Reference values for nerve function assessments among a study population in northern India - II: Thermal sensation thresholds

Objective: This paper presents normal reference values for thermal sensation for a study population with no known neurological condition in northern India. It was part of the INFIR Cohort Study, a prospective study of people newly diagnosed with multibacillary leprosy, the objective being to identify early changes in nerve function predictive of new onset impairment and reactions. Methods: Data on warm and cold sensation in five bilateral nerves was collected from 326 healthy subjects stratified by sex and by age and drawn from the same general population as the subsequent leprosy-affected cohort. Reference values were computed from log-transformed data after the exclusion of outliers. Results: Normal reference values are presented in the form of 95th percentiles for warm and 5th percentile for cold sensation within eight age and sex groups and by centre. The prevalence of impairment at diagnosis among the leprosy-affected cohort is described and illustrated The high prevalence of lost warm sensation in the leprosy-affected cohort suggests that this is an important early indicator for nerve involvement in leprosy.