Subgrouping Leprosy Patients with Neuropathic Pain in Central Brazil Based on Pain-Related Sensory Abnormalities

Background: Leprosy is a significant cause of nontraumatic peripheral neuropathy and neuropathic pain (NP). Generally, patients with NP exhibit a variety of symptoms and sensory signals, creating an individual phenotypic profile of pain. This involves identifying and grouping a set of symptoms and signs that characterize an individual's pain experience. Neuropathic pain can be confirmed using the DN4 screening tool, which includes 7 items related to symptoms and 3 items related to physical examination. Identifying clusters of symptoms in patients with NP and distinguishing them into subgroups through statistical analysis of the most relevant and discriminating aspects of the pain phenotype can more robustly reflect the different mechanisms or combinations of mechanisms involved in its genesis.

Objective: To identify subgroups of leprosy patients with NP based on pain-related sensory abnormalities.

Methods: A cross-sectional descriptive study was performed on patients with NP caused by leprosy who were treated at a school hospital in Central Brazil to characterize the painful symptoms and establish NP sensorial phenotypes. The sociodemographic, clinical, and NP phenotype characterization was performed using the Neuropathic Pain Questionnaire 4 (DN4). Identifying groups of patients with similar individual phenotypic profiles was done using exploratory factor analysis.

Results: A total of 132 patients with leprosy and associated NP were evaluated during 2017 and 2018. Most patients were female (56.8%) with borderline leprosy (72.7%) and with a mean (SD) age of 48.7 (13.5) years. Signs and symptoms related to sensory deafferentation were predominant: numbness and hypoesthesia to touch and needle pinprick. The characterization of the sample by sensorial phenotypes identified four subgroups that best described the patients with leprosy NP and that corresponded to 62% of all variations found. In two subgroups, a predominance of signs and symptoms of sensorial loss corresponded to 38% of the patients. The other two were characterized by signs of hyperactivity of the somatosensory system.

Conclusions: NP phenotypes associated with leprosy are characterized by numbness, tingling, pins, needling, and hypoesthesia to touch and needle pinprick. The sensory phenotype of leprosy-associated NP has four phenotypic subgroups. There were two groups related to sensory loss that are compatible with this long-term neuropathy and the two others with signs of pathological sensory input.