Clinico-sonological study of peripheral nerve involvement in leprosy in a tertiary care medical center, India

Abstract Introduction The diagnosis of Hansen’s disease (HD) relies on the detection of the cardinal signs of leprosy. Clinical examination for nerve thickening carries significant inter observer variability, which emphasizes the significance of non-invasive investigations like nerve ultrasound. Objectives To describe the sonological characteristics of peripheral nerve involvement in Hansen’s disease. Methods A descriptive study spanning 1year was conducted among 37 consecutive patients with clinical features suggestive of leprosy who attended the Dermatology OPD in Government T.D. Medical College, Alappuzha (a tertiary care medical college in Kerala, India). After taking informed consent, history, complete dermatological examination including sensory, motor systems and peripheral nerves were done. Ultrasonography of bilateral ulnar nerves, median nerves, common peroneal nerves and posterior tibial nerves of all patients were done, assessing their cross sectional area, echo reflectivity and vascularity. All data were entered in Microsoft Excel sheet and analysed using SPSS 20.0 statistical software. Results The mean age was 39.9 years. Male to female ratio was 3.1:1. 21.6% were immigrants. 86.5% belonged to multibacillary type and 13.5% were paucibacillary. The most common type of leprosy was borderline tuberculoid. 3 pure neuritic leprosy cases were identified. 40.5% had lepra reactions, 80% of which being type 1 reaction. Initial presentation was in the form of lepra reaction in 6 patients. 83.7% patients had peripheral nerve enlargement at the time of presentation. 81.1% had impaired nerve sensation, 40.54% patients had motor function impairment, 43% patients had grade 2 disability and 1 patient had cranial nerve involvement. Out of the total 296 nerves imaged, 29 nerves which were not thickened clinically were found to be thickened while 7 nerves which were clinically identified as thickened, were found non-thickened on USG. On comparing clinical and sonological thickening of peripheral nerves, significant p value was obtained for all except left posterior tibial nerve. Hypoechogenicity was noted in 77 nerves. Increased vascularity was seen in only 7 nerves, out of which 4 were in type 1 reaction and 3 were in type 2 reaction. Conclusion Our study sheds light on the different clinical and sonological dimensions of leprosy. As peripheral nerve thickening is a cardinal feature of leprosy, clinical examination alone may end up in missing this crucial diagnosis. Ultrasonography being a newer, non-invasive and easily available investigation proves useful to study the changes in nerves even among patients without palpably enlarged nerves or neurological signs.