syncope.pdf

Syncope Syncope is a transient, self-limited loss of consciousness due to acute global impairment of cerebral blood flow. The onset is rapid, duration brief, and recovery spontaneous and complete. Other causes of transient loss of consciousness need to be distinguished from syncope; these include...

Syncope Syncope is a transient, self-limited loss of consciousness due to acute global impairment of cerebral blood flow. The onset is rapid, duration brief, and recovery spontaneous and complete. Other causes of transient loss of consciousness need to be distinguished from syncope; these include:- Seizures Vertebrobasilar ischemia Hypoxemia A syncopal prodrome (presyncope) is common, although loss of consciousness may occur without any warning symptoms. Typical presyncopal symptoms include dizziness, lightheadedness or faintness, weakness, fatigue, and visual and auditory disturbances The causes of syncope The causes of syncope can be divided into three general categories: (1) Neurally mediated syncope ( vasovagal syncope) (2) Orthostatic hypotension (3) Cardiac syncope (1) Neurally mediated syncope ( vasovagal syncope) Neurally mediated syncope comprises a heterogeneous group of reflexes causing episodic vasodilation (or loss of vasoconstrictor tone) and bradycardia occur in varying combinations, resulting in temporary failure of blood pressure control. Peripheral Chemoreceptor System for Control of Respiratory Activity Stimulus (2) Orthostatic hypotension Orthostatic hypotension, defined as a reduction in systolic blood pressure of at least 20 mmHg or diastolic blood pressure of at least 10 mmHg within 3 min of standing or head-up tilt on a tilt table, is a manifestation of sympathetic vasoconstrictor (autonomic) failure Characteristic symptoms of orthostatic hypotension include lightheadedness, dizziness, and presyncope (near-faintness) occurring in response to sudden postural change. Tilt table testing (3) Cardiac syncope Cardiac (or cardiovascular) syncope is caused by arrhythmias and structural heart disease. Arrhythmias :Bradyarrhythmias that cause syncope include those due to severe sinus node dysfunction (e.g., sinus arrest or sinoatrial block) and atrioventricular (AV) block (e.g., Mobitz type II and complete AV block). Ventricular tachyarrhythmias frequently cause syncope. Structural heart disease like hypertrophic obstructive cardiomyopathy and aortic stenosis. High-Risk Features Indicating Hospitalization or Intensive Evaluation of Syncope APPROACH TO THE PATIENT WITH SYNCOPE The initial evaluation should include a detailed history, thorough questioning of eyewitnesses, and a complete physical and neurologic examination. Blood pressure and heart rate should be measured in the supine position and after 3 min of standing to determine whether orthostatic hypotension is present. An ECG should be performed if there is suspicion of syncope due to an arrhythmia or underlying cardiac disease. APPROACH TO THE PATIENT WITH SYNCOPE Syncope is easily diagnosed when the characteristic features are present; however, several disorders with transient real or apparent loss of consciousness may create diagnostic confusion (seizure) Tonic-clonic movements are the hallmark of a generalized seizure Incontinence of urine may occur with both seizures and syncope(more with seizures) Seizures, unlike syncope, are rarely provoked by emotions or pain. Seizures, unlike syncope, usually associated with tongue biting. Loss of consciousness associated with a seizure usually lasts longer than 5 min and is associated with prolonged postictal drowsiness and disorientation. Partial or partial-complex seizures with secondary generalization are usually preceded by an aura, commonly an unpleasant smell. Treatment of cardiac disease depends on the underlying disorder. Nonpharmacologic interventions should be introduced. Patient education regarding staged moves from supine to upright Warnings about the hypotensive effects of large meals Instructions about the isometric counter-pressure maneuvers that increase intravascular pressure Raising the head of the bed to reduce supine hypertension. Intravascular volume should be expanded by increasing dietary fluid and salt. Physical countermeasures to increase orthostatic tolerance Treatment of cardiac disease depends on the underlying disorder. Pharmacologic interventions should be introduced. Fludrocortisone acetate and Vasoconstricting agents such as midodrine, l dihydroxyphenylserine, and pseudoephedrine should be introduced Some patients with intractable symptoms require additional therapy with supplementary agents that include pyridostigmine, yohimbine, desmopressin acetate (DDAVP), and erythropoietin  Other CNS Cardinal Manifestations Confusion, a mental and behavioral state of reduced comprehension, coherence, and capacity to reason, is one of the most common problems encountered in medicine Delirium, a term used to describe an acute confusional state, Dizziness is an imprecise symptom used to describe a variety of sensations that include vertigo, light-headedness, faintness, and imbalance Vertigo is a sense of spinning or other motion(sense of rotation) light-headedness is commonly applied to pre-syncopal sensations due to brain hypoperfusion but also may refer to disequilibrium and imbalance Dementia is an acquired deterioration in cognitive abilities that impairs the successful performance of activities of daily living.