[Chiari malformation (type 1) with regeneration of removed C1 lamina after foramen magnum decompression: a case report].

We present the case of a 20-year-old female who underwent foramen magnum decompression and laminectomy of C1-C3 as well as incision of only the outer layer of the dura, for her symptomatic Chiari malformation (type 1) with syringomyelia, at the age of 9 years. She required additional surgery with removal of regenerated bone and dural plasty for the remaining and recurrent stenosis. The remaining stenosis may have been caused by the use of a technique without dural plasty and insufficient decompression of the bony structure. Further, the regeneration of C1 lamina could have been responsible for the recurrent stenosis. Her symptoms, which included gait disturbance, hypesthesia, excessive sweating, and nocturnal enuresis, manifested themselves when she was at the age of 2 years and progressed since that time. These symptoms didn't improve after the first surgery. However, after the second surgery, the gait disturbance and nocturnal enuresis were partially resolved. It is rare for new bone generation to necessitate reoperation. However, it should be noticed that careful follow-up is important after decompressive surgery for Chiari malformation in young patients.