The lumbrosacral MRIs (see Figures 1 and 2) demonstrate nerve root enhancement of the cauda equina on axial post-contrast T1-weighted sequences.
The localization of progressive weakness includes spinal cord lesions (such as transverse myelitis or anterior spinal artery syndrome), peripheral neuropathies (such as those caused by heavy metals), neuromuscular junction diseases (such as that caused by organophosphate pesticides, myasthenia gravis, botulism, and myopathies (such as dermatomyositis). The presence of progressive ascending weakness, areflexia, autonomic dysfunction, elevated CSF protein without pleocytosis, and enhancement of the cauda equina nerve roots on lumbrosacral MRIs make the diagnosis of Guillain-Barré syndrome most probable in this patient.
Guillain-Barré syndrome is an acute, idiopathic, monophasic, acquired inflammatory demyelinating polyradiculoneuropathy (AIDP) that affects both children and adults. It is a heterogeneous syndrome, with several variant forms. AIDP is the prototype of Guillain-Barré syndrome, and it is the most common form in North America, Europe, and most of the developed world (where it accounts for about 85-90% of cases).
Guillain-Barré syndrome can occur at any age, but there appears to be a bimodal distribution, with peaks in young adulthood (15-35 y) and in the elderly (50-75 y). The cause of Guillain-Barré syndrome is unknown, but the disorder is thought to result from a postinfectious immune-mediated process called molecular mimicry that predominantly damages the myelin sheath of peripheral nerves. Approximately two thirds of patients report a history of an antecedent respiratory tract or gastrointestinal infection 2-4 weeks before the onset of neurologic symptoms. Various infectious agents have been associated with Guillain-Barré syndrome, although Campylobacter is the most frequent. Other organisms that commonly precede Guillain-Barré syndrome include cytomegalovirus, Epstein-Barr virus, Haemophilus influenzae, Mycoplasma pneumoniae, the enterovirus family, hepatitis A and B, herpes simplex virus, and Chlamydophila (formerly Chlamydia) pneumoniae. Zika virus has been linked to Guillain-Barré syndrome. Increased risk of Guillain-Barré syndrome after influenza vaccination has not been consistently demonstrated.
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