Syncope | The Massachusetts General Hospital Handbook of Neurology

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

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

> 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.