Involvement Beyond Peripheral Nerves in Pure Neuritic Leprosy: An MR Imaging Study

Pure neuritic leprosy (PNL) is an uncommon form of leprosy involving peripheral nerves alone. Some isolated case reports and observational studies have shown imaging changes in the CNS in patients with leprosy. This prospective observational study evaluates the involvement of the nervous system beyond peripheral nerve among patients with PNL with MR imaging.

We screened patients presenting with features of neuropathy and/or thickened nerves. Patients were subjected to detailed clinical examination, routine tests along with nerve conduction study, and biopsy of peripheral nerve, usually the sural nerve. MRI of brachial and lumbar plexus, dorsal root ganglia, spinal cord, and brain were evaluated in patients with histopathologically confirmed Hansen neuritis.

Of 86 patients screened for PNL, 52 were positive on nerve biopsy. Most patients were men (86.53%) and the mean age was 45.72 ± 15.25 years. Asymmetrical polyneuropathy was the most common nerve conduction study pattern in 55.76% (29/52) patients. We found abnormal imaging findings in 21 (40.38%) patients. Ganglionitis was the most common finding seen in 14 (26.92%) patients followed by plexitis (15.38%) and myelitis (11.53%). Patients with MRI lesions were younger and were found to have more functional impairment and raised CSF protein.

In PNL, many patients have subclinical involvement of dorsal root ganglion, brachial plexus, lumbar plexus, and spinal cord. Exact pathophysiology of CNS involvement is not clear; however, imaging of the above-mentioned regions may help in early diagnosis and prevent complications. These MRI findings in PNL are important considerations when assessing patients with peripheral neuropathy.