Diagnostic challenges and lessons learned of Guillain-Barré syndrome mimicking central nervous system infection – a case report

BACKGROUND: Guillain-Barré syndrome (GBS) is an immune-mediated disorder affecting the peripheral nervous system, often triggered by infections, vaccinations, trauma, or surgery. Typically, it presents as progressive, symmetric limb weakness with hyporeflexia. However, some GBS subtypes can present atypically with symptoms like headache, facial palsy, and confusion. These symptoms overlap significantly with central nervous system (CNS) infections, often causing diagnostic delays. CASE PRESENTATION: A 57-year-old man was admitted with cough, sputum, and shortness of breath, having received a rabies vaccination a month earlier. He developed headache, dysphagia, progressive muscle weakness, and impaired consciousness, requiring Intensive Care Unit (ICU) transfer, endotracheal intubation, and mechanical ventilation. The initial cerebrospinal fluid (CSF) metagenomic next-generation sequencing (mNGS) detected Pseudomonas aeruginosa (sequence count: 6094), combined with fever and a series of clinical symptoms before transfer to the ICU, CNS infection was considered. Treatment with piperacillin-tazobactam, meropenem, and ciprofloxacin yielded no improvement. Albumino-cytological dissociation in the CSF led to a neurology consultation for suspected GBS, and intravenous immunoglobulin (IVIg) therapy began. Negative CSF bacterial cultures and mNGS, along with positive anti-GT1a IgM ganglioside antibodies and electromyogram(EMG) result indicating nerve damage, confirmed the GBS diagnosis. After five days of IVIg, the patient was weaned from mechanical ventilation and showed significant neurological recovery. CONCLUSION: The significant clinical overlap between GBS and CNS infections poses a major diagnostic and therapeutic challenge. This case highlights the importance of thorough history-taking, comprehensive neurological assessment, careful interpretation of lab results, and early neurologist involvement to minimize diagnostic delays in GBS and prevent subsequent treatment delays.