Guillain-Barré syndrome



Overview

Guillain Barre syndrome (GBS) is characterized as a rare autoimmune disease. The body’s immune system mistakenly attacks the nervous system. Early symptoms of this disease include tingling sensations primarily in the extremities. These sensations can spread rather quickly ultimately causing overall body paralysis. The cause of GBS is unknown, however, it is consistently preceded by an infection such as a lung infection, or the stomach flu. Guillan-Barre patients typically recover from this disease but may experience some lingering affects.

Functional Anatomy

A neuron has four fundamental but significant parts for operating naturally. The Dendrites are the projections off of the cell body that receive nerve impulses from other nerves. The nucleus is located in the cell body or soma, this is also where the metabolic reactions happen. In the soma, there are normal organelles such as the Mitochondria, Golgi apparatus, and lysosomes. They also contain Nissl bodies which are unique to nerve cells. On the soma there is a part called the axon hillock which is where the axon emerges. the axon is the part of the neuron that relay electrical nerve impulses and can be up to one meter in length. Once the impulse has reached the axon terminals, they synapse onto the dendrites of the next cell.

Neuron.png

http://neuroscience.uth.tmc.edu/s1/introduction.html

Some nerves have Schwann cells, these cells produce a myelin sheath around the axon with small spaces in between called the Nodes of Ranvier. These are important for impulse transduction speeds which are proportionate to the amount of myelin produced.


neuron with shwann cells.jpg external image axon.gif

http://www.britannica.com/EBchecked/topic/528567/Schwann-cell
http://faculty.washington.edu/chudler/cv.html

Physiological Properties

At rest, neurons are polarized to -60 mV. This is due to the separation of extracellular Sodium (Na+) and Chloride (Cl-) ions and intracellular Potassium (K+) ions. When a nerve cell receives a signal, the neurotransmitters released at the synaptic cleft from the presynaptic neuron bind to receptors of the postsynaptic neuron opening mechanically gated ion channels producing an influx of Na+ and an efflux of K+ and active transportation of K+ back into the cell via ATP-dependent Na+/K+ pumps. The movement of ions causes a depolarization of the membrane which in turn causes voltage gated ion channels to open and further the response of influx and efflux of ions, down their concentration gradients. The inside of the membrane becomes depolarized spatially and temporally. These electrical potentials are summated at the axon hillock which generate an action potential if the region reaches threshold at -45 mV. Once the action potential is generated, it travels down the axon to the terminal endings where neurotransmitters are released into the synaptic cleft and are received by the postsynaptic neuron.


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Input Pathways

The sensory receptors in the periphery detecting differences in proprioception, and fine touch send information through the Dorsal Column Medial-Lemniscal (DCML) tract up to the higher centers, ultimately the corresponding portion of the homunculus of the primary somatosensory cortex. All the sensory receptor cell bodies are located in the dorsal root ganglion near the spinal cord, with axons that reach the different sensing locations. As the receptors sense differences, impulses go through the dorsal root and into the dorsal horn of the spinal cord. The receptors in thoracic area and lower extremities up to T7 axons form the gracile fascicle in the dorsal part of the spinal cord, also, starting at T6, the upper extremities and upper body travel in the cuneate fascicle of the dorsal column. They ascend in the spinal cord ipsilaterally as the first order neuron and end in either the cuneate nucleus or gracile nucleus in the caudal medulla where they synapse with the second order neuron. From the caudal medulla, they decussate and go through the internal arcuate fibers and join the medial lemniscus that travel to the ventral posterolateral nucleus of the thalamus where they synapse with the third order neuron that travels through the internal capsule and then through the corona radiata to the somatosensory cortex.

The sensory receptors detecting temperature and pain and pressure send input through the anterolateral system which includes the anterior and lateral spinothalamic tract. Like the DCML, the receptors have the cell body in the dorsal root ganglion. For pain and temperatre, the input goes from the periphery, through the dorsal root ganglion and synapse in the dorsal horn with a second order neuron that decussates to the contralateral lateral column. For crude touch and pressure, they decussate to the contralateral anterior tract. They ascend to the thalamus where they synapse with the third order neuron and go to the primary somatosensory cortex through the internal capsule and corona radiata.



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Output Pathways

Motor commands descend down the spinal cord through the corticospinal tract. The signal starts in the primary motor cortex and goes down though the cerebral peduncle then to the caudal medulla where the axons bifurcate and form the lateral and anterior corticospinal tracts. Most of the axons, about 90% decussate in the medulla and go to the contralateral lateral funiculus where they descend and synapse with lower motor neurons directly or with interneurons at all levels of the spinal cord that control distal musculature.

The anterior corticospinal tract will not decussate at the thalamus, it will descend ipsilaterally in the anterior funiculus where they exit only in sections C1-L3 of the spinal cord. Once they have reached its termination point, it decussates and synapses with lower motor neurons or interneurons in the contralateral side that control the proximal musculature.

Pathology

Guillian-Barré syndrome can affect anyone, male or female but usually between the ages of 30-50, however it is rare affecting about 1 or 2 out of 100,000 people. GBS can have an extreme affect on the nerves as the peripheral nerves are the demylinated and injured. This causes delays in the system which doesn't allow the signals to be transmitted efficiently. The brain will not be able to recognize textures, experience areflexia, or even be desensitized to pain. Bacterium from different infections are thought to change the nature of cells within the nervous system, causing the immune system to treat them as foreign. The most common bacterium that causes the GBS is Campylobacter jejuni which is common of gastrointestinal disorders. This Bacterium is thought to insert Immunoglobulin G into the axolemma. IgG causes binding to pathogens which are targeted for destruction by the immune system. In GBS the IgG binds to myelin surrounding the axons which causes the immune system to break down the myelin sheath. The destruction of these sheaths is what causes the symptoms.

Symptoms:
  • Blood pressure fluctuations
  • Trouble breathing
  • Areflexia
  • Muscle weakness
  • Numbness
  • Difficulty swallowing
  • Tingling
  • Desensitization of pain
  • Uncoordinated movements


Treatment for GBS patients needs supportive care and therapy. Acute onset could cause patients to need intubation for breathing assistance, it is advised for patients to be hospitalized for monitoring. Plasmapheresis is a procedure that takes blood from the arm, flushes it thorough a machine that eliminates antibodies and replaces the blood without the plasma which is quickly compensated. Muscles may not be used because of disruptions in pathways which is why manual physical therapy is essential to prevent muscular atrophy. When the patient has recovered enough, they begin physical therapy slowly to insure muscular strength build up.

Summary

Guillian-Barré syndrome is a non-contagious autoimmune disease that attack the nervous system, more specifically the periphery. It is usually preceded by an infection such as the stomach flu or lung infections. GBS causes delays in sensory and motor transduction because the C.jejuni bacteria inserts antibodies on the axolemma and targets them to be destroyed by T and B cells of the immune system. It can be acute and require hospitalization. This disease is rare and it is treatable by plasmapheresis which treats the blood and replaces the blood without the plasma which is to be replaced naturally by the body. When recovering, physical therapy is essential for muscular strength.

Glossary

Autoimmune- antibodies produced against own body substances

Homunculus- a representation of the body that corresponds to the amount of innervation

Fascicle- a bundle of axons

decussate- cross over

Ipsilateral- Same side

Atrophy- a degeneration of cells, a partial or complete wasting away of cells or body part

Axolemma- outer covering of the axon.

T Cells- a lymphocyte derived from the thymus gland active in the immune system

B cells- a lymphocyte derived from bone marrow, active in the immune system

Areflexia- absence of a reflex
Further Reading

Guillian-Barré Syndrome Research

Guillian-Barré in depth

GBS pathology, Clinical, and Therapeutical Aspects

Guillian-Barré Syndrome and molecular mimicry theory

Quiz

1) T/F GBS affects the the Spinal Cord
2) T/F GBS is not contagious
3) T/F Hospitalization is required for acute onset.
4) T/F Schwann Cells are not affected by GBS
5)T/F GBS affects 2 out of 100,000 people

6) GBS infects:
a) Muscle cells
b) Glands
c) Axon myelin sheath in the periphery
d) Cardiac cells

7) Resting Membrane potential is:
a) -70 mV
b) -45 mV
c)+30 mV
d) -15 mV

8) Which pathway does pain and temperature ascend in?
a) Rubrospinal Tract
b) Tectospinal Tract
c) Vestibulospinal Tract
d) Spinothalamic Tract

9) Which pathway does proprioception and fine touch ascend in?
a) Dorsal Column-Medial Lemniscal Tract
b) Vestibulospinal Tract
c) Spinothalamic Tract
d) Reticulospinal Tract

10) Which of the following is a treatment for GBS:
a) Plasmapheresis
b) Hemiparesis
c) Chemotherapy
d) Ibuprofen tablets

List the different symptoms associated with GBS.


Comment on the preceding infections of GBS and how it affects the axons in the periphery.

Why is it important for patients to participate in physical therapy?

Answers:
1) F
2) T
3) T
4) F
5) T
6) C
7) B
8) D
9) A
10) A

Sources:

Knierim, J. Motor Systems. Neuroscience Online. Retrieved from http://neuroscience.uth.tmc.edu/s3/chapter02.html

Cohen. J, Fadul. C, Jenkyn. L, Ward. T. Disorders of the Nervous System. Retrieved from http://www.dartmouth.edu/~dons/part_3/chapter_23.html

Kuwabara. S. Guillain-Barré Syndrome: Epidemiology, Pathophysiology, and management. http://www.ncbi.nlm.nih.gov/pubmed/15018590

Shahrizaila N, Nobuhiro. Y. Review Article Guillain-Barré Syndrome Animal Model: The first proof of molecular mimicry in Human Autoimmune Disorder (2011) Biomed Research International Retrieved from http://www.hindawi.com/journals/biomed/2011/829129/

Fish. M, Liewelyn. G. Review Article The Guillain-Barré Syndrome Retrieved from http://www.acnr.co.uk/SO08/ACNRSO08_guillian.pdf

Nobuhiro. Y, Hartung. HP. Review Article: Medical Progess Guillain-Barré Syndrome. Department of Neuroscience: University of Singapore NY. June 4,2012

Ianella. S, Guillain-Barré Syndrome: Pathological, Clinical, and Therapeutical Aspects (2005) Nova Biomedical Books

Newswanger. D, Warren. C. Guillain-Barré Syndrome (May 2004) Practical Therapeutics American Family Physician A peer-reviewed journal of the American Academy of Family Physicians Retreived from http://www.aafp.org/afp/2004/0515/p2405.h

Young.PA, Young.PH, Tolbert. D, Clinical Neuroscience Second Edition (2008) Lippincott Williams & Wilkins Philadelphia PA.