Pseudogout showing meningoencephalitic symptoms: crowned dens syndrome.

We report a 70-year-old man who presented symptoms resembling those of meningoencephalitis and who was subsequently diagnosed as having a crowned dens syndrome. The patient exhibited severe neck pains, headache, high fever and a pain in his knee joints together with symptoms of the central nervous system. The patient's cerebrospinal fluid was almost clear and showed no sign of viral infection. An analysis of the synovial fluid in the right knee joint revealed typical calcium pyrophosphate dehydrate crystal deposition and a diagnosis of pseudogout was therefore made. A tomographic examination of the neck showed periodontoid calcification. The patient was first treated with non-steroidal anti-inflammatory drug, but its effect was only minimal. On the other hand, the administration of corticosteroid resulted in a dramatic improvement in his condition.