Factors predicting the resectability of intramedullary spinal cord tumors and the progression-free survival following microsurgical treatment
Michael G. Fehlings and David Mercier
Giannina L. Garcés-Ambrossi, Matthew J. McGirt, Vivek A. Mehta, Daniel M. Sciubba, Timothy F. Witham, Ali Bydon, Jean-Paul Wolinksy, George I. Jallo and Ziya L. Gokaslan
With the introduction of electrophysiological spinal cord monitoring, surgeons have been able to perform radical resection of intramedullary spinal cord tumors (IMSCTs). However, factors associated with tumor resectability, tumor recurrence, and long-term neurological outcome are poorly understood.
The authors retrospectively reviewed 101 consecutive cases of IMSCT resection in adults and children at a single institution. Neurological function and MR images were evaluated preoperatively, at discharge, 1 month after surgery, and every 6 months thereafter. Factors associated with gross-total resection (GTR), progression-free survival (PFS), and long-term neurological improvement were assessed using multivariate regression analysis.
The mean age of the patients was 41 ± 18 years and 17 (17%) of the patients were pediatric. Pathological type included ependymoma in 51 cases, hemangioblastoma in 15, pilocytic astrocytoma in 16, WHO Grade II astrocytoma in 10, and malignant astrocytoma in 9. A GTR was achieved in 60 cases (59%). Independent of histological tumor type, an intraoperatively identifiable tumor plane (OR 25.3, p < 0.0001) and decreasing tumor size (OR 1.2, p = 0.05) were associated with GTR. Thirty-four patients (34%) experienced acute neurological decline after surgery (associated with increasing age [OR 1.04, p = 0.02] and with intraoperative change in motor evoked potentials [OR 7.4, p = 0.003]); in 14 (41%) of these patients the change returned to preoperative baseline within 1 month. In 31 patients (31%) tumor progression developed by last follow-up (mean 19 months). Tumor histology (p < 0.0001) and the presence of an intraoperatively identified tumor plane (hazard ratio [HR] 0.44, p = 0.027) correlated with improved PFS. A GTR resulted in improved PFS for hemangioblastoma (HR 0.004, p = 0.04) and ependymoma (HR 0.2, p = 0.02), but not astrocytoma. Fifty-five patients (55%) maintained overall neurological improvement by last follow-up. The presence of an identifiable tumor plane (HR 3.1, p = 0.0004) and improvement in neurological symptoms before discharge (HR 2.3, p = 0.004) were associated with overall neurological improvement by last follow-up (mean 19 months).
Gross-total resection can be safely achieved in the vast majority of IMSCTs when an intraoperative plane is identified, independent of pathological type. The incidence of acute perioperative neurological decline increases with patient age but will improve to baseline in nearly half of patients within 1 month. Long-term improvement in motor, sensory, and bladder dysfunction may be achieved in a slight majority of patients and occurs more frequently in patients in whom a surgical plane can be identified. A GTR should be attempted for ependymoma and hemangioblastoma, but it may not affect PFS for astrocytoma. For all tumors, the intraoperative finding of a clear tumor plane of resection carries positive prognostic significance across all pathological types.
Giannina L. Garcés-Ambrossi, Matthew J. McGirt, Roger Samuels, Daniel M. Sciubba, Ali Bydon, Ziya L. Gokaslan and George I. Jallo
Although postsurgical neurological outcomes in patients with tethered cord syndrome (TCS) are well known, the rate and development of neurological improvement after first-time tethered cord release is incompletely understood. The authors reviewed their institutional experience with the surgical management of adult TCS to assess the time course of symptomatic improvement, and to identify the patient subgroups most likely to experience improvement of motor symptoms.
The authors retrospectively reviewed 29 consecutive cases of first-time adult tethered cord release. Clinical symptoms of pain and motor and urinary dysfunction were evaluated at 1 and 3 months after surgery, and then every 6 months thereafter. Rates of improvement in pain and motor or urinary dysfunction over time were identified, and presenting factors associated with improvement of motor symptoms were assessed using a multivariate survival analysis (Cox model).
The mean patient age was 38 ± 13 years. The causes of TCS included lipomyelomeningocele in 3 patients (10%), tight filum in 3 (10%), lumbosacral lipoma in 4 (14%), intradural tumor in 3 (10%), previous lumbosacral surgery in 2 (7%), and previous repair of myelomeningocele in 14 (48%). The mean ± SD duration of symptoms before presentation was 5 ± 7 months. Clinical presentation included diffuse pain/parasthesias in both lower extremities in 13 patients (45%), or perineal distribution in 18 (62%), lower extremity weakness in 17 (59%), gait difficulties in 17 (59%), and bladder dysfunction in 14 (48%). Laminectomy was performed in a mean of 2.5 ± 0.7 levels per patient, and 9 patients (30%) received duraplasty. At 18 months postoperatively, 47% of patients had improved urinary symptoms, 69% had improved lower extremity weakness and gait, and 79% had decreased painful dysesthesias. Median time to symptomatic improvement was least for pain (1 month), then motor (2.3 months), and then urinary symptoms (4.3 months; p = 0.04). In patients demonstrating improvement, 96% improved within 6 months of surgery. Only 4% improved beyond 1-year postoperatively. In a multivariate analysis, the authors found that patients who presented with asymmetrical lower extremity weakness (p = 0.0021, hazard ratio 5.7) or lower extremity hyperreflexia (p = 0.037, hazard ratio = 4.1) were most likely to experience improvement in motor symptoms.
In the authors' experience, pain and motor and urinary dysfunction improve postoperatively in the majority of patients. The rate of symptomatic improvement was greatest for pain resolution, followed by motor, and then urinary improvement. Patients who experienced improvement in any symptom had done so by 6 months after tethered cord release. Patients with asymmetrical motor symptoms or lower extremity hyperreflexia at presentation were most likely to experience improvements in motor symptoms. These findings may help guide patient education and surgical decision-making.
Risheng Xu, Giannina L. Garcés-Ambrossi, Matthew J. McGirt, Timothy F. Witham, Jean-Paul Wolinsky, Ali Bydon, Ziya L. Gokaslan and Daniel M. Sciubba
Adequate decompression of the thoracic spinal cord often requires a complete vertebrectomy. Such procedures can be performed from an anterior/transthoracic, posterior, or combined approach. In this study, the authors sought to compare the clinical outcomes of patients with spinal metastatic tumors undergoing anterior, posterior, and combined thoracic vertebrectomies to determine the efficacy and operative morbidity of such approaches.
A retrospective review was conducted of all patients undergoing thoracic vertebrectomies at a single institution over the past 7 years. Characteristics of patients and operative procedures were documented. Neurological status, perioperative variables, and complications were assessed and associations with each approach were analyzed.
Ninety-one patients (mean age 55.5 ± 13.7 years) underwent vertebrectomies via an anterior (22 patients, 24.2%), posterior (45 patients, 49.4%), or combined anterior-posterior approach (24 patients, 26.4%) for metastatic spinal tumors. The patients did not differ significantly preoperatively in terms of neurological assessments on the Nurick and American Spinal Injury Association Impairment scales, ambulatory ability, or other comorbidities. Anterior approaches were associated with less blood loss than posterior approaches (1172 ± 1984 vs 2486 ± 1645 ml, respectively; p = 0.03) or combined approaches (1172 ± 1984 vs 2826 ± 2703 ml, respectively; p = 0.05) but were associated with a similar length of stay compared with the other treatment cohorts (11.5 ± 9.3 [anterior] vs 11.3 ± 8.6 [posterior] vs 14.3 ± 6.7 [combined] days; p = 0.35). The posterior approach was associated with a higher incidence of wound infection compared with the anterior approach cohort (26.7 vs 4.5%, respectively; p = 0.03), and patients in the posterior approach group experienced the highest rates of deep vein thrombosis (15.6% [posterior] vs 0% [other 2 groups]; p = 0.02). However, the posterior approach demonstrated the lowest incidence of pneumothorax (4.4%; p < 0.0001) compared with the other 2 cohorts. Duration of chest tube use was greater in the combined patient group compared with the anterior approach cohort (8.8 ± 6.2 vs 4.7 ± 2.3 days, respectively; p = 0.01), and the combined group also experienced the highest rates of radiographic pleural effusion (83.3%; p = 0.01). Postoperatively, all groups improved neurologically, although functional outcome in patients undergoing the combined approach improved the most compared with the other 2 groups on both the Nurick (p = 0.04) and American Spinal Injury Association Impairment scales (p = 0.03).
Decisions regarding the approach to thoracic vertebrectomy may be complex. This study found that although anterior approaches to the thoracic vertebrae have been historically associated with significant pulmonary complications, in our experience these rates are nevertheless quite comparable to that encountered via a posterior or combined approach. In fact, the posterior approach was found to be associated with a higher risk for some perioperative complications such as wound infection and deep vein thromboses. Finally, the combined anteriorposterior approach may provide greater ambulatory and neurological improvements in properly selected patients.