Orthostatic syncope

Orthostatic syncope refers to syncope resulting from a postural decrease in blood pressure, termed orthostatic hypotension.^[1]

Orthostatic hypotension occurs when there is a persistent reduction in

Complications of orthostatic syncope include:[1]

1. Trauma or injury from falls during an episode of orthostatic syncope.
2. Stroke
   from changes in blood pressure due to decrease blood flow to the brain.
3. Cardiovascular complications including heart failure, chest pain, and arrhythmias
   .

Neurally mediated causes include conditions that cause either primary or secondary failure of the autonomic system:^[3]

• alcoholics, nutritional (vitamin B12 deficiency), amyloidosis
• Idiopathic
  postural hypotension
• Multi-system atrophies (parkinsonism, progressive cerebellar degeneration, dementia with Lewy bodies)
• Acute dysautonomia (seen in a variant of Guillain–Barré syndrome)
• Toxin, drug or infection-induced
  neuropathy

Non-neurally mediated causes include:^[3]

• Medications (
  vasodilators
  )
• Decreased
  effective intravascular volume
  )
• Physical deconditioning
• Sympathectomy

Pathophysiology

The

• Seizures
• Hypoglycemia
• head trauma
• Drug or alcohol intoxication
• Metabolic conditions including hypothyroidism, hypoxemia

Management

The history and physical examination are essential components in the evaluation of a patient with orthostatic syncope. The history may reveal a cause for

Review of the past medical history will reveal associated predisposing medical conditions (diabetes, Parkinsonism, dementia). ^[1] Patient compliance with both pharmacological and nonpharmacological therapy is recommended for successful treatment. ^[1]

Treatment of orthostatic syncope depends on the underlying cause and includes both nonpharmacological and pharmacological measures. ^[3][4]

Nonpharmacological treatment measures aim at either increasing venous return to the heart while decreasing venous pooling in the lower extremities or increasing blood volume to maintain blood pressure in the supine position and include^[3][4]:

1. Avoiding physical deconditioning in the elderly which helps maintain muscle tone in lower extremities
2. abdominal binders
3. leg crossing
4. Review of home medications and discontinue diuretics and vasodilators if possible
5. Increase water and fluid intake to about 2-3 liters per day, avoid dehydration, bolus water ingestion of 500mls of water in 2 to 3 minutes especially in the morning
6. Dietary measures including liberal salt diet 6-10g/day, eating small frequent low carbohydrate meals a day in case of postprandial orthostatic hypotension, avoid alcohol intake
7. In patients with
   autonomic dysfunction and supine hypertension, raising the head of the bed to 10 degrees at night reduces nocturnal diuresis
8. Life style modification by avoiding activities that increase
   core temperature and cause peripheral vasodilatation such as avoiding saunas, spas, hot tubs, prolonged hot showers, and excessive high-intensity exercise

The goal of pharmacological treatment is to increase blood volume or peripheral vascular resistance and includes[3]^[4]:

1. Midodrine 2.5 to 15 mg orally once to thrice daily
2. Fludrocortisone 0.1 to 0.2 mg daily in the morning titrated up to 1 mg daily if needed
3. Pyridostigmine 30 to 60 mg orally trice daily
4. Yohimbine 5.4 to 10.8 mg orally trice daily
5. Octreotide 12.5 to 50 ug subcutaneously twice daily
6. Cafergot such as caffeine 100 mg and ergotamine
   100 mg