Object: The aim of this study was to assess risk factors for postoperative seizures after deep brain stimulation (DBS) lead implantation surgery and the impact of such seizures on length of stay and discharge disposition.
Methods: The authors reviewed a consecutive series of 161 cases involving patients who underwent implantation of 288 electrodes for treatment of movement disorders at a single institution to determine the absolute risk of postoperative seizures, to describe the timing and type of seizures, to identify statistically significant risk factors for seizures, and to determine whether there are possible indications for seizure prophylaxis after DBS lead implantation. The electronic medical records were reviewed to identify demographic details, medical history, operative course, and postoperative outcomes and complications. To evaluate significant associations between potential risk factors and postoperative seizures, both univariate and multivariate analyses were performed.
Results: Seven (4.3%) of 161 patients experienced postoperative seizures, all of which were documented to have been generalized tonic-clonic seizures. In 5 (71%) of 7 cases, patients only experienced a single seizure. Similarly, in 5 of 7 cases, patients experienced seizures within 24 hours of surgery. In 6 (86%) of the 7 cases, seizures occurred within 48 hours of surgery. Univariate analysis identified 3 significant associations (or risk factors) for postoperative seizures: abnormal findings on postoperative imaging (hemorrhage, edema, and or ischemia; p < 0.001), age greater than 60 years (p = 0.021), and transventricular electrode trajectories (p = 0.023). The only significant factor identified on multivariate analysis was abnormal findings on postoperative imaging (p < 0.0001, OR 50.4, 95% CI 5.7-444.3). Patients who experienced postoperative seizures had a significantly longer length of stay than those who were seizure free (mean ± SD 5.29 ± 3.77 days vs 2.38 ± 2.38 days; p = 0.002, Student 2-tailed t-test). Likewise, final discharge to home was significantly less likely in patients who experienced seizures after implantation (43%) compared with those patients who did not (92%; p = 0.00194, Fisher exact test).
Conclusions: These results affirm that seizures are an uncommon complication of DBS surgery and generally occur within 48 hours of surgery. The results also indicate that hemorrhage, edema, or ischemia on postoperative images ("abnormal" imaging findings) increases the relative risk of postoperative seizures by 30- to 50-fold, providing statistical credence to the long-held assumption that seizures are associated with intracranial vascular events. Even in the setting of a postimplantation imaging abnormality, long-term anticonvulsant therapy will not likely be required because none of our patients developed chronic epilepsy.