Neuropathic pain in leprosy
ABSTRACT
Neuropathic pain appears to be much more common in leprosy than has been generally appreciated. Emphasis in leprosy control programs has been on the distribution of multidrug therapy, on early and better detection, and on the prevention of disability related to anesthetic limbs. Most have thus been inattentive to the problem of neuropathic pain in leprosy patients. Neuropathic pain does not respond to the usual analgesics employed for reactions, for example, and so it is important that those treating leprosy patients give this problem the special attention it requires, both in diagnosis and in treatment.RÉSUMÉ
Les douleurs neurogènes de la lèpre pourraient bien être beaucoup plus fréquentes que ce qui a été considéré auparavant. L'effort des programmes de contrôle de la lèpre a été orienté vers la distribution de la polychimiothérapie, une détection meilleure et plus précoce et dans la prévention des handicaps associés à des membres anesthésiés. La plupart de ces programmes ont ainsi apporté peu d'attention au problème des douleurs neurogènes chez les patients hanséniens. Les douleurs neurogènes ne répondent pas aux analgésiques usuels employés pour traiter par exemple les réactions et il est donc important que les personnes engagées dans le traitement des patients hanséniens considèrent particulièrement cet aspect, tant en ce qui concerne le diagnostic que le traitement.RESUMEN
El dolor neuropático en la lepra parece ser mucho más común de lo que usualmente se considera. Los programas de control de la lepra han hecho mucho énfasis en la distribución de drogas para la poliquimioterapia, en la temprana y mejor detección de la enfermedad, y en la prevención de las incapacidades relacionadas con los miembros anestésicos. Muchos programas han puesto poca atención al problema del dolor neuropático en los pacientes con lepra. El dolor neuropático no response a los analgésicos usualmente empleados en las reacciones de la lepra, por ejemplo. Por esto, es muy importante que los encargados del tratamiento de los pacientes con lepra den a este problema la atención especial que requiere, tanto en el diagnóstico como en el tratamiento.Stump, et al.'s paper, "Neuropathic pain in Leprosy patients," published in this issue of the JOURNAL, is a timely and important contribution to the evaluation and management of leprosy sufferers. In the wider medical world the management of chronic pain is developing as a specialty in its own right complete with journals and international conferences devoted to the subject. It is an interesting coincidence that a review article on the same topic has just been published in the most recent edition of Leprosy Review (1).
In the leprosy world, we have been slow to catch on to the existence of chronic neuropathic pain occurring in leprosy patients. Hastings' textbook Leprosy (1995) does not mention it at all, and there have been remarkably few papers published on the subject in the world leprosy literature. Yet Stump and his colleagues report that 56% of the 358 patients assessed for neuropathic pain in his study either had experienced or were experiencing episodes of pain of sufficient intensity to interfere with activities of daily life or sleep. The statistics they adduce are in line with findings from the few other studies that have been carried out amongst leprosy sufferers. How could we have missed it for so long?
There are several overlapping answers to that question. For several years most programs, NGO and Government alike, have simply been extremely busy and focussed on case finding and multi-drug therapy (MDT) administration. This has been extraordinarily successful in reducing prevalence and clearing the backlog of patients in the community. In many places the heat has now come out of that approach and perhaps there is a little more space to reflect on what our patients-including "cured" patients- are actually experiencing. Another important focus in leprosy programs and in research of the last decade or so has been the detection and management nerve function impairment (NFI) and the prevention of disability. Both of these foci-detection and treatment, and prevention of disability- have had anaesthesia at the hub, since it is the absence of sensation that leads both to the diagnosis of leprosy (and therefore to treatment), and to the development of the most damaging disabilities and consequent handicap and stigma. We have been so attuned to painlessness that we have missed the fact that a very significant proportion of our leprosy sufferers experience pain as part of their dis-ease. Furthermore, they may continue to suffer long after they have been declared "cured" and are lost to follow-up. That we should have been so deaf and blind to this most basic of complaints-pain-is extraordinary.
As already alluded to, there has been a paucity of studies into neuropathic pain carried out amongst leprosy sufferers and very few references to it at all in the world literature. There is a clear need for more research into this subject and for the findings to be applied as rapidly as possible. However, much is known already about the diagnosis and management of neuropathic pain in general that could easily be applied now. If it is as common as Stump et al. suggests-and it probably is-then we should get on with it now.
If we are to begin to help leprosy sufferers with chronic neuropathic pain then as a first step we must ask them about it. It should not be left to experts in research centers to ask the questions; it should become part of the routine history taking of every paramedical worker. Before that can happen, training institutions must incorporate this message. Leprosy workers need to understand the difference between nociceptive and neuropathic pain, and Stump, et al. rightly draw attention to this. Crucially, it should be understood that neuropathic pain will not respond to simple analgesia, but rather to different drugs such as tricyclics and anticonvulsants. Then, the treatment of neuropathic pain must become mainline. Perhaps a good word to use here is demystify. Neuropathic pain is regarded by some doctors as a little technical, rarefied even. The subject needs to be demystified, it needs to make the jump to become the regular.
Perhaps the situation we are in is akin to the situation that existed a decade or so ago, before the widespread use of corticosteroids at "field level" to treat acute NFI and reactions. We knew how to measure NFI, and we had an effective drug, prednisolone, but it took a paradigm shift in thought and practice for this technology to be widely and simply applied so that the maximum number of people could benefit. In the same way, it is known how to diagnose neuropathic pain (and it is not difficult), and at least one very cheap and effective drug is available (amitriptyline). A widespread application of this knowledge down to the grassroots level could be of considerable benefit to a large number of people.
The current cut-and-dried WHO recommendations for the treatment of leprosy focuses very much on bacteriological cure with discharge after relatively short courses of treatment. It is well known that this largely ignores the existence of new nerve damage after release from treatment, but to date there has been very little appreciation of the way that this ignores the presence of neuropathic pain among "cured" leprosy sufferers, as Stump et al. points out in his conclusions. Indeed, the prevalence of neuropathic pain he found is actually higher than that often quoted for NFI amongst leprosy patients.
In summary, Stump's paper both documents and highlights the existence of a common and significant problem amongst leprosy patients, one that has been remarkably overlooked. There is a need to demystify the diagnosis and treatment of neuropathic pain and to develop simple strategies that will enable the widespread application of simple and effective techniques for its management.
-Richard Croft
REFERENCE
1. HAANPÄÄ, M. LOCKWOOD, D. N. J., and HIETA-HARJU, A. Neuropathic pain in leprosy. Lepr. Rev. 75 (2004) 7-18.
Received for publication on 23 March 2004.
Accepted for publication on 14 April 2004.