Pathophysiology
Guillain-Barré syndrome (GBS) is an autoimmune disorder of an acute inflammatory neuropathy that is triggered or preceded by certain infections. It is now both demyelinating and axonal in pathology (Winer, 2014). The autoimmune response of the body is triggered by the cross-reactivity between the microorganism and the nerve tissue. Bacterial or viral infection caused by the pathogens Campylobacter jejuni, cytomegalovirus, Epstein-Barr virus and Mycoplasma pneumoniae are the common pathogens known to trigger GBS (Kuwabara, 2004). The etiology of 60% of cases of Guillain-Barré syndrome (GBS) remains unidentified. GBS cases ride during the winter and are usually preceded by a respiratory tract infection or an iinfluenza virus infection. A study was made in 2009 on the correlation between Guillain-Barré syndrome and influenza virus infection. The study used time-series methods to study the monthly incidences of GBS with unknown causes and influenza-like illness. The study provided evidence on the role of influenza virus on triggering GBS. After an infection of influenza virus in adults, there is a higher risk of GBS than that after vaccination of either live attenuated vaccines or inactivated vaccines (Sivadon‐Tardy et al., 2009).
In GBS, inflammation of the myelin sheath of the nerves occurs which leads to the inflammatory cascade – lymphocytes and macrophages arrive and cause demyelination of the affected peripheral nerves. In demyelination, there is an impaired transmission of electrical pulses in the affected nerves and results to a deterioration or loss of function in the organs with the damaged nerves. If the motor nerves are affected, muscle weakness can occur. Flaccid paralysis or areflexia can also result if the motor nerves are damaged. Paresthesia, tingling and numbness are the results of the posterior sensory nerve roots being affected. A wildly fluctuating blood pressure and cardiac arrhythmias are the consequences of the autonomic nervous system being disrupted (Chang, Daly & Elliott, 2006).
The most common type of GBS is the ascending GBS or acute motor axonal neuropathy (AMAN) with manifestations such as symmetrical weakness and numbness that start in the lower extremities and progresses to the trunk, upper extremities then cranial nerves. Involvement in cranial nerves will bring about signs depending on the nerve affected. For example, involvement of the 7th cranial nerve affects the muscles responsible for smiling and frowning. Descending GBS or acute motor axonal neuropathy (AMAN) is purely motor loss and there is no sensory loss (Chang, Daly & Elliott, 2006). The subtypes AMAN(acute motor axonal neuropathy ) and AMSAN ( Acute Motor Sensory Axonal Neuropathy) occurred more frequently in patients infected with C. jejuni than the subtype AIDP (Acute inflammatory demyelinating polyneuropathy) (Newswanger & Warren, 2004). Respiratory failure may occur in severe cases if the nerves in the intercostal muscles and the diaphragm are disrupted.
The three phases of GBS are acute, plateau and recovery. Following a viral infection, symptoms may appear 10-14 days. In the 3rd or 4th week, the symptoms may increase intensity. Upon the onset of the symptoms, respiratory failure can occur within 48 hours. During the plateau phase, there is no exacerbation or improvement. This phase lasts from a couple of days to two weeks. If there is a remyelination and regrowth of axons, recovery phase occurs. This phase ranges from four months to three years.
Diagnosis
Guillain-Barré syndrome may be diagnosed by a General Practitioner by clinical assessment and through an examination. GBS has similar manifestations with other nervous system disorders and in order to rule out other conditions, electromyography and lumbar puncture are done. In electromyography, the nerve responses in the muscles of a patient with GBS are detected as slower than normal due to nerve damage. With Lumbar puncture, CSF is aspirated from the lumbar spinal canal using a needle. CSF with elevated protein higher than 0.55 g per dL without abnormal number of cells in CSF is the common findings in GBS.
Treatment
The treatment and management of GBS can either be one of the following: (a) intensive care and ventilator support with patients who are severely paralyzed and (b) immunomodulating treatments that stop the progression of the disease. Corticosteroids are often use to relieve or reduce inflammation but these drugs do not change the outcome of GBS when used alone. Intravenous immunoglobulin (IVIg) given in high doses and plasma exchange can limit nerve damage therefore helping in resolving the disease. IV immunoglobulin therapy’s mechanism of action is a combination of the effects of complement inactivation, inhibition of cytokine, idiotypic antibodies neutralization and Fc receptors saturation on macrophages. (Kuwabara, 2004).
References
Chang, E., Daly, J., & Elliott, D. (2006). Pathophysiology applied to nursing practice. Sydney: Mosby Elsevier.
Kuwabara, S. (2004). Guillain-Barré Syndrome: Epidemiology, Pathophysiology and Management. Researchgate. http://dx.doi.org/64(6):597-610
NEWSWANGER, D., & WARREN, C. (2004). Guillain-Barré Syndrome. Am Fam Physician. http://dx.doi.org/69(10):2405-2410.
SivadonâTardy, V., Orlikowski, D., Porcher, R., Sharshar, T., Durand, M., & Enouf, V. et al. (2009). Guillainâ€Barré Syndrome and Influenza Virus Infection. Clinical Infectious Diseases, 48(1), 48-56. http://dx.doi.org/10.1086/594124
Winer, J. (2014). An Update in Guillain-Barré Syndrome. Autoimmune Diseases, 2014, 1-6. http://dx.doi.org/10.1155/2014/793024
