Neuritic leprosy: epidemiology and therapeutic responsiveness

A 10-year Retrospective Descriptive Study on Pure Neuritic Leprosy from a Tertiary Referral Centre

CONTEXT

Pure neuritic leprosy is a risk factor for grade 2 disability owing to the early nerve damage.

AIMS

To study the clinical patterns of neuritic leprosy, to determine the percentage of patients manifesting grade 2 disability at the time of diagnosis and to identify any risk factors for the same.

SETTINGS AND DESIGN

Retrospective descriptive study from previous case records of pure neuritic leprosy patients who attended a tertiary centre from 1st July 2007 to 30th June 2017.

SUBJECTS AND METHODS

Data on patients who satisfied the World Health Organization (WHO) cardinal criteria for diagnosis of leprosy, who had no skin lesion of leprosy and had acid-fast bacilli negative status on skin smears were collected using a pre-set proforma.

STATISTICAL ANALYSIS USED

The Chi-square test was used to assess statistical significance and logistic regression model was applied to avoid the effects of confounding factors.

RESULTS

A diagnostic delay of >1 year was observed in 44% patients. At the time of diagnosis, grade 2 disability was documented in 60 (80%) of patients. No statistically significant risk factor was identified for grade 2 disability.

LIMITATIONS

Retrospective nature and the study conducted in a tertiary care centre not reflecting the status in the community were the limitations.

CONCLUSIONS

Grade 2 disability noted in 80% of patients points to the inherent nature of disease to cause early nerve damage. Diagnostic delay of >1 year documented in 44% of patients underscores the diagnostic challenges in the absence of skin lesions.

Leprosy late-onset neuropathy: an uncommon presentation of leprosy

Clinical and pathological findings in leprosy are determined by the natural host immune response to Mycobacterium leprae. We previously described cases of painful neuropathy (PN) with no concurrent cause apart from a past history of leprosy successfully treated. Four leprosy previously treated patients who developed a PN years after multidrug therapy (MDT) are reported. The mean patient age was 52.75 years (47-64). The mean time interval of the recent neuropathy from the previous MDT was 19 years (12-26). A painful multiplex neuritis or polyneuropathy were observed respectively in two cases. Electrophysiological studies disclosed a sensory axonal neuropathy in two cases. Microvasculitis with no bacilli was seen in nerve biopsy. Neuropathic symptoms were improved with prednisone. We consider these cases as being a leprosy late-onset neuropathy (LLON) form of presentation. A delayed immune reaction could explain the late appearance of LLON.

Interleukin-4 regulates the expression of CD209 and subsequent uptake of Mycobacterium leprae by Schwann cells in human leprosy

The ability of microbial pathogens to target specific cell types is a key aspect of the pathogenesis of infectious disease. Mycobacterium leprae, by infecting Schwann cells, contributes to nerve injury in patients with leprosy. Here, we investigated mechanisms of host-pathogen interaction in the peripheral nerve lesions of leprosy. We found that the expression of the C-type lectin, CD209, known to be expressed on tissue macrophages and to mediate the uptake of M. leprae, was present on Schwann cells, colocalizing with the Schwann cell marker, CNPase (2',3'-cyclic nucleotide 3'-phosphodiesterase), along with the M. leprae antigen PGL-1 in the peripheral nerve biopsy specimens. In vitro, human CD209-positive Schwann cells, both from primary cultures and a long-term line, have a higher binding of M. leprae compared to CD209-negative Schwann cells. Interleukin-4, known to be expressed in skin lesions from multibacillary patients, increased CD209 expression on human Schwann cells and subsequent Schwann cell binding to M. leprae, whereas Th1 cytokines did not induce CD209 expression on these cells. Therefore, the regulated expression of CD209 represents a common mechanism by which Schwann cells and macrophages bind and take up M. leprae, contributing to the pathogenesis of leprosy.

Pure neural leprosy: steroids prevent neuropathy progression

Multidrug therapy (MDT), with rifampicin, dapsone, and clofazimine, treats leprosy infection but is insufficient in arresting or preventing the nerve damage that causes impairments and disabilities. This case-series study evaluates the benefits of the combined use of steroids and MDT in preventing nerve damage in patients with pure neural leprosy (PNL). In addition to MDT, 24 patients (88% male aged 20-79 years, median=41) received a daily morning dose of 60 mg prednisone (PDN) that was gradually reduced by 10 mg during each of the following 5 months. PNL was clinically diagnosed and confirmed by nerve histopathology or PCR. A low prevalence (8.3%) of reaction was observed after release from treatment. However, most of the clinical parameters showed significant improvement; and a reduction of nerve conduction block was observed in 42% of the patients. The administration of full-dose PDN improved the clinical and electrophysiological condition of the PNL patients, contributing to the prevention of further neurological damage.

An immunohistochemical, clinical and electroneuromyographic correlative study of the neural markers in the neuritic form of leprosy

The nerve biopsies of 11 patients with pure neuritic leprosy were submitted to routine diagnostic procedures and immunoperoxidase staining with antibodies against axonal (neurofilament, nerve growth factor receptor (NGFr), and protein gene product (PGP) 9.5) and Schwann cell (myelin basic protein, S-100 protein, and NGFr) markers. Two pairs of non-adjacent histological cross-sections of the peripheral nerve were removed for quantification. All the fascicles of the nerve were examined with a 10X-ocular and 40X-objective lens. The immunohistochemistry results were compared to the results of semithin section analysis and clinical and electroneuromyographic data. Neurofilament staining was reduced in 100% of the neuritic biopsies. NGFr positivity was also reduced in 81.8%, PGP staining in 100% of the affected nerves, S100 positivity in 90.9%, and myelin basic protein immunoreactivity in 90.9%. Hypoesthesia was associated with decreased NGFr (81.8%) and PGP staining (90.9%). Reduced potential amplitudes (electroneuromyographic data) were found to be associated with reduced PGP 9.5 (63.6%) and nerve fiber neurofilament staining (45.4%) by immunohistochemistry and with loss of myelinated fibers (100%) by semithin section analysis. On the other hand, the small fibers (immunoreactive dots) seen amid inflammatory cells continued to be present even after 40% of the larger myelinated fibers had disappeared. The present study shows an in-depth view of the destructive effects of leprosy upon the expression of neural markers and the integrity of nerve fiber. The association of these structural changes with the clinical and electroneuromyographic manifestations of leprosy peripheral neuropathy was also discussed.

Small-fiber polyneuropathy in leprosy without skin changes: study of 17 cases

Leprosy is one of the most common diseases of the peripheral nerves. In some cases there is only neural involvement without skin changes (neuritic form). The neuropathy has often a distal stocking and glove distribution with thermal and pinprick anesthesia and preservation of proprioception. There is no weakness, the tendon reflexes may be preserved and sometimes the nerves are thickened. We reported 17 patients with a predominantly small-fiber polyneuropathy due to leprosy. All patients had distal temperature and pain anesthesia with different individual variations. The tendon reflexes were normal in seven patients and in eight there was thickening of the nerves. The nerve conduction was normal in three patients. Sural nerve biopsy consisted of: 1) inflammatory infiltrates, 2) vacuolated "foamy" cells, 3) fibrosis of endoneurium, perineurium, and epineurium, 4) partial or total loss of nerve fibers, 5) large number of bacilli. We concluded that in countries where leprosy is frequent, nerve biopsy is an obligatory procedure in patients with predominantly small-fiber polyneuropathy.

The diagnosis of leprosy among patients with symptoms of peripheral neuropathy without cutaneous lesions: a follow-up study

Forty-four patients with neuritic leprosy were individually followed for periods ranging from 4 months to almost 4 years for the purpose of ascertaining the presence and/ or absence of leprosy. The neural symptoms presented were sensory impairment (41), parasthesia (28), nerve enlargement (22), nerve tenderness (20), paresia (20), amyotrophy (8). Leprosy was diagnosed in ten out of the total number of patients studied. Leprosy was confirmed by the appearance of reactional neuritis (4), reversal reaction (2), biopsy of the hypoesthesic area (3) and the appearance of non-reactional cutaneous lesion. We reported an experience in the diagnosis of neuritic leprosy and its most frequent clinical presentation with which clinicians have to be acquainted. We can also state that the clinical follow-up was an effective strategy for the diagnosis of the disease when diagnostic facilities are not available or have not confirmed the diagnosis.

[Ulnar nerve palsy in leprosy without skin changes: biopsy of the superficial branch of the ulnar nerve in the hand]

Leprosy is one of the most common diseases of peripheral nerves in the world. In Brazil it is particularly frequent, being a major health problem. In tuberculoid leprosy the ulnar nerve is the most common affected nerve. Sometimes there are no skin changes. In these cases in spite of nerve thickening only the nerve biopsy is capable to make a specific diagnosis. We performed a biopsy in the dorsal sensory branch of the ulnar nerve in the hand in 17 patients with ulnar palsy with thickening of the nerve in the elbow, without skin changes. The pathological findings consisted mainly of: loss of fibers (14 cases), inflammatory infiltration (13), fibrosis (12), demyelination and remyelination (9), presence of granuloma (6) and presence of bacilli (5 cases). We conclude that in case of ulnar nerve palsy in leprosy without skin changes, the biopsy of the dorsal sensory branch of this nerve in the hand is a good procedure for the diagnosis of leprosy.