• John D Heiss, Davis P Argersinger, William H Theodore, John A Butman, Susumu Sato, and Omar I Khan.
• Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland.
• Neurosurgery. 2019 Jul 1; 85 (1): E4-E15.

BackgroundMinimally invasive therapies for drug-resistant epilepsy (DRE) have been advocated. A study of convection-enhanced delivery (CED) of muscimol, a GABAA receptor agonist, was previously completed in non-human primates.ObjectiveTo investigate the safety and anti-epileptic effects of intracerebral muscimol infusion into the epileptic focus of patients with DRE.MethodsIn this phase 1 clinical trial, 3 adult patients with DRE underwent CED into the seizure focus of artificial CSF vehicle followed by muscimol for 12 to 24 h each using a crossover design. Basic pathophysiology of the epileptic focus was examined by assessing the infusions' effects on seizure frequency, electroencephalogram (EEG) spike-wave activity, and power-spectral EEG frequency.ResultsInter-ictal neurological function remained normal in all patients. Pathological examination of resected specimens showed no infusion-related brain injuries. Seizure frequency decreased in 1 of 3 patients during muscimol infusion but was unchanged in all patients during vehicle infusion. Mean beta frequencies did not differ significantly before, during, or after infusion periods. Infused fluid provided insufficient MRI-signal to track infusate distribution. In the 2 yr after standard epilepsy surgery, 1 patient had temporary reduction in seizure frequency and 2 patients were seizure-free.ConclusionCED of muscimol into the epileptic focus of patients with DRE did not damage adjacent brain parenchyma or adversely affect seizure surgery outcome. This study did not confirm that intracerebral muscimol infusion effectively suppressed seizures. A surrogate tracer is recommended to track infusion distribution to the epileptic focus and surrounding structures in future studies using CED to suppress the seizure focus.Published by Oxford University Press on behalf of Congress of Neurological Surgeons 2018.

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