Electrophysiology and Ultrasound of Respiratory Muscles and Respective Nerves to Predict Respiratory Insufficiency in ALS

electromyography of a set of muscles usually examined during diagnosis of ALS (typically tongue, bilateral deltoid, first dorsal interosseur, abductor pollicis brevis, paraspinals, vastus lateralis, anterior tibialis and additionally bilateral sternocleidomastoideus and rectus abdominis). In each muscle recording in relaxation and in maximal voluntary effort will be done. The presence of signs of acute (fibrillations, sharp waves) and chronic (fasciculations, reduction of the recording of the effort) denervation as well as presence of activity coupled with the rhythm of respiration will be assessed.

Ultrasonographic measurements include cross-sectional area (CSA) and diameter of bilateral phrenicus, vagus and accessory nerves as well as diameter of diaphragm. The diameter of diaphragm will be measured during normal, quiet respiration as well as at the peak inspiration and expiration.

Assessment of partial oxygen (PaO2) and partial carbondioxide pressure (PaCO2) in arterial blood.

Slow vital capacity (SVC) will be measured as the full exhalation done after inspiration which will follow a period of quiet breathing. The test will be performed thrice and the final value will be the average value.