Study: Childhood strokelimited sensitivity for CT, limited access to MRI

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CT remains the modality of choice for detecting hemorrhagic stroke in children, while MRI wields significantly greater sensitivity for acute ischemic stroke, which means added delays to treatment due to MRI’s limited access in emergency care, according to a study published Feb. 2 in the Annals of Emergency Medicine.

Though rare, childhood stroke presents an urgent and often delayed emergency to physicians, resulting in large part from a lack of knowledge among emergency department (ED) physicians about the condition’s signs and symptoms. Moreover, children present differently and require distinctive treatments when presenting with acute ischemic stroke and hemorrhagic stroke.

In light of the absence of any studies assessing differences between acute ischemic and hemorrhagic strokes and with four previous studies having identified delays in treatment due to limited knowledge, the researchers sought to determine the clinical characteristics of radiologically-confirmed pediatric stroke in the ED, and to compare CT and MRI diagnostics of the condition.

The researchers retrospectively identified 81 pediatric patients, including 47 with acute ischemic strokes, 31 with hemorrhagic strokes and three with transient ischemic attacks. The most common symptoms recorded during acute ischemic stroke were focal limb weakness (observed in 64 percent of patients), facial weakness (60 percent), speech disturbance (46 percent) and limb incoordination/ataxia (26 percent). For hemorrhagic stroke, prevailing symptoms included headache (73 percent), vomiting (58 percent) and altered mental status (48 percent).

In the acute ischemic stroke/transient ischemic attack group, 36 of 50 patients underwent CT as the initial imaging modality, which was nondiagnostic in 16 of these patients. In the 17 scans performed at Royal Children’s Hospital in Melbourne, Australia, the site of the study, the median time from ED arrival to exam was 4 hours 20 minutes. MRI was performed on 47 patients and was the initial imaging modality for 14 of these patients, with the remaining three children presenting counterindications to MRI.

MRI confirmed stroke diagnosis in all 47 patients, though in 21 percent of children the exam was not performed for at least 24 hours after stroke onset.

CT was performed on 30 of 31 hemorrhagic stroke patients, confirming stroke diagnosis in all cases. The median time to imaging in the 17 CT scans performed at Royal Children’s Hospital was 2 hours 26 minutes after arrival in the ED. The only patient not undergoing CT had a diagnostic MRI performed at another institution prior to arrival at Royal Children’s.

“The key findings of this study are that symptoms and signs of pediatric acute ischemic stroke and hemorrhagic stroke are different and that CT imaging has limited sensitivity in detecting acute ischemic stroke,” Adriana Yock-Corrales, MD, from Royal Children’s Hospital emergency department and co-authors wrote.

Yock-Corrales and colleagues acknowledged that their retrospective study design was not ideal and might have affected their dataset.

The authors argued their study “suggests that urgent MRI is the best imaging modality for detection of acute ischemic stroke. Unfortunately, this is a major time-limiting step because of limited access to urgent MRI and the need for sedation or general anesthesia in children younger than 5 years.”

“CT is still considered to be the modality of choice in the emergency setting to detect the presence of hemorrhage acutely after the onset of symptoms,” the authors affirmed, “but MRI may be the more appropriate first-line neuroimaging modality to confirm the diagnosis of acute ischemic stroke.”