Neurosurgical “pearls” and neurosurgical evidence
E. Antonio Chiocca
Dima Suki, Hiba Abouassi, Akash J. Patel, Raymond Sawaya, Jeffrey S. Weinberg and Morris D. Groves
The authors tested the hypothesis that patients with metastatic posterior fossa lesions (MPFLs) treated with resection have a higher risk of leptomeningeal disease (LMD) than those with MPFLs treated with stereotactic radiosurgery (SRS).
Between 1993 and 2004, 379 patients with MPFLs were treated with resection or SRS at The University of Texas M. D. Anderson Cancer Center. The authors' primary study outcome was the incidence of LMD, as diagnosed with cerebrospinal fluid cytological analysis and/or neuroimaging.
Resection was performed in 260 patients, whereas 119 patients underwent SRS. The median patient age was 56 years, 51% of patients were male, and 93% had a Karnofsky Performance Scale score $ 70. The most common primary cancers were those of the lung, breast, and kidney, as well as melanoma. Leptomeningeal dissemination of cancer occurred in 33 patients: 26 in the resection group and 7 in the SRS group (resection group: rate ratio [RR] 2.06, 95% confidence interval [CI] 0.89–4.75, p = 0.09). Piecemeal tumor resection (137 cases) was associated with a significantly higher risk of LMD than en bloc resection (123 cases; RR 3.4, 95% CI 1.43–8.12, p = 0.006) or SRS (RR 3.37, 95% CI 1.41–8.04, p = 0.006), and there was no significant difference in the risk for LMD between en bloc resection and SRS (en bloc resection: RR 0.98, 95% CI 0.34–2.81, p = 0.98). The multivariate RR and significance associated with piecemeal resection, however, were consistent, with a strong effect (RR 2.45, 95% CI 1.19–5.02, p = 0.02) and no indication of biases associated with tumor size, location, or cystic/necrotic appearance.
There is an increased risk of LMD after piecemeal resection of an MPFL. This increase, although clinically and statistically significant, is not as alarming as previously reported and is absent when en bloc removal is achieved. Further assessment of the role of resection in a controlled prospective setting is warranted.
Akash J. Patel, Dima Suki, Mustafa Aziz Hatiboglu, Vikas Y. Rao, Benjamin D. Fox and Raymond Sawaya
Brain metastases are the most common intracranial neoplasms and are on the increase. As radiation side effects are increasingly better understood, more patients are being treated with surgery alone with varying outcomes. The authors previously reported that en bloc resection of a single brain metastasis was associated with decreased incidences of leptomeningeal disease and local recurrence compared with piecemeal resection. However, en bloc resection is often feared to cause an increased incidence of postoperative complications. This study aimed to answer this question.
The authors reviewed data from patients with a previously untreated single brain metastasis, who were treated with resection at The University of Texas M.D. Anderson Cancer Center (1993–2012). Data related to the patient, tumor, and methods of resection were obtained. Discharge Karnofsky Performance Scale (KPS) scores and 30-day postoperative complications were noted. Complications were considered major when they persisted for longer than 30 days, resulted in hospitalization or prolongation of hospital stay, required aggressive treatment, and/or were life threatening.
During the study period, 1033 eligible patients were identified. The median age was 58 years, 83% had a KPS score greater than 70, and 81% were symptomatic at surgery. Sixty-two percent of the patients underwent en bloc resection of their tumor, and 38% underwent piecemeal resection. There were significant differences between the 2 groups in terms of preoperative tumor volume, tumor functional grade, and symptoms at presentation, among others. The overall complication rates were 13% for patients undergoing en bloc resection and 19% for patients undergoing piecemeal resection (p = 0.007). The incidences of major complications and neurological complications were also significantly different. There was a trend in the same direction for major neurological complications, although it was not significant. Among patients undergoing piecemeal resection of tumors in eloquent cortex, 24% had complications (13% had major, 18% had neurological, 9% had major neurological, and 13% had select neurological complications; 4% died within 1 month of surgery). Among those undergoing en bloc resection of such tumors, 11% had complications (6% had major, 8% had neurological, 4% had major neurological, and 4% had select neurological; 2% died within 1 month of surgery). The differences in overall, major, neurological, and select neurological complications were statistically significant, but 1-month mortality and major neurological complications were not. In addition, within subcategories of tumor volume, the incidence of various complications was generally higher for patients undergoing piecemeal resection than for those undergoing en bloc resection.
The authors' results indicate that postoperative complication rates are not increased by en bloc resection, including for lesions in eloquent brain regions or for large tumors. This gives credence to the idea that en bloc resection of brain metastases, when feasible, is at least as safe as piecemeal resection.
Benjamin D. Fox, Hassan H. Amhaz, Akash J. Patel, Daniel H. Fulkerson, Dima Suki, Andrew Jea and Raymond E. Sawaya
Medical student exposure to neurosurgery is limited. To improve the educational interactions between neurosurgeons and medical students as well as neurosurgical medical student rotations or clerkships (NSCs) we must first understand the current status.
Two questionnaires were sent, one to every neurosurgery course coordinator or director at each US neurosurgery residency program (99 questionnaires) and one to the associated parent medical school dean's office (91 questionnaires), to assess the current status of NSCs and the involvement of neurosurgeons at their respective institutions.
We received responses from 86 (87%) of 99 neurosurgery course coordinators or directors and 64 (70%) of 91 medical school deans' offices. Most NSCs do not have didactic lectures (53 [62%] of 86 NSCs), provide their medical students with a syllabus or educational handouts (53 [62%] of 86), or have a recommended/required textbook (77 [90%] of 86). The most common method of evaluating students in NSCs is a subjective performance evaluation. Of 64 medical school deans, 38 (59%) felt that neurosurgery should not be a required rotation. Neurosurgical rotations or clerkships are primarily offered to students in their 4th year of medical school, which may be too late for appropriate timing of residency applications. Only 21 (33%) of 64 NSCs offer neurosurgery rotations to 3rd-year students.
There is significant room for improvement in the neurosurgeon-to–medical student interactions in both the NSCs and during the didactic years of medical school.
Akash J. Patel, Dima Suki, Mustafa Aziz Hatiboglu, Hiba Abouassi, Weiming Shi, David M. Wildrick, Frederick F. Lang and Raymond Sawaya
Local recurrence (LR) of a resected brain metastasis occurs in up to 46% of patients. Postoperative whole-brain radiation therapy (WBRT) reduces that incidence. To isolate factors associated with the risk of LR after resection, the authors only studied patients who did not receive adjuvant radiotherapy.
The authors reviewed data from 570 cases involving patients who had undergone resection of a previously untreated single brain metastasis at The University of Texas M. D. Anderson Cancer Center between 1993 and 2006 without receiving postoperative WBRT. All tumors were measured preoperatively on MR images. The resection method (en bloc resection [EBR] or piecemeal resection [PMR]) was noted at the time of surgery. Predictors of LR were assessed using the Cox proportional hazards model.
The median patient age was 58 years, 55% were male, and 88% had a Karnofsky Performance Scale Score ≥ 80. The most common primary cancers were those of the lung (28%), skin (melanoma, 21%), kidney (19%), and breast (11%). Piecemeal resection was performed in 201 patients (35%) and EBR in 369 (65%). Local recurrence developed in 84 patients (15%). The histological type of the primary cancer did not significantly predict LR; however, 7 of 22 patients with sarcoma developed LR (p = 0.16). The authors identified 2 variables that increased the risk of LR. Undergoing PMR carried a significantly higher LR risk than EBR (crude hazard ratio [HR] 1.7, 95% CI 1.1–2.6, p = 0.03). Tumors exceeding the median volume (9.7 cm3) had a significantly higher LR risk than those that were < 9.7 cm3 (crude HR 1.7; 95% CI 1.1–2.6; p = 0.02). In the multivariate analysis, small tumors removed by EBR had a significantly lower LR risk.
The LR risk of a single brain metastasis is influenced by biological factors (such as tumor volume) and treatments (such as the resection method). Early administration of postoperative WBRT may be particularly warranted when such negative tumor-related prognostic factors are noted or when treatment-related ones such as PMR are unavoidable.