What is Guillain-Barre syndrome?:
Guillain-Barre syndrome is an autoimmune disorder in which peripheral nerves are damaged and cannot transmit signals efficiently. The disease typically progresses from the legs up the body to the trunk and may even affect the respiratory system, causing almost complete paralysis.
In Guillain-Barre syndrome, the myelin sheath protecting the nerves are damaged, so signals traveling along the nerves are not transmitted properly.
Because nerves cannot transmit signals to muscles, muscles will not function properly, thus causing paralysis.
What causes Guillain-Barre syndrome?:
No one knows exactly what causes Guillain-Barre syndrome or why some people get it and other do not. Most people who get Guillain-Barre syndrome do so after having a bacterial or viral infection.
These axons transmit signals from the body of the nerve cell to muscles in order to make muscles contract, and send signals from sensory receptors to the cell body in order to allow us to feel.
It can be helpful to think of an axon as being a kind of wire that sends electrical impulses to or from different areas of the body. Like wires, most axons work better if they are surrounded by insulation.
Instead of the rubber coating that coats electrical wires, many axons are wrapped in myelin. Myelin is made by glial support cells that surround the axon of the nerve. These glial cells protect and nourish the axon, as well as helping speed up the traveling electrical signal.
Whereas an unmyelinated axon requires ions to flow in and out of the entire length of the axon, myelinated axons only require that the nerve do this at selected points.
These points are called nodes, where the myelin has breaks in it to allow ions to flow. In essence, rather than traveling the entire length of the axon, the electrical signal jumps quickly from node to node, speeding things along.
How Guillain-Barré Syndrome Works
Guillain-Barré Syndrome is caused by the body’s immune system attacking the peripheral nerves.
The fact that the syndrome usually comes on after an infection (or extremely rarely, after an immunization) has led us to suspect that at a molecular level, some infectious agents look like parts of the nervous system. This causes the immune system to mistake the identity of peripheral nerves, thinking that parts of the nerve are an infection. As a result, the immune system releases antibodies that attack the peripheral nerves.
How Guillain-Barré Syndrome affects an individual person depends on where the antibodies attack the nerve. For this reason, Guillain-Barré is perhaps best thought of as a family of disorders, which can cause different kinds of problems.
Acute Inflammatory Demyelinating Polyneuropathy (AIDP) is the most common subtype of Guillain-Barré, and what most physicians think of when the term “Guillain-Barré” is used. In AIDP, antibodies don’t attack the nerve cells directly, but instead damage the glial support cells that surround the axon of the nerve. Typically, this leads to sensory changes and weakness that starts in the toes and fingertips and spreads upwards, worsening over a matter of days to weeks. People with Guillain-Barré may also suffer from a deep aching pain in their weakened areas and back. Like most forms of Guillain-Barré, both sides of the body tend to be equally affected in AIDP.
While AIDP is the most common type of Guillain-Barré, there are many others. These include the following:
Acute Motor and Sensory Axonal Neuropathy (AMSAN):
In AMSAN, antibodies damage the axon directly instead of the myelin sheath. They do this by attacking the nodes where the myelin breaks to allow the ion exchange that spreads the electrical signal. AMSAN can be very aggressive, with symptoms sometimes progressing to total paralysis within just a day or two. Furthermore, the recovery from AMSAN can take a year or more. Rather than a complete recovery, it is not uncommon for people with AMSAN to have some lasting problems, such as clumsiness or numbness in their fingers.
Acute Motor Axonal Neuropathy (AMAN):
In AMAN, only nerves controlling movement are affected, so there is no numbness. People tend to recover more rapidly and completely from AMAN than the other forms of Guillain-Barré.
Guillain-Barré is most concerning when it changes how we breathe or protect our airway. In the Miller-Fisher variant of Guillain-Barré, the face and eyes are attacked first. The loss of the control of throat muscles can make it impossible to swallow without food or saliva going into the lungs, increasing the risk of pulmonary infections and choking. While all forms of Guillain-Barré require close monitoring to see if the patient may need to be intubated or placed on mechanical ventilation, the Miller-Fisher variant requires especially close attention.
Acute Panautonomic Neuropathy:
Most varieties of Guillain-Barré also affect the autonomic nervous system in some way, resulting in the loss of control of functions like sweating, heart rate, temperature, and blood pressure. Acute panautonomic neuropathy is a rare type in which movement and sensation is left intact, but the autonomic functions are lost. This can lead to lightheadedness, cardiac arrhythmias, and more.
The most common symptom of Guillain-Barré is a progressive loss of strength that sometimes includes a loss of sensation and autonomic control. Whereas most peripheral neuropathies worsen over a matter of months to years, Guillain-Barré changes over days and sometimes hours. Because Guillain-Barré can lead to weakness that is so severe that an afflicted person cannot even breathe on their own, it is important that you get help as soon as possible if you notice these symptoms.
Yuen T. So, Continuum: Peripheral Neuropathies, Immune-Mediated Neuropathies, Volume 18, Number 1, February 2012
Braunwald E, Fauci ES, et al. Harrison’s Principles of Internal Medicine. 16th ed. 2005.