Functional sensibility of the hand in leprosy patients.

The aims of this cross-sectional comparative study was to compare the results of Semmes-Weinstein monofilament testing (SWM) and moving 2-point discrimination (M2PD) with four tests of functional sensibility: recognition of objects, discrimination of size and texture and detection of dots. Ninety-eight leprosy in- and outpatients at Green Pastures Hospital in Pokhara, Nepal were tested with each of the above tests and the results were compared to see how well they agreed. Using the tests of functional sensibility as reference points, we examined the validity of the SWM and M2PD as predictors of functional sensibility. There was definite, but only moderate correlation between thresholds of monofilaments and M2PD and functional sensibility of the hand. A normal result with the SWM and/or M2PD had a good predictive value for normal functional sensibility. Sensitivity was reasonable against recognition of objects and discrimination of textures as reference tests (80-90% and 88-93%), but poor against discrimination of size and detection of dots (50-75% and 43-65%). Specificity was high for most combinations of SWM or M2PD with any of the tests of functional sensibility (85-99%). Above a monofilament threshold of 2 g, the predictive value of an abnormal test was 100% for dot detection and 83-92% for textural discrimination. This indicates that impairment of touch sensibility at this level correlates well with loss of dot detection and textural discrimination in patients with leprous neuropathy. For M2PD the pattern was very similar. Above a threshold of 5 mm, 95-100% of affected hands had loss of dot detection and 73-80% had loss of textural discrimination. Monofilament testing and M2PD did not seem suitable as proxy measures of functional sensibility of the hand in leprosy patients. However, a normal threshold with monofilaments and/or M2PD had a good predictive value for normal functional sensibility. Above a monofilament threshold of 2 g and/or a M2PD threshold of 5 mm, textural discrimination was abnormal in most hands.

Intra- and inter-tester reliability of sensibility testing in leprosy.

We conducted an intra- and inter-tester agreement study of three sensory screening tests used in nerve function assessment of leprosy patients: the Semmes-Weinstein monofilament (SWM) test, moving 2-point discrimination (M2PD), and the pin prick test. The weighted kappa (Kw) statistic was used as the reliability coefficient. The SWM had intra-observer Kws ranging from 0.83 to 0.92 and inter-observer Kws ranging from 0.76 to 0.89. The M2PD had intra- and inter-tester Kws ranging from 0.75 to 0.82 and 0.54 to 0.82, respectively. Inter-tester agreement for the pin prick test ranged from 0.45 to 0.85. There was evidence that the main source of variability between testers was testing skill and experience. Among the experienced physiotechnicians there was no significant difference between intra- and inter-tester reliability. We conclude that reliability of the SWM test was very good, closely followed by the M2PD test. Reliability of the pin prick test was less good than that of the SWM and M2PD, making it less suitable for serial testing.

Nerve function impairment in leprosy: an epidemiological and clinical study--Part 2: Results of steroid treatment.

This retrospective cohort study aimed to determine the progress of sensory and motor function during and after steroid treatment, and to identify any prognostic factors for the outcome of treatment. The study used one hundred and sixty-eight leprosy patients registered at Green Pastures Hospital, Pokhara, West Nepal, who were treated with one of four different corticosteroid regimens for impairment of nerve function. The function of the main peripheral nerve trunks affected in leprosy was assessed with a nylon filament to test touch thresholds (TST) and a manual voluntary muscle test (VMT) to quantify muscle strength. The TST and VMT scores at 3 months after initiation of steroid treatment served as the main outcome measure. The significance of potential prognostic factors was evaluated with logistic regression. At 3 months, the sensory and motor function of the majority of patients with 'recent' impairment ( = less than 6 months duration) had improved significantly (p < 0.01, Wilcoxon matched pairs signed-ranks test). The likelihood of 'good' recovery (prognosis) for both sensibility and motor function was directly related to the severity of the nerve damage at the beginning of treatment. Although nerve function improved in 30-84% (depending on the type of nerve) of patients, an active search for better methods of treatment and improved regimens is justified. The need for early assessment and treatment is stressed.

Silent neuropathy in leprosy: an epidemiological description.

This paper presents epidemiological data on silent nerve function impairment in leprosy based on a retrospective study of 536 patients registered at Green Pastures Hospital, Pokhara, West Nepal. Because of the multiple possible aetiologies it is proposed that the clinical phenomenon should be named 'Silent Neuropathy' (SN). We defined this as sensory or motor impairment without skin signs of reversal reaction or erythema nodosum leprosum (ENL), without evident nerve tenderness and without spontaneous complaints of nerve pain (burning or shooting pain), paraesthesia or numbness. The functioning of the main peripheral nerve trunks known to be affected in leprosy was assessed using a nylon filament to test touch thresholds and a manual voluntary muscle test to quantify muscle strength. Almost 7% of new patients had SN at first examination. The incidence rate of SN among the 336 new patients who were available for follow-up was 4.1 per 100 person years at risk. In total, 75% of all SN episodes diagnosed after the start of chemotherapy occurred during the first year of treatment. During steroid treatment the sensory and motor function in nerves affected by SN improved significantly (p = 0.012, Wilcoxon matched-pairs signed ranks test) over a period of 3 months. The patients with more extensive clinical disease (3/9 or more body areas involved, more than 3 enlarged nerves or a positive skin smear) were found to be at increased risk of developing SN. We discuss 4 different possible aetiologies of SN: 1, Schwann cell pathology; 2, nerve fibrosis; 3, cell-mediated immune reaction; and 4, intra-neural ENL. Some epidemiological evidence is presented that suggests that SN cannot be equated with a 'reversal reaction expressing itself in the nerves'. It is recommended that all patients should have a nerve function assessment at every visit to the clinic at least during their first year of treatment. Regular nerve function assessment is essential to detect SN at an early stage and to prevent permanent impairment of nerve function.

Reactions in leprosy: an epidemiological study of 386 patients in west Nepal.

This paper presents epidemiological data on reversal reaction (RR) and erythema nodosum leprosum reaction (ENL) from a retrospective study of 386 leprosy patients newly registered at Green Pastures Hospital, Pokhara, West Nepal. The average follow-up time was 21 months. The prevalence of RR at first examination was 28% (23-32), and the prevalence of ENL reaction was 5.7% (2.3-9.2). The overall incidence rates among the 335 patients that were available for follow-up were 8.7 (6.5-12)/100 person years at risk (PYAR) for RR and 3.2 (1.5-6.7)/100 PYAR for ENL. Relapse of RR was common (1.4/patient). In all, 52% of RR were complicated by new nerve function impairment, against 59% of ENL reactions. The finding of other investigators that most RRs occur during the first year of treatment was confirmed by this study. The most significant risk factor for RR was extent of clinical disease measured by a count of body areas with clinical signs of leprosy. The risk of developing a RR for patients with 'extensive disease' (3 or more out of 9 body areas involved) was 10 times that of patients with limited disease (Rate Ratio 10 (1.3-76), p = 0.026). The study indicated that the following categories of patients in Nepal are at high or increased risk of developing a RR: 1, borderline patients during their first year of MDT; and 2, patients with more extensive clinical disease as described above.

Nerve damage in leprosy: an epidemiological and clinical study of 396 patients in west Nepal--Part 1. Definitions, methods and frequencies.

A historic cohort study was performed to determine the prevalence and incidence rates of nerve function impairment (NFI) as demonstrated by sensory testing with a nylon monofilament and standard tests of motor function. The records of 396 new leprosy patients registering at Green Pastures Hospital, Pokhara, between January 1988 and January 1992 were analysed. The mean follow-up period was 21 months. In all, 36% (141/396) of patients had either sensory or motor function impairment at their initial examination. For each nerve the prevalence of sensory and motor impairment is reported separately. The posterior tibial nerve was the most frequently affected (sensory) nerve (21%). Sensory impairment of the ulnar nerve was found in 17% of the patients; 8.8% had sensory impairment of the median nerve. The overall incidence rate of motor function impairment was 7.5 (5.4-10) per 100 person years at risk (PYAR). Sensory impairment had a significantly higher rate of 13 (10-17)/100 PYAR (rate ratio (1.8 (1.2-2.7), p = 0.0076). Bl patients had a significantly higher incidence rate of nerve function impairment than BT patients (rate ratio 2.3 (1.4-3.7), p = 0.006). Altogether 152/396 (39%) of the patients required corticosteroid treatment for 'recent' or 'acquired' impairment, and 78 of the patients (20%) developed severe nerve function impairment during or after antileprosy treatment. Analysis of potential risk factors for nerve function impairment showed a significant association with the extent of clinical disease expressed as the number of body areas (out of 9) with primary or secondary signs of leprosy (rate ratio 5.0 (1.5-17), p = 0.0091). It was concluded that nerve function impairment is a serious problem, often occurring during or after multidrug therapy. The extent of clinical disease expressed as a count of body areas involved, or of skin or nerve lesions may identify patients who are at increased risk of nerve damage.