Neuroimaging misinformation
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* Allan J. Fox

Publicizing the serious risks of traumatic dissection causing vertebrobasilar stroke, as Malvinder Parmar did recently,1 is essential to limit any associated risks, especially those that might result from vigorous chiropractic manipulation. However, the CT image published with Parmar's letter1 damages the credibility of documented information on this condition. The image shows the suprasellar cisterns and the upper pons, distant from the vertebral arteries. Specifically, the white arrow shows low density, indicating infarction in the right pons, and the black arrow shows the right suprasellar cisterns. The density between the anterior and posterior clinoids is typical for ossification of the dura connecting the clinoids. Calcification of the internal carotid is less likely. The scan slice does not show the vertebral artery, an editorial mistake as serious as labelling a knee “foot.”

Another error concerns the mention of calcification of the right vertebral artery. Calcification would not cause pontine infarction. Rather, it is an epiphenomenon of atherosclerotic disease. There is also no specific propensity for ipsilateral vertebral dissection to cause ipsilateral pontine stroke. Dissection of either vertebral artery can cause ipsilateral or contralateral infarction. Only infarction of the posterior inferior cerebellar artery is side specific.

**Allan J. Fox** Neuroradiologist Sunnybrook and Women's College Health Sciences Centre Toronto, Ont.

## Reference

1.  1. Parmar MS. Telephone stroke [letter]. CMAJ 2002; 167(10):1104.
    
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