NEW ORLEANS—Among patients with false negative results on diffusion-weighted imaging (DWI) tests, ataxic hemiparesis and internuclear ophthalmoplegia are the most common stroke syndromes, according to research presented at the 64th Annual Meeting of the American Academy of Neurology. The majority of patients with false negative DWI tests had posterior circulation or lacunar stroke.
To identify the stroke syndromes that are most likely to be DWI negative, Jennifer Watts, MBBS, Stroke Unit Resident at the Fremantle Hospital and Health Service in Australia, and colleagues examined the records for 996 patients who were admitted to the Fremantle Hospital Stroke Unit between November 2005 and June 2011 and diagnosed with acute ischemic stroke. The researchers identified 701 patients who had had an MRI, 31 of whom had no DWI changes.
Of these 31 patients, 16 had a confirmed diagnosis of acute ischemic stroke. Their median age was 72, and 11 were male. Eleven patients had hypertension, two had atrial fibrillation, two had type 2 diabetes, and two had dyslipidemia. The patients’ median time from stroke onset to MRI scan was one day; median NIH Stroke Scale score at the time of MRI was 3. The MRI evidence for 11 patients was consistent with small vessel disease.
Experienced stroke neurologists and neuroradiologists reviewed the 16 patients’ case notes and found that five patients had ataxic hemiparesis, and five had internuclear ophthalmoplegia. Three patients had lateral medullary syndrome, two had hemiballismus, and one had dysphasia. In addition, eight patients had posterior circulation stroke, seven had lacunar stroke, and one had partial anterior circulation stroke.
Four patients received a follow-up MRI, and two exhibited a new signal change that had not been observed on the previous scan. Neither of the patients with ischemia on the second MRI had new or progressive neurologic deficits before the new imaging./p>
“Accepting the large assistance MRI provides in respect to the diagnosis of stroke in the acute setting, we recommend that there not be a total reliance on this investigation for the diagnosis of stroke,” Tony Alvaro, MBBS, FRACP, Head of the Stroke Unit at Fremantle Hospital, told Neurology Reviews. “Based on our study, this [principle] appears to be particularly relevant for posterior circulation and lacunar stroke syndromes./p>
“Though we did not specifically assess the utility of repeat scanning in our series, we did demonstrate evidence of stroke in some patients who did undergo repeat scanning,” Dr. Alvaro continued. “Therefore, future studies may assist with the correct method of confirming the diagnosis of stroke.”