Diagnosis

MRI

A contrast brain MRI is usually the first test. Certain scan features can suggest a leak, although a normal brain MRI does not rule SIH out. Because most leaks start in the spine, a spinal MRI may also be done. This can show fluid outside the sac that holds the spinal cord, which helps guide further tests.

LP

A lumbar puncture is not a reliable way to confirm or exclude SIH. The pressure can be low, normal, or occasionally high. SIH is mainly a problem of low CSF volume rather than always low pressure.

Conventional CT myelography

This test injects contrast into the CSF and then scans with CT after a delay. It shows the CSF space well but often does not pinpoint the leak. It usually does not show CSF-venous fistulas.

Dynamic myelography

This is the best test for finding fast leaks and CSF-venous fistulas. Contrast is injected into the CSF and imaging starts straight away using fluoroscopy or CT. Lying on the side and simple breathing or pressure manoeuvres can make a hidden fistula show up.

In simple terms, the fluoroscopic approach involves:

• Local anaesthesia, usually without sedation.
• Careful positioning based on MRI findings.
• A small needle in the lower back to inject saline and contrast.
• Short, real-time X-ray runs to look for leak sites, with extra runs if needed.
• A low-dose CT afterwards in some cases.
• Usual post-lumbar puncture care and brief bed rest.