Dural sac restenosis due to regeneration of the resected C1 lamina in a patient with Chiari malformation: a case report and literature review.

Although foramen magnum decompression (FMD) is effective for the treatment of Chiari malformation type I (CM1), reoperations may be required in cases of insufficient decompression. We encountered a patient who experienced restenosis due to regeneration of resected C1 laminae and required reoperation after FMD.We present the case of a 14-year-old boy with symptomatic CM1 and syringomyelia who underwent FMD with outer dura layer incision and C1 laminectomy. He experienced gait disturbance, hyperesthesia, and hyperhidrosis, which did not improve after the surgery. He experienced recurrence of the stenosis at the age of 16 years, for which he underwent resection of the regenerated C1 arch and duraplasty. His symptoms gradually resolved after the second surgery.The recurrence might have been caused by regeneration of the C1 laminae. Bone regeneration rarely necessitates reoperation. Frequent follow-up is important after decompression surgery for Chiari malformation in young patients.