Chiari malformation type 1 (CM1) is accompanied by basilar invagination (BI) in some cases. The general surgical treatment for it is foramen magnum decompression, followed by occiput-cervical fusion with or without atlantoaxial facet joint distraction and fixation. However anterior decompression (often, odontoidectomy), which is usually difficult through the transoral access, is mandatory in some cases because of insufficient neurological recovery after posterior intervention.
To elucidate the advantage of endoscopic endonasal skull base surgery for CM1 with BI.
Consecutive 3 patients (age range 37-50 years) who underwent endoscopic endonasal and/or transoral anterior decompression for CM1 with BI, followed by or following instrumented posterior fixation, were enrolled. Their clinical results were assessed using the Functional Independence Measure (FIM).
At a mean follow-up duration of 24.3 (range 17-38) months, clinical success was achieved in all cases. The mean recovery rate was 62.3 (range 15-100)%. Conclusions: In CM1 with BI cases, anterior decompression is occasionally mandatory, although it is not generally adopted because of its technical difficulty. Endoscopic decompression via the endonasal route is a useful option for a complex pathology such as CM1+BI (Inoue T, JNS spine 2018).