Symptomatic unruptured isolated middle cerebral artery dissection: clinical and magnetic resonance imaging features

Isolated middle cerebral artery dissection (MCAD) is a rare but important clinical entity. The purpose of this study is to demonstrate the clinical and magnetic resonance imaging (MRI) features of symptomatic unruptured isolated MCAD.

We retrospectively analyzed clinical characteristics and MRI features of eight consecutive ischemic stroke patients diagnosed with unruptured isolated MCAD over a 1-year period.

All the patients had symptoms of cerebral infarction, whereas one patient was presented as transient ischemic attack. The most common finding of MCAD on the magnetic resonance angiography (MRA) images was irregular stenosis, found in six patients, followed by double lumen in three, while there was an occlusion in one, as well as stenosis and dilation in one. A total of five of seven patients demonstrated susceptibility vessel signal in the involved segment of MCA on susceptibility-weighted imaging. The high-resolution cross-sectional MRI (hrMRI) delineated intramural hematoma and double lumen in seven patients, respectively, and intimal flap in three, while gadolinium-enhanced T1-weighted images (WI) visualized mural linear or intramural crescentic enhancement in all the patients. In acute and chronic phase, the intramural hematomas appeared isointense or slightly hyperintense or unrecognizable, while gadolinium-enhanced T1WI showed slight to obvious enhancement. Subacute hematomas had a characteristic of crescentic hyperintense on T1- and T2WI.

The presence of unruptured isolated MCAD should be considered when a healthy young subject suffers from a sudden onset of ischemic symptoms or a minor head trauma accompanied by headache. Early MRA with combination of hrMRI precontrast and contrast-enhanced T1-weighted sequence may be helpful in definite diagnosis.