eMedicine Specialties > Neurology > Neuromuscular Diseases

Periodic Paralyses: Treatment & Medication

Author: Naganand Sripathi, MD, Director, Neuromuscular Clinic, Department of Neurology, Henry Ford Hospital
Contributor Information and Disclosures

Updated: Aug 26, 2009

Treatment

Medical Care

Treatment is often necessary for acute attacks of hypokalemic periodic paralysis (PP) but seldom for hyperkalemic periodic paralysis (PP). Prophylactic treatment is necessary when the attacks are frequent.

• Hypokalemic periodic paralyses
  • During attacks, oral potassium supplementation is preferable to IV supplementation. The latter is reserved for patients who are nauseated or unable to swallow. Potassium chloride is the preferred agent for an acute attack (assuming a normal renal function).¹⁰  A reasonable initial dose for a 60-120 kg man (ie, 0.5-1 mEq/kg) is 60 mEq. Typically, 40-60 mEq of K⁺ raises the potassium concentration by 1.0-1.5 mEq/L, and 135-160 mEq of K⁺ raises plasma potassium by 2.5-3.5 mEq/L. Aqueous potassium is favored for quicker results. If there is no response in 30 minutes, an additional 0.3 mEq/kg may be given. This should be repeated up to 100 mEq of potassium. Beyond this, monitoring of serum potassium is warranted prior to further supplementation. Typically, one should not exceed a total dose of 200 mEq in a day. 
  • Intravenous potassium is reserved for cardiac arrhythmia or airway compromise due to ictal dysphagia or accessory respiratory muscle paralysis. IV potassium chloride 0.05-0.1 mEq/kg body weight in 5% mannitol as a bolus is preferable to continuous infusion. Mannitol should be used as solvent, as both sodium and dextrose worsen the attack. Only 10 mEq at a time should be infused with intervals of 20-60 minutes, unless in situations of cardiac arrhythmia or respiratory compromise. This is to avoid hyperkalemia at the end of an attack with shift of potassium from intracellular compartment into the blood. Continuous ECG monitoring and sequential serum potassium measurements are mandatory.
  • For prophylaxis, acetazolamide is administered at a dose of 125-1500 mg/d in divided doses. Dichlorphenamide 50-150 mg/d has been shown recently to be equally effective. This can be used as a first line of therapy or in patients who became refractory after initial improvement with acetazolamide. Potassium-sparing diuretics like triamterene (25-100 mg/d) and spironolactone (25-100 mg/d) are second-line drugs to be used in patients in whom the weakness worsens, or in those who do not respond to carbonic anhydrase inhibitors. Spironolactone may cause gynecomastia, but this is less with eplerenone. Blood pressure monitoring is advised. Because these diuretics are potassium sparing, potassium supplements may not be necessary.
• Thyrotoxic PP: Treatment consists of controlling thyrotoxicosis and beta-blocking agents. Potassium supplementation, propranolol, and spironolactone may be helpful during the attacks as well as for prophylaxis. Propranolol in doses of 20-40 mg twice a day may be sufficient to control recurrent attacks of periodic paralysis.
• Hyperkalemic periodic paralyses
  • Fortunately, attacks are usually mild and rarely require treatment. Weakness promptly responds to high-carbohydrate foods. Beta-adrenergic stimulants, such as inhaled salbutamol, also improve the weakness (but are contraindicated in patients with cardiac arrhythmias).
  • In severe attacks, therapeutic measures that reduce hyperkalemia are utilized. Continuous ECG monitoring is always needed during the treatment. Thiazide diuretics and carbonic anhydrase inhibitors are used as prophylaxis. Thiazide diuretics have few short-term side effects; they are tried as first-line treatment. Occasionally, thiazide diuretics may result in paradoxical hypokalemic weakness, which responds to potassium supplementation.
• Paramyotonia congenita: Because weakness is uncommon, treatment is aimed at reducing myotonia. While the above-mentioned diuretics can be tried, they are often not effective. Mexiletine has been shown to be helpful but is contraindicated in patients with heart block.
• Potassium-associated myotonia: Treatment with mexiletine or a thiazide diuretic may reduce the severity of the myotonia.
• Andersen-Tawil syndrome: A combination of amiodarone and acetazolamide resulted in a long-lasting improvement in one patient. Potassium supplementation, potassium-sparing diuretics, beta-adrenergic blockers, and carbonic anhydrase inhibitors have all been found effective. Implantation of a cardiac defibrillator has rarely been performed.

Surgical Care

Malignant hyperthermia susceptibility has been noted in HypoPP with calcium channel mutations. It is prudent to monitor all patients with periodic paralysis for this complication.     

Diet

• Hypokalemic PP: Low-carbohydrate and low-sodium diet may decrease the frequency of attacks.
• Hyperkalemic PP: Glucose-containing candy or carbohydrate diet with low potassium may improve the weakness.

Medication

The goals of pharmacotherapy are to reduce morbidity and prevent complications.

Carbonic anhydrase inhibitors

Carbonic anhydrase (CA) is an enzyme found in many tissues of the body, including the eye. It catalyzes a reversible reaction whereby carbon dioxide becomes hydrated and carbonic acid dehydrated.

Acetazolamide (Diamox)

Exact mechanism of action unknown. In hypokalemic PP, may decrease potassium inflow to muscle because of metabolic acidosis. In hyperkalemic PP, kaliopenic effect of CA inhibitors may be beneficial. Recent data suggest carbonic anhydrase inhibitors activate skeletal muscle BK channel (Ca²⁺ -activated potassium channel).

Dichlorphenamide (Daranide)

May improve clinical condition of patients with hypokalemic PP or hyperkalemic PP. Kaliopenic effect of CA inhibitors may be beneficial.

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