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Some types of temporary neurological
problems associated with increased risk for
stroke, dementia
Patients who experience symptoms described as transient
neurological attacks, such as temporary
amnesia or confusion, may have a higher risk
for stroke and dementia, according to a
study in the December 26 issue of JAMA.
Transient neurological attacks (TNAs) are episodes involving
temporary (less than 24 hours) neurological
symptoms.
These symptoms can be nonfocal (that can include
nonlocalizing cerebral symptoms), focal
(known as transient ischemic attacks [TIAs],
similar to ischemic stroke, except for
duration [commonly 2-15 minutes, maximum 24
hours]), or a mixture of both focal and
nonfocal.
Although it has been well-documented that patients with TIA
are at high risk of major vascular disease,
few studies have examined whether nonfocal
TNAs are a serious health threat, according
to background information in the article.
Michiel J. Bos, M.D., M.Sc., of Erasmus Medical Center,
Rotterdam, the Netherlands, and colleagues
studied the incidence and prognosis of
focal, nonfocal and mixed TNAs. The study
included 6,062 participants who were age 55
years or older and free from stroke, heart
attack, and dementia when they entered the
study (1990-1993), and were followed-up
until January 2005.
During the study a TNA occurred in 548 participants; 282 of
these were classified as focal, 228 as
nonfocal, and 38 as mixed. In both men and
women, the incidence rates for nonfocal TNAs
were almost as frequent as focal TNAs, and
for both types of events the incidence rates
strongly increased with increasing age.
Mixed TNAs were less frequent.
During follow-up, there were 619 cases of stroke, 848 cases
of ischemic heart disease, 662 vascular
deaths (also classified as having stroke
[192] or ischemic heart disease [430]) and
609 cases of dementia.
Compared with participants without TNA, participants with
focal TNA had more than twice the risk of
stroke and 2.6 times the risk of ischemic
stroke; the risk of stroke within 90 days
after focal TNA (TIA) was 3.5 percent.
Patients with nonfocal TNA had a 56 percent
higher risk of stroke and 59 percent higher
risk of dementia, than participants without
TNA.
Patients with mixed TNA were at increased risk of stroke,
especially ischemic stroke; ischemic heart
disease, especially heart attack; and
vascular death and dementia, compared with
participants without TNA.
“Our findings challenge the strong but unfounded conviction
that nonfocal TNAs are harmless. On the
contrary, our findings suggest that nonfocal
TNAs are not only a risk factor for stroke,
but also for dementia,” the authors write.
Editorial: Transient Neurological Attack - A
Useful Concept?
In an accompanying editorial, S. Claiborne Johnston, M.D.,
Ph.D., of the University of California, San
Francisco, writes that this study reports
important new information.
“… this is the first large-scale study of TNAs, and the
findings are intriguing for several reasons.
Most patients with nonfocal TNAs are
currently treated as though the condition
were benign. For some etiologies, such as
transient global amnesia, the evidence
supports this, but for most of these events,
there is no consistent evaluation, no
guidelines for treatment, and no information
on prognosis. This study argues that,
whatever is causing these events, the
prognosis justifies greater attention. More
needs to be done to identify the TNA
patients at greatest risk, to complete
evaluations, to rule out important
underlying disease, and to continue to study
this heterogeneous group.”
