Intra-cranial involvement of trigeminal nerve in a patient with borderline tuberculoid leprosy in type 1 lepra reaction

Leprosy is a chronic infectious disease primarily involving the skin, peripheral nerves and joints. Intracranial involvement however is an unusual scenario. The affection of trigeminal nerve intra-cranially has not been reported by far. We report a leprosy patient with trigeminal nerve involvement presenting as facial pain and paraesthesias which was initially diagnosed as trigeminal tumour and considered for gamma-knife surgery. He was referred to dermatology for evaluation of erythema and oedema on the left side of face. Examination showed single, well to ill-defined hypoaesthetic, erythematous plaque on face. He also had a thickened left common peroneal nerve (CPN) and decreased sensation over left foot. Nerve conduction study showed absent compound motor action potential in left CPN. High-resolution ultrasonography with colour doppler showed enlargement of left CPN and left posterior tibial nerve. Skin biopsy was suggestive of borderline tuberculoid leprosy in type I reaction and the intracranial space occupying lesion was theorized to be an inflammatory nodule due to T1R. The patient was started on WHO multidrug therapy multibacillary regime along with prednisolone for T1R. The CEMRI brain 2 months post-treatment initiation showed a grossly normal study confirming our suspicion of it being an inflammatory swelling. We report an unusual presentation of BT leprosy downgrading to BL leprosy in type-1 reaction with intracranial involvement. Awareness regarding such a presentation is essential for neurologists and dermatologists alike not only for early diagnosis and prompt treatment of this potentially disabling disease, but also to avoid unnecessary interventions.