Flattened facial colliculus on magnetic resonance imaging in Machado-Joseph disease.

Atrophy of the pontine tegmentum and facial colliculus is a characteristic pathological feature of Machado–Joseph disease. We assessed whether this finding can be detected by conventional brain magnetic resonance imaging. A total of 17 patients with genetically confirmed Machado–Joseph disease, 15 disease controls (spinocerebellar ataxia type 6 and dentatorubral-pallidoluysian atrophy), and 17 normal subjects were examined using a 1.5-Tesla magnetic resonance imaging scanner. The widths of the facial colliculus, pontine tegmentum, and pontine base and the area of the fourth ventricle were measured on axial T2-weighted imaging. Pathological examination was performed in 9 Machado–Joseph disease patients. In addition, visual inspection of the facial colliculus was evaluated by receiver operating characteristic analysis. The width of the facial colliculus was significantly smaller in Machado–Joseph disease patients (0.37 ± 0.16 mm; mean ± standard deviation) than in normal subjects (0.73 ± 0.30 mm; P < .01), whereas the width of the pontine tegmentum was smaller in both Machado–Joseph disease (4.85 ± 0.58 mm) and dentatorubral-pallidoluysian atrophy (4.72 ± 0.59) patients than in normal subjects (6.35 ± 0.74 mm; P < .01). Visual evaluation of the facial colliculus showed sufficient area under the receiver operating characteristic curves to differentiate Machado–Joseph disease from dentatorubral-pallidoluysian atrophy (0.78) and spinocerebellar ataxia type 6 (0.87). Pathological evaluation showed significant atrophy of the facial colliculus in all Machado–Joseph disease patients. Atrophy of the facial colliculus is a feasible magnetic resonance imaging finding for diagnosing Machado–Joseph disease, and it is easily found as a flattening of the fourth ventricular floor. © 2012 Movement Disorder Society