Stroke mimic diagnoses presenting to a hyperacute stroke unit
Dawson et al1 provide valuable data on the prevalence and nature of stroke mimics. We wish to draw attention to the evolving concept of ‘magnetic resonance imaging (MRI) negative stroke’ – persistent symptoms diagnosed as stroke but with no confirmatory neurological signs or imaging abnormality. In particular, we are seeing an increasing number of insurance claims for ‘stroke’ where there is no objective evidence of brain injury.
The original World Health Organization stroke definition2 required clinical signs consistent with stroke to be present. However, the recent definitions proposed by the American Heart Association and American Stroke Association3 included the following:
‘clinical evidence of cerebral, spinal cord or retinal focal ischemic injury based on symptoms persisting ≥24 hours or until death, and other aetiologies excluded’
‘an episode of acute neurological dysfunction presumed to be caused by ischemia or haemorrhage, persisting ≥24 hours or until death but without sufficient evidence to be classified as another type of stroke.’
In 1999, Ay et al identified 27 ‘clinically definite stroke’ cases with normal brain diffusion-weighted imaging (DWI) MRI on admission.4 63% were ultimately shown to have had a stroke in the clinically relevant area on interval MRI, but the remaining third had normal follow-up imaging. These patients were considered likely to have a variety of stroke mimics, as described by Dawson et al, or episodes of transient ischaemia lasting >24 hours and sometimes days.
In 2011, an Edinburgh group published a prospective study in which the diagnosis of stroke was made from case records by a panel of experts (neuroradiologist, vascular neurologist and stroke physician) who then reviewed the clinical and brain imaging data 21–52 months later.5 246 out of 253 patients were diagnosed with ‘definite stroke’ on presentation. While 81/246 (33%) had negative DWI at presentation, a quarter also had no MRI abnormality on follow-up. The authors concluded that ‘there is a high rate of negative MRI and DWI among patients with minor stroke (a third)’ and that ‘a negative MRI or DWI does not exclude the diagnosis of stroke’.
Therefore, there is now a narrative that stroke can be diagnosed on the basis of symptoms alone. We question this. Dawson et al rightly draw attention to the significant consequences of a stroke diagnosis on medical management and social and work activities. While it is recognised that DWI may not detect acute stroke, in our view persistent neurological symptoms and dysfunction are unlikely to be due to ischaemic stroke in the absence of neurological signs or relevant MRI abnormality on follow-up.
Conflicts of interest
The authors have no conflicts of interest to declare.
- © Royal College of Physicians 2017. All rights reserved.
References
- Dawson A
- Aho K, Harmsen P, Hatano S et al. Cerebrovascular disease in the community: results of a WHO collaborative study. Bull World Health Organ 1980;58:113–30.
- Sacco RL, Kasner SE, Broderick JP et al. An updated definition of stroke for the 21st century: a statement for healthcare professionals from the American Heart Association/American Stroke Association. Stroke 2013;44:2064–89.
- Ay H, Buonanno FS, Rordorf et al. Normal diffusion-weighted MRI during stroke like deficits. Neurology 1999;52:1784–92.
- Doubal FN, Dennis MS, Wardlaw JM. Characteristics of patients with minor ischaemic strokes and negative MRI: a cross sectional study. J Neurol Neurosurg Psychiat 2011;82:540–42.
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