Surgical volume of simple tethered spinal cord releases: review of a large pediatric neurosurgical service experience

Abstract

OBJECTIVEThe 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.METHODSThe 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.RESULTSA 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.CONCLUSIONSSimple 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.