Abstracts

Rationale: When medically intractable epilepsy is multifocal or focal but poorly localized, neuromodulation can be useful therapy. One such technique is thalamic deep brain stimulation (DBS) targeting the anterior nucleus of the thalamus (ANT). Unfortunately, the ANT is difficult to visualize in standard MRI sequences, and indirect targeting of this nucleus is difficult due to thalamic variability and atrophy in patients with epilepsy.  The following study describes the novel use of the Fast Gray Matter T1 Inversion Recovery (FGATIR) MRI sequence to delineate the mammillothalamic tract for direct targeting of the ANT through visualizing the termination of the mammillothalamic tract in the ANT. Methods: Preoperative MRI was acquired the day prior to surgery. Imaging was performed on a 3 Tesla Siemens Prisma scanner (Siemens AG, Healthcare Sector, Erlangen, Germany) using a 64-channel head and neck coil. As part of the imaging protocol, a non-contrast Magnetization-Prepared Rapid Gradient-Echo (MP-RAGE), , and diffusion tensor imaging (DTI) were obtained for targeting purposes. ANT was directly targeted using the FGATIR sequence and bilateral Medtronic 3389 leads were placed (Figure 1 and 2). Results: At last follow-up (2 months), the patient reported an approximate 75% decrease in seizure frequency, as well as a decrease in seizure severity. Conclusions: We report the novel use of direct targeting of the ANT using FGATIR imaging for treatment of refractory epilepsy. The FGATIR sequence may allow for improved direct targeting of the ANT for DBS by means of providing a direct target through visualization of the mammillothalamic tract rather than an indirect target as has been traditionally used. Funding: No funding was received in support of this abstract.