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Anshit Goyal, Che Ngufor, Panagiotis Kerezoudis, Brandon McCutcheon, Curtis Storlie, and Mohamad Bydon

OBJECTIVE

Nonhome discharge and unplanned readmissions represent important cost drivers following spinal fusion. The authors sought to utilize different machine learning algorithms to predict discharge to rehabilitation and unplanned readmissions in patients receiving spinal fusion.

METHODS

The authors queried the 2012–2013 American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) for patients undergoing cervical or lumbar spinal fusion. Outcomes assessed included discharge to nonhome facility and unplanned readmissions within 30 days after surgery. A total of 7 machine learning algorithms were evaluated. Predictive hierarchical clustering of procedure codes was used to increase model performance. Model performance was evaluated using overall accuracy and area under the receiver operating characteristic curve (AUC), as well as sensitivity, specificity, and positive and negative predictive values. These performance metrics were computed for both the imputed and unimputed (missing values dropped) datasets.

RESULTS

A total of 59,145 spinal fusion cases were analyzed. The incidence rates of discharge to nonhome facility and 30-day unplanned readmission were 12.6% and 4.5%, respectively. All classification algorithms showed excellent discrimination (AUC > 0.80, range 0.85–0.87) for predicting nonhome discharge. The generalized linear model showed comparable performance to other machine learning algorithms. By comparison, all models showed poorer predictive performance for unplanned readmission, with AUC ranging between 0.63 and 0.66. Better predictive performance was noted with models using imputed data.

CONCLUSIONS

In an analysis of patients undergoing spinal fusion, multiple machine learning algorithms were found to reliably predict nonhome discharge with modest performance noted for unplanned readmissions. These results provide early evidence regarding the feasibility of modern machine learning classifiers in predicting these outcomes and serve as possible clinical decision support tools to facilitate shared decision making.

Open access

Timothy J. Kaufmann, Vance T. Lehman, Lily C. Wong-Kisiel, Panagiotis Kerezoudis, and Kai J. Miller

BACKGROUND

Open surgical treatment of insular epilepsy holds particular risk of injury to middle cerebral artery branches, the operculum (through retraction), and adjacent language-related white matter tracts in the language-dominant hemisphere. Magnetic resonance imaging (MRI)-guided laser interstitial thermal therapy (LITT) is a surgical alternative that allows precise lesioning with potentially less operative risk. The authors presented the case of a 13-year-old girl with intractable, MRI-negative, left (dominant hemisphere) insular epilepsy that was treated with LITT. Diffusion tensor imaging (DTI) tractography was used to aid full posterior insular lesioning in the region of stereo electroencephalography–determined seizure onset while avoiding thermal injury to the language-related superior longitudinal fasciculus (SLF)/arcuate fasciculus (AF) and inferior fronto-occipital fasciculus (IFOF).

OBSERVATIONS

DTI tractography was used successfully in planning insular LITT and facilitated a robust insular ablation with sharp margins at the interfaces with the SLF/AF and IFOF. These tracts were spared, and no neurological deficits were induced through LITT.

LESSONS

Although it is technically demanding and has important limitations that must be understood, clinically available DTI tractography adds precision and confidence to insular laser ablation when used to protect important language-related white matter tracts.

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Mohammed Adeeb Sebai, Panagiotis Kerezoudis, Mohammed Ali Alvi, Jang Won Yoon, Robert J. Spinner, and Mohamad Bydon

OBJECTIVE

Spinal peripheral nerve sheath tumors (PNSTs) are a group of rare tumors originating from the nerve and its supporting structures. Standard surgical management typically entails laminectomy with or without facetectomy to gain adequate tumor exposure. Arthrodesis is occasionally performed to maintain spinal stability and mitigate the risk of postoperative deformity, pain, or neurological deficit. However, the factors associated with the need for instrumentation in addition to PNST resection in the same setting remain unclear.

METHODS

An institutional tumor registry at a tertiary care center was queried for patients treated surgically for a primary diagnosis of spinal PNST between 2002 and 2016. An analysis focused on patients in whom a facetectomy was performed during the resection. The addition of arthrodesis at the index procedure comprised the primary outcome. The authors also recorded baseline demographics, tumor characteristics, and surgery-related variables. Logistic regression was used to identify factors associated with increased risk of fusion surgery.

RESULTS

A total of 163 patients were identified, of which 56 (32 had facetectomy with fusion, 24 had facetectomy alone) were analyzed. The median age was 48 years, and 50% of the cohort was female. Age, sex, and race, as well as tumor histology and size, were evenly distributed between patients who received facetectomy alone and those who had facetectomy and fusion. On univariate analysis, total versus subtotal facetectomy (OR 9.0, 95% CI 2.01–64.2; p = 0.009) and cervicothoracic versus other spinal region (OR 9.0, 95% CI 1.51–172.9; p = 0.048) were significantly associated with increased odds of performing immediate fusion. On multivariable analysis, only the effect of total facetectomy remained statistically significant (OR 6.75, 95% CI 1.47–48.8; p = 0.025).

CONCLUSIONS

The authors found that total facetectomy and cervicothoracic involvement may be highly associated with the need for concomitant arthrodesis at the time of index surgery. These findings may help surgeons to determine the best surgical planning for patients with PNST.

Free access

Panagiotis Kerezoudis, Anshit Goyal, Ross C. Puffer, Ian F. Parney, Fredric B. Meyer, and Mohamad Bydon

OBJECTIVE

Acute traumatic subdural hematoma (atSDH) can be a life-threatening neurosurgical emergency that necessitates immediate evacuation. The elderly population can be particularly vulnerable to tearing bridging veins. The aim of this study was to evaluate inpatient morbidity and mortality, as well as predictors of inpatient mortality, in a national trauma database.

METHODS

The authors queried the 2016–2017 National Trauma Data Bank registry for patients aged 65 years and older who had undergone evacuation of atSDH. Patients were categorized into three age groups: 65–74, 75–84, and 85+ years. A multivariable logistic regression model was fitted for inpatient mortality adjusting for age group, sex, race, presenting Glasgow Coma Scale (GCS) category (3–8, 9–12, and 13–15), Injury Severity Score, presence of coagulopathy, presence of additional hemorrhages (epidural hematoma [EDH], intraparenchymal hematoma [IPH], and subarachnoid hemorrhage [SAH]), presence of midline shift > 5 mm, and pupillary reactivity (both, one, or none).

RESULTS

A total of 2508 patients (35% females) were analyzed. Age distribution was as follows: 990 patients at 65–74 years, 1096 at 75–84, and 422 at 85+. Midline shift > 5 mm was present in 72% of cases. With regard to additional hemorrhages, SAH was present in 21%, IPH in 10%, and EDH in 2%. Bilaterally reactive pupils were noted in 90% of patients. A major complication was observed in 14.4% of patients, and the overall mortality rate was 18.3%. In the multivariable analysis, the presenting GCS category was found to be the strongest predictor of postoperative inpatient mortality (3–8 vs 13–15: OR 3.63, 95% CI 2.68–4.92, p < 0.001; 9–12 vs 13–15: OR 2.64, 95% CI 1.79–3.90, p < 0.001; 30% of overall variation), followed by the presence of SAH (OR 2.86, 95% CI 2.21–3.70, p < 0.001; 25% of overall variation) and the presence of midline shift > 5 mm (OR 2.40, 95% CI 1.74–3.32, p < 0.001; 11% of overall variation). Model discrimination was excellent (c-index 0.81). Broken down by age decile group, mortality increased from 8.0% to 15.4% for GCS 13–15 to around 36% for GCS 9–12 to almost as high as 60% for GCS 3–8, particularly in those aged 85 years and older.

CONCLUSIONS

The present results from a national trauma database will, the authors hope, assist surgeons in preoperative discussions with patients and their families with regard to expected postoperative outcomes following surgical evacuation of an atSDH.

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Panagiotis Kerezoudis, Rohin Singh, Anshit Goyal, Gregory A. Worrell, W. Richard Marsh, Jamie J. Van Gompel, and Kai J. Miller

OBJECTIVE

Insular lobe epilepsy is a challenging condition to diagnose and treat. Due to anatomical intricacy and proximity to eloquent brain regions, resection of epileptic foci in that region can be associated with significant postoperative morbidity. The aim of this study was to review available evidence on postoperative outcomes following insular epilepsy surgery.

METHODS

A comprehensive literature search (PubMed/MEDLINE, Scopus, Cochrane) was conducted for studies investigating the postoperative outcomes for seizures originating in the insula. Seizure freedom at last follow-up (at least 12 months) comprised the primary endpoint. The authors also present their institutional experience with 8 patients (4 pediatric, 4 adult).

RESULTS

A total of 19 studies with 204 cases (90 pediatric, 114 adult) were identified. The median age at surgery was 23 years, and 48% were males. The median epilepsy duration was 8 years, and 17% of patients had undergone prior epilepsy surgery. Epilepsy was lesional in 67%. The most common approach was transsylvian (60%). The most commonly resected area was the anterior insular region (n = 42, 21%), whereas radical insulectomy was performed in 13% of cases (n = 27). The most common pathology was cortical dysplasia (n = 68, 51%), followed by low-grade neoplasm (n = 16, 12%). In the literature, seizure freedom was noted in 60% of pediatric and 69% of adult patients at a median follow-up of 29 months (75% and 50%, respectively, in the current series). A neurological deficit occurred in 43% of cases (10% permanent), with extremity paresis comprising the most common deficit (n = 35, 21%), followed by facial paresis (n = 32, 19%). Language deficits were more common in left-sided approaches (24% vs 2%, p < 0.001). Univariate analysis for seizure freedom revealed a significantly higher proportion of patients with lesional epilepsy among those with at least 12 months of follow-up (77% vs 59%, p = 0.032).

CONCLUSIONS

These findings may serve as a benchmark when tailoring decision-making for insular epilepsy, and may assist surgeons in their preoperative discussions with patients. Although seizure freedom rates are quite high with insular epilepsy treatment, the associated morbidity needs to be weighed against the potential for seizure freedom.

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Mohammed Ali Alvi, Lorenzo Rinaldo, Panagiotis Kerezoudis, Leonardo Rangel-Castilla, Mohamad Bydon, Harry Cloft, and Giuseppe Lanzino

OBJECTIVE

The impact of FDA approval of flow-diversion technology for the treatment of supraclinoid internal carotid artery aneurysms and the publication of the Carotid Occlusion Surgery Study, both of which occurred in 2011, on the utilization of extracranial-intracranial (EC-IC) bypasses is not known.

METHODS

The National Inpatient Sample (NIS) was queried for hospitalizations for EC-IC bypass performed from 2008 to 2016. Diagnoses of interest included an unruptured intracranial aneurysm (UIA), subarachnoid hemorrhage (SAH), carotid occlusive disease (COD), and moyamoya disease. The authors assessed trends in EC-IC bypass utilization for these diagnoses and the incidence of adverse discharges, defined as discharge to locations other than home, and the rate of mortality.

RESULTS

A total of 1640 EC-IC bypass procedures were performed at 558 hospitals during the study period, with 1148 procedures at 448 hospitals performed for a diagnosis of interest. The most frequent surgical indication was moyamoya disease (65.7%, n = 754), followed by COD (23.2%, n = 266), SAH (3.2%, n = 37), and a UIA (7.9%, n = 91). EC-IC bypass utilization for COD decreased from 0.21 per 100 admissions of COD in 2010 to 0.09 per 100 admissions in 2016 (p = 0.023). The frequency of adverse discharges increased during the study period from 22.3% of annual admissions in 2008 to 31.2% in 2016 (p = 0.030) when analysis was limited to procedures performed for a diagnosis of interest. Per volume, the top 5th percentile of hospitals, on average, performed 18.4 procedures (SD 13.2) per hospital during the study period, compared to 1.3 procedures (SD 1.3) that were performed in hospitals within the bottom 95th percentile. The rate of adverse discharges was higher at low-volume institutions when compared to that at high-volume institutions (33.8% vs 28.7%; p = 0.029). Over the study period, the authors noted a trend toward a reduced percentage of total surgical volume performed at high-volume hospitals (p < 0.001).

CONCLUSIONS

The authors observed a decrease in the utilization of EC-IC bypass for COD during the study period. An increase in the rate of adverse discharges was also noted, coinciding with more procedures being performed at lower-volume centers.

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Mohammed Ali Alvi, Lorenzo Rinaldo, Panagiotis Kerezoudis, Leonardo Rangel-Castilla, Mohamad Bydon, Harry Cloft, and Giuseppe Lanzino

OBJECTIVE

The impact of FDA approval of flow-diversion technology for the treatment of supraclinoid internal carotid artery aneurysms and the publication of the Carotid Occlusion Surgery Study, both of which occurred in 2011, on the utilization of extracranial-intracranial (EC-IC) bypasses is not known.

METHODS

The National Inpatient Sample (NIS) was queried for hospitalizations for EC-IC bypass performed from 2008 to 2016. Diagnoses of interest included an unruptured intracranial aneurysm (UIA), subarachnoid hemorrhage (SAH), carotid occlusive disease (COD), and moyamoya disease. The authors assessed trends in EC-IC bypass utilization for these diagnoses and the incidence of adverse discharges, defined as discharge to locations other than home, and the rate of mortality.

RESULTS

A total of 1640 EC-IC bypass procedures were performed at 558 hospitals during the study period, with 1148 procedures at 448 hospitals performed for a diagnosis of interest. The most frequent surgical indication was moyamoya disease (65.7%, n = 754), followed by COD (23.2%, n = 266), SAH (3.2%, n = 37), and a UIA (7.9%, n = 91). EC-IC bypass utilization for COD decreased from 0.21 per 100 admissions of COD in 2010 to 0.09 per 100 admissions in 2016 (p = 0.023). The frequency of adverse discharges increased during the study period from 22.3% of annual admissions in 2008 to 31.2% in 2016 (p = 0.030) when analysis was limited to procedures performed for a diagnosis of interest. Per volume, the top 5th percentile of hospitals, on average, performed 18.4 procedures (SD 13.2) per hospital during the study period, compared to 1.3 procedures (SD 1.3) that were performed in hospitals within the bottom 95th percentile. The rate of adverse discharges was higher at low-volume institutions when compared to that at high-volume institutions (33.8% vs 28.7%; p = 0.029). Over the study period, the authors noted a trend toward a reduced percentage of total surgical volume performed at high-volume hospitals (p < 0.001).

CONCLUSIONS

The authors observed a decrease in the utilization of EC-IC bypass for COD during the study period. An increase in the rate of adverse discharges was also noted, coinciding with more procedures being performed at lower-volume centers.

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Mohammed Ali Alvi, Redab Alkhataybeh, Waseem Wahood, Panagiotis Kerezoudis, Sandy Goncalves, M. Hassan Murad, and Mohamad Bydon

OBJECTIVE

Transpsoas lateral interbody fusion is one of the lateral minimally invasive approaches for lumbar spine surgery. Most surgeons insert the interbody cage laterally and then insert pedicle or cortical screw and rod instrumentation posteriorly. However, standalone cages have also been used to avoid posterior instrumentation. To the best of the authors’ knowledge, the literature on comparison of the two approaches is sparse.

METHODS

The authors performed a systematic review and meta-analysis of the available literature on transpsoas lateral interbody fusion by an electronic search of the PubMed, EMBASE, and Scopus databases using PRISMA guidelines. They compared patients undergoing transpsoas standalone fusion (TP) with those undergoing transpsoas fusion with posterior instrumentation (TPP).

RESULTS

A total of 28 studies with 1462 patients were included. Three hundred and seventy-four patients underwent TPP, and 956 patients underwent TP. The mean patient age ranged from 45.7 to 68 years in the TP group, and 50 to 67.7 years in the TPP group. The incidence of reoperation was found to be higher for TP (0.08, 95% confidence interval [CI] 0.04–0.11) compared to TPP (0.03, 95% CI 0.01–0.06; p = 0.057). Similarly, the incidence of cage movement was found to be greater in TP (0.18, 95% CI 0.10–0.26) compared to TPP (0.03, 95% CI 0.00–0.05; p < 0.001). Oswestry Disability Index (ODI) and visual analog scale (VAS) scores and postoperative transient deficits were found to be comparable between the two groups.

CONCLUSIONS

These results appear to suggest that addition of posterior instrumentation to transpsoas fusion is associated with decreased reoperations and cage movements. The results of previous systematic reviews and meta-analyses should be reevaluated in light of these results, which seem to suggest that higher reoperation and subsidence rates may be due to the use of the standalone technique.

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Lorenzo Rinaldo, Brandon A. McCutcheon, Meghan E. Murphy, Daniel L. Shepherd, Patrick R. Maloney, Panagiotis Kerezoudis, Mohamad Bydon, and Giuseppe Lanzino

OBJECTIVE

The mechanism by which greater institutional case volume translates into improved outcomes after surgical clipping of unruptured intracranial aneurysms (UIAs) is not well established. The authors thus aimed to assess the effect of case volume on the rate of various types of complications after clipping of UIAs.

METHODS

Using information on the outcomes of inpatient admissions for surgical clipping of UIAs collected within a national database, the relationship of institutional case volume to the incidence of different types of complications after clipping was investigated. Complications were subdivided into different categories, which included all complications, ischemic stroke, intracerebral hemorrhage, medical complications, infectious complications, complications related to anesthesia, and wound complications. The relationship of case volume to different types of complications was assessed using linear regression analysis. The relationships between case volume and overall complication and stroke rates were fit with both linear and quadratic equations. The numerical cutoff for institutional case volume above and below which the authors found the greatest differences in mean overall complication and stroke rate was determined using classification and regression tree (CART) analysis.

RESULTS

Between October 2012 and September 2015, 125 health care institutions reported patient outcomes from a total of 6040 cases of clipping of UIAs. On linear regression analysis, increasing case volume was negatively correlated to both overall complications (r2 = 0.046, p = 0.0234) and stroke (r2 = 0.029, p = 0.0557) rate, although the relationship of case volume to the complication (r2 = 0.092) and stroke (r2 = 0.067) rate was better fit with a quadratic equation. On CART analysis, the cutoff for the case number that yielded the greatest difference in overall complications and stroke rate between higher- or lower-volume centers was 6 cases/year and 3 cases/year, respectively.

CONCLUSIONS

Although the authors confirm that increasing case volume is associated with reduced complications after clipping of UIAs, their results suggest that the relationship between case volume and complications is not necessarily linear. Moreover, these results indicate that the effect of case volume on outcome is most evident between very-low-volume centers relative to centers with a medium-to-high volume.

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Panagiotis Kerezoudis, Rohin Singh, Veronica Parisi, Gregory A. Worrell, Kai J. Miller, W. Richard Marsh, and Jamie J. Van Gompel

OBJECTIVE

The prevalence of epilepsy in the older adult population is increasing. While surgical intervention in younger patients is supported by level I evidence, the safety and efficacy of epilepsy surgery in older individuals is less well established. The aim of this study was to evaluate seizure freedom rates and surgical outcomes in older epilepsy patients.

METHODS

The authors’ institutional electronic database was queried for patients older than 50 who had undergone epilepsy surgery during 2002–2018. Cases were grouped into 50–59, 60–69, and 70+ years old. Seizure freedom at the last follow-up constituted the primary outcome of interest. The institutional analysis was supplemented by a literature review and meta-analysis (random effects model) of all published studies on this topic as well as by an analysis of complication rates, mortality rates, and cost data from a nationwide administrative database (Vizient Inc., years 2016–2019).

RESULTS

A total of 73 patients (n = 16 for 50–59 years, n = 47 for 60–69, and n = 10 for 70+) were treated at the authors’ institution. The median age was 63 years, and 66% of the patients were female. At a median follow-up of 24 months, seizure freedom was 73% for the overall cohort, 63% for the 50–59 group, 77% for the 60–69 group, and 70% for the 70+ group. The literature search identified 15 additional retrospective studies (474 cases). Temporal lobectomy was the most commonly performed procedure (73%), and mesial temporal sclerosis was the most common pathology (52%), followed by nonspecific gliosis (19%). The pooled mean follow-up was 39 months (range 6–114.8 months) with a pooled seizure freedom rate of 65% (95% CI 59%–72%). On multivariable meta-regression analysis, an older mean age at surgery (coefficient [coeff] 2.1, 95% CI 1.1–3.1, p < 0.001) and the presence of mesial temporal sclerosis (coeff 0.3, 95% CI 0.1–0.6, p = 0.015) were the most important predictors of seizure freedom. Finally, analysis of the Vizient database revealed mortality rates of 0.5%, 1.1%, and 9.6%; complication rates of 7.1%, 10.1%, and 17.3%; and mean hospital costs of $31,977, $34,586, and $40,153 for patients aged 50–59, 60–69, and 70+ years, respectively.

CONCLUSIONS

While seizure-free outcomes of epilepsy surgery are excellent, there is an expected increase in morbidity and mortality with increasing age. Findings in this study on the safety and efficacy of epilepsy surgery in the older population may serve as a useful guide during preoperative decision-making and patient counseling.