Spinal lipomas in children: outcome of 270 procedures.

Spinal lipomas are a common cause of spinal cord tethering. Recently, prophylactic surgical removal of spinal lipomas has been questioned, especially of the conus medullaris. Unfortunately, few statistically significant series have been reported. A total of 213 children with spinal lipomas were operated on at the Children's Memorial Hospital in Chicago, Ill., USA, on whom 270 procedures were carried out between 1975 and 1995. The status of these children was retrospectively reviewed to determine the differences in outcome between patients prophylactically operated on before the onset of symptoms and those operated on after the onset of symptoms. Fifty-five patients presented with a lipoma of the filum terminale and 158 with a lipoma of the conus medullaris. In the filum terminale group, 28 were asymptomatic at the initial operation, and 27 presented with symptoms. Of the asymptomatic children with filum terminale lipomas, none worsened after surgery, and all remained asymptomatic throughout follow-up (mean follow-up: 3.4 years). Benefits were also observed for the symptomatic patients in this group as no cases of further deterioration were noted, and 5 patients returned to normal clinical status. In the conus group, 71 patients were asymptomatic at initial surgery, and 87 presented with symptoms. In the case of conus medullaris lipomas, 9 of the 71 children who were operated on prophylactically, later deteriorated (mean follow-up: 6.2 years) and required a second untethering operation which resolved all symptoms in 4 cases. Thus, 5 of 71 deteriorated, while 66 remained normal (93%) throughout the period of follow-up. On the other hand, of the 87 patients operated on after the onset of symptoms, 36 (41%) deteriorated further and required subsequent reoperations. In these 87 children, the final outcome at the end of follow-up (mean follow-up: 6.6 years) showed that 20 (23%) patients had deteriorated compared to initial presentation and 44 (51%) remained at initial clinical baseline, while 23 (26%) improved or returned to normal clinical status. Prophylactic surgery in the case of the asymptomatic infant with a spinal lipoma showed a clear benefit. Good outcome was also observed when surgery was carried out after the onset of symptoms. Prophylactic surgery also had a better general outcome by actuarial calculations when only patients with a follow-up of more than 5 years were considered. Deterioration occurred in 5 (16.7%) of the 30 children with a follow-up of more than 5 years, while 25 (83.3%) remained normal. Furthermore, in cases which had prophylactic surgery, there was not only a smaller incidence of deterioration requiring a reoperation, but this group of patients also experienced a longer time interval between initial surgery and the need for reoperation compared to the patients operated on after the onset of symptoms. The authors conclude that spinal lipomas should be operated on as soon as possible on a prophylactic basis, and careful and constant follow-up should be carried out to permit prompt reintervention in cases with deterioration.