Filum terminale lipoma surgery
Filum terminale lipoma becomes a surgical entity when it manifests as clinical or radiological tethered cord syndrome.
When patients have tethered cord syndrome and a low lying conus surgical intervention would be considered appropriate by most, with the filum sectioned either just at the tip of the conus or lower down in the lumbar theca 1).
In asymptomatic patients, management is equally simple, in that nothing need be done.
Difficulty arises in patients who have some symptoms suggesting tethered cord syndrome, but whose conus terminates at a normal level. Controversy as to the benefits of division of a fatty filum in such patients exists 2).
Intraoperative neuromonitoring (IONM) has been suggested as a valuable tool in children for tethered cord syndrome surgery. FTL is distinct and cannot be compared with complex tethered cord syndrome (TCS).
Untethering an FTL is a relatively straightforward microsurgical exercise, usually based on anatomical findings. Neurological morbidity in FTL untethering is extremely low. The necessity of IONM in FTL has not been evaluated. The objective of a study of Lalgudi Srinivasan et al. was to identify the role of IONM in untethering an FTL
Available electronic data and case files were interrogated to identify children (0-18 years) who underwent an untethering of FTL between 2008 and 2019. They had a shift in the policy and tried to use IONM as often as possible in all tethered cord surgery from 2014. All children were categorised under 'IONM implemented' or 'no IONM' group. Outcomes analysed were as follows: (1) Clinical status on short-term and long-term follow-up, (2) alteration of surgical course by IONM and (3) complications specifically associated with IONM.
Among 80 children included in this study, IONM was implemented in 37 children and 43 children underwent untethering without IONM. 32.5% of children were 'syndromic'. Seventy-five percent of children were under age 3 years during surgery. Both groups (No IONM vs. IONM implemented) were well matched in most variables. Majority of 'no IONM' surgeries were performed prior to 2014. There was no neurological morbidity in the entire cohort. Mean duration of follow-up was 49.10 (± 33.67) months. Short-term and long-term clinical status remained stable in both cohorts. In 16 children, the filum was stimulated. Based on there protocol, majority had a negative response. One child showed a positive response, contradicted by thorough microscopic inspection. Despite a positive response, the filum was untethered. IONM was not associated with any complication in this study 3).