Vascular malformations of the thalamus with normal angiograms.

We describe two patients with fatal vascular malformations of the thalamus whom we thought had gliomas. They had progressive neurological impairment with subacute onset as adults. Computed tomography showed lesions of increased density with slight post-contrast enhancement; cerebral angiography was normal. Without biopsy, they received radiation therapy without benefit. Two other patients with similar radiological studies have done well with conservative treatment. We believe that these lesions have a distinctive appearance on CT, that vascular malformations can be diagnosed, even with normal cerebral angiograms, and distinguished with reasonable certainty from gliomas.