Neurology Teaching! Guillain-Barre Syndrome Edition

Welcome to another installment of neurology teaching! I am a neurology resident who loves teaching medical students, fellow residents, and my patients.

Today let's learn about a fascinating condition called Guillain-Barre syndrome.

If you like this post, check out some older installments below:
Intro: https://imgur.com/gallery/DTKTFU1
Strokes: https://imgur.com/gallery/jzjpPoD
Meningitis: https://imgur.com/gallery/ANw2CDd
Parasites: https://imgur.com/gallery/Fsm9Buv
Intracranial pressure: https://imgur.com/gallery/s8OvBL2
Pupils: https://imgur.com/gallery/Xksvovi
Multiple Sclerosis: https://imgur.com/gallery/eahHOpS
Chiari Malformations: https://imgur.com/gallery/CdXf6L7
Prion diseases: https://imgur.com/gallery/R0CDHFe
Status epilepticus: https://imgur.com/gallery/fkBp0JN
Status epilepticus: https://imgur.com/gallery/OgHmb40

Guillain-Barre syndrome defines a variable group of disorders which affect the peripheral nerves.

Above, we see a diagram of a generic peripheral nerve. These are the nerves that have exited the central nervous system (brain and spinal cord). At the bottom of the diagram we see that most individual nerve fibers are coated with an insulating substance called myelin.

Myelin is produced by special cells called Schwann cells and functions as an electric insulator, allowing nerve signals to travel faster. Myelin coats many peripheral nerve axons, or the message-sending part of nerves.

Guillain-Barre Syndrome comes in three general flavors:
1. Mainly demyelination-- probably autoimmune reaction against an antigen (so far unknown) on myelin, resulting in loss of this insulating substance. This is usually called AIDP -- acute inflammatory demyelinating polyneuropathy.

2. Mainly axonal loss-- autoimmune attack against exposed parts of the peripheral nerve axon. This is usually called AMAN-- acute motor axonal neuropathy; or AMSAN-- acute motor-sensory axonal neuropathy.

3. Miller-Fisher variant-- autoimmune attack against ganglioside antigen which involves primarily the nerves that provide movement to the eyeballs, but may also affect other nerves that provide input to the face, throat, pupils, neck. There are further subvariants within this type, but will focus on M-F.

In two-thirds of people symptoms begin within 4-6 weeks of a preceding viral illness, most commonly GI illness. Sometimes no clear provoking factor is identified. In rare cases trauma, pregnancy, and vaccination can provoke GBS. The risk of GBS is much higher from influenza itself than from the vaccine. Having GBS is not a contra-indication for vaccination, however having GBS that was likely caused by a specific vaccine is typically a contra-indication for receiving that same vaccine again.

Symptoms reach their worst classically within 4 weeks, but two-thirds of people bottom out at 2 weeks.

Initial symptoms may be vague, often including new severe back pain. This is followed quickly by progressive weakness. Classically this is "ascending", meaning starting from the lower legs and hands and progressing up. Occasionally there may be sensory loss, but in the vast majority of cases the predominant symptom is weakness.

One-quarter to one-third of affected patients can develop weakness of their muscles of breathing and require a ventilator.

More than half of patients have weakness of the muscles of the face, eyes, or throat.

The autonomic nervous system is also affected and can cause wildly variable blood pressure, heart arrhythmias, abnormal sweating.

Miller Fisher variant is characterized by a triad of weakness of eye movement (ophthalmoplegia), incoordination (ataxia) and lack of reflexes (areflexia). One-quarter will also develop weakness elsewhere.

Lack of reflexes is a common finding in AIDP variant as well. Reflexes are lost early in the course of the disease, making it a useful clue for diagnosis prior to severe symptoms.

Diagnosis is largely clinical-- meaning is made without supportive imaging or blood tests.

The diagnostic criteria include progressive muscle weakness in more than one limb (usually over 2-4 weeks and symmetric) and decreased or absent reflexes.

However, there are tests which support diagnosis and which can be considered to rule out alternative diagnoses when there is doubt.

In practice we will typically do a lumbar puncture to obtain spinal fluid to analyze. Typically in Guillain-Barre syndrome there is an increase in protein in the spinal fluid without a corresponding increase in inflammatory cells-- termed albuminocytologic dissociation. You can also test for specific antibodies if desired.

In some patients you may obtain MRI of the spine if there is a history of trauma or if the onset of symptoms is very quick. In my experience spine imaging is not usually obtained.

All people with a suspected diagnosis of Guillain-Barre syndrome should be admitted to the hospital for monitoring, unless they are already in the recovery phase or have clearly plateaued and have mild symptoms. This is because of the high risk for progression of disease and disability associated with that-- need for rehab, ventilator, feeding tube, etc.

Strength of breathing is monitored closely. If the need for ventilator support is imminent, it is better to put in the breathing tube before the patient is in crisis.

Treatment is initiated as early as possible. Treatment is usually intravenous immune-globulin (IVIG) which is a bunch of pooled antibodies which decrease the disease-causing autoimmune process by decreasing the abnormal antibody's probability of encountering its corresponding antigen. The alternative is a process called plasma exchange (PLEX) where the patient's blood plasma is filtered and donor plasma replaces the patient's plasma. This is more costly and requires special (very large) IVs.

When treatment is started within 2 weeks (IVIG) to 4 weeks (PLEX) there is evidence that the duration to recovery will be decreased. Treatment is not known to reliably improve the severity of symptoms.

Recovery occurs over months, with more than half of patients reaching full recovery at one year.

One-tenth may have severe weakness persisting over the long term.

One in twenty to one in ten may have prolonged need for a ventilatory for several months with associated delayed and incomplete recovery.

In those that require the ventilator due to severe weakness, there is a mortality rate of 20%.

Poor outcomes are associated with advanced age, rapid progression of symptoms, severe weakness, need for ventilator.

Thanks for following along, and letting me share my love of neurology with all of you!