Confirmation of Guillain-Barré Syndrome (GBS) usually involves a combination of clinical evaluation and specific diagnostic tests, primarily a spinal tap.
Here's a breakdown of the process:
Initial Assessment
If your doctor suspects GBS, they will:
- Review your medical history: This includes any recent illnesses, infections (like Campylobacter jejuni, Zika virus, or cytomegalovirus), or vaccinations.
- Discuss your symptoms: They'll ask about the nature, progression, and distribution of your muscle weakness, tingling, or pain.
- Perform a physical and neurological exam: This evaluates your muscle strength, reflexes, nerve function, and coordination.
Diagnostic Tests
After the initial assessment, your doctor will likely order one or more tests to confirm the diagnosis. The primary tests used to confirm GBS are:
Spinal Tap (Lumbar Puncture)
- What it is: A procedure where a needle is inserted into the lower back to collect cerebrospinal fluid (CSF), the fluid that surrounds the brain and spinal cord.
- How it helps: In GBS, the CSF typically shows elevated protein levels but a normal white blood cell count. This combination, called albuminocytologic dissociation, is a strong indicator of GBS.
- Important note: While elevated protein is common, it may not be present early in the illness, so a normal spinal tap early on doesn't necessarily rule out GBS. Repeat testing might be necessary.
Electromyography (EMG) and Nerve Conduction Studies (NCS)
- What they are: These tests measure the electrical activity of muscles and nerves. EMG involves inserting a needle electrode into a muscle, while NCS uses electrodes placed on the skin to stimulate nerves.
- How they help: These tests can detect nerve damage characteristic of GBS, such as slowed nerve conduction velocity or abnormal electrical activity in muscles.
- Important note: Similar to spinal tap results, EMG and NCS findings may be normal early in the course of GBS, and repeat testing might be required.
Other Considerations
While spinal tap and EMG/NCS are the primary tests, other tests might be performed to rule out other conditions that can mimic GBS. These might include blood tests, imaging studies (like MRI), or tests for specific infections.
In summary, confirming GBS involves a combination of clinical evaluation, CSF analysis (spinal tap), and electrodiagnostic testing (EMG/NCS). The results of these tests, along with a thorough medical history and neurological examination, help doctors make an accurate diagnosis.
