A Presenile Patient with Filar Lipoma Who Developed Tethered Spinal Cord Syndrome Triggered by Lumbar Canal Stenosis

Abstract

Lumbar canal stenosis (LCS) has been reported as a precipitating factor by which a tethered spinal cord, which is asymptomatic during childhood, develops into tethered cord syndrome (TCS) in adulthood. However, only a few reports on surgical strategies for such cases are available. A 64-year-old woman presented with unbearable pain in the left buttock and dorsal aspect of the thigh approximately 1 year ago. Magnetic resonance imaging showed cord tethering with a filar-type spinal lipoma and LCS due to the thickening of the ligamentum flavum at the L4-5 vertebral level. Five months after the decompressive laminectomy for the treatment of LCS, an untethering surgery was performed at the dural cul-de-sac at the S4 level. The severed end of the filum was elevated rostrally by 7 mm, and the pain subsided postoperatively. This case study shows that surgeries for both lesions should be indicated for adult-onset TCS triggered by LCS.

Keywords: filar lipoma; lumbar canal stenosis; tethered spinal cord syndrome; untethering.

Fig. 1

(a-c) Midsagittal views of T2-weighted (T2WI) (a) and T1-weighted magnetic resonance images (b), and axial view of T2WI (c) at the L4-5 vertebral level (a, red arrow) demonstrate spinal cord tethering with a filar-type spinal lipoma (b, yellow arrows) and lumbar canal stenosis (LCS) due to the thickening of the ligamentum flavum. (d) Postoperative three-dimensional (3D) reconstruction of a bone-targeted computed tomographic scan shows the extent of the decompressive laminectomy at L4-5 with the preservation of the spinous process (red arrows). An ectopic bone covering the spina bifida at the S3 and upper part of the S4 level is also noted (blue arrows). (e-f) A month after decompressive surgery for LCS, an axial view of T2WI (e) reveals a successfully enlarged dural sac at the L4-5 level. No change is noted in the degree of spinal cord tethering on a midsagittal view of T2WI (f).

Fig. 2

(a, b) Schematic drawing of the operative findings. (a) Dural opening at the S3 and S4 vertebral levels reveals a fatty filum terminated slightly to the left of the midline of the dural cul-de-sac. (b) The filum is severed at the rostral part of the operative field, and the severed end of the filum is elevated rostrally. The caudal part of the filum is also severed at the dural cul-de-sac and resected as a column. (c) Four months after the second surgery, serial sagittal views of 3D heavily T2WI (slice thickness, 1 mm) show a successful untethering surgery. The severed end is located at the upper part of S3 vertebral level (yellow arrows). (d, e) On the axial section of the resected filum, histopathologically, glial fibrillary acidic protein (GFAP)-positive neuroglial tissue is observed in the center of the fibroadipose tissue. The location of the section is indicated as a red line in (b). The area of the enlarged view is indicated as a dotted square in (d). Hematoxylin and eosin (H&E).