Terminal myelocystocele with holocord syringomyelia: Short report

Terminal myelocystoceles are rare lesions.[1,2,3,4] They constitute approximately 5% of skin-covered lumbosacral masses and are characterized by the following features: (1) a lumbosacral spina bifida, (2) an arachnoid-lined meningocele that directly communicates with the spinal subarachnoid space, and (3) a low-lying hydromyelic cord that traverses the meningocele and expands into a large terminal cyst.[3] We have reported a rare case of terminal myelocystocele associated with holocord syringomyelia here.

A 5-day-old female child of non-consanguineous parents was brought for neurosurgical consultation with a swelling in the low back since birth. Examination revealed a conscious child with a head circumference of 36 cm. The tone and power of the upper extremities were normal, and the child had paraplegia with urinary and bowel incontinence. There was cystic, transilluminant swelling partially covered by a parchment-like skin in the summit. Magnetic resonance imaging (MRI) examination revealed a sacral meningocele into which a grossly dilated hydromyelic cord was found to be herniating [Figure 1a-d]. The pathological anatomy was best brought out by three-dimensional (3D) constructive interference in steady state (CISS) sequences [Figure 1d]. Based on the MRI images, a diagnosis of terminal myelocystocele with holocord syrinx was made. The child did not have any associated anomaly of the lower urinary and anorectal systems. During surgery, the neck of the sac was isolated, and the last deformed lamina was removed. The dura was opened from the normal area toward the sac. On opening the sac, a grossly dilated, trumpet-like hydromyelic cord was found adherent to the summit of the sac. The dilated hydromyelic cord was detethered from the sac, and the syringocele was drained. Once the syrinx was drained, the cord collapsed, and the meningocele sac was excised and repaired. Postoperative period was uneventful. There was no change in the neurological status of the child when examined 4 months after the surgery.

Figure 1.

Sagittal MRI sequences (a) T1-weighted, (b) T2-weighted, (c) MR myelography, and (d) 3D-CISS sequence; arrow points to the fluid containing hydromyelic cord herniating into the meningocele sac

Terminal and non-terminal myelocystoceles have been described in detail in many publications.[1,2,3,4] However, the occurrence of terminal myelocystocele with holocord syringomyelia has been described only once before by Hashiguchi.[5] In the index case being reported as well as in the case reported by Hashiguchi et al., among all the sequences, the 3D-CISS sequences delineated the pathology more clearly than other sequences. This case is being reported to highlight (1) the rare combination of terminal myelocystocele with holocord syringomyelia and (2) the importance of performing 3D-CISS sequences in patients with spinal dysraphism to delineate the pathology better. Failure to recognize this entity will lead to inappropriate treatment. If this lesion is erroneously diagnosed as a simple spina bifida cystica, ligation of the sac at the neck will lead to aggravation of tethering effect and neurological worsening.