Objective: It is well known that patients with brainstem infarctions sometimes experience dizziness, vertigo and falls, although the exact mechanism is not clear. Therefore, we designed a study to quantify autonomic function in patients with brainstem infarction.

Methods: We examined autonomic function in 15 patients with brainstem infarctions, who had a history of vertigo, nausea, floating sensation and/or general fatigue during standing, and 31 age-matched controls using the composite autonomic scoring scale (CASS), which was used to grade autonomic function. The patients underwent initial autonomic assessment and then were subjected to aniracetam therapy. The drug was given orally (dose of 600 mg/day) for a duration of 56 days. Upon completion of aniracetam administration, the CASS was again tested.

Results: Upon initial assessment, the patients had mild reductions in mean blood pressure (MBP) and lack of an increasing heart rate (HR) within 5 min of head up-tilt, an impairment in BP correction during late phase II and reduced phase IV beat-to-beat BP response to the Valsalva maneuver, and reduced heart rate response to deep breathing (HRdb). CASS indicated mild autonomic dysfunction. After 8 weeks of treatment with aniracetam, the patients' symptoms improved and the autonomic tests showed improvement in autonomic function.

Conclusions: Part of the pathogenesis of recurrent vertigo or dizziness with brainstem infarction might be due to mild autonomic dysfunction. Aniracetam, which activates the cholinergic system in brain, might correct the cardiovagal system in these patients. The CASS may be a sensitive tool for assessing mild autonomic dysfunction in patients with brainstem infarction.