Foramen magnum syndrome from pseudogout of the atlanto-occipital ligament. Case report.

The authors report a case of progressive foramen magnum syndrome due to deposits of calcium pyrophosphate dihydrate crystals, which caused reactive hypertrophy in the posterior longitudinal ligament at C-1 and in the transverse ligament of the atlas in an 84-year-old woman. This is the first reported case of symptomatic pseudogout in this anatomic location. Rapid neurological recovery followed transoral decompression of the cervicomedullary junction.