CSF disease - Spontaneous intracranial hypotension syndrome - Ep.1/2

CSF session: Spontaneous Intracranial Hypotension

The session opened with a historical and clinical overview by Dr. Anne Ducros, who traced the origins of our understanding of intracranial hypotension to Dr. Georges Schaltenbrand in 1938, who coined the term “hypoliquorrhea.” For many years, little progress followed until recent decades saw a resurgence in awareness thanks to improved imaging and more nuanced classification. Dr. Ducros emphasized that orthostatic headache, while the most recognizable symptom, is just the visible “tip of the iceberg” of Spontaneous Intracranial Hypotension (SIH). The broader, often underrecognized clinical spectrum includes tinnitus, sound distortion, superficial siderosis, and even frontotemporal dementia.

In our own practice, we’ve only recently begun actively working up suspected SIH cases, with orthostatic headache as the most common entry point. However, this session expanded our clinical radar, I now feel the need to be more vigilant in considering SIH even in patients with atypical or chronic neurologic symptoms.

A live case demonstration by Dr. Federico Cagnazzo featured a patient who initially presented with bilateral chronic subdural hematomas and orthostatic headache. Drs. Vincent and Adnan Siddiqui discussed the critical need to first address subdural hematomas, either surgically or via middle meningeal artery embolization, before proceeding with further SIH workup. This sequence was also followed in the live patient.

Dr. Federico then walked through a structured SIH workflow starting with a contrast MRI brain evaluated using the BERN score, which we already apply routinely in our diagnostic process. The score assigns weighted values to six key imaging markers (e.g., venous engorgement, pachymeningeal enhancement, subdural collections etc.), and helps stratify patients into low, medium, or high likelihood for CSF leaks.

Next, a whole spine MRI with high-resolution 3D heavy weighted T2 sequences with fat suppression is used to assess for Spontaneous Longitudinal Epidural Collections (SLEC). For SLEC-negative cases, like the one demonstrated, the recommended next step is a dynamic myelogram, either with dual-energy CT / photon-counting CT or DSA based digital subtraction myelogram (DSM). In our practice, we currently use DSA based dynamic digital subtraction myelography, which remains effective in experienced hands.

Few technical advises by experts to note while performing a DSM

1. The maximum contrast that can be injected is no more than 15cc

2. To let out some CSF after injecting contrast to relieve the intrathecal pressure before removing the LP needle

3. To use a pillow under the head to elevate the head thereby preventing the contrast to flow into the intracranial subarachnoid space to prevent any potential intracranial complications like seizures etc.

4. To always perform a dual energy CT myelogram if available or a cone beam CT myelogram immediately after the dynamic study to better delineate the draining veins and to compare the final onyx cast with the initial study

The session also included an outstanding anatomical discourse by Prof. Dr. Jacques Théron, who challenged traditional illustrations of the spinal venous plexus. He clarified that epidural veins are predominantly anterolateral to the thecal sac, not posterior, and typically lack valves. This revelation, supported by visuals from his book Spinal Phlebography, significantly changes how I’ll interpret venographic pathways and embolization routes in the future.

A particularly thought-provoking moment came from Dr. Xavier Barreau, who asked why, in the absence of venous valves, retrograde blood flow into the subarachnoid space is not observed. It’s a question that calls for deeper anatomical research and may even reshape how we think about venous fistula dynamics.

The technical part of the live case concluded with Dr. Federico achieving access to the left T9 radicular vein via the hemiazygous system—navigating from the left iliac vein through the IVC, SVC, azygous, and hemiazygous veins. He placed dual microcatheters above and below the target segment for controlled Onyx delivery. The final cast covered the epidural plexus one level above and below the fistula, crossing midline—an elegant and complete result.

We haven’t yet attempted such embolization in our center, but I feel we’re well prepared to do so for the right case. The anatomical understanding and procedural planning demonstrated here provide a clear roadmap.

This session was a remarkable blend of history, diagnostic logic, venous anatomy, and procedural innovation. It has expanded not just my knowledge but also the confidence in recognizing and treating this often-overlooked condition. As we encounter more patients with vague chronic symptoms, I believe SIH will move higher on our differential lists and more often onto our angio table.