From the Guidelines
The most important next test to perform in a patient with suspected Guillain-Barré Syndrome (GBS) presenting with decreased bilateral lower extremity strength and absent reflexes following gastroenteritis is a lumbar puncture with cerebrospinal fluid (CSF) analysis, as this test typically reveals albuminocytologic dissociation, characterized by elevated protein levels with normal white blood cell counts, which is a hallmark finding in GBS 1.
Key Considerations
- The diagnostic workup is crucial for confirming GBS, as early diagnosis allows for prompt initiation of immunomodulatory therapy such as intravenous immunoglobulin (IVIG) at 2g/kg divided over 5 days or plasma exchange, which can significantly improve outcomes by limiting nerve damage from the autoimmune response triggered by the preceding infection 1.
- Additionally, nerve conduction studies and electromyography (EMG) should be performed to demonstrate the characteristic demyelination pattern and confirm the diagnosis, as these electrophysiological studies can show slowed nerve conduction velocities, conduction blocks, or temporal dispersion consistent with demyelination 1.
- Blood tests should also be ordered to rule out other conditions, including complete blood count, metabolic panel, and specific antibody tests like anti-ganglioside antibodies (particularly anti-GM1 and anti-GQ1b) 1.
Monitoring and Management
- Regular assessment is required to monitor disease progression and the occurrence of complications, including routine measurement of respiratory function, muscle strength, and functional disability 1.
- Patients should be monitored for swallowing and coughing difficulties, and autonomic dysfunction should be assessed via electrocardiography and monitoring of heart rate, blood pressure, and bowel and bladder function 1.
Treatment
- Treatment strategies, such as IVIg and plasma exchange, are equally effective and should be initiated promptly to improve outcomes 1.
- The choice of treatment depends on the individual patient's needs and the availability of resources, but IVIg is usually the treatment of choice due to its ease of administration and widespread availability 1.
From the Research
Diagnosis and Testing for Guillain-Barré Syndrome
The patient's symptoms, including decreased strength in bilateral lower extremities and absent reflexes after a recent episode of gastroenteritis, suggest Guillain-Barré Syndrome (GBS) as the most likely diagnosis. To avoid complications and confirm the diagnosis, the most important next test to perform is:
- Nerve conduction studies (NCS) and electromyography (EMG), as they are essential for differentiating between demyelinating and axonal subtypes of GBS 2, 3, 4.
- Cerebrospinal fluid testing to show increased protein levels but a normal white blood cell count, which is a characteristic feature of GBS 2, 5.
Importance of Early Diagnosis and Testing
Early diagnosis and testing are crucial in GBS, as they can help identify patients who are at risk of developing severe complications, such as respiratory failure 6. The H reflex is the most sensitive test for early GBS, and upper extremity sensory nerve action potential (SNAP) is also frequently abnormal in early GBS 3.
- Repeated measurements of NCS and EMG can provide additional information and help monitor disease progression 4.
- Electrodiagnostic studies, including motor nerve conduction studies, can help predict the onset of respiratory paralysis in GBS 6.
Clinical Predictors of Respiratory Paralysis
Clinical predictors of respiratory paralysis in GBS include:
- Early peak disability
- Autonomic dysfunction
- Bulbar weakness 6 These predictors can help identify patients who are at high risk of developing respiratory failure and require close monitoring and early intervention.