From the Guidelines
The diagnosis of Guillain-Barré Syndrome (GBS) relies primarily on cerebrospinal fluid (CSF) analysis and nerve conduction studies, as well as clinical examination and blood tests to rule out other conditions. The diagnostic process for GBS involves a combination of these tests to confirm the presence of the disease and distinguish it from other neurological disorders.
Key Diagnostic Tests
- CSF analysis typically shows albuminocytologic dissociation, characterized by elevated protein levels (>45 mg/dL) with normal white blood cell counts (<10 cells/μL) 1.
- Nerve conduction studies reveal slowed nerve conduction velocities, conduction blocks, or temporal dispersion consistent with demyelination in the most common form of GBS 1.
- Clinical examination showing progressive symmetric weakness and areflexia is also crucial in diagnosing GBS 1.
- Blood tests to rule out other conditions, such as infections or autoimmune diseases, are also important 1.
Additional Diagnostic Tools
- Lumbar puncture should be performed as soon as GBS is suspected, though protein elevation may not appear until 1-2 weeks after symptom onset 1.
- Electrophysiological studies are most useful after the first week of symptoms 1.
- MRI with gadolinium may show nerve root enhancement in some cases, although this is not a primary diagnostic tool.
Importance of Early Diagnosis
Early diagnosis of GBS is critical to initiate appropriate treatment and improve outcomes. The most recent and highest quality study recommends that diagnosis be based on a combination of clinical features, CSF examination, and nerve conduction studies 1. This approach helps to confirm the diagnosis of GBS and distinguish it from other neurological disorders that may present similarly.
From the Research
Diagnostic Tests for Guillain-Barré Syndrome (GBS)
The diagnosis of Guillain-Barré Syndrome (GBS) is based on a combination of clinical presentation, laboratory tests, and electrophysiological studies. The key diagnostic tests include:
- Elevated cerebrospinal fluid protein level 2
- Electrophysiological changes such as marked slowing of conduction velocities, prolonged distal latencies, dispersion of the evoked responses, and frequent evidence of conduction block 2
- Nerve conduction studies (NCS) and electromyography (EMG) to assess the extent of nerve damage 3, 4, 5
- Cerebrospinal fluid (CSF) analysis to rule out other conditions such as infection or inflammation 3, 6
Electrophysiological Criteria
Several electrophysiological criteria have been proposed for the diagnosis of GBS, including:
- National Institute of Neurological Disorders and Stroke (NINDS) criteria 3
- Dutch criteria 3
- Brighton criteria 3
- Hadden's criteria 5
- Rajabally's criteria 5
Clinical Criteria
Clinical criteria, such as the presence of relatively symmetrical and progressive flail-type weakness of more than one limb, with or without ataxia and/or ophthalmoplegia, are also important for the diagnosis of GBS 3.
Limitations and Challenges
There is no gold standard test for the diagnosis of GBS, and the yield of different diagnostic criteria can vary 3. The timing of nerve conduction studies after symptom onset and repeated measurements during the disease course can influence the diagnostic accuracy 5. Additionally, the presence of reversible conduction failure can make diagnosis more challenging 5.