32 Low-Lying Conus


32 Low-Lying Conus

Cole T. Lewis, Octavio Arevalo, Rajan P. Patel, and David I. Sandberg

32.1 Case Presentation

A 9-month-old, former 30-week premature male patient, presents with a history of mosaic tetrasomy 22q (cat eye syndrome). No spine-related symptoms or signs were found at physical examination (PE).

32.2 Imaging Analysis

Sagittal short tau inversion recovery (STIR) image of the lumbar spine from a 9-month-old infant (▶ Fig. 32.1). The conus medullaris tip is located at mid L3 level (arrow), without any other associated cord, thecal sac, bone, or filum abnormality.

Fig. 32.1

32.3 Differential Diagnosis

  • Low-lying conus medullaris:

    • It refers to a low position of a normal-appearing conus medullaris with respect to the vertebral level.

    • It is usually located between the T12–L1 and L1–L2 disk level; however, in 6.4% of population it can be found between the upper and middle third of L2. 1

  • Tethered spinal cord:

    • A low-lying conus medullaris pulled down by a thick filum terminale.

    • The conus medullaris is located at or below the inferior end plate of L2 and is attached to a thickened filum or filum lipoma.

    • In 25% of cases, there is central canal dilatation. 2

  • Open or closed spinal dysraphism:

    • This is a wide spectrum of malformations including spinal lipoma, myelomeningocele, meningocele, dermoid, and dermal sinus tract.

32.4 Imaging Pearls

  • Low-lying conus medullaris:

    • The normal conus medullaris does not end below the middle third of the L2 body. 3

    • There is no abnormality in the thecal sac, roots, or filum terminale. 3 , 4 , 5

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Jun 28, 2020 | Posted by in NEUROLOGICAL IMAGING | Comments Off on 32 Low-Lying Conus

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