Effect of skin thickness on sensory nerve action potential amplitude.

OBJECTIVE: It has been shown that finger circumference negatively correlates with sensory nerve action potential amplitude (SNAP-A). Also fat people have lower sensory nerve amplitudes. Factors that cause electrodes displaced further away from underlying nerves, such as increased cutaneous and subcutaneous tissue, will lower SNAP-A. This study was designed to evaluate correlation between skin thickness and SNAP amplitude. METHODS: Thirty-seven healthy 22-40-year-old subjects were selected. Nineteen (51.4%) were males and 18 (48.6%) were females, without significant difference between males and females regarding their ages. For all subjects, height and weight were measured. Anteroposterior and mediolateral diameters of the proximal phalanges of the index and little fingers and also finger circumferences were measured. Palmar digital skin thickness was measured in two ways: first with sonography machine, and second with skin fold caliper. Median and ulnar nerve sensory and motor conduction studies were performed. RESULTS: In bivariate analysis, SNAP-A correlated negatively with female sex, height, anteroposterior diameter of the fingers, finger circumference and skin thickness measured by sonography, but in multiple regression analysis only skin thickness measured by sonography could predict SNAP-A. CONCLUSIONS: This study demonstrates that among physiological factors of sex, height, BMI and also finger size measures, skin thickness is the best predictor of SNAP-A. SIGNIFICANCE: In clinical practice, this effect must be taken into account when making determination of abnormality based on sensory nerve amplitude.

Stroke in Isfahan, Iran: hospital admission and 28-day case fatality rate.

BACKGROUND: In Isfahan, a city in the middle of Iran, a community intervention trial has been started for cardiovascular disease prevention and control via reducing its risk factors and improvement of relevant healthy behavior. A surveillance system was needed to monitor vascular diseases, especially stroke, during and following this community intervention program. METHODS: A prospective study on hospitalized stroke patients was done in Isfahan, Iran, from 2000 to 2003. All hospitalized stroke events were recorded via a system adopted from the World Health Organization Monitoring Trends and Determinants in Cardiovascular Disease (MONICA) project, yet ignoring the MONICA age limitation. The age-adjusted hospital admission rate was calculated. Patients and/or their families were followed and asked regarding the patients' survival status. RESULTS: The age-adjusted hospital admission rate in Isfahan was increasing from 2000 to 2003 (rising from 84.16 to 103.23/100,000). The 28-day case fatality rates were nearly the same during these years and were about 32%. Ischemic stroke events made up the majority of cases (about 70%), and intracerebral hemorrhage events had the second highest prevalence (25%). CONCLUSIONS: This study showed that the stroke hospital admission rate might be increasing in Isfahan. A community-based stroke incidence study is needed to elucidate stroke epidemiology in Isfahan, Iran, as a Middle East country.