Neurosyphilis Mimicking Behavioral Variant of Frontotemporal Dementia in a 59-Year-Old Man

Abstract

We present the case of a man exhibiting a clinical phenotype of behavioral variant of frontotemporal dementia (bvFTD). The man had developed psychiatric disturbances with verbal aggressiveness over a few months, followed by cognitive and frontal behavioral disorders, fulfilling the clinical criteria for bvFTD. Atrophy and hypometabolism in frontotemporal regions were consistent with the diagnosis. However, serum-screening exams for syphilis infection were positive, and CSF analysis, despite a negative Venereal Disease Research Laboratory Test, suggested the diagnosis of neurosyphilis. After specific antibiotic therapy, the man’s behavioral abnormalities and cognitive deficits notably improved, confirming neurosyphilis as the cause of the clinical phenotype. The cognitive deficits completely recovered 1 year post therapy and remained stable for 2 years. After ∼2½ years from the first treatment, the man’s behavioral disorders mildly worsened, at which time we re-evaluated him. His cognition was stable, and a positive Venereal Disease Research Laboratory Test confirmed the diagnosis of neurosyphilis. With this case, we demonstrated that in some instances, neurosyphilis can mimic frontotemporal dementia. As a cause of treatable dementia, it should be considered in the differential diagnosis of bvFTD, particularly when psychiatric symptoms and a rapid cognitive decline are noted, even in the presence of brain atrophy and/or hypometabolism.

A Narrative Review of the Many Psychiatric Manifestations of Neurosyphilis: The Great Imitator

“…In another case, Caroppo et al described the findings of a 59-year-old man who presented with clinical symptoms of a behavioral variant of frontotemporal dementia [ 16 ]. The patient developed psychiatric disturbances with verbal aggressiveness over the course of a few months, which was followed by cognitive and behavioral disorders.…”

“…Screening exams for syphilis turned out to be positive in subsequent testing, and there were abnormal CSF findings which pointed to neurosyphilis as the diagnosis. With antibiotic treatment, the patient's behavioral symptoms along with cognitive impairments showed marked improvement, confirming neurosyphilis as the cause of the psychiatric disturbance [ 16 ]. This case illustrates that neurosyphilis can mimic frontotemporal dementia and should, therefore, be kept high on the differential diagnosis as treatment can halt disease progression and lead to remarkable improvement in the disease course.…”

Neurosyphilis Initially Misdiagnosed as Behavioral Variant Frontotemporal Dementia: Life-Changing Differential Diagnosis

“…Although these cases provide valuable information, there are certain aspects to consider. In their cerebrospinal fluid (CSF) analysis during treatment, Prynn et al [ 10 ] and Caroppo et al [ 11 ] found negative results for syphilis infection, while serum screening exams for syphilis infection returned positive. Additionally, while both cases showed significant cognitive improvement shortly after treatment, Prynn et al [ 10 ] did not conduct follow-up neuropsychological testing or provide a detailed behavioral description.…”

“…Additionally, while both cases showed significant cognitive improvement shortly after treatment, Prynn et al [ 10 ] did not conduct follow-up neuropsychological testing or provide a detailed behavioral description. In the case of Caroppo et al [ 11 ], the man’s behavioral disorders resurfaced 2½ years aftertreatment.…”

“…However, there have been few reports on the case of neurosyphilis that have been initially misdiagnosed as bvFTD. To the best of our knowledge, there are only two reports on such a case [10,11]. Although these cases provide valuable information, there are certain aspects to consider.…”