Magnetic resonance investigation of the upper spinal cord in pure and complicated hereditary spastic paraparesis.

Neuropathological studies of hereditary spastic paraparesis (HSP) have described axonal loss involving corticospinal and somatosensory tracts in the spinal cord. This MRI-based study was intended to investigate in vivo diameter alterations of the spinal cord in HSP, including both pure HSP (p-HSP, n = 20) and complicated HSP (c-HSP, n = 10). Standard MRI examinations of the cervical and thoracic spinal cord in HSP patients and a control group (n = 54) were analyzed by standardized spinal cord planimetry. In HSP patients, significant atrophy of the upper spinal cord compared to controls was observed at p < 0.001 both at the cervical and at the thoracic level. Myelon diameters at both levels were also significantly reduced in the two HSP subgroups in an additional comparison with age-matched subgroups of controls each, but p-HSP and c-HSP groups themselves did not differ. Marked atrophy of the upper spinal cord seems to be associated with HSP, assumedly due to the central-distal axonopathy. However, the differences between p-HSP and c-HSP could not be visualized by structural MRI at spinal cord level.