Proton magnetic resonance spectroscopy in Kennedy syndrome

Objective: To seek regional metabolite abnormalities in patients with Kenne dy disease (KD) using proton magnetic resonance spectroscopy. Design: Nine patients with KD showing the typical phenotype without clinica l signs of upper motor neuron involvement were compared with 17 male, age-m atched, healthy control subjects. Relative metabolite concentration for N-a cetyl (NA) groups, choline-containing groups (Cho), phosphocreatine(Cr), an d lactate (Lac) were determined in the brainstem and the motor region. Results: Pathologic Lac signals suggesting impaired energy metabolism were absent in patients and controls. In the brainstem area, patients with KD sh owed a significant reduction in the NA/Cho metabolite ratio (P = .01). In t he motor region, NA/Cho (P = .04) and NA/Cr (P = .03) ratios were significa ntly reduced. The reduction of the NA/Cho ratio in the motor region mainly resulted from decreased metabolite ratios in 3 patients. Changes in metabol ite ratios did not correlate with the number of trinucleotide cytosine-aden ine-guanine repeats from leukocytes. Because of the relatively small sample size due to the rarity of KD, these results should be considered prelimina ry. Conclusions: Spectroscopic data fail to provide further evidence for altere d energy metabolism in KD. Metabolite changes in the brainstem indicate a r eduction of the neuronal marker NA or elevated Cho. These findings may refl ect neuronal loss or gliosis consistent with the known pathologic features. In a subset of patients, altered metabolite ratios best explained by neuro nal loss suggest subclinical involvement of the motor region. The extent of metabolite changes does not correlate with the trinucleotide repeat length .