Small-fibre neuropathy in leprosy the role of in vivo confocal microscopy: A cross-sectional study.

Background Leprosy (or Hansen's disease) continues to present considerable challenges regarding containment and early diagnosis. Leprosy is considered to be primarily a neural disease that first affects the sensory function of small fibres. Although the condition is well described in terms of clinical manifestations and histology, few studies have been undertaken to detect damage done to small-fibre sensory nerves. In vivo confocal microscopy is a useful tool for conducting a detailed evaluation of these structures, although its use in individuals affected by leprosy has still not been explored. Objective To evaluate in vivo confocal microscopy findings in Hansen's disease patients and their association with clinical variables relating to this disease. Method A cross-sectional case-series type study was carried out between October 2019 and May 2021, in Recife, Pernambuco, Brazil. Socio-demographic and clinical data were gathered from 21 patients with leprosy. The douleur neuropathique 4 neuropathic pain questionnaire was used to evaluate pain. In vivo confocal microscopy of the cornea was employed to evaluate the small-calibre fibres. Findings were compared with those for a control group of 23 healthy individuals. Results In relation to clinical parameters, 90.5% of the patients were classified as "multibacillary" according to the World Health Organization criteria, and 70% as dimorphic or borderline, in accordance with the Madrid classification. Around 52.4% had received a diagnosis after one year or less of living with the disease, while 95.2% presented alterations in small-fibre sensory function and 35% presented such alterations in the large fibre. Neuropathic pain was present in 81% of the patients. In vivo confocal microscopy found no statistically significant difference in mean age and distribution according to sex between the Hansen disease patients and the control group of healthy individuals. The median-of-means for dendritic cells and volume of sub-basal nerve fibres in the control group were used to test for normality. Both eyes of all leprosy patients examined contained higher number of dendritic cells than the median value and a volume of sub-basal nerve fibres lower than the mean. These differences were statistically significant (P < 0.001 and P < 0.001, respectively). Multibacillary individuals had a median number of dendritic cells two times that of paucibacillary individuals (P = 0.035). Limitations No association was found between the variables examined using in vivo confocal microscopy and clinical variables relating to small-fibre damage, the neuropathic pain questionnaire or alterations detected by the neurological examination. We believe, however, that Cochet-Bonnet esthesiometry of the cornea may have revealed such an association. Conclusion In vivo confocal microscopy is a useful diagnostic tool for detecting small fibre loss in individuals affected by leprosy and may constitute a useful addition to the range of tools available to help curb the effects of neuropathy in these patients.

Leprosy piRnome: exploring new possibilities for an old disease.

Leprosy, which is caused by the human pathogen Mycobacterium leprae, causes nerve damage, deformity and disability in over 200,000 people every year. Because of the long doubling time of M. leprae (13 days) and the delayed onset of detectable symptoms, which is estimated to be approximately 3-7 years after infection, there is always a large percentage of subclinically infected individuals in the population who will eventually develop the disease, mainly in endemic countries. piRNAs comprise the largest group of small noncoding RNAs found in humans, and they are distinct from microRNAs (miRNAs) and small interfering RNAs (siRNAs). piRNAs function in transposon silencing, epigenetic regulation, and germline development. The functional role of piRNAs and their associated PIWI proteins have started to emerge in the development of human cancers and viral infections, but their relevance to bacterial diseases has not been investigated. The present study reports the piRNome of human skin, revealing that all but one of the piRNAs examined are downregulated in leprosy skin lesions. Considering that one of the best characterized functions of piRNAs in humans is posttranscriptional mRNA silencing, their functions are similar to what we have described for miRNAs, including acting on apoptosis, M. leprae recognition and engulfment, Schwann cell (SC) demyelination, epithelial-mesenchymal transition (EMT), loss of sensation and neuropathic pain. In addition to new findings on leprosy physiopathology, the discovery of relevant piRNAs involved in disease processes in human skin may provide new clues for therapeutic targets, specifically to control nerve damage, a prominent feature of leprosy that has no currently available pharmaceutical treatment.

The association between neuropathic pain and disability grades in leprosy.

OBJECTIVE: To detect neuropathic pain in people who have had leprosy and correlate this association with the WHO Degree of Physical Disability classification (DPD-WHO). PATIENTS AND METHODS: Data were collected from medical records, interviews and physical examinations of patients treated in 2013 in a regional referral service that attends 102 municipals. Clinical and general data, the DPD-WHO classification and the Douleur Neuropathique 4 Questionnaire (DN4) were utilised to determine the profile and to diagnose neuropathic pain. RESULTS: Of 84 treated patients, 37 (44.1%) had leprosy-related pain at the time of the interview. The mean age was 53 years, 51.4% were women; 75.7% had multibacillary disease and 72.9% had some kind of reactional episode. Of the 37 patients with pain, 22 (59.5%) had neuropathic pain and 15 (40.5%) had nociceptive pain. The most frequently reported symptoms related to neuropathic pain, apart from numbness (64.9%), were tingling and touch hypoesthesia (56.8%). Of 22 patients with neuropathic pain, 20 had some physical disability; 14 (63.6%) had Grade I disability, six (27.2%) Grade II, and two (9.3%) Grade zero disability. An association was found between neuropathic pain and degree of disability (P-value < 0.05). CONCLUSION: Of the patients who reported pain related to leprosy, 59.5% had neuropathic pain. The DN4 seems to be suitable for determining the presence of neuropathic pain in leprosy. There is an association between the degree of disability and neuropathic pain, i.e. patients with neuropathic pain tend to have a physical disability too.

Chronic neuropathic pain in treated leprosy.

The existence of chronic neuropathic pain in treated leprosy has received scant attention. We describe the clinical findings of 16 patients with multibacillary leprosy who had chronic stimulus-independent pain despite finishing their treatment. With confirmation, our results could be of importance in the establishment of "care after cure" programmes for patients with leprosy.