[Filum Lipoma]

Filum lipomas, a subtype of spinal lipomas, are ectopic fat tissue deposits of the filum terminale categorized as closed spinal dysraphism. They are occasionally and incidentally observed on MRI images, but generally require little surgical treatment. Early untethering surgery is recommended for symptomatic patients, whereas asymptomatic patients presenting normal level of the conus medullaris require no therapy and are regarded as having a normal variation. Prophylactic untethering surgery can be an option for asymptomatic patients with low set conus medullaris. Untethering surgery should be safely conducted using electrophysiological procedures. Herein, we summarize the clinical characteristics of the filum lipoma and describe our routine surgical procedures.