Use of prone position magnetic resonance imaging for detecting the terminal filum in patients with occult tethered cord syndrome

Clinical article

Restricted access

Object

The pathophysiology of occult tethered cord syndrome (OTCS) with no anatomical evidence of a caudally shifted conus and a normal terminal filum is hard to understand. Therefore, the diagnosis of OTCS is often difficult. The authors hypothesized that the posterior displacement of the terminal filum may become prominent in patients with OCTS who are in a prone position if filum inelasticity exists, and they investigated prone-position MRI findings.

Methods

Fourteen patients with OTCS and 12 control individuals were examined using T2-weighted axial MRI with the patients in a prone position on a flat table. On each axial view, the distance between the posterior and anterior ends of the subarachnoid space (A), the distance between the posterior end of the subarachnoid space and the terminal filum (B), the distance between the posterior end of the subarachnoid space and the dorsal-most nerve among the cauda equina (C), and the distance between the posterior end of the subarachnoid space and the ventral-most nerve (D) were measured. The location ratios of the terminal filum, the dorsal-most nerve, and the ventral-most nerve were calculated by the ratio of A to B (defined as TF = B/A), A to C (defined as DN = C/A), and A to D (defined as VN = D/A), respectively. Patients underwent sectioning of the terminal filum with the aid of a surgical microscope. The low-back pain Japanese Orthopaedic Association score was obtained before surgery and at the final follow-up visit.

Results

On prone-position axial MRI, the terminal filum was separated from the cauda equina and was shifted caudally to posterior in the subarachnoid space in all patients with OTCS. The locations of the caudal cauda equina shifted to ventral in the subarachnoid space. The TF values in the OTCS group were significantly lower than those in the control group at the L3–4 (p = 0.023), L-4 (p = 0.030), L4–5 (p = 0.002), and L-5 (p < 0.001) levels. In contrast, the DN values in the OTCS group were significantly higher than those of the control group at the L-2 (p = 0.003), L2–3 (p = 0.002), L-3 (p < 0.001), L3–4 (p < 0.001), L-4 (p = 0.007), L4–5 (p = 0.003), and S-1 (p = 0.014) levels, and the VN values in the OTCS group were also significantly higher than those of the control group at the L2–3 (p = 0.022), L-3 (p = 0.027), L3–4 (p = 0.002), L-4 (p = 0.011), L4–5 (p = 0.019), and L5–S1 (p = 0.040) levels. Sections were collected during surgery for histological evaluation, and a decreased elasticity within the terminal filum was suggested. Improvements in the Japanese Orthopaedic Association score were observed at the final follow-up in all patients.

Conclusions

The authors' new method of using the prone position for MRI shows that the terminal filum is located significantly posterior and the cauda equina is located anterior in patients with OTCS, suggesting a difference in elasticity between the terminal filum and cauda equina.

Abbreviations used in this paper:JOA = Japanese Orthopaedic Association; OTCS = occult tethered cord syndrome.
Article Information

Contributor Notes

Address correspondence to: Kazuyoshi Nakanishi, M.D., Ph.D., Department of Orthopaedic Surgery, Programs for Applied Biomedicine, Division of Clinical Medical Science, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. email: kazn@hiroshima-u.ac.jp.Please include this information when citing this paper: published online November 9, 2012; DOI: 10.3171/2012.10.SPINE12321.
Headings
References
  • 1

    Bao NChen ZHGu SChen QMJin HMShi CR: Tight filum terminale syndrome in children: analysis based on positioning of the conus and absence or presence of lumbosacral lipoma. Childs Nerv Syst 23:112911342007

    • Search Google Scholar
    • Export Citation
  • 2

    Bauer DFShoja MMLoukas MOakes WJTubbs RS: Study of the effects of flexion on the position of the conus medullaris. Childs Nerv Syst 24:104310452008

    • Search Google Scholar
    • Export Citation
  • 3

    Flanigan RCRussell DPWalsh JW: Urologic aspects of tethered cord. Urology 33:80821989

  • 4

    Hendrick EBHoffman HJHumphreys RP: The tethered spinal cord. Clin Neurosurg 30:4574631983

  • 5

    Hoffman HJHendrick EBHumphreys RP: The tethered spinal cord: its protean manifestations, diagnosis and surgical correction. Childs Brain 2:1451551976

    • Search Google Scholar
    • Export Citation
  • 6

    Hüttmann SKrauss JCollmann HSörensen NRoosen K: Surgical management of tethered spinal cord in adults: report of 54 cases. J Neurosurg 95:2 Suppl1731782001

    • Search Google Scholar
    • Export Citation
  • 7

    Iskandar BJFulmer BBHadley MNOakes WJ: Congenital tethered spinal cord syndrome in adults. Neurosurg Focus 10:1e72001

  • 8

    Izumida SInoue SKataoka HTajima TTajima NNakano N: Assessment of treatment for low back pain. Nippon Seikeigeka Gakkai Zasshi 60:3913941986

    • Search Google Scholar
    • Export Citation
  • 9

    Khoury AEHendrick EBMcLorie GAKulkarni AChurchill BM: Occult spinal dysraphism: clinical and urodynamic outcome after division of the filum terminale. J Urol 144:2 Pt 24264291990

    • Search Google Scholar
    • Export Citation
  • 10

    Komagata MEndo KNishiyama MIkegami HImakiire A: Management of tight filum terminale. Minim Invasive Neurosurg 47:49532004

  • 11

    Metcalfe PGray DKiddoo D: Management of the urinary tract in spina bifida cases varies with lesion level and shunt presence. J Urol 185:6 Suppl254725512011

    • Search Google Scholar
    • Export Citation
  • 12

    Metcalfe PDLuerssen TGKing SJKaefer MMeldrum KKCain MP: Treatment of the occult tethered spinal cord for neuropathic bladder: results of sectioning the filum terminale. J Urol 176:182618302006

    • Search Google Scholar
    • Export Citation
  • 13

    Meyrat BJVernet OBerger Dde Tribolet N: Pre- and postoperative urodynamic and anorectal manometric findings in children operated upon for a primary tethered cord. Eur J Pediatr Surg 3:3093121993

    • Search Google Scholar
    • Export Citation
  • 14

    Nazar GBCasale AJRoberts JGLinden RD: Occult filum terminale syndrome. Pediatr Neurosurg 23:2282351995

  • 15

    Pang DWilberger JE Jr: Tethered cord syndrome in adults. J Neurosurg 57:32471982

  • 16

    Satar NBauer SBShefner JKelly MDDarbey MM: The effects of delayed diagnosis and treatment in patients with an occult spinal dysraphism. J Urol 154:7547581995

    • Search Google Scholar
    • Export Citation
  • 17

    Selçuki MCoşkun K: Management of tight filum terminale syndrome with special emphasis on normal level conus medullaris (NLCM). Surg Neurol 50:3183221998

    • Search Google Scholar
    • Export Citation
  • 18

    Selçuki MUnlü AUğur HCSoygür TArikan NSelçuki D: Patients with urinary incontinence often benefit from surgical detethering of tight filum terminale. Childs Nerv Syst 16:1501552000

    • Search Google Scholar
    • Export Citation
  • 19

    Selçuki MVatansever SInan SErdemli EBağdatoğlu CPolat A: Is a filum terminale with a normal appearance really normal?. Childs Nerv Syst 19:3102003

    • Search Google Scholar
    • Export Citation
  • 20

    Selden NR: Minimal tethered cord syndrome: what's necessary to justify a new surgical indication?. Neurosurg Focus 23:2E12007

  • 21

    Selden NRNixon RRSkoog SRLashley DB: Minimal tethered cord syndrome associated with thickening of the terminal filum. J Neurosurg 105:3 Suppl2142182006

    • Search Google Scholar
    • Export Citation
  • 22

    Steinbok PGarton HJGupta N: Occult tethered cord syndrome: a survey of practice patterns. J Neurosurg 104:5 Suppl3093132006

  • 23

    Steinbok PKariyattil RMacNeily AE: Comparison of section of filum terminale and non-neurosurgical management for urinary incontinence in patients with normal conus position and possible occult tethered cord syndrome. Neurosurgery 61:5505562007

    • Search Google Scholar
    • Export Citation
  • 24

    Steinbok PMacNeily AE: Section of the terminal filum for occult tethered cord syndrome: toward a scientific answer. Neurosurg Focus 23:2E52007

    • Search Google Scholar
    • Export Citation
  • 25

    Vernet OO'Gorman AMFarmer JPMcPhillips MMontes JL: Use of the prone position in the MRI evaluation of spinal cord retethering. Pediatr Neurosurg 25:2862941996

    • Search Google Scholar
    • Export Citation
  • 26

    Warder DEOakes WJ: Tethered cord syndrome and the conus in a normal position. Neurosurgery 33:3743781993

  • 27

    Wehby MCO'Hollaren PSAbtin KHume JLRichards BJ: Occult tight filum terminale syndrome: results of surgical untethering. Pediatr Neurosurg 40:51582004

    • Search Google Scholar
    • Export Citation
  • 28

    Witkamp TDVandertop WPBeek FJNotermans NCGooskens RHvan Waes PF: Medullary cone movement in subjects with a normal spinal cord and in patients with a tethered spinal cord. Radiology 220:2082122001

    • Search Google Scholar
    • Export Citation
  • 29

    Yamada SIacono RPAndrade TMandybur GYamada BS: Pathophysiology of tethered cord syndrome. Neurosurg Clin N Am 6:3113231995

  • 30

    Yamada SKnerium DSMandybur GMSchultz RLYamada BS: Pathophysiology of tethered cord syndrome and other complex factors. Neurol Res 26:7227262004

    • Search Google Scholar
    • Export Citation
  • 31

    Yamada SWon DJPezeshkpour GYamada BSYamada SMSiddiqi J: Pathophysiology of tethered cord syndrome and similar complex disorders. Neurosurg Focus 23:2E62007

    • Search Google Scholar
    • Export Citation
TrendMD
Cited By
Metrics

Metrics

All Time Past Year Past 30 Days
Abstract Views 561 430 59
Full Text Views 174 83 0
PDF Downloads 225 61 1
EPUB Downloads 0 0 0
PubMed
Google Scholar