[The corticospinal tract lesion of amyotrophic lateral sclerosis--magnetic resonance imaging of the spinal cord].

Magnetic resonance imaging by gradient echo method demonstrated lesions of the lateral corticospinal tract at cervical cord levels in three ALS patients. Patient 1 was a 43-year-old woman with common form of ALS. She developed right-side predominant pyramidal signs, and right-side predominant prolongation of central motor conduction time. MRI showed hypersignal intensity areas in the dorsal region of the lateral column at the 4th and 5th cervical segments with right-side predominancy. Patient 2 was a 65-year-old man with pseudopolyneurtic form of ALS, who showed lower motor neuron signs without a pyramidal sign. MRI of the 3rd and 4th cervical cord segments demonstrated bilateral hypersignal intensity areas in the dorsal part of the lateral column. Patient 3 was a 62-year-old man with common form of ALS, who showed marked bilateral pyramidal signs with Babinski's sign. MRI of the 5th cervical spinal cord segment demonstrated bilateral hypersignal intensity areas in the dorsolateral column. Thus obtained MR images of the spinal cord corresponded well to the postmortem-confirmed degeneration of the spinal corticospinal tract. MRI of the spinal cord performed by gradient echo method would provide additional information on the upper motor neuron involvement in ALS.