Neuroimaging in Leprosy: A Case Series Exploring Domains Beyond Peripheral Nerves

Background and objective: Leprosy, an infectious disease caused by Mycobacterium leprae, induces irreversible damage, necessitating early detection. The disease's neurotropism, which extends to the peripheral nerves, is well recognized. In recent years, there has been an acknowledgment of its expanding horizon beyond this traditional boundary. This study aims to explore the involvement of atypical sites such as the central nervous system, brachial plexus, and spinal nerve root ganglion through dedicated neuroimaging via magnetic resonance imaging (MRI) across diverse spectra of leprosy.

Methods: In a retrospective case series conducted from July 2020 to July 2022 at a tertiary care hospital, leprosy patients with specific neurological signs were analyzed. Neurologists had recommended MRI for suspected central nervous system (CNS)/proximal nerve root involvement in these patients. Two expert radiologists assessed the MRI imaging results.

Results: Eleven such patients were identified, of which six with positive MRI findings were scrutinized. Six multidrug therapy (MDT) naive male leprosy patients in the age range of 24-44 years were analyzed. MRI revealed signal intensity alterations (SIA) in the brain, cervical cord, and bilateral/unilateral brachial plexus/ganglion. After a year of MDT, follow-up imaging revealed diverse responses: complete resolution of brain SIA (n=1), persistent declining hyperintensity in the cervical cord with declining (n=1), unchanged ganglionitis/plexitis (n=2), and no observable changes in cord and brachial plexus SIA (n=1).

Conclusion: This study reveals diverse neuroimaging patterns in leprosy patients. Neuroimaging may reveal abnormalities, particularly in patients with leprosy presenting with lower motor neuron-type facial palsy. A deeper understanding of these radiological findings could offer valuable insights into the pathophysiology of leprosy.