Nervous System Case
The nervous system that coordinates
the activities of muscles and regulates organs in the human body (Farlex, 2016).
It is composed of nerve cells that go throughout the entire body, and is divided
into the central nervous system (CNS) and the peripheral nervous system (PNS)
(Kantor, n.d.). The nervous system takes information from the outside world and
processes it to trigger reactions. The CNS includes nerves in the brain and in
the spinal cord, and are enclosed by skull and vertebral canal of the spine
(PubMed Health, n.d.). All other nerves of the body are controlled by the
peripheral nervous system (PubMed Health, n.d.). The nervous system is
important for conducting activities of daily life, and for processing
Guillain-Barré Syndrome (GBS) is a
disorder in which the body’s immune system attacks itself. More specifically,
it attacks the peripheral nervous system. Because of this outcome the nerves
become damaged, which leads to limb loss of reflexes, paralysis, and limb
weakness (Mayo Clinic, 2017). Initial symptoms of GBS is weakness in the limbs
and tingling sensations in both legs. The limb weakness and abnormal sensations
will progress to the upper limbs of the body, which can develop rapidly or be
prolonged over the course of months. It is common for the weakness to peek at
approximately at two weeks (Winer, 2002). The symptoms usually worsen over time
and may lead to paralysis. Breathing, blood pressure and heart rate may be
affected, but the symptoms begin to stabilize and eventually the individual
will begin to recover. Recovery varies from individual to individual and can
range from months to years. Nonetheless, even the most intense cases of GBS
typically recover significantly.
Who is Affected? Why?
are two forms of GBS: Acute Motor Axonal Neuropathy (AMAN) and Acute
Inflammatory Demyelinating Polyneuropathy (AIDP). About 80-90% of GBS cases are
AIDP, making it the most common form, characterized by demyelination (Kuwabara,
2004). AMAN, the second form of GBS, is less common among cases, occurring only
10-15% and is characterized by pure motor axonal degeneration (Kuwabara, 2004).
While there is no known cause for either forms of GBS, 60-70% of cases develop
GBS after an infection in the upper respiratory or digestive tracts (Hartung
& Yuki, 2012). Infections in these tracts are often caused by bacteria but
disappear prior to the development of GBS. There is also a small number of
cases that suggest that surgery, vaccines, or zika virus (infection spread by
mosquitos) trigger GBS, however, no solid evidence has been proven.
GBS can occur at any age, but there is
a slight peak among adolescents and young adults that may be due to an
increased risk of infection (Hartung & Yuki, 2012). A slight peak has also
been demonstrated in the elderly, which may result from weakened immune system,
increasing the risk of autoimmune disorders (Hartung & Yuki, 2012). Moreover,
GBS is more common amongst men than women (Hartung & Yuki). While GBS is a
rare autoimmune disorder, the death rate is low, with a rate of 10% (Kuwabara,
How does this happen?
The immune system’s main
job is to attack foreign bodies and organisms that enter the human body. However,
in patients with GBS, the immune system is compromised, and rather than
attacking foreign bodies, it attacks the body nerves in the PNS. This is
referred to as an autoimmune disease. AIDP is characterized by demyelination.
To explain this better, a myelin sheath surrounds nerve axons, and acts as a
relay station for nerve impulses. This causes the nerve impulses to move
efficiently and move far distances to activate muscles. Destruction of the
myelin sheaths may ultimately attack Schwann cell membranes, which are
responsible for production of myelin sheaths (Hahr, 1998). Because of demyelination,
nerve impulses move slower, resulting in tingling sensations, muscles paresis,
and paralysis. Muscles then become unable of responding to the instructions
sent from the brain. If there is more extensive damage to other parts of the
nerve, they may completely stop working causing paralysis.
AMAN is characterized by the
stretching of the Nodes of Ranvier. The Nodes of Ranvier are crucial components of the nerve bodies, since they help carry
nerve signals to muscles quickly and efficiently. This causes a collection of
white blood cells (WBC), which attack these nodal regions (Esposito & Longo, 2016). The presence of WBC in the nodal region will cause further
disfiguration of the axons, impairing signals to muscle fibers. Therefore, the stretching
of the nodes of Ranvier impair the nerve signals that carry information to
target cells. The stretching of the nodes also leads to acute paralysis and loss
of reflexes but sensory functions are maintained (Landau, Dabby, Amir &
While GBS has different
types, in each case, signals to the arms and legs are more likely to be
impaired because of the distance travelled in both cases, signals to the arms
and legs are at a much greater risk for disruption because they must travel the
farthest. Thus, sensations of tingling and muscle paresis first develop in the
hands and feet and then progress towards the centre of the body.