Rare Abdominal Pain Onset in Guillain-Barré Syndrome: A Case Report of Acute Motor Sensory Axonal Neuropathy

Introduction

Guillain-Barré syndrome (GBS) is the leading cause of acute neuromuscular paralysis, resulting in respiratory failure that necessitates ventilation. The fatality rate of this condition ranges from 4% to 14%. Each year, GBS affects 1.3 to 4 individuals per 100 000 people worldwide [1]. The most common form of this clinical condition is distinguished by pathology, such as acute inflammatory demyelinating polyradiculoneuropathy (AIDP), acute motor axonal neuropathy (AMAN), or acute motor and sensory axonal neuropathy (AMSAN). A subset of patients also experience significant autonomic dysfunction, a condition known as acute panautonomic neuropathy (APN). In Western countries, AIDP occurs more frequently than the axonal variants. Although GBS usually presents with ascending weakness and sensory disturbances, abdominal pain as an initial symptom is very uncommon.

This atypical presentation can present as a diagnostic challenge since abdominal pain is not characteristic of GBS and may delay its diagnosis. AMSAN, a severe subtype of GBS, is distinguished by the sudden onset of weakness in distal areas, diminished or absent deep-tendon reflexes, symptoms affecting sensation, and respiratory failure. The rapid progression of symptoms in AMSAN often leads to quadriparesis shortly after initial presentation, distinguishing it from other GBS subtypes. Abdominal pain in patients with AMSAN may be attributed to autonomic dysfunction or sensory nerve involvement in the abdominal region. Although the exact mechanism underlying abdominal pain in AMSAN remains unclear, it is crucial to consider the diverse clinical manifestations of the GBS.

Case Report

A 42-year-old man with no previous medical condition presented with a 3-day history of abdominal and back pain. Prior to this, he visited his general practitioner and the emergency department of a different hospital. The abdominal pain was described as crampy and intermittent, which disrupted his daily activities at times. He had not experienced any fever, diarrhea, vomiting, or urogenital symptoms prior to the illness.

The patient reported no significant weight loss and denied the use of tobacco, alcohol, or illicit substances. Initial baseline laboratory investigations were unremarkable, and 1 day after admission with supportive management, he was discharged with a provisional diagnosis of acute gastritis. The following day, he was readmitted to the hospital with worsening cramping abdominal pain, along with reduced sensation and weakness, which started in his lower limbs and gradually affected his upper limbs. He had difficulty walking, was wobbly, and struggled with swallowing food, choking on solid foods, and he had voice changes. His vital signs parameters were within normal limits. However, neurological examination revealed significant weakness, with muscle power rated at 0/5 in both upper and lower limbs. The patient also exhibited hypotonia, areflexia, and sensory loss of the lower limbs. Rapid deterioration continued, and a few hours later, he developed difficulty breathing and was promptly intubated.

A repeat laboratory investigation, including complete blood count, renal profile, and liver function tests, was within normal parameters and unremarkable (Table 1). Additionally, the anti-ganglioside antibody assay produced negative findings. The CT scan of the brain revealed an old infarct in the right frontal lobe, with no evidence of intracranial bleeding. A chest X-ray indicated the possibility of aspiration pneumonia.

The patient was referred to a neurologist for further management. An MRI of the entire spine revealed a smooth conus medullaris and cauda equina, diffuse thickening with post-contrast enhancement, and the ventral and dorsal roots were homogeneously enhancing (Figures 1, 2). The results of the nerve conduction study indicated severe axonal motor polyneuropathy with sensory involvement. This was evidenced by significantly reduced compound muscle action potentials (CMAPs) amplitudes and extended distal latencies in the median and ulnar nerves during motor testing. While the clinical examination suggested sensory involvement, sensory studies could not be fully completed due to suboptimal technical conditions.

A cerebrospinal fluid (CSF) study showed albuminocytological dissociation, as evidenced by elevated CSF protein levels of 2.1 g/L and a white cell count of 0, indicative of widespread inflammation of the nerve roots. The serological analyses revealed the presence of Mycoplasma pneumoniae and Haemophilus influenzae, with corresponding cycle threshold (CT) values of 35 and 36. Notably, Burgdorferi serology was not conducted.

The diagnosis of AMSAN, a subtype of GBS was made based on clinical presentation, nerve conduction studies, MRI spine, and CSF analysis. Initially, the patient was treated with intravenous immunoglobulin (IVIG) 0.4 g/kg/day for 5 days. Following the absence of significant neurological improvement after 8 days, the patient underwent 5 cycles of plasma exchange. Subsequently, the patient exhibited marked clinical and symptomatic improvement. Over time. Over time, he progressed from being bedridden to sitting up and regained strength, with muscle power rated at 4/5 in the upper and lower limbs. After spending a total of 64 days in the hospital, including 39 days in the intensive care unit (ICU), he was discharged. By this point, he was able to walk with assistance.

Discussion

GBS is a rare autoimmune disorder encompassing several significant subtypes: AIDP, AMAN, AMSAN, Miller-Fisher syndrome, and APN. The hallmark of GBS is rapidly progressing ascending weakness, often accompanied by mild sensory loss and areflexia, typically reaching its peak over the course of several weeks [2]. Clinically, it presents as acute flaccid paralysis, variable sensory disturbances, and elevated protein levels in the CSF, without pleocytosis.

GBS can also present atypically with severe abdominal pain, as seen in some post-vaccination cases in which patients experience lower-limb weakness and urinary retention [3]. However, in our patient, no such association with vaccination was observed.

While abdominal pain is not commonly associated with GBS, there have been a few documented cases in which it was the initial presenting symptom, as reported by Wong et al [4], Michas et al [5], and Shekhar et al [6]. It is estimated that two-thirds to three-quarters of GBS patients experience significant pain, typically localized to the lower back and lower limbs. This pain can arise from various factors, such as inflammation of the large myelinated nerve fibers, leading to limb muscle pain (dysesthesia) or nerve root inflammation, causing radicular pain that radiates through the limbs. Small-fiber involvement can also contribute to the pain experienced in GBS [7]. Abdominal pain in GBS can be triggered by sensory nerve inflammation, dorsal nerve root inflammation, or gastrointestinal autonomic dysfunction. However, in our patient, there were no accompanying autonomic symptoms or signs, making it unlikely that autonomic dysfunction caused the abdominal pain. Our case closely resembles that of Wong et al [4], where the patient initially presented with abdominal pain, followed by progressive leg weakness, without a clear link between these 2 symptoms. The association of dysautonomia symptoms suggesting APN variant is non-specific in this presentation, as the patient exhibits no significant cardiovascular manifestations such as hypotension, tachycardia, or arrhythmias. Furthermore, urinary and gastrointestinal symptoms were not clinically manifested [8].

In the management of GBS, both IVIG and plasma exchange (plasmapheresis) have been shown to reduce recovery time, and evidence suggests that both treatments have similar curative effects [9]. However, there are no guidelines recommending their combined use, as they do not offer additional benefits. The patient’s treatment protocol initially consisted of 5 cycles of IVIG; however, this course of IVIG therapy failed to yield significant symptomatic improvement. As a result, the medical team opted to transition to plasma exchange as an alternative therapeutic approach. As highlighted in a systematic review by Rapheal et al [10], moderate-quality evidence shows that plasma exchange improves most outcomes compared to supportive care alone. This includes faster recovery of walking with assistance, faster recovery of walking unaided, and quicker improvement in disability grade. In our patient, plasma exchange was initiated after IVIG failed to result in noticeable clinical or neurological recovery. Fortunately, after completing 5 uneventful cycles of plasma exchange over 9 days, the patient showed substantial symptom improvement.

Although studies have shown that combining plasma exchange with IVIG or using them in sequence does not provide superior results compared with either treatment alone [11], plasma exchange can still be a preferred option, particularly in cases where cost is a consideration. In patients from low socioeconomic backgrounds or in developing countries, plasmapheresis may offer a more cost-effective therapeutic approach. However, it has been noted that patients receiving plasma exchange tend to have a longer hospital stay compared to those treated with IVIG, as reported in the Yashoda GBS Registry [12] in India.

Conclusions

This case highlights the importance of recognizing atypical presentations of GBS, particularly its AMSAN subtype. Our patient’s initial presentation of severe abdominal pain, followed by rapid neurological deterioration, underscores the need for clinicians to maintain a high index of suspicion for GBS, even when symptoms diverge from the classic ascending paralysis pattern. It also emphasizes the value of considering alternative treatments when initial therapies prove ineffective. Lastly, this serves as a reminder to clinicians to consider GBS in patients presenting with unexplained abdominal pain followed by neurological symptoms, potentially leading to earlier diagnosis and treatment initiation.