The evaluation of surgical treatment options in the Chiari Malformation Type I

There have been several treatment modalities to reduce the volume of the syringomyelic cavity and the pressure on the brainstem in Chiari Malformation Type I (CM-I). Foramen magnum decompression with and without duroplasty were compared in this retrospective study.

From 2003 to 2006, 27 patients suffering from CMI were operated on at our institute. The following were measured: the ratio of the syringomyelic cavity to the spinal cord; pre-operative tonsillar herniation from the foramen magnum; pre- and postoperative tonsillo-dural distance; and spinoposterior fossa dural angle.

83.3 % of the patients in the non-duroplasty and 73.3% of the patients in the duroplasty group were symptom free. The ratio of syrinx regression was 28+/-10% in the non-duroplasty and 36+/-33% in the duroplasty group. The tonsillodural distance was 3.1+/-1.8 mm in the non-duroplasty and 4.6+/-2.1 mm in the duroplasty group (p>0.05). The spino-posterior fossa dural angle was 133.6+/-9.44 degrees preoperatively and 136.7+/-9.78 degrees postoperatively in the non-duroplasty (p=0.376); 123.7+/-11.7 degrees preoperatively and 129.8+/-11.1 degrees postoperatively in the duroplasty group (p=0.885); no significant difference was found postoperatively (p=0.55, z=1.92), respectively. One patient was re-operated in the non-duroplasty group and thereafter duroplasty was performed.

Almost the same clinical outcomes can be achieved with and without duroplasty. There might be an option to perform duroplasty if simple procedure fails.