The Massachusetts General Hospital Handbook of Neurology

Authors: Flaherty, Alice W.; Rost, Natalia S.

Title: Massachusetts General Hospital Handbook of Neurology, The, 2nd Edition

Copyright 2007 Lippincott Williams & Wilkins

> Table of Contents > Adult Neurology > Syncope

Syncope

A. H&P

Try to find a witness who can describe the event.

• 1. Precipitants: Exertion, stress, meals, alcohol, drug, cough, swallowing, urination, postural change, head movements, poor POs.

• 2. Sequelae: Tonic/clonic movements, drowsiness, confusion, neuro changes, nausea, sweating, cold, incontinence, tongue biting, injury from fall, amnesia.

• 3. Exam: Orthostatic BP and HR (immediate and delayed), BP in both arms, bruits (carotid, subclavian, supraorbital, temporal), heart exam. Look for trauma from fall. Stool guaiac.

B. Causes

• 1. Cardiac:

  • a. Arrhythmic: AV block, sick sinus syndrome, long QT interval, pacer malfunction.

  • b. Obstructive: MI, global ischemia, valve stenosis or dysfunction, PE, pulmonary HTN, aortic dissection, tamponade, left atrial myxoma .

• 2. Vascular reflex:

  • a. Vasovagal: From fear, urination, Valsalva maneuver.

  • b. Orthostatic:

    • 1) Hyperadrenergic: Volume depletion, varicose venous pooling, supine hypotension of late pregnancy (pressure on aorta).

    • 2) ANS dysfunction: Vasoactive or antidepressant drugs, neuropathies, spinal cord dz, paraneoplastic dz, parkinsonian syndromes.

  • c. Carotid sinus hypersensitivity: A diagnosis of exclusion; can be elicited in 1/3 of normal old men.

    • 1) Cardioinhibitory: Common. Carotid sinus massage (see p. 206) causes sinus pause; blocked by atropine.

    • 2) Vasodepressor: Rare. Carotid sinus massage causes low SBP; blocked by epinephrine, not atropine.

• 3. Neurological: Vertebrobasilar TIA (carotid TIAs almost never cause syncope), seizure, subclavian steal, NPH.

• 4. Metabolic: Hypoxia, hypoglycemia, hyperventilation.

• 5. Psychiatric.

C. Tests

Rule out risk of sudden death; reserve further testing for recurrent syncope only.

• 1. Cardiovascular: EKG for MI, LV hypertrophy, arrhythmia. Consider echocardiogram, Holter monitor, ETT; perhaps signal averaged EKG, tilt test, cardiac electrophysiology study.

• 2. Blood: CBC, electrolytes, toxin screen, CPK.

• 3. CXR: If suspect PE ( ABG, V/Q scan), CHF, pericardial effusion, mitral stenosis.

P.119

• 4. Neuro tests (low yield unless focal deficit or bruits): CTA or MRA, carotid and cranial ultrasound, EEG.

• 5. Carotid sinus massage: See Arrhythmia, p. 205. Cardiac pause of >3 sec or SBP drop >30 points with sx or >50 points without sx is abnormal. Abnormal response confirms cause only if it reproduces sx and other causes are excluded.

D. Orders

VS q shift with orthostatic BPs, guaiac all stools, cardiac monitor, IV fluids slowly, keep BP >140. For ANS insufficiency, see Hypotension, p. 211.