Posters Sessions

Michael Schulder, North Shore LIJ Health System, Manhasset, NY; Guy Schwartz, MD, Manhasset, NY Introduction. Subthalamic nucleus (STN) DBS electrodes typically are inserted via a coronal entry point. Unilateral transparietal placement has been previously described. We present a case of bilateral transparietal STN electrode placement. History. The patient is a 62 year old woman with a 7-year history of worsening PD. Progressive increases in levodopa requirements led to severe dyskinesias. In 2010 she underwent bilateral transcoronal STN DBS surgery at another institution, with excellent results. About one year after surgery the right frontal electrode became exposed. She declined explantation at first. Multiple attempts at antibiotic treatment and flap-based closure led to a fungal cellulitis and ultimate explantation. The patient requested re-implantation of STN electrodes. Transparietal entry points were planned due to the unusability of her coronal scalp. Results. Each STN electrode was implanted separately. Surgery was done using a CRW frame and FrameLink software on a StealthStation. After CT scanning the patient was positioned with her head turned to the contralateral side (Figure 1). Entry points were adjusted to avoid passage of the insertion cannulas through the ventricles or deep sulci (Figure 2). Microelectrode recording was begun 15 mm proximal to target. Electrodes were implanted with the 0 contact at the STN floor. IPGS were placed via the previous subclavicular incisions at separate sessions. The patient is being maintained on interleaving bipolar stimulation bilaterally (3[+]2[-] at 4.0V and 2[-]1[+] at 1.0V on the right; 2[+]1[-] at 4.0V and 1[+]0[-] 0.5V on the left; at 60 microsec and 125Hz). Levodopa was discontinued due to disabling peak-dose dyskinesias. Her UPDRS III score on stimulation as compared to off stimulation has declined by 27%. Conclusion. Patients who are candidates for DBS of the STN can have bilateral electrodes safely placed via a transparietal approach, if for technical reasons the coronal entry sites are not suitable.