Acute transverse myelitis in an immunocompetent patient: syphilis and cytomegalovirus-a case report.

Background: Acute transverse myelitis (ATM) is a pathological heterogenous inflammatory condition which causes acute or subacute spinal cord dysfunction. Diagnosis is challenging as the absence of magnetic resonance imaging (MRI) spinal cord lesions do no exclude this as a differential when patients present with well-defined dermatomal paraesthesia or myotome weakness. In approximately 40% of patient, there is a lack of MRI cord abnormalities. In addition, there are numerous of causes of ATM which contributes to diagnostic difficulty. The aim of this report is to highlight the challenges of diagnosing ATM, especially in the case of syphilis and cytomegalovirus. Case Description: A 56-year-old man with a background of high-risk promiscuous behaviour, presents with a symmetrical hand and feet desquamating rash with associated lumbago. Subsequently, he develops sensory impairment in his truncal region. Cerebrospinal fluid (CSF) findings revealed lymphocytosis and elevated protein however, MRI head and whole spine were normal. Together, the patient was diagnosed with ATM. Serology was positive for syphilis [Treponema pallidum haemagglutination assay (TPHA) and rapid plasma reagin (RPR)] as well as cytomegalovirus (CMV) immunoglobulin M (IgM) and immunoglobulin G (IgG), while human immunodeficiency virus (HIV) was negative. On first inspection, the most obvious diagnosis was deemed to be syphilis given the history and presentation with concurrent development of neurosyphilis. However, concurrent CMV IgM positivity obscures the underlying aetiology. He was treated with ceftriaxone and corticosteroids for syphilis, and doxycycline for concomitant chlamydia. At 4-month follow-up, CSF protein had improved and lymphocytosis resolved, although CMV IgM remained positive. His sensory deficits gradually improved, with complete recovery after 6 months, without antiviral therapy. Conclusions: This case illustrates the diagnostic challenges of ATM when multiple infections coexist. While neurosyphilis was initially suspected, normal MRI findings and the persistence of CMV IgM suggest CMV myelitis as the more likely aetiology. Clinicians should consider CMV in the differential diagnosis of ATM even in immunocompetent patients, particularly when serology suggests recent infection but CSF polymerase chain reaction (PCR) and MRI findings are negative.