What Is Guillain-Barre Syndrome?

Guillain-Barré syndrome (GBS) is an autoimmune disorder of the peripheral nervous system, meaning that the body’s own immune system attacks the nerves outside of the brain and spinal cord.

GBS actually refers to a group of disorders associated with muscle weakness, sensory loss, the malfunction of involuntary nerves (dysautonomia), or some combination of the three problems.

An uncommon condition, Guillain-Barré Syndrome only affects one or two people per 100,000.

This article explains how the condition affects the nervous system and the different subtypes of GBS.

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What Is GBS?

Guillain-Barré Syndrome develops when the body’s immune system attacks the peripheral nerves.

Peripheral Nerves

Peripheral nerve cells are the nerves that carry information between your brain and the rest of your body. Each of these nerves sends signals down a long, thin extension called an axon to tell muscles to contract or to carry information about your senses. Thus, these nerves control how the body moves and experiences sensations.

Like wires, many axons are insulated, wrapped in myelin, a fatty coating made of glial cells that protect the axon and help speed up the traveling electrical signal.

How GBS Affects Nerves

Guillain-Barré Syndrome usually comes on after an infection (or extremely rarely, after an immunization). The immune system, turned on to fight the disease, mistakes parts of the peripheral nerve for the infection. As a result, antibodies are released that attack the peripheral nerves.

This autoimmune response can cause several subtypes of GBS, each of which leads to a variety of symptoms such as muscle weakness.

Types of Guillain-Barré Syndrome

How Guillain-Barré Syndrome affects an individual person depends on where the antibodies attack the nerve. For this reason, Guillain-Barré is often thought of as a family of disorders, which can cause different kinds of problems. Four subtypes of GBS include:

  • Acute motor and sensory axonal neuropathy
  • Acute motor axonal neuropathy
  • Miller-Fisher variant
  • Acute panautonomic neuropathy

Acute Inflammatory Demyelinating Polyneuropathy (AIDP)

Acute Inflammatory Demyelinating Polyneuropathy (AIDP) is the most common subtype of Guillain-Barré although, overall, it's a rare disorder that occurs in only one out of every 100,000 persons. In AIDP, antibodies don’t attack the nerve cells directly. Instead, they damage the glial 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. You may also suffer from deep aching pain in these weakened areas and your back.

In AIDP and most other forms of Guillain-Barré Syndrome, both sides of the body tend to be equally affected.

Acute Motor and Sensory Axonal Neuropathy (AMSAN)

In AMSAN, antibodies do not attack the myelin sheath or glial cells; instead, they damage the axon directly. They do this by attacking nodes, places along the nerve where the myelin breaks to allow ions to flow and pass along electrical signals.

AMSAN can be very aggressive. Symptoms progress rapidly and can lead to total paralysis of all four limbs in fewer than seven days along with severe muscle wasting.

Recovery from AMSAN can take a year or more. Rather than 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)

AMAN accounts for fewer than 10% of GBS cases. Only nerves controlling movement are affected. This results in weakness of the lower arms and legs, but there is no numbness. People tend to recover more rapidly and completely from AMAN than the other forms of Guillain-Barré.

Miller-Fisher Variant

Miller-Fisher is a rare variant of GBS that is associated with problems of the head and face rather than with limb paralysis. Symptoms may include:

  • Weakness or paralysis of the eye muscles
  • Inability to swallow and/or speak
  • Loss of tendon reflexes
  • Respiratory complications

While all forms of GBS carry a risk of intubation or the possibility of being placed on mechanical ventilation, the risk may be higher with the Miller-Fisher variant.

Acute Panautonomic Neuropathy

Acute panautonomic neuropathy is a rare type of GBS in which movement and sensation are left intact, but the autonomic nervous system, which controls vital involuntary functions like breathing, digestion, and heart rate, is affected.

Most varieties of Guillain-Barré Syndrome affect the autonomic nervous system in some way, resulting in the loss of control of functions like sweating, heart rate, temperature, and blood pressure.

As involuntary nerve functions are lost, symptoms can progress to include the following types of problems.

Digestive issues

Cardiorespiratory symptoms

Bladder problems

  • Difficulty urinating
  • Leaking urine

Other issues may include excessive sweating, sexual dysfunction, and unexplained weight loss.


Guillain-Barré Syndrome is a rare disorder that usually follows an infection or, in some cases, a vaccination. The body’s immune system attacks peripheral nerves, causing pain, numbness, muscle weakness, and possible paralysis. There are four common subtypes of Guillain-Barré Syndrome. Each affects the body differently and may result in different symptoms.

A Word From Verywell

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 a 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.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institute of Neurological Disorders and Stroke. Guillain-Barré syndrome fact sheet.

  2. American Association of Neuromuscular & Electrodiagnostic Medicine. Acute Inflammatory Demyelinating Polyneuropathy.

  3. Jankovic J. Disorders of Peripheral Nerves. Bradley and Daroff's Neurology in Clinical Practice. 2022.

  4. Mahatoo A, Topiwala K, Nouh A, Zhang Y, Silverman I, Daniel A. Acute Motor Axonal Neuropathy (Aman) presenting with truncal and appendicular ataxia (P2.453). Neurology. 2018;90(15 Supplement).

  5. National Institute of Neurological Disorders and Stroke. Miller Fisher Syndrome.

  6. MedlinePlus. Autonomic neuropathy.

Additional Reading
  • 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.

By Peter Pressman, MD
Peter Pressman, MD, is a board-certified neurologist developing new ways to diagnose and care for people with neurocognitive disorders.