Impact of tethered cord release on symptoms of Chiari II malformation in children born with a myelomeningocele

PURPOSE: The role of distal traction in the form of a tethered spinal cord in exacerbating anatomical findings or symptoms of Chiari II malformation (CIIM) has been debated for decades. Despite the association of Chiari II malformation with myelomeningocele, the impact of tethered cord release on CIIM symptoms in patients has not been explored. METHODS: A retrospective review of 59 patients born with a myelomeningocele was performed. A total of 92 untethering procedures were performed in which symptoms of CIIM were present in 29 cases. In 57 out of 92 cases, the patients did not have symptoms of CIIM prior to untethering. Six cases were excluded because cervicomedullary decompression was performed prior to untethering. The response of CIIM symptoms, syrinx size, and cerebellar tonsil position were examined before and after spinal cord untethering. RESULTS: Forty-four characteristic signs and symptoms of CIIM were present prior to 29 untetherings. Thirty-three of 44 (75%) symptoms improved following spinal cord untethering, though no symptom resolved completely. Syrinx size and cerebellar tonsil position were unchanged following untethering. CONCLUSION: The authors conclude that mild to moderate symptoms of CIIM may respond positively to spinal cord untethering, potentially by normalization cerebrospinal fluid flow dynamics. Symptom improvement occurs despite the lack of radiographic evidence of CIIM resolution.