SIR: On the threshold of the 21st century, dementia, and especially Alzheimer's disease, is considered one of the main public health problems among elderly patients.1,2 At the beginning of the century, an infectious disease, late-stage neurosyphilis (NS), represented the most important cause of dementia.3
Nowadays, considering NS in the differential diagnosis of neurologic/psychiatric symptoms is of special importance when evaluating persons with human immunodeficiency virus (HIV) infection because of the strong epidemiologic association between these two infections.4 However, people who do not belong to the risk groups for acquired immunodeficiency syndrome (AIDS)—mainly elderly individuals who contracted syphilis decades ago, most of them without adequate treatment for the disease—may [later] develop NS and be misdiagnosed. Besides, the clinical presentation of NS often does not follow the traditional course of the pre-antibiotic era.5 Thus, NS among elderly patients is often not suspected, and delay in diagnosis is a frequent problem.
We tried to determine the prevalence of NS in hospitalized elderly neurology patients. We made a retrospective study (1990—1997) of elderly patients attending the Internal Medicine, Geriatrics, and Neurology Departments, where NS was diagnosed according to CDC criteria.6 HIV serology was negative in all patients.
Six hospitalized elderly patients with NS were identified, 1.33 per 1,000 of the studied population, 5 men and 1 woman. The average age was 70.3±6.0 years (range 65—78 years). NS occurred an average of 32.8 years after the onset of the disease. The mean time between the onset of symptoms and diagnosis of NS was 27 months, despite the fact that 5 patients (83.3%) had previously shown a clear picture of clinical syphilis. A history of prior studies or treatments was reported in 3 cases (50%). The main consulting symptoms were intellectual deterioration in 3 cases (50%), stroke in 2 (33.3%), and a urinary sepsis in a patient with permanent urinary catheter secondary to bladder disturbances and ataxia. Cerebrospinal fluid analysis detected pleocytosis in 4 cases (66.6%), with an average count of 19 cells/mm3. Most neuroradiologic examinations (computed tomography scan and magnetic resonance imaging) showed pathological findings, mainly diffuse atrophy of the cortex and white matter infarctions, although these were frequently nonspecific.
We can conclude that NS among elderly patients remains an important public health problem. New cases are not adequately detected, and delay in diagnosis is common: often clinical presentation does not follow the traditional course; mental changes may imitate other types of dementia and psychiatric disorders; and stroke is often attributed to age and associated risk factors. All elderly patients with neurological or psychiatric disorders of doubtful etiology should have syphilis serology checked routinely.