Even apparently low risk patients with transient ischaemic attack (TIA) and symptoms should be investigated with brain MRI scan for diffusion restriction, research suggests.

The international Diagnosis of Uncertain-Origin Benign Transient Neurological Symptoms (DOUBT) study, which included Australian centres, comprised more than 1,000 patients with clinical assessment then MRI within eight days of symptom onset.

The study found acute infarcts (ie, DWI-positive lesions detected on brain MRI scans) were observed in 13.5% of patients. About two thirds had a single lesion and the rest had multiple lesions.

It also found 52% of patients were initially diagnosed with provisional ischaemia, including minor stroke or TIA, on clinical assessment including a detailed history and neurologic examination.

Only 33.6% of patients for whom the treating physician thought that the patient had a deficit consistent with a stroke actually had evidence of ischaemia on MRI scans.

The final diagnosis was revised in 30% of patients after brain MRI.

One-year follow-up showed the risk of stroke to be low (0.7%) but substantially higher in the group with multiple lesions (4.3%).

“The implication of this finding is that if the diagnosis of TIA or minor stroke is considered, even with low-risk features, early MRI must be completed within 1 week to make a definitive diagnosis of ischemic stroke,” the study authors said.

“A total of 30.0% of patients in this population had a change in their final clinical diagnosis, partially based on findings from urgent MRI.”

“More important, the risk of recurrence can be stratified by MRI findings.”

The researchers said the failure to make a correct diagnosis of stroke results in a missed opportunity for stroke prevention while the incorrect diagnosis of stroke results in use of therapy such as antiplatelet therapy that has the capacity to harm in healthy elderly people.

The corollary was that normal MRI scans were reassuring in this population with a high negative predictive value (99.8%) for future stroke, they noted.

The multicentre study included neurologists from Northern Clinical School, University of Sydney, Royal North Shore Hospital and the Melbourne Brain Centre at the Royal Melbourne Hospital.

An accompanying editorial in JAMA Neurology said a definitive diagnosis could be elusive in patients presenting with symptoms of short duration or a lower-risk phenotype.

Yet patients with symptoms considered low risk often undergo less extensive evaluations.

The DOUBT study provided important new data to reinforce the necessity of performing MRI scans in patients with TIA or minor stroke, they said.

“These data argue that an MRI is a necessary component of the evaluation in virtually all patients presenting with symptoms suggestive of a TIA or minor stroke, including those with short-duration motor or language deficits or persistent low-risk neurologic symptoms,” they wrote.