BACKGROUND The pursuit of improved accuracy for localization and electrode implantation in deep brain stimulation (DBS) and stereoelectroencephalography (sEEG) has fostered an abundance of disparate surgical/stereotactic practices. Specific practices/technologies directly modify implantation accuracy; however, no study has described their respective influence in multivariable context. OBJECTIVE To synthesize the known literature to statistically quantify factors affecting implantation accuracy. METHODS A systematic review and meta-analysis was conducted to determine the inverse-variance weighted pooled mean target error (MTE) of implanted electrodes among patients undergoing DBS or sEEG. MTE was defined as Euclidean distance between planned and final electrode tip. Meta-regression identified moderators of MTE in a multivariable-adjusted model. RESULTS A total of 37 eligible studies were identified from a search return of 2,901 potential articles (2002-2018) – 27 DBS and 10 sEEG. Random-effects pooled MTE = 1.91 mm (95% CI: 1.7-2.1) for DBS and 2.34 mm (95% CI: 2.1-2.6) for sEEG. Meta-regression identified study year, robot use, frame/frameless technique, and intraoperative electrophysiologic testing (iEPT) as significant multivariable-adjusted moderators of MTE (P < .0001, R2 = 0.63). Study year was associated with a 0.92-mm MTE reduction over the 16-yr study period (P = .0035), and robot use with a 0.79-mm decrease (P = .0019). Frameless technique was associated with a mean 0.50-mm (95% CI: 0.17-0.84) increase, and iEPT use with a 0.45-mm (95% CI: 0.10-0.80) increase in MTE. Registration method, imaging type, intraoperative imaging, target, and demographics were not significantly associated with MTE on multivariable analysis. CONCLUSION Robot assistance for stereotactic electrode implantation is independently associated with improved accuracy and reduced target error. This remains true regardless of other procedural factors, including frame-based vs frameless technique.

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OBJECTIVE The authors compared primary lumbar spine fusions with revision fusions by using patient Oswestry Disability Index (ODI) scores to evaluate the impact of the North American Spine Society (NASS) evidence-based medicine (EBM) lumbar fusion indications on patient-reported outcome measures of revision surgeries. METHODS This study was a retrospective analysis of a prospective observational cohort of patients who underwent elective lumbar fusion between January 2018 and December 2019 at a single quaternary spine surgery service and had a minimum of 6 months of follow-up. A prospective quality improvement database was constructed that included the data from all elective lumbar spine surgeries, which were categorized prospectively as primary or revision surgeries and EBM-concordant or EBM-discordant revision surgeries based on the NASS coverage EBM policy. In total, 309 patients who met the inclusion criteria were included in the study. The ODIs of all groups (primary, revision, revision EBM concordant, and revision EBM discordant) were statistically compared. Differences in frequencies between cohorts were evaluated using chi-square and Fisher’s exact tests. The unpaired 2-tailed Student t-test and the Mann-Whitney U-test for nonparametric data were used to compare continuous variables. Logistic regression was performed to determine the associations between independent variables (surgery status and NASS criteria indications) and functional outcomes. RESULTS Primary lumbar fusions were significantly associated with improved functional outcomes compared with revisions, as evidenced by ODI scores (OR 1.85, 95% CI 1.16–2.95 to achieve a minimal clinically important difference, p = 0.01). The percentage of patients whose functional status had declined at the 6-month postoperative evaluation was significantly higher in patients who had undergone a revision surgery than in those who underwent a primary surgery (23% vs 12.3%, respectively). An increase in ODI score, indicating worse clinical outcome after surgery, was greater in patients who underwent revision procedures (OR 2.14, 95% CI 1.17–3.91, p = 0.0014). Patients who underwent EBM-concordant revision surgery had significantly improved mean ODI scores compared with those who underwent EBM-discordant revision surgery (7.02 ± 5.57 vs −4.6 ± 6.54, p < 0.01). CONCLUSIONS The results of this prospective quality improvement program investigation illustrate that outcomes of primary lumbar fusions were superior to outcomes of revisions. However, revision procedures that met EBM guidelines were associated with greater improvements in ODI scores, which indicates that the use of defined EBM guideline criteria for reoperation can improve clinical outcomes of revision lumbar fusions.

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BACKGROUND United States (U.S.) healthcare is a volume-based inefficient delivery system. Value requires the consideration of quality, which is lacking in most healthcare disciplines. OBJECTIVE To assess whether patients who met specific evidence-based medicine (EBM)-based criteria preoperatively for lumbar fusion would achieve higher rates of achieving the minimal clinical important difference (MCID) than those who did not meet the EBM indications. METHODS All elective lumbar fusion cases, March 2018 to August 2019, were prospectively evaluated and categorized based on EBM guidelines for surgical indications. The MCID was defined as a reduction of ≥5 points in Oswestry Disability Index (ODI). Multiple logistic regression identified multivariable-adjusted odds ratio of EBM concordance. RESULTS A total of 325 lumbar fusion patients were entered with 6-mo follow-up data available for 309 patients (95%). The median preoperative ODI score was 24.4 with median 6-mo improvement of 7.0 points (P &lt; .0001). Based on ODI scores, 79.6% (246/309) improved, 3.8% (12/309) had no change, and 16% (51/309) worsened. A total of 191 patients had ODI improvement reaching the MCID. 93.2% (288/309) cases were EBM concordant, while 6.7% (21/309) were not. In multivariate analysis, EBM concordance (P = .0338), lower preoperative ODI (P &lt; .001), lower ASA (American Society of Anesthesiologists) (P = .0056), and primary surgeries (P = .0004) were significantly associated with improved functional outcome. EBM concordance conferred a 3.04 (95% CI 1.10-8.40) times greater odds of achieving MCID in ODI at 6 mo (P = .0322), adjusting for other factors. CONCLUSION This analysis provides validation of EBM guideline criteria to establish optimal patient outcomes. The EBM concordant patients had a greater than 3 times improved outcome compared to those not meeting EBM fusion criteria.

OBJECTIVE Accurate electrode placement is key to effective deep brain stimulation (DBS). The ventral intermediate nucleus (VIM) of the thalamus is an established surgical target for the treatment of essential tremor (ET). Retrospective tractography-based analysis of electrode placement has associated successful outcomes with modulation of motor input to VIM, but no study has yet evaluated the feasibility and efficacy of prospective presurgical tractography-based targeting alone. Therefore, the authors sought to demonstrate the safety and efficacy of probabilistic tractography–based VIM targeting in ET patients and to perform a systematic comparison of probabilistic and deterministic tractography. METHODS Fourteen patients with ET underwent preoperative diffusion imaging. Probabilistic tractography was applied for preoperative targeting, and deterministic tractography was performed as a comparison between methods. Tractography was performed using the motor and sensory areas as initiation seeds, the ipsilateral thalamus as an inclusion mask, and the contralateral dentate nucleus as a termination mask. Tract-density maps consisted of voxels with 10% or less of the maximum intensity and were superimposed onto anatomical images for presurgical planning. Target planning was based on probabilistic tract-density images and indirect target coordinates. Patients underwent robotic image-guided, image-verified implantation of directional DBS systems. Postoperative tremor scores with and without DBS were recorded. The center of gravity and Dice similarity coefficients were calculated and compared between tracking methods. RESULTS Prospective probabilistic targeting of VIM was successful in all 14 patients. All patients experienced significant tremor reduction. Formal postoperative tremor scores were available for 9 patients, who demonstrated a mean 68.0% tremor reduction. Large differences between tracking methods were observed across patients. Probabilistic tractography–identified VIM fibers were more anterior, lateral, and superior than deterministic tractography–identified fibers, whereas probabilistic tractography–identified ventralis caudalis fibers were more posterior, lateral, and superior than deterministic tractography–identified fibers. Deterministic methods were unable to clearly distinguish between motor and sensory fibers in the majority of patients, but probabilistic methods produced distinct separation. CONCLUSIONS Probabilistic tractography–based VIM targeting is safe and effective for the treatment of ET. Probabilistic tractography is more precise than deterministic tractography for the delineation of VIM and the ventralis caudalis nucleus of the thalamus. Deterministic algorithms tended to underestimate separation between motor and sensory fibers, which may have been due to its limitations with crossing fibers. Larger studies across multiple centers are necessary to further validate this method.

BACKGROUND:Spinal synovial cysts are lesions that most commonly occur in the lumbar region. The need for an instrumented spinal fusion in addition to lumbar decompression with removal of the synovial cyst is unknown.OBJECTIVE:To test the hypothesis that select patients who underwent decompression with instrumented fusion for lumbar synovial cysts would be less likely to have subsequent surgery (SS) in a 2-year period than patients treated with laminectomy alone.METHODS:This retrospective cohort study was performed using IBM MarketScan Commercial Claims and Encounters Database. Patients who had a lumbar synovial cyst diagnosis and laminectomy surgery with or without fusion surgery were included in this study. Patients were tracked for SS 2 years after surgery. Laminectomy patients were propensity score–matched to laminectomy with fusion (LF) patients using a 2:1 ratio. The log-rank test and Cox regression were used to compare the cumulative incidence of SS between groups.RESULTS:There were 7664 and 1631 patients treated with laminectomy and LF before matching. After matching, there were 2212 laminectomy and 1631 LF patients and patient characteristics were balanced. The 2-year incidence of recurrent SS was 3.1% ([CI]: 2.2%, 4.0%) and 1.7% (95% CI: 0.9%, 2.5%) laminectomy and LF, respectively. Compared with laminectomy, LF had a statistically significant lower risk of recurrent SS (hazard ratio: 0.56 [95% CI: 0.32-0.97]; P-value: .04).CONCLUSION:All patients who had concomitant lumbar fusion showed decreased chance of having a cyst- or noncyst-related recurrence SS when compared with all patients undergoing laminectomy alone, regardless of diagnosis at the time of SS.