Foot Drop as the Initial Manifestation of HIV Infection with Focal Brain Lesions: A Case Report and Diagnostic Challenge.

BACKGROUND: Neurological involvement in HIV infection encompasses a broad clinical spectrum, most commonly presenting as peripheral neuropathy. However, focal motor deficits such as isolated foot drop are rare, and cases accompanied by Central Nervous System (CNS) involvement pose significant diagnostic challenges. CASE: A 53-year-old male patient was referred to our clinic after testing positive for anti-HIV during the evaluation of a one-month history of foot drop and sore throat. On admission, neurological examination revealed isolated motor weakness without additional deficits. Brain Magnetic Resonance Imaging (MRI) demonstrated multiple T2 hyperintense lesions with contrast enhancement, consistent with HIV-associated CNS involvement presenting as a focal enhancing brain lesion. Cerebrospinal Fluid (CSF) analysis excluded opportunistic infections and neurosyphilis. Electromyography (EMG) demonstrated findings consistent with incidental chronic L5 radiculopathy. RESULTS: Antiretroviral therapy with bictegravir/emtricitabine/tenofovir alafenamide (B/FTC/ TAF) was initiated. At six months of follow-up, marked clinical improvement in foot drop was observed, accompanied by regression of lesions on follow-up MRI. CONCLUSION: This case highlights that foot drop may represent a rare initial manifestation of HIV infection and may reflect combined neuroaxis involvement affecting both central and peripheral nervous systems, rather than an isolated peripheral mononeuropathy. Early initiation of antiretroviral therapy can lead to both clinical and radiological improvement.