Stroke mimics and chameleons

Abstract

Purpose of review A stroke mimic is a situation in which a diagnosis of stroke at admission is not confirmed, and a stroke chameleon is a situation in which a stroke is revealed by clinical symptoms that are not usual in stroke. The objective of this review is to identify the most frequent clinical situations in which stroke mimics and chameleons are encountered and consequences for the patient. Recent findings The safety profile of intravenous thrombolysis (IVT) in patients who have stroke mimics is excellent, and intracranial hemorrhages are rare. Modern neuroimaging techniques help identifying most mimics. For stroke chameleons the role of imaging may be less important, especially when the clinical presentation is not suggestive of a brain disorder that request immediate neuroimaging. Education of health providers to identify such situations is crucial. Summary Stroke mimics account for up to 25% of admissions for probable strokes. The proportion of patients with stroke mimics decreases with use of MRI at baseline. Mimics cannot always be ruled out in emergency. The problem with mimics is that stroke facilities are not properly used, and patients may receive IVT. However, thrombolysis is usually well tolerated in mimics and we should not spend much time in all patients to improve diagnostic accuracy, knowing that the time lost is harmful in all patients, and will only prevent treating one mimic out of 100 patients. The problem with chameleons is more serious, because patients are not identified, and are not properly treated.

Recent developments in imaging of epilepsy

“…During the past decade, increased availability of advanced neuroimaging methods in emergency units has supported advances in knowledge about peri-ictal abnormalities related to transient biological processes associated with epileptic seizures. The vast majority of imaging data relate to the emergency diagnostic workup of acute ischemic stroke [2 ▪▪ ,3–7,8 ▪▪ ]. Peri-ictal clinical symptoms may mimic those of an acute ischemic stroke, and most of the adult patients suspected of presenting with a stroke mimic have a seizure due to a remote symptomatic cause or nonconvulsive status epilepticus (NCSE) [9].…”

Neurologists should not blame emergency physicians for stroke mimics, but train them to identify chameleons

“…They may receive an inappropriate treatment with rt-PA, but in this case, they have a very small risk of complication 5,6 . Finally, the only problem with mimics is an inappropriate use of available facilities 7 . Is this really a major problem?…”

“…Stroke chameleons are additional serious issues in emergency practice 7 . They are false negative, i.e., undiagnosed strokes.…”

“…They may have the presentation of acute peripheral vertigo, peripheral nerve palsy, seizure, movement disorders, acute behaviour disturbances, and so on. These patients are identified with delay and do not benefit from reperfusion therapies, or are not identified at all and do not benefit from secondary prevention measures 7 . Are they frequent?…”

Stroke mimicking an acute coronary syndrome: a stroke chameleon that is worth knowing

“…In comparison to stroke mimics, stroke chameleons are more serious issues in emergency practice [3] because they may lead to delayed hospital admissions, loss of chance to receive intravenous thrombolysis or to undergo mechanical thrombectomy, and delayed admission in stroke units. Patients with chameleons are also less likely to be properly investigated and consequently to receive an appropriate secondary prevention, leading to higher rates of long-term disability and mortality [4].…”