Most Strokes After TIA Occur Within 90 Days
NEW YORK, June 9 (Reuters Health)—Sixty percent of strokes seen after a transient ischemic attack (TIA) in patients with intracranial atherosclerotic disease occur within 90 days of the index event, according to a report in the June Archives of Neurology. Moreover, the risk of an early stroke after a TIA is comparable to the risk seen after a prior stroke.
“We are unaware of any prior studies that have attempted to quantify or qualify the early risk of stroke (within three to four months) after the occurrence of a TIA due to narrowing of a large brain artery,” lead author Dr. Bruce Ovbiagele, from the University of California at Los Angeles, told Reuters Health.
“We found that those with a TIA and those with a stroke ... carried the same early risk of future stroke, and that evidence of infarcts on brain imaging predicted early stroke risk after a TIA,” he noted. These findings “indicate that TIA patients should be taken just as seriously as stroke patients, since they carry similar early stroke risks, and that brain imaging can delineate future stroke risk.”
The findings are based on analysis of data for 569 patients enrolled in the Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) study, a randomized trial conducted at 59 sites. The subjects included 222 with a TIA in the preceding three months, 241 with a stroke, and 106 with both. All of the subjects had angiography-verified 50% to 99% narrowing of a major intracranial artery.
The 90-day risk of a stroke after TIA was 6.9%, which is statistically comparable to the 4.7% rate seen after a stroke. Among TIA-only patients, 60% of all strokes occurred within 90 days of the index event, compared with 34.4% of strokes seen after a prior stroke. Patients with both a stroke and TIA at baseline were roughly twice as likely as subjects with either condition alone to experience an early stroke, the researchers found. In TIA patients, the only significant predictor of an early stroke (HR = 4.7) was the presence of cerebral infarct on baseline neuroimaging, the report indicated.
Further research is needed, Dr. Ovbiagele said, to confirm the current findings and “to identify specific interventions that can be given promptly to reduce the early risk of stroke in these types of TIA patients. We are currently exploring the latter.”
Arch Neurol. 2008;65(6):733-737.
MRI Activity and Antibody Levels Chart MS Therapy Progress
NEW YORK, June 10 (Reuters Health)—During the initial stages of interferon beta treatment in patients with relapsing-remitting multiple sclerosis, monitoring by means of MRI scans and anti–interferon beta neutralizing antibodies (NAb) can be useful in predicting clinical response, Italian researchers reported in the June issue of the Journal of Neurology, Neurosurgery, and Psychiatry.
“Either having an MRI scan with signs of disease activity or a positive NAb test will predict a bad clinical response over the next two years of interferon beta treatment,” lead investigator Dr. Luca Durelli told Reuters Health.
Dr. Durelli, of Ospedale San Luigi Gonzaga, Turin, and colleagues studied 147 patients who underwent repeated MRI scans and NAb assays during the first six months of interferon beta therapy.
The researchers found a positive scan had a predictive sensitivity of 52% and a specificity of 80% for clinical disease activity in the following 18 months. The negative predictive value was 73%, and the positive predictive value was 62%. For NAb positivity, the corresponding values were 71% and 66%, and 92% and 29%. The combination of an active scan and NAb positivity had a sensitivity of 71%, a specificity of 86%, a negative predictive value of 94%, and a positive predictive value of 50%.
In other words, continued Dr. Durelli, “Patients developing both MRI activity as well as NAb positivity carry a 50% risk of developing clinical activity.... This could be an indication to switch them to a different immune-modulatory or immune-suppressive treatment.”
J Neurol Neurosurg Psychiatry. 2008;79(6):646-651.
Horizontal Head Impulse Test Helps Spot Stroke
NEW YORK, June 27 (Reuters Health)—The horizontal head impulse test (h-HIT) is useful in differentiating acute cerebellar strokes from vestibular neuritis, researchers reported in the June 10 issue of Neurology.
The test consists of a rapid, passive head rotation while the patient fixates on a central object. The normal vestibulo-ocular reflex is an equal and opposite eye movement that keeps the eyes stationary in space. Fixation cannot be maintained, however, if there is loss of vestibular afferent input.
“Thousands of patients are seen annually in US emergency departments with acute vestibular syndrome,” investigator Dr. Jorge C. Kattah told Reuters Health. This involves “vertigo, nausea and vomiting with nystagmus, unsteady gait, and head motion intolerance.