Recurrent Tethering: A Common Long-Term Problem after Lipomyelomeningocele Repair

Abstract

The authors reviewed the records of 94 patients who underwent initial repair of a lipomyelomeningocele between 1982 and July 1996 at the Children’s Hospital of Pittsburgh to determine the incidence and time course of symptomatic retethering. In each of these patients, the initial operative goals were to microsurgically debulk as much of the lipoma as possible to allow the conus to move freely within the spinal canal, to divide any tethering arachnoidal adhesions, to close the pia if possible and to reconstitute a capacious thecal sac, using a dural graft if necessary. With a median follow-up of 58 months, 19 of these patients (20.2%) required 28 subsequent operations for symptomatic retethering. Median time between the initial procedure and reoperation for retethering was 52 months. The primary complaint of 12 patients was intractable low-back or leg pain. Other common symptoms were progressive bowel and/or bladder dysfunction, deterioration of motor function and foot deformities. The decision to reoperate was based predominantly on the clinical situation of the patient; magnetic resonance imaging was used to confirm the location and extent of tethering. Patients with transitional lipomas had a significantly higher frequency of symptomatic retethering than those with caudal or dorsal lesions (p < 0.05). No other clinical or technical feature correlated with an increased frequency of retethering. In particular, none of a variety of types of dural graft materials appeared to entirely prevent symptomatic retethering. Following reoperation, pain complaints resolved and many of the other symptoms improved partially or resolved completely. Although the long-term results were also favorable in the majority of patients, a small subgroup (n = 6) exhibited repetitive symptomatic tethering that proved increasingly difficult to treat. We concluded that symptomatic retethering is a common problem in children with lipomyelomeningoceles, even after an adequate initial operation. To date, no type of graft material has been shown to entirely prevent this problem. Close long-term surveillance of such patients is required to allow detection and treatment of symptomatic retethering.