Neuropathic Pain In Leprosy: Deep Profiling And Stratification Of Patient Groups

Leprosy is a chronic granulomatous infectious disease, affecting the skin and nerves. Neuropathic pain (NP), which is defined as pain caused by a lesion or disease of the somatosensory nervous system, is now being recognized as an important complication of leprosy. It occurs in 10-20% of patients as a result of persisting nerve damage. Patient with NP is associated with significant suffering, morbidity and limitation of quality of life. Thus, the accurate identification of NP in patients with pain is required. The clinical aspects of NP in leprosy patients in India were investigated using highly specialised assessment tool; quantitative sensory testing (QST). A case control study was conducted in 90 patients with and without pain. Two validation studies were conducted among healthy volunteers in London (18 participants) and Mumbai (52 participants). Somatosensory profiles were compared in leprosy patients to healthy control subjects. The pattern revealed a novel profile of loss of cool and warm detection thresholds and also mechanical detection but with preservation of vibration detection. This is different to profiles seen in other NP conditions. The QST parameters were effective in detecting neuropathy, but were not able to distinguish between patients with and without NP. Patients with leprosy NP had a high rate of abnormal findings in almost all QST parameters in the maximum pain area over the ulnar nerve. Their sensory profiles were categorised into two subgroups. The majority of patients have spontaneous pain with evidence of sensory loss, but no signs of sensory gain. The second subgroup had profoundly impaired pain and temperature sensation, but light mechanical stimuli often produce pain. Patients with NP had a poor quality of life and psychological well-being compared to pain-free neuropathy.