|Year : 2021 | Volume
| Issue : 1 | Page : 41-42
Pseudo-hyperdense MCA sign: The value of comparing CT densities of vessels on both sides
Department of Neurosurgery, National Neurosciences Centre, Kolkata, West Bengal, India
|Date of Submission||04-Feb-2021|
|Date of Decision||14-Jun-2021|
|Date of Acceptance||18-Jul-2021|
|Date of Web Publication||27-Aug-2021|
Dr. Prasad Krishnan
Department of Neurosurgery, National Neurosciences Centre, Kolkata, West Bengal
Source of Support: None, Conflict of Interest: None
Hyperdense middle cerebral artery (MCA) sign is a well-recognised sign of stroke radiology. However, less often reported is the pseudo 'hyperdense MCA sign' that looks ominous and may confound the clinician into thinking that he is dealing with a case of ischaemic stroke. We report a 56-year-old male who nearly underwent thrombolysis due to this sign seen on initial computed tomography imaging and highlight the way to avoid this pitfall.
Keywords: Hounsfield units, hyperdense middle cerebral artery sign, thromboembolic stroke
|How to cite this article:|
Krishnan P. Pseudo-hyperdense MCA sign: The value of comparing CT densities of vessels on both sides. J Cerebrovasc Sci 2021;9:41-2
|How to cite this URL:|
Krishnan P. Pseudo-hyperdense MCA sign: The value of comparing CT densities of vessels on both sides. J Cerebrovasc Sci [serial online] 2021 [cited 2021 Dec 1];9:41-2. Available from: http://www.jcvs.com/text.asp?2021/9/1/41/324818
| Introduction|| |
A 56-year-old male presented with disorientation, slurred speech and generalised weakness of 2 hours duration. He was not a known diabetic but was a hypertensive on medications. A computed tomography (CT) scan of the brain revealed hyperdense middle cerebral artery (MCA) on the right side [Figure 1], and he was diagnosed as having an ischaemic stroke. He was being prepared for thrombolysis, and blood investigations were sent, and a magnetic resonance (MR) imaging scan was done. However, this showed no brightness on diffusion-weighted imaging and no restriction in apparent diffusion coefficient scans [Figure 2]. Flow voids in bilateral MCAs on T2-weighted imaging were seen. MR angiography also revealed patent MCA on both sides [Figure 3]. Thrombolysis was withheld. His blood reports revealed hyponatremia which was thought to be the cause of his symptoms. He recovered with conservative treatment in a few hours. Further investigations revealed haemoglobin of 13.5 g% and hypertriglyceridemia. The CT images were re-assessed, and the Hounsfield units (HU) density of the hyperdense artery was found to be 46 HU. Careful observation showed hyperdense dots of the contralateral peripheral MCA branches as well. A diagnosis of pseudohyperdense MCA sign was then made.
|Figure 1: Computed tomography scan of the brain showing hyperdense middle cerebral artery on the right side. A hyperdense dot of the left middle cerebral artery branch is also visible on close examination on the left side|
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|Figure 2: Diffusion-weighted images (a and b) showing no parenchymal hyperintensity suggestive of an acute infarct. Apparent diffusion coefficient scans (c) also do not show any restriction|
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|Figure 3: (a) Axial T2 weighted image showing flow voids of middle cerebral artery on both sides. (b) Magnetic resonance angiography also reveals patent vessels bilaterally|
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| Discussion|| |
Hyperdense arteries on plain CT scan was first recognised as sign of thromboembolic stroke by Gács et al. in 1983. It is due to focally high haematocrit following thrombus formation that has high attenuation values in the CT scan as compared to normal vessels with flowing blood. The hyperdense MCA sign has been described as having high specificity but relatively low sensitivity (around 30% – as it may not always be present) and is the earliest CT scan finding in thromboembolic stroke. Although considered to be a bad prognostic indicator, it has been used to guide thrombolytic therapy, in patients who present early.
However, there are a few conditions such as polycythemia vera and cocaine ingestion (where the blood viscosity is high), herpes simplex encephalitis or contusions (where surrounding parenchyma is more hypodense) and vessel wall calcification where the artery may be seen in the absence of an intraluminal thrombus. These conditions will affect the contralateral vessels too and Koo et al. have emphasised that in all true cases of the hyperdense MCA sign the ratio of HU densities of the involved to the non-involved MCA must be >1.2. Retrospectively, in our case, this was found to be 1.03 (46 HU and 44 HU for the right and left sided MCA, respectively).
To conclude, an awareness of the entity of pseudo 'hyperdense MCA sign' and the possible predisposing factors is essential to avoid a misdiagnosis of stroke and attendant overtreatment. In doubtful cases comparing the HU densities of both MCAs or performing MR imaging will clinch the diagnosis.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]