INTRODUCTION

Guillain-Barré syndrome (GBS) is an acute inflammatory polyneuropathy of autoimmune etiology, of worldwide distribution, generally triggered by infectious agents ¹ and characterized by a progressive decrease in muscle strength and osteotendinous reflexes ². The overall incidence varies between 0.8 and 3 cases per 100,000 persons ^{3 , 4}, the reported mortality rate varies between 3% and 7% and case fatality ranges from 3% to 20% ^{5 , 6}. In Peru, an epidemiological study of GBS cases showed that the overall case fatality was 3.5% and this figure was higher in older men ⁷.

People who die from GBS previously develop severe disease characterized by the absence of motor response from the four limbs, respiratory failure requiring mechanical ventilation, dysautonomia phenomena manifested by tachycardia, bradycardia, insomnia, anxiety, palpitations, orthostatic hypotension and syncope ⁸. The known factors that condition severity are: age over 60 years, inadequate diagnosis and delay in receiving medical treatment ^{9 , 10}. However, there are some little studied clinical factors such as the velocity of neurological deterioration that could be related to the severity of the disease.

The aim of this study was to identify the velocity of disease progression as a predictor of severity in patients with GBS. In addition, the clinical and laboratory characteristics of the patients were described in an exploratory manner, according to their epidemiological history.

MATERIALS AND METHODS

RESULTS

Of 121 patients who entered the study, 27 (22%) were lost during follow-up due to the following: voluntary discharge in 9 (0.7%) patients; 11 (0.9%) were referred to another public or private hospital center; and 7 (0.6%) were diagnosed with another disease during hospital follow-up, such as encephalitis, infectious polyneuropathy or cerebrovascular disease. Finally, 94 cases with GBS were evaluated; mean age of the patients was 42 years (range 8-73); 77.8% presented severe GBS (Hughes scale >3); 64 (68%) were male; mean hospital stay was 19 days (range 1-129). The average time of illness at admission was 4 days; 12 (12.8%) patients had some comorbidity; 3% received some type of vaccination in the last month before admission; the average body mass index (BMI) was 26.4 (Table 1).

Infectious symptoms prior to muscle weakness were present in 71 (81%) patients with GBS, of whom 45 (47.8%) had diarrhea and 22 (23.4%) had a flu-like syndrome (Table 1). The duration of these symptoms averaged 3 days. The average time between the onset of these symptoms and the onset of motor weakness was 5 days (range 1-21).

The site of the onset of motor weakness in the upper limbs was evident in 63 (67.1%) patients and 31 (32.9%) patients started with weakness in the lower limbs (Table 1). The distribution by site of onset of weakness was not significantly different when compared with GBS severity (p = 0.121).

The pharmacological treatment administered was immunoglobulin in 86 (91.0%) patients and plasmapheresis in 6 (7.0%) patients (Table 1). The mean Hughes scale at hospital discharge was 2 (range 0-5). Regarding complications, 9 (10.0%) patients presented some type of dysautonomia. Admission to mechanical ventilation was necessary for 8 (8.5%) patients.

CSF analysis did not show results associated with GBS severity (Table 2); the values of carbon dioxide pressure (PCO₂) evidenced in arterial gas analysis and monocyte count in hemogram were higher in severe GBS (p = 0.001 and p = 0.023, respectively).

In the multivariate analysis, DPV for more than 3 days behaved as a protective factor for not developing severe disease (RR = 0.27; 95%CI: 0.07 - 0.95; p value = 0.041) (Table 3). Likewise, it is evident that the lower the DPV value, the greater the probability that the disease will become more severe (Table 4).

DISCUSION

This study identified that the most important factor that conditions the course of severe disease in GBS is DPV. The scale used to determine the degree of severity was the Hughes scale ¹². This study showed that 78% of patients with GBS were admitted in wheelchair or bedridden (Hughes >3), this percentage of severity was similar to the data obtained by Yosria et al. ¹³ and Parmar et al. ¹⁴ who reported that the majority of patients seen with GBS had grade ≥ IV, with 75% and 83.7% respectively. These authors explain that the reason for the high frequency of disease severity was the delay in treatment administration. This study confirmed that the velocity of weakness progression is associated with severity, showing that patients with DPV less than or equal to one day have about 80% probability of developing severe disease.

The average DPV was three days in patients with severe GBS, similar to a study ¹⁵, that also found elevated concentrations of antibodies against gangliosides GM1, GD1a, GalNac-GD1a and Gd1b in peripheral nerve axons, these antibodies can be induced by infectious agents such as Campylobacter jejuni ¹⁶, which produce damage in the myelin sheath segment and to the proximal nerve root ⁶.

Several studies agree that severe cases of GBS can occur at any age and regardless of sex ¹⁵. Although other studies indicate that GBS is more frequent in men and with an average age ranging from 32 to 44 years ^{17 - 18}, similar findings have been evidenced in our study, where 68% of those affected were male and the average age was 42 years; however, these two characteristics were not associated with the severity of the disease.

According to the study by Mao et al. ¹⁹ the case fatality rate for GBS is 6%, according to the findings from our study the case fatality rate was 2%, much lower than that found in other studies, this low rate could be due to the typical form of presentation. The causes of death were related to delayed admission to mechanical ventilator or prolonged exposure to mechanical ventilator. In this study, 2 patients died, one of them was admitted in poor general condition and died on the first day of hospitalization due to delayed admission to mechanical ventilator and the second due to infectious complications caused by pan-resistant Acinetobacter baumanni due to prolonged use of mechanical ventilator on day 112 of hospitalization.

The most frequent complication was the presence of dysautonomia which was evident in 19% of patients with severe GBS. There are other clinical and laboratory characteristics in patients with severe GBS such as bicipital areflexia, PCO₂ values > 30 and monocytes > 490, but which were not significantly higher in the group of patients with severe GBS when the multivariate analysis was performed.

The findings of the CSF evaluation found normal or slightly elevated lymphocytes < 50 cells/mm3 and that protein levels were elevated from the first week of illness, this shows in more than 90% of those affected by GBS ²⁰. This study shows the results of CSF analysis at the first week of admission; the average CSF protein values were 52 mg/dL and albumin-cytologic dissociation was seen in 90% of cases. The elevation of CSF protein is due to increased antibody deposits, complements and myelin products upon breakdown, while the level of IgG and anti-ganglioside antibodies are related to the prognosis of the disease ²¹.

The velocity of neurological disease progression is a practical and accessible evaluation method that should be considered by physicians and included in GBS severity prediction scales. In this study, we observed that when the value is equal to or less than one day, the probability of the patient developing the severe form is approximately 80% and this probability is reduced to 60% if it is two days, behaving as a predictor of poor prognosis when the DPV is less than two days and with possible requirement of mechanical ventilation.

The strength of this study lies in the nature of longitudinal data collection to assess the velocity of disease progression as a predictor of GBS severity. However, this study has some limitations. First, the losses of patients during the months of follow-up that accounted for more than 20%; thus, it is necessary to find out what happened to those lost patients to assess the nature of the final outcome, deceased or recovered. Second, there are some data that were not explored in depth, such as the electromyography study, due to the lack of equipment to perform this evaluation in some hospitals or due to the high demand for this equipment during the period of the GBS outbreak. Finally, although we presented a strong correlation between DPV and severity of GBS, our findings should be verified with a prospective study with a larger number of patients including serological analysis of inflammatory markers.

The results of our study support the hypothesis that, in patients with GBS, neurological DPV should be assessed and that a duration of less than two days was found to be associated with a high probability of severe disease, thus reflecting the impact of DPV on severity and its possible usefulness as a prognostic marker.