Background. In order to improve management, the files and tissue sections of 28 cases of malignant peripheral nerve sheath tumors (MPNST) diagnosed at the University of Virginia Health Sciences Center between 1960 and 1990 were reviewed. Methods. Clinical data tabulated included age, sex, race, the presence or absence of von Recklinghausen neurofibromatosis type 1 (NF‐1), tumor size, tumor location, type of treatment, and status of surgical margins. Pathologic study included assessment of mitotic rate, divergent differentiation, cellular atypia, necrosis, and vascular reaction. Results. The median disease‐free survival time was 11 months, and the median overall survival time was 44 months. Overall survival and disease‐free survival were significantly influenced by patient age, tumor location, tumor size, extent of surgery, and quality of margins. Patients with a family history of neurofibromatosis also had better disease‐free survival. None of the other clinical variables correlated with survival. Conclusions. The authors recommended that patients with NF‐1 be followed closely for MPNST development. For most cases, treatment should include aggressive surgery with wide surgical margins combined with adjuvant radiation therapy. Chemotherapy may have a role for treatment failures.
A frequent problem in estimating logistic regression models is a failure of the likelihood maximization algorithm to converge. In most cases, this failure is a consequence of data patterns known as complete or quasi-complete separation. For these patterns, the maximum likelihood estimates simply do not exist. In this paper, I examine how and why complete or quasi-complete separation occur, and the effects they produce in output from SAS ® procedures.I then describe and evaluate several possible solutions.
A new surgical technique for the treatment of lumbar spinal stenosis features extensive unilateral decompression with undercutting of the spinous process and, to preserve stability, uses contralateral autologous bone fusion of the spinous processes, laminae, and facets. The operation was performed in 29 patients over a 19-month period ending in December of 1991. All individuals had been unresponsive to conservative treatment and presented with low-back pain in addition to signs and symptoms consistent with neurogenic claudication or radiculopathy. Nine had undergone previous lumbar decompressive surgery. The minimum and mean postoperative follow-up times were 2 and 2 1/2 years, respectively. The mean patient age was 64 years; only two patients were younger than 50 years of age. Of the patients with neurogenic claudication, 69% reported complete pain relief at follow-up review. Of those with radicular symptoms, 41% had complete relief and 23% had mild residual pain that was rated 3 or less on a pain-functionality scale of 0 to 10. For the entire sample, this surgery decreased pain from 9.2 to 3.3 (p < 0.0001) on the scale. Sixty-nine percent of patients were satisfied with surgery. Low-back pain was significantly relieved in 62% of all patients (p < 0.0001). Low-back pain relief correlated negatively with number of levels decompressed (p < 0.05). To assess fusion, follow-up flexion/extension radiographs were obtained, and no motion was detected at the surgically treated levels in any patient. The results suggest that this decompression procedure safely and successfully treats not only the radicular symptoms caused by lateral stenosis but also the neurogenic claudication symptoms associated with central stenosis. In addition, the procedure, by using contralateral autologous bone fusion along the laminae and spinous processes, can preserve stability without instrumentation.
The case is reported of a 28-year-old man with "ectopic" craniopharyngioma recurring in the epidural space 21 years after the original tumor was resected. Previously described cases of similar remote recurrences as well as some features of the biological behavior of craniopharyngioma are discussed. The rarity of this postoperative complication is addressed.
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