Neurosyphilis Mimicking Herpes Simplex Encephalitis on Magnetic Resonance Imaging: A Case Report

Abstract

Patient: Male, 49-year-old Final Diagnosis: Neurosyphilis Symptoms: Behavioral disturbance • confusion • disorientation • hallucinations • memory loss Medication: Penicillin G • acyclovir Clinical Procedure: Lumbar puncture Specialty: Infectious Diseases • Neurology • Radiology Objective: Rare disease Background: Neurosyphilis is a central nervous system infection caused by Treponema pallidum , that can develop at any time after the initial infection. The clinical signs of neurosyphilis are very variable, as well as its radiological features, and it is a diagnostic challenge. Knowledge of clinical symptoms and correct laboratory diagnostics, combined with routine radiological examination and additional diagnostic tools, such as high-resolution, three-dimensional FLAIR sequence, T2-weighted, and T1-weighted contrast-enhanced magnetic resonance imaging (MRI) are key to making an accurate diagnosis of neurosyphilis. Case Report: We present the clinical case of a patient who presented a 1-year history of vague clinical symptoms and was misdiagnosed with herpes simplex virus (HSV) encephalitis. Initial head MRI revealed extensive cerebral white matter lesions with cortical contrast enhancement, mainly of anterior and medial parts of the left temporal lobe, as typically seen in HSV encephalitis. Empirical therapy with acyclovir was started until a diagnosis of syphilis was confirmed with laboratory findings. Later, the therapy was changed to penicillin G. The patient’s condition improved after receiving targeted treatment. A control MRI scan was performed, and previously detected changes in the brain had decreased significantly. Conclusions: MRI is the imaging of choice to support the diagnosis of neurosyphilis. Our findings suggest that neuroimaging can play an important role in indicating suspicion of syphilitic encephalitis. Enhancement of the anterior and medial parts of the temporal lobe is an atypical imaging finding, and it can simulate an infection with HSV. Early treatment is critical to a positive outcome.

Neurosyphilis Presenting as Syndrome of Limbic Encephalitis Mimicking Herpes Simplex Virus Neuro-Infection Diagnosed Using CXCL13 Point-of-Care Assay—Case Report

“…Neurosyphilis cases presenting as LE are rare. To our knowledge, there are three case reports of encephalitis affecting the limbic system caused by neurosyphilis that were initially misdiagnosed as HSV encephalitis [ 11 , 12 , 13 ]. There are also various cases of the syndrome of limbic encephalitis caused by neurosyphilis masquerading as autoimmune LE [ 14 , 15 , 16 ].…”

“…Second, the most prominent clinical presentations were memory loss and confusion. Third, the CSF examination revealed pleocytosis with lymphocyte predominance and an elevated CSF protein concentration [ 11 , 12 , 13 , 14 ]. The originality of our case report is the utilisation of the CXCL13 assay to assess the intrathecal synthesis of CXCL13 chemokine at the time of presentation.…”

“…Neurosyphilis might rarely present as temporal lobe and limbic system involvement with characteristic radiologic traits of encephalitis caused by other infectious agents, especially herpes simplex virus (HSV) or autoimmune limbic encephalitis (LE). This may lead to an incorrect initial diagnosis, especially if neurosyphilis is not considered [ 11 , 12 , 13 , 14 , 15 , 16 ]. LE is a severe clinical condition characterized by inflammation of the limbic system.…”

“…HSV is the most common aethiopathogen of the infectious syndrome of LE. Because of a wide spectrum of possible aetiologies, a differential diagnosis of patients presenting with symptoms of LE and radiologic evidence of inflammation of the limbic system is often challenging [ 11 ]. The intrathecal synthesis of C-X-C motif ligand 13 (CXCL13) has been described in spirochetes infections such as neuroborreliosis and neurosyphilis and might be used as a complementary biomarker of spirochaetal neuro-infection [ 17 ].…”

Atypical Neurosyphilis Predominantly Affects the Cingulate Gyrus: A Rare Case Report

“…Additionally, MRI signal abnormalities may be observed in the parietal, temporo-occipital, and thalamic regions [7,8], while the involvement of the cingulate gyrus is rare. A search was conducted on PubMed and Embase using the terms "neurosyphilis" and "cingulate gyrus" to identify studies reporting cingulate gyrus involvement in patients with NS, and only four published cases were found [5,[9][10][11]. The presented case may be the rst report of atypical NS with predominant involvement of the cingulate gyrus.…”