthotonus, and extremities flexion at the age of 14. The facial expression and the speech were less affected. He underwent bilateral GPi DBS for the treatment of general dystonia.

Method: Preoperative brain MRI was done for surgical planning. The operation was done under generalized anesthesia (GA). The implantation of electrode was guided by microelectrode and LFP recordings. Reconstruction of DBS electrode and estimation of VTA was performed by using LEAD-DBS. Programming of stimulation was initialized one day after the DBS surgery. The post-operative improvement due to stimulation were assessed.

Results: In the reconstruction of DBS electrodes, the lowermost contacts from both sides located at GPi, while the uppermost contacts at Globus pallidus externa.
Intraoperative LFP showed highest alpha peak at lowermost contact in both sides under GA, which were selected for the chronic stimulation.
In the 6^th week of stimulation, the patient could walk without assistant. FMDRS improved from  81.5 to 15 (82%), while UDRS improved from 101.5 to 17 (83%).

Conclusion: Bilateral GPi DBS is effective for a general dystonia with EIF2AK2 mutation. The intraoperative LFP recording of GPi was proved to be helpful for the selection of active contacts for the chronic stimulation.

References: Kuipers, D.J.S., et al., EIF2AK2 Missense Variants Associated with Early Onset Generalized Dystonia. Ann Neurol, 2021. 89(3): p. 485-497.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/bilateral-gpi-dbs-for-the-treatment-of-a-general-dystonia-with-eif2ak2-mutant-report-of-globus-pallidus-local-field-potentials-and-the-therapeutic-outcome/