Isolated unilateral trismus as a presentation of Chiari malformation: case report.

The authors present a case of Chiari malformation manifesting as isolated trismus, describe the typical symptoms associated with Chiari malformation, and discuss the potential anatomical causes for this unique presentation. A 3-year-old boy presented with inability to open his jaw for 6 weeks with associated significant weight loss. The results of medical and radiological evaluation were negative except for Type I Chiari malformation with cerebellar tonsils 12 mm below the level of the foramen magnum. The patient underwent Chiari decompression surgery. Postoperatively, his ability to open his mouth was significantly improved, allowing resumption of a regular diet. Postoperative MRI revealed almost complete resolution of the syringobulbia. To the best of the authors' knowledge, this is the first reported case of isolated trismus from Chiari malformation with syringobulbia.