Prominent brain axonal damage and functional reorganization in "pure" adrenomyeloneuropathy.

BACKGROUND

Cerebral involvement is usually absent in pure adrenomyeloneuropathy (AMN). Recently, nonconventional MR studies have reported brain abnormalities in patients with pure AMN, providing evidence that occult cerebral involvement may occur in this disease. It remains unclear, however, whether these brain abnormalities reflect centripetal extension of spinal cord long-tract axonopathy or can be the expression of a pathologic process largely involving the brain.

METHODS

Conventional MRI and proton MR spectroscopic imaging (1H-MRSI) data of four patients with pure AMN were compared to those of four men with spinal cord injury (SCI) and 10 age-matched healthy men (HM). Resonance intensity areas of N-acetylaspartate (NAA) and choline were calculated as ratios to creatine (Cr) in voxels located in white matter (WM) regions. Functional MRI (fMRI) data during simple motor task were obtained in a separate session in three patients with AMN and three age-matched HM.

RESULTS

Conventional MRI examinations were normal in all patients. On 1H-MRSI, NAA/Cr values were lower in all WM regions of patients with AMN than in those of patients with SCI (p < 0.05) and HM (p < 0.01). In contrast, patients with SCI showed NAA/Cr values lower than HM only in the periventricular WM (p = 0.04). At fMRI, patients with AMN showed a more pronounced activation than HM in all movement-associated cortical regions contralateral to the hand moved and an exclusive voxel activation of the primary motor, somatosensory, and posterior parietal cortices ipsilateral to the hand moved.

CONCLUSIONS

CNS damage in pure adrenomyeloneuropathy is not confined exclusively to spinal cord and seems to primarily involve the brain.