|Year : 2017 | Volume
| Issue : 3 | Page : 148-149
Stroke chameleons: Uncommon presentations of a common disease
Pushpendra Nath Renjen1, Dinesh Chaudhari2
1 Department of Neurology, Institute of Neurosciences, Indraprastha Apollo Hospitals, New Delhi, India
2 Department of Neurology, Institute of Neurosciences/Internal Medicine, Indraprastha Apollo Hospitals, New Delhi, India
|Date of Web Publication||27-Oct-2017|
Pushpendra Nath Renjen
C-85, Anand Niketan, New Delhi - 110 076
Source of Support: None, Conflict of Interest: None
Stroke is one of the major causes of death and morbidity worldwide and carries an important economic impact. The diagnosis is still a clinical one, supported by brain imaging. However, up to 30% of suspected stroke presentations have a different diagnosis. In these cases, two scenarios must be considered: a false positive diagnosis, or “stroke mimic”, and a false negative or “stroke chameleon”. The diagnosis of acute ischemic stroke is often straightforward. The sudden onset of a focal neurologic deficit in a recognizable vascular distribution with a common presentation - such as hemiparesis, facial weakness and aphasia - identifies a common syndrome of acute stroke. But differential diagnostic problems remain because there are several subtypes of stroke and also because some non-vascular disorders may have clinical pictures that appear identical to strokes. Acute ischemic stroke (AIS) with neurological deficit is a very debilitating condition, especially in younger patients and the rate of false positive diagnosis of ischemic stroke labeled ''stroke mimics'' ranges from 1.3% to 25%.
Keywords: Chameleons, mimic, stroke, TIA
|How to cite this article:|
Renjen PN, Chaudhari D. Stroke chameleons: Uncommon presentations of a common disease. Apollo Med 2017;14:148-9
| Introduction|| |
Stroke is one of the major causes of death and morbidity worldwide and carries an important economic impact. The diagnosis is still a clinical one, supported by brain imaging. However, up to 30% of suspected stroke presentations have a different diagnosis. In these cases, two scenarios must be considered: a false-positive diagnosis or “stroke mimic,” and a false-negative or “stroke chameleon.” The diagnosis of acute ischemic stroke (AIS) is often straightforward. The sudden onset of a focal neurologic deficit in a recognizable vascular distribution with a common presentation, such as hemiparesis, facial weakness, and aphasia, identifies a common syndrome of acute stroke. However, differential diagnostic problems remain because there are several subtypes of stroke and also because some nonvascular disorders may have clinical pictures that appear identical to strokes. AIS with neurological deficit is a very debilitating condition, especially in younger patients and the rate of false-positive diagnosis of ischemic stroke labeled “stroke mimics” ranges from 1.3% to 25%.
| Stroke Chameleons|| |
As opposed to stroke mimics, a related but not well-explored concept is what may be called a “stroke chameleon.” This concept encompasses syndromes that do not appear to represent a stroke on initial presentation but are later found to represent an acute stroke. Stroke chameleons may present as malaise, loss of consciousness, encephalopathy, and acute psychosis and a myriad of other conditions. Stroke chameleons imitate other diseases due to their tempo of onset (e.g., gradual progression or stuttering) or have symptoms that do not necessarily implicate an arterial territory. It is uncommon to consider these patients for thrombolysis, but their recognition enables patients to benefit from secondary prevention. This article is focused on such stroke chameleons; [Table 1] gives some further examples.
| Discussion|| |
In a recent study conducted by Richoz et al., they studied acute stroke chameleons in a university hospital. They found that acute ischemic strokes are missed in patients with younger age with a lower cerebrovascular risk profile and may be masked by other acute conditions. Patients with chameleons present more often with milder strokes or coma, fewer focal signs, and cerebellar strokes and have higher disability and mortality rates at 12 months. These findings may be used to raise awareness in emergency departments to recognize and treat such patients appropriately.
Most strokes present as a deficit or loss of function. Uncommonly, movement disorders will present from a focal lesion such as ischemic stroke or hemorrhage. Acute hemiballismus, or unilateral dyskinesis, often result from acute vascular lesions in the subthalamic nucleus or connections. The movements may vary from wild flinging movements to mild uncontrollable unilateral movements. The key to diagnosis is the abrupt onset of symptoms and risk factors for cerebrovascular disease. A review notes that any kind of dyskinesia, hypokinetic as well as hyperkinetic, may be found from lesions at many different levels in the frontal motor cortical and subcortical regions.
Sensory complaints of either unusual sensations or loss of sensation are common in parietal and thalamic strokes. At times, the sensory manifestation of a stroke may take on the characteristics of another clinical condition. Chest pain and limb pain that mimicked that of myocardial infarction was reported in a small series of patients; most had thalamic strokes, but one had a lateral medullary infarct. Confusional states, agitation, and delirium have all been reported as a consequence of focal neurologic injury; structures involving the limbic cortex of the temporal lobes and the orbitofrontal regions are commonly involved. These states must be distinguished from the neglect syndromes and fluent aphasias, in which patients are often reported as confused but careful examination demonstrates a clear focal deficit.
Stroke can have an unusual presentation and can often not be immediately recognized. A thorough neurological examination, particularly focusing on the head impulse test, evaluation of nystagmus, and skew deviation, can properly distinguish a peripheral lesion from a vertebrobasilar stroke. Other findings, such as monoplegia or delirium, may infrequently be the sole manifestation of stroke. Diagnostic accuracy in stroke has been increased by improvement in imaging techniques. However, higher resolution brain imaging means that there is a greater risk of finding “incidentalomas,” not relevant to the presenting complaint. It is, therefore, essential to relate the clinical picture to the radiographic images.
| Conclusion|| |
Precise identification of stroke at the time of presentation can be difficult. Furthermore, coexisting medical conditions and the performance of physicians influence the correct diagnosis. The full workup (including magnetic resonance imaging) of all patients that may have a stroke is probably not feasible, and an initial clinical evaluation is still an important screening tool. The clinician should also recall that ischemic stroke, like other common diseases, does have uncommon manifestations. Acute stroke should be considered in neurologic syndromes where abrupt onset of symptoms figures prominently, particularly in patients with cerebrovascular risk factors.
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