Seronegative dementia paralytica: report of a case.

Dementia paralytica may present diagnostic difficulties when routine serological test using a non-treponemal antigen is non-reactive. We present an illustrative demented patient who initially had negative VDRL test both in his serum and cerebrospinal fluid. However, the brain biopsy specimen showed active meningoencephalitis. By special staining technique, a spiral organism was found in the brain exhibiting morphology perfectly compatible with treponema pallidum. Later in the course, the VDRL became reactive in the blood but remained non-reactive in the cerebrospinal fluid. On the basis of the experience of other workers in the field and ours with this patient, we advise the use of FTA-ABS test as a screening procedure in patients with neurological problems of possible syphilitic origin. We urge further research in this field.