Plasmapheresis in neurological diseases

1. Big picture

Plasmapheresis, clinically usually called plasma exchange (PLEX), is an acute immunotherapy used in neurological diseases where circulating pathogenic antibodies, immune complexes, complement, or inflammatory plasma factors contribute to the disease.

The key exam sentence:

Plasma exchange is useful in antibody-mediated immune neurological diseases, especially myasthenia gravis, Guillain-Barré syndrome, CIDP, severe NMOSD attacks, and selected autoimmune encephalitis or demyelinating relapses.

It is not useful for degenerative motor neuron diseases such as ALS or spinal muscular atrophy.

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2. Definition

Plasmapheresis / plasma exchange is a procedure in which the patient’s plasma is removed and replaced with albumin solution, fresh frozen plasma, or another replacement fluid.

The aim is to remove circulating pathogenic factors such as:

• autoantibodies;
• immune complexes;
• complement components;
• cytokines;
• paraproteins;
• inflammatory mediators;
• toxins in selected non-neurological contexts.

In neurology, it is mainly used for immune-mediated diseases.

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3. Mechanism of action

Plasma exchange works by physically removing pathogenic plasma components.