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Brain stem stroke causing baroreflex failure and paroxysmal hypertension
A M Phillips1, D L Jardine, P J Parkin
1Department of General Medicine, Christchurch Hospital, New Zealand,
Stroke
|August 6, 2000
Summary
Brain stem stroke can cause neurogenic hypertension due to baroreflex dysfunction and increased sympathetic activity. This case highlights the link between medullary infarcts and paroxysmal hypertension.
Area of Science:
- Neurology
- Cardiovascular Physiology
- Neuroscience
Background:
- Paroxysmal neurogenic hypertension is rarely reported after brain stem stroke.
- The underlying mechanisms involve sympathetic overactivity and impaired baroreflex function.
- This study investigates these mechanisms using microneurography.
Observation:
- A 75-year-old woman experienced paroxysmal hypertension (220/110 mm Hg) post-left medullary infarct.
- Symptoms included tachycardia, diaphoresis, and headache, triggered by postural changes.
- Elevated serum catecholamines and reduced heart rate variability were noted.
Findings:
- Muscle sympathetic nerve activity (MNSA) was significantly increased (61 bursts/min vs. normal 34+/-18).
- The relationship between MNSA burst amplitude and diastolic blood pressure was altered.
- Autonomic responses to cold pressor and handgrip tests remained intact.
Implications:
- Unilateral brain stem infarction, particularly in the nucleus tractus solitarius region, can lead to neurogenic hypertension.
- This suggests partial baroreflex dysfunction and heightened sympathetic drive.
- Findings contribute to understanding brain stem stroke complications and autonomic regulation.