The use and abuse of survival analysis and Kaplan-Meier curves in surgical trials.

BACKGROUND: Survival analysis based on Cox regression and Kaplan-Meier curves, initially devised for oncology trials, have frequently been used in other contexts where fundamental statistical assumptions (such as a constant hazard ratio) are not satisfied. This is almost always the case in trials that compare surgery with medical management. METHODS: We review a trial that compared extracranial-intracranial bypass surgery (EC-IC bypass) with medical management (MM) of patients with symptomatic occlusion of the carotid or middle cerebral artery, where it was claimed that surgery was of no benefit. We discuss a hypothetical study and review other neurovascular trials which have also used survival analysis to compare results. RESULTS: The trial comparing EC-IC bypass and MM did not satisfy the fundamental proportional hazard assumption necessary for valid analyses. This was also the case for two prior EC-IC bypass trials, as well as for other landmark neurovascular studies, such as the trials comparing endarterectomy with MM for carotid stenoses, or for the trial that compared intervention and MM for unruptured brain arteriovenous malformations. While minor deviations may have little effect on large trials, it may be impossible to show the benefits of surgery when trial size is small and deviations large. CONCLUSION: Survival analyses are inappropriate in RCTs comparing surgery with conservative management, unless survival is calculated after the postoperative period. Alternative ways to compare final clinical outcomes, using for example a fixed follow-up period, should be planned for preventive surgical trials that compare intervention with conservative management.

Repeat Surgery for Recurrent or Refractory Trigeminal Neuralgia: A Systematic Review and Meta-Analysis.

OBJECTIVE: Surgery can effectively treat Trigeminal neuralgia (TN), but postoperative pain recurrence or nonresponse are common. Repeat surgery is frequently offered but limited data exist to guide the selection of salvage surgical procedures. We aimed to compare pain relief outcomes after repeat microvascular decompression (MVD), percutaneous rhizotomy (PR), or stereotactic radiosurgery (SRS) to determine which modality was most efficacious for surgically refractory TN. METHODS: A PRISMA systematic review and meta-analysis was performed, including studies of adults with classical or idiopathic TN undergoing repeat surgery. Primary outcomes included complete (CPR) and adequate (APR) pain relief at last follow-up, analyzed in a multivariate mixed-effect meta-regression of proportions. Secondary outcomes were initial pain relief and facial numbness. RESULTS: Of 1299 records screened, 61 studies with 68 treatment arms (29 MVD, 14 PR, and 25 SRS) comprising 2165 patients were included. Combining MVD, PR, and SRS study data, 68.8% achieved initial CPR after a repeat TN procedure. On average, 49.6% of the combined sample of MVD, PR, and SRS had CPR at final follow-up, which was on average 2.99 years postoperatively. The proportion (with 95% CI) achieving CPR at final follow-up was 0.57 (0.51-0.62) for MVD, 0.60 (0.52-0.68) for PR, and 0.35 (0.30-0.41) for SRS, with a significantly lower proportion of pain relief with SRS. Estimates of initial CPR for MVD were 0.82 (0.78-0.85), 0.68 for PR (0.6-0.76), and 0.41 for SRS (0.35-0.48). CONCLUSIONS: Across MVD, PR, and SRS, about half of TN patients maintain complete CPR at an average follow-up time of 3 years after repeat surgery. In treating refractory or recurrent TN, MVD and PR were superior to SRS in both initial pain relief and long-term pain relief at final follow-up. These findings can inform surgical decision-making in this challenging population.

Impact of frailty on 30-day death, stroke, or myocardial infarction in severe carotid stenosis: Endarterectomy versus stenting.

OBJECTIVE: Carotid endarterectomy (CEA) and carotid artery stenting (CAS) are used for stroke prevention in patients with carotid stenosis. It remains unclear which surgical approach produces the best outcomes for elderly and frail patients. We investigated the impact of age and frailty on 30-day combined outcomes of death, stroke, and myocardial infarction (MI) in patients who received CEA or CAS for severe symptomatic carotid stenosis. METHODS: A retrospective analysis of the NSQIP database identified patients with severe carotid stenosis who received either CEA or CAS between 2015 and 2020 for study inclusion. Frailty was measured by the Modified Frailty Index 5-item (mFI-5), which stratified patients as non-frail (score=0), pre-frail (=1), frail (=2), or severely frail (=3). Age was subdivided into 65 years or younger, 66-84 years, and 85 years or older. The primary outcome was 30-day combined rates of death, stroke, and MI, as analyzed by multivariate logistic regression analyses, adjusted for sex, body mass index, smoking status, anesthetic type, and contralateral carotid stenosis. RESULTS: A total of 18,074 patients were included in analyses, of which 14,428 received CEA (80 %) and 3646 received CAS (20 %). Mean age was 70.8 and 70.5 years for CEA and CAS, respectively. The rate of combined outcome of death, stroke or MI at 30 days was significantly higher in CEA (3.3 %) than CAS (1.3 %) (χ2 =41.90, p < 0.001). Increasing frailty was associated with higher rates of the primary outcome in CEA patients (χ2 =30.26, p < 0.001) but not CAS (χ2 =6.95, p = 0.07). A 6-component risk score was constructed for the combined outcomes in CEA, which predicted adverse events with 80.7 % accuracy. CONCLUSIONS: Age and frailty have a significant impact on the risk of death, stroke, and MI at 30 days in patients with severe, symptomatic carotid stenosis who receive CEA, but not CAS. NON-STANDARD ABBREVIATIONS AND ACRONYMS: Body mass index (BMI), carotid artery stenting (CAS), carotid endarterectomy (CEA), current procedural technology (CPT), myocardial infarction (MI), modified Frailty Index 5-item (mFI-5), American College of Surgeons National Surgical Quality Improvement Program (NSQIP).

Association between Graduate Degrees and Publication Productivity in Academic Neurosurgery.

OBJECT: Many neurosurgeons pursue graduate degrees as part of their training. In some jurisdictions, graduate degrees are considered a necessary condition of employment in academic neurosurgery. However, the relationship between possession of a graduate degree and eventual research productivity is not well established. We used bibliometric methods to analyze publications from academic Canadian neurosurgeons, with an emphasis on level of graduate training. METHODS: All neurosurgeons holding academic appointments at Canadian institutions from 2012-2016 were included. Over that time frame, Scopus was used to quantify the number of papers, number of citations, 5-year h-index and 5-year r-index, CiteScore, authorship position, and paper type (clinical or basic science). Publication output was compared between neurosurgeons grouped as MD-only, MD-Masters, or MD-PhD. RESULTS: In total, 2557 abstracts from 131 Canadian neurosurgeons were analyzed. We found that MD-Masters neurosurgeons published significantly more total papers, clinical papers, and first/last author papers than MD-only neurosurgeons. MD-PhD neurosurgeons had the same findings, in addition to more basic science papers, in journals with a higher CiteScore, 5-year h-index, and 5-year r-index than both other groups. These results were preserved even with significant outliers removed. There was no difference if graduate degrees were obtained before or after starting residency. There was no correlation with career length and number of recent papers published. CONCLUSION: The attainment of a graduate degree has an important association with future publication productivity for academic neurosurgeons. These data should be useful for hiring committees considering the value of graduate degrees from applicants for positions in academic neurosurgery.

Concurrent Glossopharyngeal Neuralgia and Hemi-Laryngopharyngeal Spasm (HeLPS): A Case Report and a Review of the Literature.

BACKGROUND AND IMPORTANCE: Hemi-laryngopharyngeal spasm (HeLPS) has been recently described but is not yet widely recognized. Patients describe intermittent coughing and choking and can be cured following microvascular decompression of their Xth cranial nerve. This case report and literature review highlight that HeLPS can co-occur with glossopharyngeal neuralgia (GN) and has been previously described (but not recognized) in the neurosurgical literature. CLINICAL PRESENTATION: A patient with GN and additional symptoms compatible with HeLPS is presented. The patient reported left-sided, intermittent, swallow-induced, severe electrical pain radiating from her ear to her throat (GN). She also reported intermittent severe coughing, throat contractions causing a sense of suffocation, and dysphonia (HeLPS). All her symptoms resolved following a left microvascular decompression of a loop of the posterior inferior cerebellar artery that was pulsating against both the IXth and Xth cranial nerves. A review of the senior author's database revealed another patient with this combination of symptoms. An international literature review found 27 patients have been previously described with symptoms of GN and the additional (but not recognized at the time) symptoms of HeLPS. CONCLUSION: This review highlights that patients with symptoms compatible with HeLPS have been reported since 1926 in at least 4 languages. This additional evidence supports the growing recognition that HeLPS is another neurovascular compression syndrome. Patients with HeLPS continue to be misdiagnosed as conversion disorder. The increased recognition of this new medical condition will require neurosurgical treatment and should alleviate the suffering of these patients.