Zyste am Filum terminale

Newborn with
a sacral dimple. Sagittal US of the spine (above) shows the conus medullaris to terminate normally at the L1-L2 level. A hypoechoic cystic structure is seen just inferior to the conus and is better seen on the zoomed image (below). The diagnosis was filar cyst.
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Radiopaedia • CC-by-nc-sa 3.0 • de

A filar cyst is an incidental finding on neonatal lumbar sonography located in the filum terminale of the spinal cord. It is considered a normal variant and is often confused for a ventriculus terminalis, a smooth dilated cavity of the central canal, located within the conus medullaris.

The incidence of filar cysts is inversely related to age and they have not been reported in adults, suggesting a developmental variant which regresses with age. However, it also remains a question whether they truly exist or are simply artifactual, as no correlate is typically identifiable on MRI nor has been verified on autopsy.

Radiographic features

Ultrasound

Longitudinally-oriented, elongated, anechoic, cyst-like structure caudal to the conus medullaris within the midline filum terminale.

MRI

Typically, no correlate to the filar cysts on ultrasound are seen on MRI, which could be due to insufficient resolution of spinal MRI in small neonates

Siehe auch:
Assoziationen und Differentialdiagnosen zu Zyste am Filum terminale:
Tumoren der
Kauda und des Filum terminale
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