Due to the loss of cerebrospinal fluid (CSF) in the spinal region, affected patients typically experience changes in the brain region as well. These changes result from the fact that the missing CSF must be compensated by an increase in volumes of other structures, which can be detected on magnetic resonance imaging (MRI). Our research group at Inselspital succeeded in defining the six most sensitive signs for CSF loss syndrome among a large number of imaging criteria and in combining them into a simple diagnostic score. Based on these criteria, the likelihood of the presence of CSF loss syndrome can be estimated and classified as "low," "intermediate," or "high".

The 6 indirect signs on head MRI in patients with SIH:

1. Contrast enhancement of the dura
2. Subdural fluid collections (subdural hematomas and hygromas)
3. Dilatation of the large veins and sinuses
4. Enlargement of the pituitary gland leading to effacement of the suprasellar cistern (< 4 mm)
5. Brain-sagging: effacement of the prepontine cistern (< 5 mm)
6. Brain-sagging: decreased mamillopontine distance (< 6.5 mm)

(A) The illustration shows a normal brain.
(B) The illustration shows typical changes in a patient with CSF loss syndrome:

1. Rounded and dilated veins and sinuses.
2. Contrast enhancement of the meninges (dura).
3. Deposition of blood products on the surface of the brain.
4. Enlarged pituitary gland.
5. Enlarged intercavernous sinus.
6. Effacement of the suprasellar cistern (< 4mm).
7. Subdural collections (subdural hematomas or hygromas).

The greatest challenge in finding the exact location of the CSF leak is that the tear or fistula, which is only a few millimeters in size, can occur anywhere along the entire spinal column. In this regard, the search for the CSF leak is often like looking for a needle in a haystack.

To answer these questions, we at Inselspital have developed a special step-by-step diagnostic protocol, which is performed with great care and in a highly standardized manner by a specialized and experienced neuroradiologist. In the first step, a spinal MRI is performed, which allows us to assess whether CSF is detectable outside the dura. The MRI provides information that is crucial for planning in case of further examination by myelography.

MR images of the spine show CSF that is detectable outside of the dura (arrows). The CSF has leaked through a small hole in the dura somewhere along the spinal column - the exact location of this hole is unknown based on MR-imaging alone and further clarification by dynamic myelography is required.

The procedure is performed with the patient fully awake. After thorough disinfection, sterile draping and local anesthesia, a special puncture needle is advanced between the spinous processes of the lower lumbar vertebrae in the direction of the spinal canal under X-ray guidance. The needle is advanced until cerebrospinal fluid (CSF) spontaneously drips out. Once the correct needle position has been achieved, approx. 20 ml of radiopaque contrast agent is injected into the spinal canal (intrathecally), which sinks downwards in the spinal canal due to the higher dead weight. Then the patient's feet are fixed to the examination table and the table is slowly tilted to the head-down position. X-ray images are acquired in order to locate the level of the CSF leak. Since the defect / hole in the dura can occur anywhere along the entire spinal column, in some cases it is not possible to find the exact location of the defect during the first examination. Nevertheless, it is possible to narrow down the suspected area and the procedure can be repeated on the following day.