Emily L. Day and R. Michael Scott
The authors sought to evaluate the utility of intraoperative MRI (ioMRI) during brain tumor excision in pediatric patients and to suggest guidelines for its future use.
All patients who underwent brain tumor surgery by the senior author at Boston Children’s Hospital using ioMRI between 2005 and 2009 were included in this retrospective review of hospital records and the neurosurgeon’s operative database. Prior to the review, the authors defined the utility of ioMRI into useful and not useful categories based on how the technology affected operative management. They determined that ioMRI was useful if it 1) effectively guided the extent of resection; 2) provided a baseline postoperative scan during the same anesthesia session; or 3) demonstrated or helped to prevent an intraoperative complication. The authors determined that ioMRI was not useful if 1) the anatomical location of the tumor had precluded a tumor’s total resection, even though the surgeon had employed ioMRI for that purpose; 2) the tumor’s imaging characteristics prevented an accurate assessment of resection during intraoperative imaging; 3) the surgeon deemed the technology not required for tumor resection; or 4) the intraoperative MR images were uninterpretable for technical reasons. Follow-up data provided another gauge of the long-term benefit of ioMRI to the patient.
A total of 53 brain tumor patients were operated on using ioMRI, 6 of whom had a second ioMRI procedure during the study period. Twenty-six patients were female, and 27 were male. The mean follow-up was 4.8 ± 3.85 years (range 0–12 years). By the criteria outlined above, ioMRI technology was useful in 38 (64.4%) of the 59 cases, most frequently for its help in assessing extent of resection.
Intraoperative MRI technology was useful in the majority of brain tumor resections in this series, especially in those tumors that were contrast enhancing and located largely within accessible areas of the brain. The percentage of patients for whom ioMRI is useful could be increased by preoperatively evaluating the tumor’s imaging characteristics to determine if ioMRI would accurately assess the extent of tumor resection, and by the surgeon’s preoperative understanding that use of the ioMRI will not lead to resection of an anatomically unresectable tumor. The ioMRI can prove useful in unresectable tumors if specific operative goals are defined preoperatively.
Emily L. Day, Mark R. Proctor and R. Michael Scott
The aim of this study was to retrospectively review, from a single busy pediatric neurosurgical service, a consecutive series of patients who had undergone surgery for a simple tethered spinal cord, which was defined by a thickened or fatty filum terminale with a normal conus. The hope was to contribute to benchmark data regarding the expected frequency of surgery for this condition.
The authors reviewed the electronic medical records of every patient with diagnosed simple tethered spinal cord, defined on spinal MRI as a thickened (> 2 mm in diameter) or fatty filum terminale, and who had undergone primary filum section at Boston Children’s Hospital between 2005 and 2011.
A total of 208 patients met the study inclusion criteria. At the time of surgery, patients ranged in age from 0.4 to 19.8 years. One hundred forty-four (69%) patients were symptomatic with one or more of the following: bowel/bladder dysfunction, 94 (45%); neurological dysfunction, 49 (24%); scoliosis, 44 (21%); or back pain, 44 (21%). Sixty-four (31%) patients were asymptomatic and were operated on prophylactically when filum pathology was discovered during the course of a workup for clinical syndromes such as anorectal anomalies and/or suspicious cutaneous lesions. No patients in this series were operated on if they had normal MRI studies, defined as a conus tip no lower than L3 and no distal tethering lesion visualized. Over the study period, approximately 1000 major surgical cases were performed in the department every year, only 30 of which were simple detethering procedures, representing well under 5% of the service’s operative volume and approximately 5 cases per surgeon per year. Clinical follow-up, available at a postoperative interval of 6.6 ± 3.8 years, demonstrated that approximately 80% of patients symptomatic with bowel or bladder involvement or neurological dysfunction had improvement or relief of their symptoms and that none of the patients treated prophylactically experienced new-onset symptoms that could be related to spinal tethering.
Simple detethering procedures were relatively uncommon in an active, well-established pediatric neurosurgical service and represented less than 5% of the service’s total case volume per year with an average of 5 cases per surgeon per year. No patients with normal MRI studies were operated on during the study period.