Morris, Jonathan M.

Object The object of this study was to determine the potential of magnetic resonance elastography (MRE) to preoperatively assess the stiffness of meningiomas. Methods Thirteen patients with meningiomas underwent 3D brain MRE examination to measure stiffness in the tumor as well as in surrounding brain tissue. Blinded to the MRE results, neurosurgeons made a qualitative assessment of tumor stiffness at the time of resection. The ability of MRE to predict the surgical assessment of stiffness was tested using a Spearman rank correlation. Results One case was excluded due to a small tumor size. In the remaining 12 cases, both tumor stiffness alone (p = 0.023) and the ratio of tumor stiffness to surrounding brain tissue stiffness (p = 0.0032) significantly correlated with the surgeons' qualitative assessment of tumor stiffness. Results of the MRE examination provided a stronger correlation with the surgical assessment of stiffness compared with traditional T1- and T2-weighted imaging (p = 0.089), particularly when considering meningiomas of intermediate stiffness. Conclusions In this cohort, preoperative MRE predicted tumor consistency at the time of surgery. Tumor stiffness as measured using MRE outperformed conventional MRI because tumor appearance on T1- and T2-weighted images could only accurately predict the softest and hardest meningiomas.

Secondary, radiation-induced neoplasms represent a significant long-term risk after radiation treatment, and radiation-induced sarcomas (RAS) have an especially poor prognosis. These have rarely been reported after irradiation for pituitary adenomas.

Object Synovial cysts of the cervical spine are rare. Further, synovial cysts of the C1–2 articulation, or retroodontoid cysts, are very rare, with fewer than 20 cases reported overall. The authors report on a single-institution series of 10 patients with C1–2 retroodontoid synovial cysts. Methods The charts of 10 patients with pathologically confirmed synovial cysts following resection between January 1998 and June 2009 were reviewed. The clinical presentation, radiographic findings, surgical management, and pre- and postoperative functional levels (reported as a modified Rankin outcome) are reported. Results All 10 patients underwent attempts at complete resection of the synovial cyst; none of the lesions were simply aspirated. All 4 patients with an initial recommendation of observation alone ultimately underwent surgery because of their swift neurological deterioration. The mean age at surgery was 75.4 ± 4.6 years (range 54–81 years). The mean presenting cyst volume was 4.6 ± 1.7 cm3. Nine of 10 patients underwent transoral resection of the cyst with posterior fusion. Six of the 10 patients underwent additional posterior laminectomy for decompression. The hospital length of stay varied from 2 to 45 days, with a mean of 19 ± 7 days. All patients undergoing transoral decompression had varying degrees of difficulty with postoperative dysphagia, diagnosed using videofluoroscopy. All patients improved in their modified Rankin Scale score after surgical intervention with a mean follow-up of 42 months (95% CI 12–72 months). Conclusions Synovial cysts of the atlantoaxial joint are rare. They occur in older patients in whom clinical deterioration is likely to occur. In most cases, these cysts can be diagnosed preoperatively. Transoral decompression with posterior fusion is an effective treatment for C1–2 degenerative cysts and can be accomplished with few complications. However, the ideal treatment for these lesions remains unknown.

Object Little information is available on follow-up MR imaging after treatment of spinal dural arteriovenous fistulas (DAVFs). The authors studied MR imaging findings in treated spinal DAVFs in relation to clinical outcomes. Methods A retrospective review of patients with spinal DAVFs who had undergone both pre- and postoperative spinal MR imaging was conducted. Postoperative MR images were obtained as routine follow-up studies or because of subjective or objective clinical deterioration. Several pre- and posttreatment MR imaging characteristics were evaluated by 2 neuroradiologists blinded to the clinical outcome. Clinical outcomes of motor, sensory, and urinary function (in relation to the patient's preoperative status) at the time of the postoperative MR imaging were obtained from the clinical record. The chi-square, Fisher exact, and rank-sum tests were performed to correlate imaging findings and changes with clinical outcomes. Results Thirty-four patients met inclusion criteria. Treatment was surgical in 33 patients and endovascular in 1 patient. Follow-up MR imaging was performed at a mean 168 ± 107 days after treatment. Twenty-seven patients (79.4%) were either clinically stable or improved, and 7 (20.6%) experienced worsening in one or more clinical outcomes. Most patients were found to have improvement of MR imaging changes. However, some degree of persistent spinal cord signal abnormality, enhancement, and swelling was observed in 31 (91.2%), 29 (85.3%), and 18 (52.3%) patients, respectively. Changes in these MR imaging characteristics compared with preoperative MR imaging did not correlate with clinical outcomes (p > 0.05), with the one exception of a significant correlation between change in urinary function and extent of spinal cord contrast enhancement (p = 0.026), a correlation of uncertain importance. Ten of the 34 patients underwent posttreatment digital subtraction angiography, and 3 of these patients had recurrent/residual DAVFs. Worsening of motor function significantly correlated with recurrent/residual DAVF (p = 0.053). Conclusions Spinal cord abnormalities persist on postoperative MR imaging studies in patients with treated spinal DAVFs, and although they tend to mildly improve with time, these changes may not correlate with clinical outcomes. However, regardless of imaging findings, worsening motor function may correlate with a recurrent or residual DAVF.

Although more prevalent in males in the 6th and 7th decade of life, spinal dural arteriovenous fistulas (SDAVFs) are an uncommon cause of progressive myelopathy. Magnetic resonance imaging and more recently Gd bolus MR angiography have been used to diagnose, radiographically define, and preprocedurally localize the contributing lumbar artery. Three-dimensional myelographic MR imaging sequences have recently been developed for anatomical evaluation of the spinal canal. The authors describe 3 recent cases in which volumetric myelographic MR imaging with a 3D phase-cycled fast imaging employing steady state acquisition (PC-FIESTA) and a 3D constructive interference steady state (CISS) technique were particularly useful not only for documenting an SDAVF, but also for providing localization when CT angiography, MR imaging, MR angiography, and spinal angiography failed to localize the fistula. In a patient harboring an SDAVF at T-4, surgical exploration was performed based on the constellation of findings on the PC-FIESTA images as well as the fact that the spinal segments leading to T-4 were the only ones that the authors were unable to catheterize. In a second patient, who harbored an SDAVF at T-6, after 2 separate angiograms failed to demonstrate the fistula, careful assessment of the CISS images led the authors to focus a third angiogram on the left T-6 intercostal artery and to perform superselective microcatheterization. In a third patient with an SDAVF originating from the lateral sacral branch, the PC-FIESTA sequence demonstrated the arterialized vein extending into the S-1 foramen, leading to a second angiogram and superselective internal iliac injections. The authors concluded that myelographic MR imaging sequences can be useful not only as an aid to diagnosis but also for localization of an SDAVF in complex cases.