title: The specific sagittal magnetic resonance imaging of intradural extra-arachnoid lumbar disc herniation.
abstract: Intradural extra-arachnoid lumbar disc herniation is a rare disease. Few MRI findings have been reported. We experienced an intradural extra-arachnoid lumbar disc herniation. We reviewed the preoperative MRI findings. Lumbar spine T2-weighted sagittal MRI showed that one line of the ventral dura was divided into two by a disc herniation. We speculated that the two lines comprised the dura and arachnoid and that a disc herniation existed between them. We believe that division of the ventral dural line on T2-weighted sagittal images is a characteristic finding of intradural extra-arachnoid lumbar disc herniation. The division of ventral dural line seemed to be a "Y," and, thus, we called it the "Y sign." The "Y sign" may be useful for diagnosing intradural extra-arachnoid lumbar disc herniation.
authors.affiliation: Department of Orthopedic Surgery, Fukushima Rosai Hospital, 3-Numajiri, Tsuzura-machi, Uchigo, Iwaki 973-8403, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Sasaji
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Horaguchi
authors.forename: Noboru
authors.initials: N
authors.lastname: Yamada
authors.forename: Kazuo
authors.initials: K
authors.lastname: Iwai