Neurosyphilis Presenting as Limbic Encephalitis: a Case Report (P10-10.007)

Abstract

<h3>Objective:</h3> To present an interesting case of neurosyphilis mimicking limbic encephalitis. <h3>Background:</h3> Neurosyphilis can occur at any stage of infection and it classically presents as meningitis, cranial neuropathies, vasculitis, tabes dorsalis, or neuropsychiatric manifestations, however rarely temporal lobe abnormalities resembling limbic encephalitis have been reported. <h3>Design/Methods:</h3> N/A <h3>Results:</h3> 51-year-old male with no past medical history presents initially with 3 weeks of altered mental status, confusion and memory loss. Prior to admission to the hospital, he presented with a generalized tonic-clonic seizure. His MRI showed T2 hyperintensities in the left hippocampus, amygdala, and mesial temporal lobe with associated diffusion restriction. Cerebrospinal fluid (CSF) studies showed 58 white blood cells/mm3 (73% lymphocytes), a protein concentration of 165 mg/dL and a glucose concentration of 35 mg/dL. HIV serology, serum cryptococcal Antigen, HSV and VZV PCR on CSF and neuronal autoantibodies on serum were negative. EEG showed left lateralized periodic discharges. The patient was initially treated with empiric anti-infective therapy including acyclovir, ceftriaxone, and ampicillin. Subsequently, serum syphilis screen was positive with reflex Rapid Plasma Reagin (RPR) titer at 1:64. CSF Venereal Disease Research Laboratory (VDRL) was positive at 1:64. In light of these results, the patient was transitioned to intravenous aqueous penicillin G 24 million units daily through continuous infusion. His mental status markedly improved after a few days of treatment. Repeat EEG showed only mild encephalopathy. He was discharged on levetiracetam and high dose IV penicillin G to complete a 14-day course. <h3>Conclusions:</h3> Syphilis is commonly known as a great imitator; it is a treatable condition so it should not be missed. We need to be more cognizant of this diagnosis when evaluating patients with temporal lobe involvement on MRI, lymphocytic pleocytosis and hypoglycorrhachia. Although HSV and autoimmune diseases are the most common causes of limbic encephalitis, as presented in our case, syphilis testing should be considered. <b>Disclosure:</b> Dr. Hu has nothing to disclose. Dr. El Helou has nothing to disclose. Nayrobi Pena Cotui has nothing to disclose. Dr. Balobaid has nothing to disclose. Dr. Montalvo Perero has nothing to disclose.