Ten thousand steps and more. He takes a deep breath, concentrates, and squeezes the grip of the device, a dynamometer, with his right hand. He diligently repeats this grip strength test several times, alternately on both sides. “I feel it’s not good”, the man lets go, with a disappointed look.
This June morning, this 50-year-old suffering from type 3 spinal amyotrophy – a genetic neuromuscular disease – undergoes a complete assessment at the physiology and neuromuscular evaluation laboratory of the Institute of Myology, at Pitié-Salpêtrière (Paris) . For three hours, thanks to a battery of tests, the team will finely assess its muscular capacities, including breathing. It rates strength and mobility in the fingers, hands, lower limbs … “I have been working daily for about thirty years to keep as much muscle as possible”, tells the patient, who in particular does three weekly sessions with a physiotherapist, including two in the swimming pool.
Stimulate fragile muscles
Did this slow down the progression of his disease? “In the 1980s and 1990s, people with myopathy or other neuromuscular disease were advised against playing sports for fear of“ breaking ”their already fragile muscles. From now on, they are recommended to practice an adapted physical activity, the benefits of which are increasingly being studied ”, explains Jean-Yves Hogrel, doctor and engineer in biomedical engineering who heads this cutting-edge laboratory, mainly funded by AFM-Telethon.
In this patient, this evaluation and monitoring of his progress are all the more important as he begins treatment with nusinersen (Spinraza), a gene therapy at a prohibitive cost: 70,000 euros per dose (the dosage being an injection every four months, after a loading dose of four injections over two months).
To measure the strength and muscular capacities of patients who often do not have much left, because they are suffering from one of the 400 listed neuromuscular diseases – of genetic origin for the most part -, Jean-Yves Hogrel’s team is tasked with principle of developing suitable tools. In the “hacking room” lined with tools and electronic components, the researchers – six permanent staff, physiotherapists, physiologists or engineers by training – designed several of these “Myotools”. These high-precision tools are now used by other research teams and the pharmaceutical industry. For example, MyoGrip, which measures grip strength (grip strength) with an accuracy of 50g and a resolution of 10g, when most commercial dynamometers are only accurate to within one or two kilos, and do not detect a force of less than a few kilos. On average, this wrist strength is 45 kilos in men, and 30 kilos in women. Proportional to the circumference of the hand, it reaches a maximum between 20 and 30 years old then decreases with age.
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