Dynamic MRI testing of the cervical spine has prognostic significance in patients with progressive upper-limb distal weakness and atrophy

摘要

Background: The syndrome of isolated progressive upper-limb distal weakness and atrophy results from disease processes affecting lower motor neurons originating in the cervical anterior horn gray matter. Lower motor neuron dysfunction restricted to the C7-T1 myotomes in the absence of neuropathy, upper motor neuron signs, sphincter disturbances or abnormality on conventional MR imaging is suggestive of either Hirayama disease (HD), or the initial manifestation of a progressive motor neuron disease such as amyotrophic lateral sclerosis (ALS). In HD the supposed etiologic mechanism is a mechanical compression of the cervical spinal cord during neck flexion; therefore, dynamic MRI (dMRI) of the cervical cord might help differentiate between these possibilities.