Researchers at the University of Eastern Finland have developed a portable 3-dimensional accelerometry and surface electromyography system that can measure the occurrence and severity of myoclonic jerks, which are sudden muscle movements experienced by patients with progressive myoclonic epilepsy. Muscle jerks can be unpleasant, but they can also lead to accidents and falls. The researchers hope that the new sensors can help them understand progressive myoclonic epilepsy a little better and eventually help with the development of new treatments and allow patients to track their progress.
Myoclonic jerks can be stimulated by movement and can be positive or negative. A positive myoclonus typically produces spontaneous muscle contraction, whereas a negative myoclonus results in impaired muscle activation. These symptoms can be unpredictable and unpleasant, but they can also lead to falls and accidents, meaning they pose a danger to patients.
Understanding how, why, and when these symptoms occur would help doctors and researchers understand the condition and develop new treatments. However, the methods for providing objective data are limited. Currently, the severity of myoclonic jerks is assessed by visual measurements by an experienced physician. This is time consuming, subjective, and only provides details about the condition in a short space of time.
Patients can provide some guidance on the severity of their symptoms, but it would be helpful for both patients and clinicians to allow technology to carry the burden of disease monitoring. The latter device aims to provide data on myoclonic jerks and appears to be suitable for home monitoring. It consists of portable surface electromyography and three-dimensional accelerometry sensors that are placed on the arm and that provide data on the frequency and severity of the shocks.
So far, the researchers have tested the technology on volunteers who wore the sensors for 48 hours each. The sensors showed good agreement with the results reported by the patients themselves and showed differences in symptoms between day and night. The sensor results also correlated well with symptom severity assessments by an experienced physician, suggesting that they are suitable for long-term home monitoring.
Measurement-based index describing myoclonic symptom variation during home measurement. The black color describes the measurements of the extensor finger muscle and the turquoise measurements of the biceps muscle. Image: Saara Rissanen.
Study in magazine Clinical neurophysiology: Portable monitoring of positive and negative myoclonus in type 1 progressive myoclonic epilepsy