1. Therapeutic Plasma Exchange for Myasthenia Gravis Clifford Blieden, MD Houston Methodist Hospital Department of Pathology and Genomic Medicine, Division of Transfusion Medicine

2. Who Are We? Physicians with residency training in Clinical Pathology with or without Anatomic Pathology Fellowship trained in Transfusion Medicine WE TAKE CALL!!!!

3. Myasthenia Gravis Neuromuscular disorder caused by circulating autoantibodies to the acetylcholine receptors in the post synaptic neuromuscular junction Associated with a variety of other autoimmune diseases such as Hashimotos thyroiditis, type I diabetes, lupus

5. Common Modalities for Diagnosing Myasthenia Gravis Serologic testing Acetylcholine receptor antibodies Muscle specific (MuSK) receptor antibodies 50% of seronegative MG patients may have antibodies to MuSK Muscle electromyography Edrophonium (cholinesterase inhibitors) test Muscle biopsy IgG deposition at neuromuscular junction by immunofluorescence

6. Current Treatment Options Medications: Increase acetylcholine (cholinesterase inhibitors; neostigmine, pyrostigmine) Decrease immune response (corticosteroids) Plasma exchange to remove antibodies Thymectomy Thymoma and MG are frequently associated

7. Plasmapharesis Word is derived from “plasma” and Greek word “aphaeresis” (take away) Blood is removed from the body and separated into separate components (plasma and red cell component) Continuous process requiring an afferent and efferent site of blood supply.

8. Why Plasma Exchange? Antibodies reside in the plasma component of the blood Removal of these antibodies temporarily decreases symptoms of myasthenia gravis Scheduled plasma exchange regimen useful in patients with disease not helped by medications

10. TPE and Myasthenia Gravis TPE is used to remove antibodies present in the plasma component May be applied in multiple settings (outpatient, inpatient, perioperative) Regarded as a category I indication (ASFA guidelines) Category I = disorders for which apheresis is accepted as first line therapy, either alone or in conjunction with other treatment modalities Patients MAY experience improvement of symptoms within 24 hours

11. Common side effects of plasma exchange Paresthesia Hypotension Urticaria Nausea Abdominal cramps

12. Hypocalcemia Common occurrence with plasma exchange due to citrate, an anticoagulant necessary to prevent blood from clotting during the exchange Citrate binds ionized calcium, hence hypocalcemia occurs Symptoms include perioral tingling, numbness Treated with IV or oral calcium supplementation

13. Hypotension Occurs in some patients Usually mild Important not to take certain blood pressure medications prior to plasma exchange (ACE inhibitors)