Susana Pinto1, Pedro Alves1, Michael Swash2, Mamede de Carvalho3. 1. Physiology institute, Instituto de Medicina Molecular, faculty of medicine, university of Lisbon, Lisbon, Portugal. 2. Physiology institute, Instituto de Medicina Molecular, faculty of medicine, university of Lisbon, Lisbon, Portugal; Department of neurology and neuroscience, Royal London hospital, Queen Mary university of London, London, UK. 3. Physiology institute, Instituto de Medicina Molecular, faculty of medicine, university of Lisbon, Lisbon, Portugal; Department of neurosciences and mental health, hospital de Santa Maria, CHLN, Lisbon, Portugal. Electronic address: mamedemg@mail.telepac.pt.
Abstract
AIMS OF THE STUDY: To compare the assessment of respiratory decline with conventional tests, measurement of diaphragm compound muscle action potential (CMAP) to phrenic nerve stimulation and diaphragm thickness to ultrasound (US) investigation in amyotrophic lateral sclerosis (ALS) patients followed for a short period of time. PATIENTS AND METHODS: We evaluated in 40 consecutive ALS patients, the clinical functional scale (ALSFRS-R), forced vital capacity (FVC), maximal voluntary ventilation (MVV), maximal inspiratory (MIP) and expiratory (MEP) pressures, sniff nasal inspiratory pressure (SNIP), Diaphragm-CMAP (latency and amplitude) and diaphragm US (maximal and minimal diaphragm thickness during full inspiration and expiration, respectively). Patients were evaluated at study entry and 4 months later. RESULTS: Clinical functional assessment (ALSFRS-R), MEP, SNIP, and Diaphragm-CMAP amplitude declined significantly. Conversely, FVC, MVV, MIP, and diaphragm thickness showed a non-significant decline. We found significant correlations between all variables measured at both evaluation times. CONCLUSION: In this study, we included patients who might be potentially eligible for a clinical trial and re-evaluated them within 4 months. In this short time, diaphragm thickness as assessed by US is not sensitive to detect changes. However, Diaphragm-CMAP amplitude was confirmed to be a sensitive non-volitional method to measure respiratory function in ALS.
AIMS OF THE STUDY: To compare the assessment of respiratory decline with conventional tests, measurement of diaphragm compound muscle action potential (CMAP) to phrenic nerve stimulation and diaphragm thickness to ultrasound (US) investigation in amyotrophic lateral sclerosis (ALS) patients followed for a short period of time. PATIENTS AND METHODS: We evaluated in 40 consecutive ALSpatients, the clinical functional scale (ALSFRS-R), forced vital capacity (FVC), maximal voluntary ventilation (MVV), maximal inspiratory (MIP) and expiratory (MEP) pressures, sniff nasal inspiratory pressure (SNIP), Diaphragm-CMAP (latency and amplitude) and diaphragm US (maximal and minimal diaphragm thickness during full inspiration and expiration, respectively). Patients were evaluated at study entry and 4 months later. RESULTS: Clinical functional assessment (ALSFRS-R), MEP, SNIP, and Diaphragm-CMAP amplitude declined significantly. Conversely, FVC, MVV, MIP, and diaphragm thickness showed a non-significant decline. We found significant correlations between all variables measured at both evaluation times. CONCLUSION: In this study, we included patients who might be potentially eligible for a clinical trial and re-evaluated them within 4 months. In this short time, diaphragm thickness as assessed by US is not sensitive to detect changes. However, Diaphragm-CMAP amplitude was confirmed to be a sensitive non-volitional method to measure respiratory function in ALS.