Quantitative assessment of facial sensation in leprosy

The trigeminal and great auricular nerves which supply sensation to the fac e are affected in leprosy. No objective sensory testing methods have been d evised for testing sensation in the face. Testing for corneal sensation to ascertain trigeminal nerve or visualization and palpation of the great auri cular nerve alone may not be enough to establish the involvement of these n erves. In a sample of leprosy patients, face sensation threshold measurements were done using a set of three Semmes-Weinstein (SW) monofilaments that gave a force of 0.05-0.07, 0.2 and 2 g. Sensation was tested by three examiners an d intra- and inter-observer testing was used as a means to validate the fin dings. Within the limitations of this study, the results indicate that use of SW m onofilaments is a fairly reliable and repeatable method for sensory testing in the face. During follow up, a single filament with a force of 0.5-0.7 g (2.83 marking number in SW filament or any other filament with a correspon ding gram force) could be used to assess sensation. A simple procedure of q uantifying sensation in these nerves is suggested. A method to incorporate trigeminal or great auricular nerve sensory testing into the existing senso ry assessment charts is also discussed.