The development of high-quality intraoperative MRI (iMRI) capability has offered a major advance in the care of patients with complex intracranial disease. To date, this technology has been limited by the need for pin fixation of the calvaria. The authors report their preliminary experience with an MRI-compatible horseshoe headrest that allows for the following: 1) iMRI in patients too young for pin fixation; 2) iMRI in patients with large calvarial defects; 3) the ability to move the head during iMRI surgery; and 4) the use of neuronavigation in such cases. The authors report 2 cases of infants in whom the Visius Surgical Theatre horseshoe headrest (IMRIS Inc.) was used. Image quality was equivalent to that of pin fixation. The infants suffered no skin issues. The use of neuronavigation with the system remained accurate and could be updated with the new iMRI information. The Visius horseshoe headrest offers a technical advance in iMRI technology for infants, for patients with cranial defects or prior craniotomies in whom pin fixation may not be safe, or for patients in whom the need to move the head during surgery is required. The image quality of the system remains excellent, and the ability to merge new images to the neuronavigation system is helpful.
Frederick A. Boop, Berkeley Bate, Asim F. Choudhri, Brian Burkholder and Paul Klimo Jr.
Berkeley G. Bate, Nickalus R. Khan, Brent Y. Kimball, Kyle Gabrick and Jason Weaver
In patients with significant epidural spinal cord compression, initial surgical decompression and stabilization of spinal metastases, as opposed to radical oncological resection, provides a margin around the spinal cord that facilitates subsequent treatment with high-dose adjuvant stereotactic radiosurgery (SRS). If a safe margin exists between tumor and spinal cord on initial imaging, then high-dose SRS may be used as the primary therapy, eliminating the need for surgery. Selecting the appropriate approach has shown greater efficacy of tumor control, neurological outcome, and duration of response when compared with external beam radiotherapy, regardless of tumor histology. This study evaluates the efficacy of this treatment approach in a series of 57 consecutive patients.
Patients treated for spinal metastases between 2007 and 2011 using the Varian Trilogy Linear Accelerator were identified retrospectively. Each received SRS, with or without initial surgical decompression and instrumentation. Medical records were reviewed to assess neurological outcome and surgical or radiation-induced complications. Magnetic resonance images were obtained for each patient at 3-month intervals posttreatment, and radiographic response was assessed as stability/regression or progression. End points were neurological outcome and local radiographic disease control at death or latest follow-up.
Fifty-seven patients with 69 lesions were treated with SRS for spinal metastases. Forty-eight cases (70%) were treated with SRS alone, and 21 (30%) were treated with surgery prior to SRS. A single fraction was delivered in 38 cases (55%), while a hypofractionated scheme was used in 31 (45%). The most common histological entities were renal cell, breast, and lung carcinomas. Radiographically, local disease was unchanged or regressed in 63 of 69 tumors (91.3%). Frankel score improved or remained stable in 68 of 69 cases (98.6%).
SRS, alone or as an adjunct following surgical decompression, provides durable local radiographic disease control while preserving or improving neurological function. This less-invasive alternative to radical spinal oncological resection appears to be effective regardless of tumor histology without sacrificing durability of radiographic or clinical response.