A diagnostic decision tree for adult cerebellar ataxia based on pontine magnetic resonance imaging

• Published in: Journal of the neurological sciences Vol. 387; pp. 187 - 195
• Main Authors: Higashi, Miwa, Ozaki, Kokoro, Hattori, Takaaki, Ishii, Takashi, Soga, Kazumasa, Sato, Nozomu, Tomita, Makoto, Mizusawa, Hidehiro, Ishikawa, Kinya, Yokota, Takanori
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-04-2018
• Subjects: Magnetic resonance imaging; Multiple system atrophy; Pons; Spinocerebellar ataxia; Multiple system atrophy; Pons; Magnetic resonance imaging; Spinocerebellar ataxia
• ISSN: 0022-510X; 1878-5883
• DOI: 10.1016/j.jns.2018.02.022

Cerebellar ataxias (CAs) are heterogeneous conditions often require differential diagnosis. This study aimed to establish a diagnostic decision tree for differentiating CAs based on pontine MRI findings. Two-hundred and two consecutive ataxia patients were clinically classified into 4 groups: (1) spinocerebellar ataxia (SCA) with brainstem involvement (SCA-BSI), (2) Pure cerebellar SCA, (3) cerebellar dominant multiple system atrophy (MSA-c), and (4) Other CA. Signal intensity in pons was graded into 3 types: hot cross bun sign (HCBS), pontine midline linear T2-hyperintensity (PMH), or normal. The distance ratio of pontine base to tegmentum, named “BT-ratio”, was measured. The presence of HCBS indicated either MSA-c with a specificity of 97.7%, or SCA2. When PMH was observed, a BT-ratio above 3.54 strongly indicated SCA-BSI, namely Machado-Joseph disease, SCA1, or dentatorubral-pallidoluysian atrophy, whereas a BT-ratio below 3.54 indicated MSA-c or SCA2. When the signal intensity was normal, a BT-ratio above 3.52 indicated SCA-BSI, whereas a BT-ratio below 3.52 suggested Pure cerebellar SCA or Other CA with pure cerebellar type. The decision tree was confirmed useful in a different 30 CA patients. We propose that differential diagnosis of CAs can be supported by combining pontine MRI signal intensity changes and BT-ratio.
•We proposed a diagnostic decision tree for cerebellar ataxias based on pontine MRI.•HCBS indicated either MSA-c or SCA2, while PMH was not a specific sign.•Pure cerebellar SCA was highly unlikely if pontine signal changes were observed.•A new index named the BT-ratio was useful in differentiating cerebellar ataxias.