Ultrasound measurement of lumbosacral spine in children
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Updated: Aug 26, 2026
Spinal Sonography for Ultrasound-Guided Lumbar Neuraxial Anesthesia
Published on: January 31, 2025
Wendy W M Lam1, Victor Ai, Virginia Wong
1Department of Radiology, Queen Mary Hospital, Hong Kong.
Insights
Ultrasound measurements of the lumbosacral spine in children can screen for tethered cord. A low oscillation amplitude at L(5)/S(1) may indicate cord abnormality or retethering.
Area of Science:
- Pediatric Radiology
- Neurosonography
- Spinal Imaging
Background:
- Tethered cord syndrome and postoperative retethering are significant pediatric neurological concerns.
- Accurate screening assessments are crucial for early diagnosis and intervention.
Purpose of the Study:
- To establish normal ultrasound measurements of the pediatric lumbosacral spine.
- To define reference values for cerebrospinal fluid pulsation in neurologically normal children.
- To assess the utility of these measurements in identifying tethered cord or postoperative retethering.
Main Methods:
- Sonography of the lumbosacral spine was performed on 108 neurologically normal children (mean age 2.1 years).
- M-mode ultrasound documented cerebrospinal fluid pulsation of the cauda equina at the posterior/anterior subarachnoid spaces and L(5)/S(1) dural sac.
- Oscillation rate and amplitude were measured and compared between normal and abnormal groups.
Main Results:
- Normal posterior/anterior subarachnoid spaces measured 2.6 mm/1.8 mm at the terminal dural sac.
- Mean oscillation amplitude and rate at L(5)/S(1) were 0.52 mm and 121/min, respectively.
- A statistically significant difference in oscillation amplitude was observed between normal and abnormal spinal cord groups.
Conclusions:
- Normal ultrasound measurements of lumbosacral spine pulsation provide a screening tool for tethered cord.
- An oscillation amplitude below 0.3 mm at L(5)/S(1) in symptomatic children warrants further investigation for cord abnormality or retethering.
Abstract:
The aim of this study was to establish normal ultrasound measurements of lumbosacral spine in children as a screening assessment of tethered cord or postoperative retethering of cord. Sonography of lumbosacral spine was performed in 108 neurologically normal children (mean age = 2.1 years) using 5- to 12-MHz linear transducer. M-mode was applied at the posterior and anterior subarachnoid spaces just below the conus medullaris and at the L(5)/S(1) dural sac to document cerebrospinal fluid pulsation of the cauda equina. The oscillation rate and amplitude were measured. Sixteen children with spinal cord anomalies (6 with low tethered cord and 10 postoperative cases of low tethered cord) were also examined. The mean posterior/anterior subarachnoid spaces of normal children were 2.6 mm/1.8 mm at the terminal dural sac. The mean oscillation amplitude and rate of the cauda equina were 0.52 mm and 121/min at the L(5)/S(1) dural sac. The oscillation amplitude at this level demonstrated a statistically significant difference between normal and abnormal groups. In conclusion, we recommend taking the fifth percentile of the normal oscillation amplitude at the L(5)/S(1) dural sac as a reference. Any oscillation amplitude of less than 0.3 mm in a symptomatic patient should alert the clinician to possible cord abnormality, cord tethering, or retethering in postoperative cases.
