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Chapter 021. Syncope (Part 5)

Cerebrovascular Disease Cerebrovascular disease alone rarely causes syncope but may lower the threshold for syncope in patients with other causes. The vertebrobasilar arteries, which supply brainstem structures responsible for maintaining consciousness, are usually involved when cerebrovascular disease causes or contributes to syncope. An exception is the rare patient with tight bilateral carotid stenosis and recurrent syncope, often precipitated by standing or walking. Most patients who experience lightheadedness or syncope due to cerebrovascular disease also have symptoms of focal neurologic ischemia, such as arm or leg weakness, diplopia, ataxia, dysarthria, or sensory disturbances. Basilar artery migraine is a rare disorder that. | Chapter 021. Syncope Part 5 Cerebrovascular Disease Cerebrovascular disease alone rarely causes syncope but may lower the threshold for syncope in patients with other causes. The vertebrobasilar arteries which supply brainstem structures responsible for maintaining consciousness are usually involved when cerebrovascular disease causes or contributes to syncope. An exception is the rare patient with tight bilateral carotid stenosis and recurrent syncope often precipitated by standing or walking. Most patients who experience lightheadedness or syncope due to cerebrovascular disease also have symptoms of focal neurologic ischemia such as arm or leg weakness diplopia ataxia dysarthria or sensory disturbances. Basilar artery migraine is a rare disorder that causes syncope in adolescents. DIFFERENTIAL DIAGNOSIS Anxiety Attacks and Hyperventilation Syndrome Anxiety such as occurs in panic attacks is frequently interpreted as a feeling of faintness or dizziness resembling presyncope. However the symptoms are not accompanied by facial pallor and are not relieved by recumbency. The diagnosis is made on the basis of the associated symptoms such as a feeling of impending doom air hunger palpitations and tingling of the fingers and perioral region. Attacks can often be reproduced by hyperventilation resulting in hypocapnia alkalosis increased cerebrovascular resistance and decreased cerebral blood flow. The release of epinephrine also contributes to the symptoms. Seizures A seizure may be heralded by an aura which is caused by a focal seizure discharge and hence has localizing significance Chap. 363 . The aura is usually followed by a rapid return to normal or by a loss of consciousness. Injury from falling is frequent in a seizure and rare in syncope since only in generalized seizures are protective reflexes abolished instantaneously. Sustained tonic-clonic movements are characteristic of convulsive seizures but brief clonic or tonic-clonic seizure-like activity can accompany