Preoperative predictors for improvement after surgical untethering in occult tight filum terminale syndrome

An occult tight filum terminale syndrome has been described wherein clinical symptoms result from tension on the spinal cord despite nondiagnostic spinal magnetic resonance imaging (MRI). Recent reports have suggested a role for surgical untethering in this patient population; however, controversy remains regarding the surgical treatment of this condition. Owing to the various clinical presentations, the relationship of presenting signs and symptoms to postoperative outcomes might be useful in surgical selection.

A retrospective review was conducted of 22 pediatric cases of surgical untethering for suspected occult tight filum terminale syndrome. All patients had nondiagnostic MRI findings, defined as a conus medullaris above the L(3) vertebral body and a filum terminale diameter of less than 2 mm. Preoperative symptoms, signs and urodynamic test results were collected and compared with surgical outcomes determined by clinical notes and postoperative urodynamics reports. Abnormal findings on presentation were categorized as dermatologic, urologic, orthopedic and neurologic.

Patient age ranged from 7 months to 17 years, and 12 were female. Sixteen (73%) patients experienced subjective and/or objective improvement following surgical untethering. Fourteen patients had abnormal preoperative urodynamic testing, of which 12 underwent postoperative urodynamic testing. Five of these 12 (42%) demonstrated objective improvement postoperatively. Patients presenting with abnormal findings in at least 2 categories were more likely to improve following untethering (88%) than those with abnormalities in only 1 category (20%; p = 0.009).

Spinal cord untethering is a treatment option for occult tight filum terminale syndrome. Further evaluation of the relationship between preoperative findings and surgical outcomes may facilitate the selection of surgical candidates.