Relationship Between Sacral Dimples and Spinal Cord Malformations in Children

Abstract

Background: Traditional teaching states that if the base of a sacral dimple is visible, associated spinal cord abnormalities are unlikely. In our experience, we noted that in several patients this was not true. We therefore set out to evaluate the incidence of spinal cord abnormalities in a cohort of children with sacral dimple. Objective: Our objective was to determine the frequency of spinal cord abnormalities detected on whole-spine MRI in children with pure sacral dimple (cutaneous dimple without associated local pigmentation or hairy patch). The frequency of neurosurgical intervention in those with a spinal cord malformation was also calculated. Materials and methods: We retrospectively reviewed all patients under the age of 16 years with clinically confirmed pure sacral dimple, who had undergone spinal MRI between 2005 and 2016. Patients with coccygeal pits were excluded from the study. We analyzed the MRI findings, calculated the incidence of cord abnormalities, and proportion of those who subsequently underwent neurosurgical procedures, such as spinal cord untethering. Other associated abnormalities were documented. Results: During the 11-year study period, 33 patients (19 boys) with confirmed sacral dimple and whole-spine MRI were identified. The median age at the time of MRI was 21 months (range 2 months to 13 years). Eleven patients (33.3%) had abnormal cord detected on the MRI. Out of them, 4 had tethered cord, 2 had low lying cord (L2/3 level). Five had lesions related to the filum terminale (dermoid, cyst, lipoma). Of the four patients with tethered spinal cord, 2 had untethering procedures, 2 so far have been managed conservatively. Of the 7 patients with other cord abnormalities, 1 had excision of sacral dermoid. Nine of the 33 patients (27%) had other congenital anomalies, including 5 with syndromes. Conclusion: In our experience, the incidence of spinal cord abnormalities in children with pure sacral dimple was 33.3%, some of which required surgery. Other congenital abnormalities were common. We recommend whole spinel MRI and a careful search for other congenital abnormalities.