Effectiveness of conus lipoma surgery-a case series

The management of conus lipomas in children can be conservative, but prophylactic radical removal has been proven to be the only way to ameliorate the natural history of this disease. We started our surgical practice aiming toward total removal of spinal cord lipomas in 2017. This study aims to present our early results.

Patients younger than 12 years of age that had a conus lipoma surgically treated between April 2017 and April 2024 were included in the study. We analysed the preoperative presence of symptoms, defined the subtype of lipoma, the presence of syringomyelia and the degree of rotation of the placode. Among the operative data, we reviewed the preservation of the bulbocavernosus reflex (BCR). Postoperatively, we analysed the onset of new neurological or urological deficits and calculated the cord/sac ratio and the amount of residual fat.

A total of 19 patients have been included, with a median follow-up of 55.1 months. Dorsal lipomas were 21%, transitional 73.6% and chaotic 5.2% cases, while using the new classification of spinal lipomas (NCSL) type 1 were 63.1%, type 2 were 31.5%, and type 3 were 5.2%. Transitional and chaotic lipomas were significantly associated with a lower level of the conus (p = 0.0002), as type 2 and 3 of the NCSL (p = 0.0441). The patients were symptomatic in 31.5% and asymptomatic in 68.4% of cases. The preoperative presence of symptoms was associated with an age at surgery higher than 3 years (p = 0.0006). The median age at surgery was 65 months. The residual fat tissue was < 20 mm³ in 36.8%, 20-1000 mm³ in 47.3% and > 1000 m³ in 15.7%. A higher residual fat was associated with transitional and chaotic lipomas (p = 0.0082) and with types 2 and 3 (NCSL) (p = 0.0409). The median cord/sac ratio was 38.1%. After surgery, a permanent urinary deterioration occurred in 5.2% and a sensory deficit in 21%. The onset of permanent urological deficits was significantly associated with the loss of the BCR (p = 0.0012).

Our results confirm the difficulty of achieving a safe and radical excision in transitional and chaotic (NCSL types 2 and 3) lipomas. These lipomas were significantly related to a higher postoperative amount of residual fat and to the occurrence of complications. For these lesions, the concept of radical resection should be shifted towards a concept of untethering by means of partial resection with maximal preservation of neurological function.