Intraoperative findings and outcome of conus spinal lipoma by types of classification based on embryonic stage

Abstract

Objective: Conus spinal lipomas are ectopic fat tissue attached to the spinal cord and are derived from the failure at primary neurulation, early secondary neurulation, or their junctional phase. They exhibit some pathomorphological variations between lipoma and neural tissues, requiring on-condition surgical procedures. The aims of this study were to elucidate their treatment outcomes by the types of recent lipoma classification based on embryonic stage and to discuss the relationship between intraoperative findings and outcomes.

Methods: This study enrolled 51 consecutive patients aged 0 month to 20 years (median, 3 months) who were surgically treated for the first time. The rate of neurological complications of surgery, postoperative cord-sac ratio, rate of redo untethering surgery, progression-free survival rate, and Kaplan-Meier curve for freedom from new spontaneous neurological deficits were investigated according to the types of Morota’s classification. The relationship between intraoperative findings and these prognostic criteria was analyzed.

Results: The progression-free survival rates were 100%, 85%, and 61% in Type 1, Type 3, and Type 2 lipoma, respectively. Type 2 lipoma exhibited a higher rate of neurological complications of surgery (17%) and redo untethering surgeries (17%) than the other types. Postoperative cord-sac ratio (81%) was also high in Type 2 lipoma. There was not a defining characteristic time observing new spontaneous neurological deficits.

Conclusion: Type 2 lipoma demonstrated relatively poor outcome compared with the other types. This is because of comparatively high-risk surgical procedures due to complicated pathomorphology. This also implied a wide and intricate cord-lipoma interface and deformed spinal roots, which were further encased by an extensive lipoma.