Indian Journal of Clinical Anatomy and Physiology

A magnetic resonance imaging study of the variations of position of conus medullaris and thecal sac in the adult population in Sikkim

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Author Details: Barun K. Sharma, Rubi Dey, Sumit Kar, Varun Kumar Singh

Volume : 4

Issue : 1

Online ISSN : 2394-2126

Print ISSN : 2394-2118

Article First Page : 8

Article End Page : 10


Introduction: The termination of the spinal cord in human beings is cone shaped and is called the Conus Medullaris (CM). Thecal Sac (TS) is a membranous sac of dura mater containing the spinal cord, cauda equina and cerebrospinal fluid. The terminations of these vary in the population across the world, which carries therapeutic implications.
Materials and Methods: A retrospective descriptive study was conducted on all patients above 18 years of age undergoing Magnetic resonance imaging (MRI) of lumbosacral spine for low backache using Achieva 1.5 Tesla MRI (Philips, Netherland) to localize the levels of conus medullaris and thecal sac.
Results: The study population comprised of 91 individuals of which 63 individuals fulfilled the inclusion criteria. The position of conus medullaris varied between upper third of T12 vertebral body to L2- L3 disc level with a mean position at mid third of L1 vertebral body. The position of the thecal sac varied between upper third of S1 vertebral body to lower third of S3 vertebral body with the mean position at upper third of S2 vertebral body.
Conclusions The mean level of termination of the conus medullaris in our study was at the level of middle third of L1 vertebral body and the mean level of thecal sac in our study was at the upper third of S2 vertebral body. Knowledge of the position of CM and TS, the distances between the two in various population groups will be of practical value in day to day clinical practice.

Conus Medullaris, Thecal Sac, Magnetic Resonance Imaging