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Pediatr Radiol (2011) 41:483487 DOI 10.1007/s00247-010-1889-y
ORIGINAL ARTICLE
Borderline low conus medullaris on infant lumbar sonography: what is the clinical outcome and the role of neuroimaging follow-up?
Neil H. Thakur & Lisa H. Lowe
Received: 16 August 2010 /Revised: 25 September 2010 /Accepted: 4 October 2010 /Published online: 16 November 2010 # Springer-Verlag 2010
AbstractBackground Isolated borderline low conus medullaris is a frequent finding on screening lumbar sonography of unknown significance that often prompts further imaging and clinical follow-up.
Objective To determine the clinical outcome and utility of follow-up neuroimaging in infants with isolated borderline low conus on lumbar sonography.
Materials and methods We reviewed 748 consecutive spinal sonograms identifying infants with conus terminating between L2-L3 disc space and mid-L3 level without other findings of tethered cord. We excluded infants with conditions associated with developmental delay and those who passed away, and compared the age of gross motor milestone achievement to normal ranges. Follow-up imaging was reviewed.
Results Isolated borderline low conus was found in 90 of 748 infants (12%) on sonography. Seventy of those infants met inclusion criteria. Follow-up imaging in 11 children (10 MRI, 1 sonogram), showed change in conus position to normal level in 10, no change in 1, and no new findings within lumbar spine. Clinical follow-up was available in 50 of 70 (71%) children meeting inclusion criteria, with normal motor milestones met in all 50 children.Conclusion Isolated borderline low conus is a common finding in infants who meet normal developmental mile-
stones suggesting that follow-up evaluation has little utility and is likely unwarranted.
Keywords Low-lying conus medullaris . Tethered cord syndrome . US . MRI . Infant
Introduction
Lumbar sonography is widely used as the first line of screening for pathologies of the infant spine [1]. With increased use and technological advancement, US has been able to identify progressively more abnormalities, as well as potential normal variants that must be differentiated from pathology [2]. The normal spinal cord conus medullaris is well documented to terminate at or above the L2-L3 disc space [1, 37]. Conversely, when the conus medullaris terminates below the L2-L3 level, it has been considered abnormal and potentially associated with tethered cord syndrome [1, 5]. In a study of children with surgically proven tethered cord, the conus...