Terminal Myelocystocele: An Unusual Presentation

Abstract

Terminal myelocystocele is an unusual form of occult spinal dysraphism. It consists of a cystic dilatation of a low-lying terminal cord herniated posteriorly through a skin-covered lumbosacral spina bifida. An arachnoid-lined meningocele, continuous with the spinal subarachnoid space, is traversed by the hydromyelic cord. Clinically, this presents with a skin-covered lumbosacral mass, but often no neurological deficit is present. We present a case of terminal myelocystocele in a child born without deficit and without an obvious back mass. Diagnosis was delayed until sphincter disturbance and lower limb inequalities developed. We discuss the presentation, imaging and operative findings in this case.

Terminal Myelocystocele: A Series of 30 Cases and Review of the Literature

“…A review of the literature suggests that their incidence can be between 4 and 8% of lumbosacral occult spinal dysraphisms [2,7,8]. No sex predilection is known [2,9]. Familial incidence is also unheard of [2,3].…”

“…Muthukumar [6], in his series, reported dystrophic skin covering the dome of the sac in 9 out of 14 patients. Rarely, a lumbosacral mass may not be evident; such a case has been reported by Cartmill et al [9]. The mass is typically lumbosacral, obliterates the intergluteal cleft, and extends upwards from the perineum for a variable distance [3].…”

Giant Terminal Lipomyelocystocele

“…Terminal myelocystocele constitutes 4-8% of lumbosacral occult spinal dysraphism [2,4,5] and very rarely can occur in the lower thoracic region [6,7] . Epidemiologically, myelocystoceles arise sporadically; there is no known familial incidence [2,8] .…”

“…The terminal cyst is lined by ependyma and dysplastic glia, and is directly continuous with the dilated central canal of the cord, probably representing a ballooned terminal ventricle [1,2] . Isolated case reports of terminal myelocystocele are available in the literature [2,4,6,9,10] . Schmitt and Kawakani [9] reported 1 case of terminal myelocystocele associated with exstrophy of the cloaca.…”

“…The bulk of cyst also bulges cephalad to expand the distal cord producing trumpet-like fl aring and prevents ascent of the cord, producing tethered cord. The cystic dilation remains tethered to the cord, preventing its ascent [2,6] . Few reports are also available suggesting a possible relationship to teratogens such as hydantoin, loperamide, and retinoic acid, although the exact etiology of this entity is not known [8,9,13] .…”