Discussion
In 1987, Renlund et al. reported the first case of CABG associated GBS in a 65 year old man who developed symptoms three days after surgery, successfully treated with plasmapheresis. (7) Since then, nine additional cases have been reported including the current case (Table 1). (8-13) While there are other extant reports of GBS following cardiothoracic surgery, the temporal precedence between surgery and GBS of 12 and 48 months seems an unlikely etiology (14,15). In nine of the ten cases, patients were male; all patients developed symptoms within 15 days after surgery. All patients were successfully treated with either IVIG, plasmapheresis or plasma exchange, and demonstrated either significant improvement or complete recovery. Six patients required mechanical ventilation, as in the current case. Average age of the patients was 61.4 years; average time between the surgical procedure and symptom onset was 7.6 days (range 1-15, median 7.5 days). Only four patients in the series underwent valvular repair, one of which was replacement, as is our case. Table data suggests either increasing incidence or reporting of cardiothoracic surgery associated GBS.
National surveillance data from the Centers for Disease Control and Prevention has documented a 5 percent incidence of GBS within 8 weeks post-surgery. (4) However, 45 percent of those patients reported an antecedent illness within that same time period. There was a direct correlation between increasing age and the incidence of GBS, as well as a male preponderance. Our patient denied any preceding upper respiratory or gastrointestinal symptoms.
In a series published by Gensicke, et.al. the risk of developing GBS during 6 weeks following surgery was 13.1 times higher than the risk in the general population. (5) None of the patients in their study had prior open heart surgery. In a very recent retrospective review of 208 cases of GBS, Nagarajan et al. reported that 15 percent of patients developed postsurgical GBS within 8 weeks of surgery. (6) Median duration from the surgical procedure to the onset of first GBS symptoms was 19 days. Interestingly, 61 percent of patients had a known diagnosis of malignancy and 29 percent had an underlying autoimmune condition. Multivariate analysis demonstrated a statistically significant association of post-surgical GBS with age, malignancy, and presence of an autoimmune disorder. (6) In Nagarajan’s series only one patient underwent CABG.
The mechanism and pathogenesis of GBS after cardiac surgery is unknown. Surgery may cause exposure of nerve roots leading to oncoantigen-mediated misdirection of autoimmune responses to epitopes within the peripheral nervous system. Immune dysregulation may be secondary to lipid soluble anesthetic agents. (6) Additionally, cardiopulmonary bypass has been associated with activation of complement, secretion of both pro- and anti-inflammatory cytokines (IL-8, IL-10), tumor necrosis factor (TNf-α), and activation of neutrophils. (16)
GBS incidence within 8 weeks of a surgical procedure appears to be more common than previously thought. GBS following open heart surgery is exceedingly rare, perhaps under diagnosed or under reported given surveillance data incidence. Clinicians should be keenly aware of this association and quickly consider the diagnosis in any patient who develops progressive weakness, pain and diminished reflexes post-operatively.