Reply

We thank Dr. Soto-Ares for his kind comments regarding our article (1) and extend our compliments on his very interesting article in the same issue of the AJNR (2). We agree with his comments that a classification based on embryology, genetics, or signaling molecules is optimal for the description of malformations; indeed, this subject was discussed in our article. However, as Dr. Soto-Ares acknowledges, such a classification is very difficult and we are a long way from having enough knowledge of cerebellar genetics and molecular biology to accomplish such a classification. For the present, we think that a radiologic classification is a useful first step in studying this complicated group of diseases, just as it has proved useful in studying cerebral cortical malformations (3, 4) and anomalies of the cerebral commissures (5, 6).

Regarding Dr. Soto-Ares’ question about the pathogenesis of focal cerebellar cortical dysplasias in the absence of cerebral anomalies, we can suggest several possibilities, including focal ischemia or infection, somatic mosaicism, or different dosages of the same mutation in the same gene in different parts of the CNS. We agree that these are important questions that are not possible to answer by radiologic investigation.

We are delighted to have interested and enlightened colleagues such as Dr. Soto-Ares working in this field of study. The contributions of Dr. Soto-Ares and his colleagues to the study of cerebellar malformations have been both interesting and enlightening (2, 7). As advances in this field result from the cooperation of all those interested in the subject, we are happy that he has found our article worthy of comment and we hope for further interactions with his group and with others who have interest in cerebellar development and maldevelopment.

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