Minimal tethered cord syndrome associated with thickening of the terminal filum

Object. The authors investigated the occurrence of anatomical abnormalities of the terminal filum in children undergoing surgical filum lysis for minimal tethered cord syndrome (TCS). Methods. Five consecutive children (age range 6-12 years) with medically refractory voiding dysfunction but no magnetic resonance (MR) imaging-documented lumbosacral abnormality on 1.5-tesla sequences underwent preoperative urodynamic studies consisting of calibrated uroflowmetry, cystometrography, and voiding cystourethrography. Urodynamic bladder function was abnormal in each case. A sixth child (5 years of age) who had progressive lower-extremity weakness, gait abnormality, and voiding dysfunction, but in whom there was no MR imaging-documented lumbosacral abnormality, was also included. These six children experienced improved bladder function after terminal filum lysis. Histologically, the terminal filum in these patients was fattier, thicker, and more densely fibrous than that in three reference patients undergoing incidental terminal filum lysis during selective dorsal rhizotomy or resection of a lumbar dermal sinus tract. All four patients with voiding dysfunction who underwent postoperative urodynamic testing experienced corresponding improvement in bladder function. Conclusions. Significant improvement of voiding dysfunction after surgical lysis of the terminal filum in children with MR imaging-documented normal lumbosacral spines was observed. In such children, in whom neurogenic dysfunction is identified by urodynamic testing, structural abnormalities of the terminal filum may exist. A prospective randomized controlled study of children undergoing surgical terminal filum lysis in cases of minimal TCS should be undertaken.