The implantation effect: delay in seizure occurrence with implantation of intracranial electrodes.

OBJECTIVE: A transient decrease in seizure frequency has been identified during therapeutic brain stimulation trials with stimulator in patients in the inactive sham group. This study was performed to examine whether the implantation of intracranial electrodes decreases seizure occurrence and explores factors that may be associated. METHODS: A retrospective review of 193 patients was performed, all evaluated with both scalp video EEG monitoring and intracranial EEG (iEEG) monitoring. Data about the number of seizures per day during the monitoring period, the number of days until the first seizure, anti-epileptic drugs (AEDs), pain medications, types of implanted electrodes, and anesthetic agents were reviewed. We conducted a repeated measure analysis for counted data using generalized estimating equations with a log-link function and adjustment for number of days and anti-epileptic medication load on the previous day to compare seizure frequencies between scalp and iEEG monitoring. RESULTS: The time to the first seizure was significantly prolonged during iEEG monitoring as compared to scalp monitoring after correction for AED withdrawal (hazard ratio: 0.81, CI 0.69-0.96). During scalp video EEG monitoring, patients experienced an average of 1.09 seizures/day vs 1.27 seizures/day during iEEG monitoring (P=.066). There was no significant difference in seizure frequency in patients that received craniotomy vs burr holes only for intracranial implantation. An increasing number of electrodes implanted increased the delay to seizures (P=.01). Of all anesthetic agents used, desflurane seemed to have an anticonvulsive effect compared to other anesthetics (P=.006). Pain medication did not influence delay to seizures. SIGNIFICANCE: Seizures are delayed during iEEG as opposed to scalp monitoring illustrating the "implantation effect" previously observed. Surgical planning should account for longer monitoring periods, particularly when using larger intracranial arrays.

Comparison of patient-reported outcomes based on implant brand in total knee arthroplasty: a prospective cohort study.

AIMS: The outcomes of total knee arthroplasty (TKA) depend on many factors. The impact of implant design on patient-reported outcomes is unknown. Our goal was to evaluate the patient-reported outcomes and satisfaction after primary TKA in patients with osteoarthritis undergoing primary TKA using five different brands of posterior-stabilized implant. PATIENTS AND METHODS: Using our institutional registry, we identified 4135 patients who underwent TKA using one of the five most common brands of implant. These included Biomet Vanguard (Zimmer Biomet, Warsaw, Indiana) in 211 patients, DePuy/Johnson & Johnson Sigma (DePuy Synthes, Raynham, Massachusetts) in 222, Exactech Optetrak Logic (Exactech, Gainesville, Florida) in 1508, Smith & Nephew Genesis II (Smith & Nephew, London, United Kingdom) in 1415, and Zimmer NexGen (Zimmer Biomet) in 779 patients. Patients were evaluated preoperatively using the Knee Injury and Osteoarthritis Outcome Score (KOOS), Lower Extremity Activity Scale (LEAS), and 12-Item Short-Form Health Survey questionnaire (SF-12). Demographics including age, body mass index, Charlson Comorbidity Index, American Society of Anethesiologists status, sex, and smoking status were collected. Postoperatively, two-year KOOS, LEAS, SF-12, and satisfaction scores were compared between groups. RESULTS: Outcomes were available for 4069 patients (98%) at two years postoperatively. In multiple regression analysis, which separately compared each implant group with the aggregate of all others, there were no clinically significant differences in the change of KOOS score from baseline to two-year follow-up between any of the groups. More than 80% of patients in each group were satisfied at this time in all domains. In a multivariate regression model, patients in the NexGen group were the most likely to be satisfied (odds ratio (OR) 1.63; p = 0.006) and Optetrak Logic patients were the least likely to be satisfied (OR 0.60; p < 0.001). CONCLUSION: TKA provides improvement in function and satisfaction regardless of the type of implant. We could not demonstrate superiority of one design above others across these groups of implants, and any price premium for one above the other systems may not be justified. Healthcare administrators may find these similarities in outcomes helpful when negotiating purchasing contracts. Cite this article: Bone Joint J 2019;101-B(7 Supple C):48-54.