The consequent vaccine transfection and translation in the nerves may spur an immune response against nerve cells potentially causing an autoimmune nerve damage, leading to conditions like Guillain–Barré syndrome. Diagnosis
The diagnosis of Guillain–Barré syndrome depends on findings such as rapid development of muscle paralysis, absent reflexes, absence of fever, and absence of a likely cause. Cerebrospinal fluid analysis (through a lumbar spinal puncture) and nerve conduction studies are supportive investigations commonly performed in the diagnosis of GBS. Testing for antiganglioside antibodies is often performed, but their contribution to diagnosis is usually limited. Blood tests are generally performed to exclude the possibility of another cause for weakness, such as a low level of potassium in the blood. An abnormally low level of sodium in the blood is often encountered in Guillain–Barré syndrome. This has been attributed to the inappropriate secretion of antidiuretic hormone, leading to relative retention of water.In many cases, magnetic resonance imaging of the spinal cord is performed to distinguish between Guillain–Barré syndrome and other conditions causing limb weakness, such as spinal cord compression. If an MRI scan shows enhancement of the nerve roots, this may be indicative of GBS. In children, this feature is present in 95% of scans, but it is not specific to Guillain–Barré syndrome, so other confirmation is also needed. Spinal fluid
Cerebrospinal fluid envelops the brain and the spine, and lumbar puncture or spinal tap is the removal of a small amount of fluid using a needle inserted between the lumbar vertebrae.
Drug induced
Zimelidine, an antidepressant, had a very favorable safety profile but as a result of rare case reports of Guillain–Barré syndrome was withdrawn from the market. Mechanism
The nerve dysfunction in Guillain–Barré syndrome is caused by an immune attack on the nerve cells of the peripheral nervous system and their support structures. The nerve cells have their body (the soma) in the spinal cord and a long projection (the axon) that carries electrical nerve impulses to the neuromuscular junction, where the impulse is transferred to the muscle. Axons are wrapped in a sheath of Schwann cells that contain myelin. Between Schwann cells are gaps (nodes of Ranvier) where the axon is exposed. Different types of Guillain–Barré syndrome feature different types of immune attack. The demyelinating variant (AIDP, see below) features damage to the myelin sheath by white blood cells (T lymphocytes and macrophages); this process is preceded by activation of a group of blood proteins known as complement. In contrast, the axonal variant is mediated by IgG antibodies and complement against the cell membrane covering the axon without direct lymphocyte involvement.Various antibodies directed at nerve cells have been reported in Guillain–Barré syndrome. In the axonal subtype, these antibodies have been shown to bind to gangliosides, a group of substances found in peripheral nerves. A ganglioside is a molecule consisting of ceramide bound to a small group of hexose-type sugars and containing various numbers of N-acetylneuraminic acid groups.