Overview

Miller-Fisher Syndrome (MFS) is a rare disease that causes the immune system, notorious for its ability to protect the body from nasty germs, and to wrongfully attack nerves, responsible for delivering the brain’s messages to every point of the body. This causes MFS’ defining symptoms: reduced ability to / difficulty performing eye movements, unsteadiness and difficulty coordinating limb movements, and an absence of the body’s ability to tolerate a load (tendon reflexes). MFS is related to Guillain-Barré syndrome (GBS); both are rare diseases where the immune system attacks the nerves often caused by Campylobacter bacterial infections. These two conditions are distinguishable by the first area of the body affected, with MFS typically starting in the upper body and GBS affecting the lower body first before spreading upwards.¹

Intravenous immunoglobulin (IVIG) therapy is a treatment designed for autoimmune conditions which aims to prevent the body from attacking itself by replenishing self-attacking immune cells with healthy immune cells from a donor. As a result, IVIG therapy reduces inflammation and prevents the attacks on the nerves seen in MFS, stopping the condition from progressing.² This article aims to explore MFS, IVIG therapy, and consequently, the benefits of IVIG therapy for MFS patients. 

Understanding miller-fisher syndrome

Pathophysiology of MFS

MFS is caused by the immune system mistakenly attacking nerve cells, necessary for carrying messages from the brain to the rest of the body. The most common cause of MFS is infection with a bacteria called Campylobacter. When the immune system tries to attack the infection, it produces antibodies which act as “off” switches to the bacteria. However, sometimes, these antibodies get confused and attack the body’s nervous tissues instead, causing MFS. 

The antibodies produced in MFS patients are termed anti-GQ1b antibodies, which bind to a molecule called GQ1b to try and destroy it. GQ1b is an essential molecule in nerve cells, especially for nerves involved in eye movement and limb coordination. It allows for cell communication and for messages to be sent across the body. When anti-GQ1b antibodies are present, an immune response is triggered against the body’s nerves, causing inflammation which impairs nerve function through damage to their protective blanket, the myelin sheath.  Damage to the myelin sheath leads to the development of symptoms.³

Symptoms and diagnosis

There are three defining symptoms and features of MFS patients:¹

1. Ophthalmoplegia: weakness of the eye muscles, making eye movement more difficult. This often presents itself as doubled or blurred vision
2. Ataxia: means ‘without coordination’ and refers to reduced muscle control over the arms and legs. This results in a lack of balance, and coordination, and increased difficulty in walking 
3. Areflexia: a loss of tendon reflexes such as the knee-jerk reaction, increasing the risk of injury

MFS can develop up to four weeks after the initial infection however; its symptoms develop rapidly and require immediate medical attention.

Diagnosing MFS involves a combination of clinical examination, patient history, and laboratory/ medical testing. In the clinic, patients present with the symptoms listed above. MFS is suspected when the patient presenting with MFS symptoms has recently had a respiratory or gastrointestinal tract infection. The condition is then confirmed as MFS with the following laboratory and medical tests:

• Blood tests: used to detect anti-GQ1b antibodies
• Lumbar puncture: used to detect protein concentration levels in the cerebrospinal fluid which, when elevated, indicate MFS
• Nerve conduction studies: can reveal abnormal nerve activity suggestive of MFS-mediated immune attack
• MRIs and CT scans: rule out other neurological conditions rather than diagnose MFS, but can provide certainty to the diagnosis

Epidemiology

GBS affects approximately 1 - 2 people out of every 100,000 in the population, with MFS making up a fraction of this total. MFS has a slight predominance in male patients, and occurs in all age groups, with no age more susceptible than others. The incidence of MFS is greater in Asian populations, accounting for 15-25% of reported GBS cases. Studies have shown an incidence rate of 18% in Hong Kong, and 8% in Thailand, reducing to 7% of GBS patients in Italy.³ 

Overview of IVIG therapy

Definition and composition of IVIG therapy

IVIG therapy is the direct infusion of healthy immune cells, with no anti-GQ1b antibodies, into a patient with an autoimmune condition using an IV (intravenous) line. 

IVIG is composed of plasma, the liquid portion of the blood which contains immune cells, donated by thousands of healthy individuals. After donation, plasma is processed to extract immunoglobulins, proteins which act as antibodies.⁴ 

Mechanism of action

There are two main ways in which IVIG therapy helps the immune system:  by modulating the immune system and providing extra antibodies. Both of these mechanisms help reduce the impact of the autoimmune condition.⁵

The immune system becomes more controlled, or modulated, when IVIG therapy is received, reducing its over-reactiveness to self. This is achieved by reducing the number of antibodies responsible for the autoimmune response and therefore, limiting potential damage.⁵ 

The additional antibodies within IVIG therapy act as a boost to the immune system, providing more antibodies to fight off infections, which is especially useful for individuals with weakened or compromised immune systems. Inflammation-causing immune cells also become blocked by these new immune cells, reducing pain and swelling.⁵

General uses of IVIG in autoimmune and neurological disorders

IVIG is used to treat various autoimmune and neurological conditions, aiming to modulate and reduce harmful immune responses. Examples include:⁶

• Immune thrombocytopenia:  where the immune system attacks blood cells called platelets, causing bleeding and bruising
• Myasthenia gravis: an autoimmune condition causing weakened skeletal muscles due to an immune attack on the connections between nerves and muscles
• Lupus: widespread immune attack across the body, characterised by joint pain, fatigue, and rashes on the skin
• Multiple sclerosis: the brain and spinal cord become targeted by the immune system causing issues with balance, coordination, vision, and bodily sensations
• GBS
• MFS

IVIG therapy in miller-fisher syndrome

The rationale for using IVIG therapy in MFS

Typically, IVIG therapy is the first-line treatment for MFS, consisting of high-dose infusions of antibodies administered daily over five days. IVIG therapy in MFS patients aims to block the effects of the anti-GQ1b antibody by neutralising these antibodies in the antibody pool, thereby preventing further damage to the myelin sheath of nerves.¹

Clinical evidence and studies supporting IVIG use

A large study involving 92 participants administered IVIG therapy to MFS patients, showing a significant reduction in symptoms and a faster recovery time. This trial supports the belief that reducing the binding of anti-GQ1b antibodies limits MFS and promotes patient recovery.⁷

Administration of IVIG

The treatment of MFS is based on the framework provided for GBS since MFS is a less common variant of GBS. However, treatment can vary between patients. Typically, a total of 2 g of IVIG is administered for every kg of body weight every day over 2 to 7 days. The protocol of treatment varies greatly depending on patient characteristics, however, an example of a 2-day protocol would entail 1 g/ kg on both days.³

Efficacy and outcomes

IVIG therapy has various short- and long-term benefits for MFS patients, including:⁷

• Rapid and sustained symptom relief
• Faster recovery time
• Increased immune system modulation
• Reduced inflammation
• Reduced risk of complications
• Improved quality of life 

Safety and side effects

Patients administered IVIG can occasionally experience side effects either during or post infusion. These side effects vary in severity but are most commonly not a cause for concern. These include:⁴

• Fever
• Headache
• Stomach pain
• Nausea 
• Joint pain
• Lower back pain
• Fatigue 

If these symptoms start to appear, infusions of IVIG are first slowed down to resolve the side effects. If no improvement is seen, the treatment is stopped.

In more extreme circumstances, the following IVIG side effects must be treated by a medical professional:⁴

• Chest tightness and breathing difficulties
• A rash
• Facial swelling
• Lower blood pressure

Summary 

MFS is a rare autoimmune disorder where the immune system wrongly attacks the body’s nerve cells. The attack on nerve cells leads to the development of the defining symptoms: eye muscle weakness, a loss of coordination, especially in the limbs, and reduced tendon reflexes. MFS is often a complication following infection of either the respiratory or gastrointestinal tract, notably caused by the bacteria Campylobacter. MFS is a rare form of GBS but is distinguishable by MFS’ tendency to affect the upper body first. Diagnosis is fairly straightforward and consists of clinical examination, patient history, and medical examination.

IVIG therapy uses healthy immune cells from donated blood plasma to replenish the antibody pool of patients with autoimmune conditions. In MFS, IVIG therapy blocks anti-GQ1b antibodies responsible for the disease symptoms and reduces inflammation and nerve damage. Clinical studies have shown preferential outcomes when IVIG is the first-line treatment, administered on a tailored patient treatment plan. While IVIG therapy is generally considered safe, common side effects including fever and fatigue can occasionally occur but are easily remedied by slowing the treatment.

Overall, IVIG therapy promises to improve the quality of life for patients with MFS swiftly and desirably.