The risk of subsequent stroke after a transient ischemic attack (TIA, or mini-stroke) is well known. As many as one person in 20 who has had a TIA will go on to have a full-blown stroke in the next 7 days. But there's another acronym - TNA - that also carries a warning.

A TNA is what neurologists call a transient neurologic attack; there are two kinds - focal and non-focal, with a 'focal' TNA being another expression for a TIA, in which the signs suggest malfunction of a single specific area of the brain, leading to numbness in a limb, speech difficulty, or loss of balance, etc. Non-focal TNAs are more diffuse, short-lived brain symptoms of uncertain origin, such as confusion, amnesia, dizziness, or fainting.

Now there's a report in the Journal of the American Medical Association concerning the prognosis following non-focal TNAs. Dutch researchers followed some 6000 people over 55 for more than 10 years. By the end of follow-up, those who'd suffered a TIA and those who'd suffered a nonfocal TNA had roughly similar clinical courses. Compared with people without any neurological attacks, the risk for a subsequent stroke among those with TIAs was 2.14 times greater; among those with nonfocal attacks, the risk was 1.56 greater; and among those with attacks showing both focal and nonfocal characteristics, the risk was 2.48 greater (but these patients were rare).

A further finding was that those patients with nonfocal TNAs also had a higher risk of major vascular diseases and dementia than those without TNAs. These results challenge the belief that nonfocal transient attacks are harmless. They should probably receive the same diagnostic and treatment regimens, short of hospitalization, accorded to TIAs.