MR OF TERMINAL MYELOCYSTOCELES

Purpose: To delineate the clinical and MR findings in children with an unusual type of spinal dysraphism, the terminal myelocystocele. Infants with a terminal myelocystocele carry a favorable neurologic prognosis if the entity is diagnosed early. Understanding the MR characteristrics of this entity will allow for earlier and more accurate diagnosis. Method: Analysis of the medical charts and MR studies in 15 children with surgically and histologically proven myelocystocele. Results: In all 15 children, MR demonstrated the primary findings of a terminal cyst of the central canal of the spinal cord which is tethered and herniated with arachnoid and cerebrospinal fluid through an area of spinal dysraphia onto the back as a mass. Of these children, 10 had additional findings (one or more) on MR of Chiari I (five cases), Chiari II (one case), cervicothoracic hydromyelia (two cases), lumbar hydromyelia (two cases), hydrocephalus (2 cases) segmentation anomalies of vertebrae (3 cases) and partial agenesis of sacrum (six cases). Of the clinical findings, all 15 children had a back mass, 10 also had cloacal exstrophy. One had imperforate anus, 10 were girls, five had ambiguous genitalia and all were neurologically intact. Conclusion: Children with a terminal myelocystocele present with a back mass and there is a high association with cloacal exstrophy. MR is the best noninvasive modality to diagnose all of the components of a terminal myelocystocele and the associated central nervous system findings.