Structural and functional brain imaging in Friedreich's ataxia.

BACKGROUND

Although the major neuropathologic changes in Friedreich's ataxia (FA) affect the spinal cord and peripheral nerves, we previously found abnormally increased glucose metabolism in the cerebral hemispheres in ambulatory patients and a return toward normal metabolism in nonambulatory patients.

OBJECTIVE

To determine whether brain atrophy accompanies the decline in cerebral glucose metabolism in FA and whether the degree of atrophy and the extent of decline in cerebral glucose metabolism are related to clinical severity.

DESIGN

Prospective series.

SETTING

University referral center.

PATIENTS

Twenty-two patients with FA and 26 patients with dizziness, headache, or minor acute head trauma, serving as control subjects, who underwent computed tomographic scans that were interpreted as normal.

MEASURES

In patients with FA and control subjects, regional atrophy was assessed using subjective and objective measures on computed tomographic scans. In patients with FA, local cerebral glucose metabolism was measured with positron emission tomography, and clinical severity was assessed with a clinical rating scale.

RESULTS

Atrophy in the cerebral hemispheres, cerebellum, and brain stem was significantly greater in patients with FA than in control subjects, and the degree of atrophy correlated with the clinical severity. Local cerebral metabolic rate for glucose declined significantly from the initially elevated levels in the thalamus, cerebellum, and brain stem in correlation with increasing clinical severity.

CONCLUSIONS

The structure and function of wide-spread brain regions including the cerebral hemispheres are abnormal in FA, and these abnormalities correlate with the clinical severity.