Diffusion-Weighted Magnetic Resonance Imaging in Brain Death

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To the Editor: The case report on diffusion-weighted imaging (DWI) in brain death by Lovblad and Bassetti1 in the February issue of Stroke may be appealing but deserves elaboration. The DWI studies in the case report shows widespread ischemia, and the MR angiography shows absence of flow in the intracranial portion of the carotid arteries. However, it is not stated in the report whether there was flow void in the extracranial carotid arteries. Its presence may have suggested a diagnosis of bilateral carotid artery occlusion (eg, due to dissection) resulting in bilateral hemispheric infarction as the cause for the patient’s coma. Additionally, the authors did not comment on whether there was flow in the basilar artery. This information may have been available to the authors but was not commented on in the text. However, much more disturbing is that this communication wrongly suggests that an imaging modality can diagnose brain death even when the clinical examination shows some remnant of brain stem reflexes. We are not certain what the authors meant by “The neurological examination after the MRI showed an intubated comatose patient who had deteriorated neurologically.”1 It is possible that the patient had met the criteria for brain death, but the authors did not provide details on clinical testing. Brain death is the irreversible loss of function of the brain and brain stem.2 3 The diagnosis of brain death in adults in the United States is not, as the authors stated, “usually supported by confirmatory tests.” The article quoted here did not propose that view.2 The guidelines proposed by the American Academy of Neurology stated that “… confirmatory test is not mandatory but desirable when specific components of the clinical testing cannot be reliably performed. …”3 Differences in recommendations for confirmatory tests after a …