Findings from our study reveal that most patients with GBS in Shenzhen are male between the ages of 20–60 years, with symptoms occurring in spring and summer. Respiratory infections were identified as the main prodromal events. Initial symptoms typically included limb weakness and abnormal sensations in the limbs, often accompanied by cranial nerve damage and autonomic involvement. AIDP emerged as the predominant type of GBS in our setting. The severity of GBS tended to be mild, with a favorable long-term prognosis. Age 60 years and older, as well as pulmonary infection, were identified as independent risk factors for developing severe GBS.
GBS occurs globally, with epidemiological surveys indicating a global incidence ranging from 0.6 to 4 per 100,000 people. The incidence of GBS varies across different regions due to differences in environmental conditions, economic status, healthcare infrastructure, and public health awareness and behaviors. While the overall incidence of GBS in Western countries ranges from 1.1 to 1.8 per 100,000 individuals [4], the incidence in China is 0.698 per 100,000. In Chinese children, the incidence of GBS is much lower, at 0.233 per 100,000, than that in adults, wherein the incidence rate is 0.829 per 100,000 [5]. Men exhibit a higher risk of developing GBS than women, with a male-to-female ratio of approximately 1.5:1 [6]. The high male-to-female ratio, suggesting an increased incidence of GBS in males, is consistent with previous reports [7]. The median age of GBS onset was 51 years, with a peak at ages 50 to 69 years [7]. In aging Europe and North America, GBS is most common in people between 50 and 80 years of age, whereas studies from Asia, South America, and sub-Saharan Africa show that GBS most commonly occurs in people between 21 and 35 years of age [8]. The age distribution observed in our study likely reflects Shenzhen’s status as an immigrant city with a predominantly young population. Univariate analysis revealed a significant difference in the age composition between the mild and severe disease groups (c2 = 6.2058, P = 0.013 < 0.05). Logistic regression analysis showed that age 60 years and above was an independent risk factor for severe disease, with older age correlating with a more severe clinical condition (OR = 3.453,95%CI:1.190-10.023). One explanation for this may be the reduced ability of myelin regeneration and slower recovery from peripheral injury associated with advanced age.
The incidence of GBS shows seasonal variation. In Europe, GBS mainly occurs in summer and autumn, whereas a study in India noted a higher occurrence in spring and summer, accounting for approximately 60% of all GBS cases [8]. Our study similarly observed a predominance of GBS cases during spring and summer. However, the severity of GBS did not exhibit a significant correlation with the onset season. This finding may be attributed to the spike in upper respiratory tract and gastrointestinal infections in spring and summer, alongside the slight seasonal difference experienced in Shenzhen. Approximately 50–75% of patients with GBS experience prodromal events up to 4 weeks before GBS onset, with Campylobacter jejuni being the most implicated infectious agent [9]. In Europe, North America, East Asia, and Southeast Asia, upper respiratory tract infections (35%) accounted for the majority of GBS cases, whereas in Bangladesh, gastrointestinal infections (27%) are more common [10]. Numerous infectious disease outbreaks worldwide, such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic of 2019, have confirmed that infections are related to the occurrence of GBS [11]. Additionally, non-infectious factors, including vaccination, surgery, pregnancy, immunosuppression, and the use of exogenous gangliosides, contribute to GBS prodromal events [12]. In our study, 60% of patients experienced prodromal events, mainly upper respiratory tract infections, while non-infectious factors accounted for a smaller proportion.
The clinical manifestations of GBS are diverse, and the initial symptoms typically include sudden symmetrical limb weakness, terminal limb numbness, pain, or cranial nerve involvement. Weakened or absent limb tendon reflexes are common signs of GBS, although some patients present with normal or hyperactive reflexes, as observed in AMAN and Bickerstaff brainstem variants [13]. Studies have shown that cranial nerve involvement occurs in 50% of the patients with GBS, often manifesting as bilateral facial muscle weakness, bulbar weakness, or extraocular muscle paralysis. Furthermore, nineteen percent of patients require ventilator assistance [14]. Autonomic dysfunction affects 38–70% of patients, with common symptoms including intestinal obstruction (42%), hypertension (39%), hypotension (37%), fever (29%), tachycardia or bradycardia (27%), and urinary retention (24%), as reported by Chakraborty [15]. Studies suggest that cranial nerve damage, especially bulbar muscle weakness and autonomic involvement, are risk factors for severe GBS and poor prognosticators [16]. Our univariate analysis indicated a relationship between cranial nerve and autonomic involvement and GBS severity, while logistic regression analysis identified cranial nerve involvement as a protective factor against severe GBS. This discrepancy may be attributed to our small sample size. Pulmonary infection during the disease course was identified as a risk factor for severe GBS, emphasizing the importance of promptly diagnosing and treating pulmonary infections to improve disease outcomes. The presence of cytoalbumin dissociation in the CSF is an important feature of GBS. The white cell count in the CSF of patients with GBS is usually normal, and the presence of marked leukocytosis (> 50 cells per microliter) suggests another disease, such as leptomeningeal malignancy or an infectious or inflammatory disease of the spinal cord or nerve roots. CSF protein levels usually range from 45 to 200 mg/dL; however, some cases may reach as high as 1000 mg/dL. The presence of cytoalbumin dissociation depends on the disease duration, with 10–30% of patients exhibiting normal CSF protein content during the second week of illness [13]. In our study, cytoalbumin dissociation in the CSF of our participants was primarily observed during the second to third weeks after the onset. Anti-ganglioside antibodies aid in identifying GBS variants. Some studies have demonstrated that patients with AMAN and AMSAN often have IgG anti-GM1 and anti-GD1a antibodies and that the presence of anti-GM2 antibodies is associated with a recent cytomegalovirus infection. Anti-GalNAc-GD1a and anti-GD1b antibodies are associated with axonal type GBS [17]. Additionally, the presence of IgG anti-GQ1b antibody is useful in diagnosing MFS, with a sensitivity of 85–90%, and is also found in Bickerstaff brainstem encephalitis (BBE), pharyngeal-cervical-brachial variant, and other patients with GBS and ophthalmoplegia [18]. Serological testing for anti-ganglioside antibodies is not mandatory for diagnosis, as a negative test result does not rule out GBS. In our study, CSF from 43 (33.07%) patients were tested for antiganglioside antibodies, with 22 (16.92%) testing positive. The anti-ganglioside antibodies evaluated in this study were mainly anti-GM1, GM2, GD1a, and GQ1b.
GBS is a heterogeneous syndrome with multiple variants and a wide spectrum [19]. AIDP accounts for 85–90% of cases in the United States and Europe, while AMAN dominates in developing countries. Doets et al. [20] found that MFS is more prevalent in Asian countries. Previous studies have highlighted that in China, AMAN is the most common type of axonal injury in GBS [21]. However, given China’s vast territory, the incidence of AIDP and AMAN varies across regions. Notably, AMAN is the predominant type in northern China, accounting for 55.3% of GBS cases, while AIDP prevails in southern China.
Intravenous immunoglobulin (IVIG) and plasma exchange (PE) are the only known immunotherapeutic approaches that accelerate recovery from GBS. Clinical trials have demonstrated the efficacy of IVIG administered within two weeks of onset and PE within four weeks, with both treatments yielding comparable outcomes [22]. Several clinical studies have confirmed that glucocorticoids alone or in combination with IVIG are not effective. Currently, national and international guidelines do not recommend glucocorticoids for the treatment of GBS. Administering a second course of IVIG therapy in patients with a poor prognosis has not been proven to be effective. In our study, IVIG (42.31%) was the most common treatment, with a large proportion also receiving IVIG combined with glucocorticoids. This trend may be attributed to disease progression during the course of GBS.
Globally, most patients with GBS achieve good recovery, with 77% walking independently at 6 months and 81% at 12 months, with over 50% achieving full recovery [23]. Although GBS has a favorable prognosis, statistics reveal that 40% of patients experience varying degrees of weakness, limb pain, numbness, and other complications, significantly impacting work efficiency and quality of life. The long-term prognosis of our study participants was favorable, potentially due to the prevalence of AIDP in the region, where the disease primarily presents as mild.
Due to the extended timeframe within which cases were recruited in this study, some patients had vague memories and could not accurately describe details about their specific recovery, potentially introducing recall bias. Other limitations of our study include the relatively small sample size and the lack of specific pathogen serological test results across different seasons.