Diagnoses & Conditions

Multifocal Motor Neuropathy (MMN)

Understanding Multifocal Motor Neuropathy (MMN)

Multifocal motor neuropathy (MMN) is rare and believed to be an autoimmune disorder. An autoimmune disorder develops when the immune system malfunctions and creates antibodies that attack and cause damage to a part of the body. In MMN, the myelin sheath of motor nerves is attacked. The myelin sheath is the protective covering over nerves, which aids in sending nerve signals from spine to muscles. This attack on the myelin sheath results in muscle weakness.

Symptoms of Multifocal Motor Neuropathy (MMN)

Symptoms of MMN include weakness usually beginning in a single limb, for example, the hand or the ankle. The weakness is usually different from one side of the body to the other. Weakness will interfere with and make everyday activities such as writing, holding eating utensils or walking difficult. Other symptoms frequently seen are muscle wasting, cramping and twitching.

Diagnosing Multifocal Motor Neuropathy (MMN)

Diagnosing MMN can be difficult for many reasons. MMN may only affect a single nerve and cause minimal weakness in one limb, it may take a long time to determine MMN as the cause. MMN only affects motor nerves and the symptoms may mimic Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig's disease. Many people ultimately diagnosed with MMN are initially told they have ALS, which can be extremely frightening and stressful. Nerve conduction studies may show a nerve conduction block in MMN, but not with ALS. Conduction blocks are difficult to detect and may contribute to misdiagnosis. Additionally, not all patients with MMN have a conduction block. Because MMN is an autoimmune disorder, there may be antibodies present that are detectable with a blood test. However, they may only be present in half of the people with MMN.

Diagnostic testing may include:

  • Electromyography (EMG) to measure muscle activity.
  • Nerve conduction studies (NCS) to measure efficiency and speed of signals of the nerves.
  • Blood work to test for an anti-GM1 antibody which may be present in MMN.

Treating Multifocal Motor Neuropathy (MMN)

The primary treatment for MMN is immune globulin therapy administered into the blood stream intravenously (IVIG). The goal of IVIG in MMN is to stop the attack on the myelin sheath. This will then cause the symptoms to subside. Strength will increase and tasks that may have become difficult will become easier. Unlike ALS, MMN is treatable. It may take one to three courses of IVIG for patients to experience improvement. Your doctor will assess your response to therapy and determine how much IVIG you need to maintain your response. Most people with MMN usually require long-term/lifetime therapy.


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This content is not intended to substitute professional medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

Contact Nufactor

At Nufactor, we are committed to providing our patients the education, support and resources necessary to complete your IVIG treatment successfully and with the desired outcomes. Please contact us with any further questions.