BHUBANESWAR: In a major breakthrough, researchers from AIIMS-Bhubaneswar have discovered the involvement of the central nervous system with pure neuritic leprosy (PNL), paving the way for early diagnosis of undiagnosed cases and targeted treatment.
A chronic infectious disease caused by bacteria Mycobacterium leprae, leprosy predominantly affects the skin - its main symptom being disfiguring sores and loss of sensation. But PNL is an uncommon form of leprosy involving peripheral nerves that leads to sensory loss, muscle weakness and nerve thickening without visible skin changes.
PNL that accounts for 20 per cent of the total leprosy cases is more common in men and typically seen in India, particularly in the states of Uttar Pradesh, Bihar and Odisha. Even as leprosy elimination has been achieved as per the WHO criteria of less than one case per 10,000 people, detection of new cases has emerged as a concern forcing the Union Health Ministry to set a target to achieve zero cases by 2030.
The study by a team of researchers led by head of neurology department Dr Sanjeev Kumar Bhoi revealed that a majority of PNL cases have the subclinical involvement of the central nervous system.
“Our study shows that PNL can subtly affect the central nervous system. Such leprosy cases are often left undiagnosed due to absence of skin-related symptoms. Testing both peripheral and central nervous involvement will definitely help detect PNL early, allowing for treatment to reduce disability risks,” said Dr Bhoi.
If a patient shows nerve-related symptoms like sensory loss or muscle weakness without skin lesions or thickening of elbow or knee nerves, doctors should consider nerve conduction studies and conduct specific tests like VEP (for vision nerve pathways), SSEP (for sensory pathways) and BAEP (for auditory pathways) for a clearer diagnosis, he said.
The study funded by the Odisha government was conducted among a set of suspected leprosy patients who visited AIIMS-Bhubaneswar between 2020 and 2023. Of 76 patients with suspected PNL, nerve biopsies confirmed definite pure neuritic leprosy in 49 patients aged between 14 and 72. The majority of patients were men with unilateral foot drop being the most common presenting feature followed by the claw hand.
Published in the peer-reviewed medical journal Acta Neurologica Belgica, this study underscored the importance of checking both peripheral and central nerve involvement for early diagnosis, treatment, and ultimately reducing disability risk among affected patients.
“We conducted nerve biopsy along with the VEP, SSEP and BAEP tests, results of which suggested that even though PNL is mainly a peripheral nerve disease, it may subtly affect the central nervous system pathways. More than 15 per cent of the patients belonged to well-to-do families and had never imagined that they could have leprosy,” Dr Bhoi added.