Muscle Imaging Tracks Progression of Motor Neuron Diseases
Whole-body MRI reveals distinct signals in patients’ muscles.
Motor neuron diseases are a group of progressive neurological disorders that destroy motor neurons, the cells that control essential voluntary muscle activity, such as speaking, walking and swallowing. A major barrier to the development of effective therapies has been the lack of biomarkers to objectively assess disease progression over short timescales in the context of clinical trials.
Researchers in the U.K. recently tackled this challenge by applying whole-body muscle magnetic resonance imaging to patients with motor neuron diseases for the first time. In a study published Oct. 31 in the Journal of Neurology, Neurosurgery & Psychiatry, 29 patients with motor neuron diseases and 22 healthy controls were assessed with clinical, electrophysiological and whole-body muscle MRI measurements at first clinical presentation and four months later.
At baseline, patients had a 30 percent higher MRI muscle signal than controls, with nearly all muscles showing a distinct signal between the two groups. The higher MRI signal in patients was also associated with greater overall disability, clinical weakness and electrophysiological evidence of muscle denervation, or the loss of nerve supply. Four months later, none of the muscles in healthy controls showed any changes in the MRI or electrophysiological measurements.
By contrast, patients’ muscles showed changes in clinical, electrophysiological and MRI measurements over this short time period. For example, the MRI signal increased by 73 percent and 82 percent in the right and left tibialis anterior, respectively. Meanwhile, these muscles showed electrophysiological evidence of denervation, as well as a decrease in power in roughly half of the patients. In future clinical trials, whole-body muscle MRI could be used to investigate patterns of disease spread in muscles inaccessible to conventional clinical and electrophysiological assessment.