Friedreich's ataxia: MR findings involving the cervical portion of the spinal cord.

OBJECTIVE: Loss of myelinated fibers and gliosis in the posterior and lateral columns of the spinal cord are histopathologic hallmarks of Friedreich's ataxia. These are accompanied by atrophy of the upper portion of the spinal cord. We performed a study to determine if MR imaging can be used to detect signal changes in the white matter tracts of the cervical spinal cord in these patients. SUBJECTS AND METHODS: The cervical spinal cord was imaged with a 0.5-T MR imaging system in 10 patients with Friedreich's ataxia and in 14 patients with cerebellar ataxias, who served as control subjects. In all of them, the examination protocol included sagittal T1-weighted spin-echo images, sagittal short T1 inversion-recovery images, and axial cardiac-gated long TR spin-echo or ungated low-flip-angle (20 degrees) gradient-recalled-echo images from C2 to C6. The anteroposterior diameter of the spinal cord at the level of C3 on axial images was measured on the display console in patients and control subjects. Two observers who did not know the clinical diagnosis were then asked to evaluate hard copies of the entire image set for each subject for possible intramedullary signal abnormalities.
RESULTS: The anteroposterior diameter of the spinal cord was decreased in all but one of the patients with Friedreich's ataxia. Abnormal signal in the posterior or lateral columns of the spinal cord was observed on sagittal and axial images in nine patients with Friedreich's ataxia and in none of the control subjects.
CONCLUSION: MR images of the cervical spinal cord in patients with Friedreich's ataxia show thinning and intramedullary signal changes in the cervical portion of the spinal cord, consistent with degeneration of posterior and lateral white matter tracts. These MR findings might be helpful for differential diagnosis in patients with progressive ataxia of uncertain clinical type.