Cranial venous outflow insufficiency; rendered almost invisible to radiological imaging by circular reasoning. Rethinking... 2024 Higgins et al

Full title: Cranial venous outflow insufficiency; rendered almost invisible to radiological imaging by circular reasoning. Rethinking normal craniocervical venous anatomy

Highlights

• Cranial venous outflow insufficiency is mired in controversy.
• This reflects a mistaken view of normal craniocervical venous anatomy.
• The cause is a long-established pattern of circular reasoning between clinician and radiologist.
• The result may be a failure of diagnosis on a significant scale.

Abstract

Background and purpose

Cranial venous outflow insufficiency, a model of brain dysfunction based on partial or intermittent obstruction to cranial venous drainage, is an attempt to explain a clinical phenotype characterised by multiple complex symptoms, including headache, fatigue and cognitive dysfunction, that can be responsible for long term neurological disability.

This concept, however, has been received with some scepticism first, because its supposed symptoms seem mainly non-organic and, secondly, because its supposed lesions can be regarded as no more than variants of normal craniocervical venous anatomy.

This reasoning, however, fails to appreciate that an understanding of normal venous anatomy has evolved, not from dedicated studies in healthy volunteers, but almost entirely from patients whose symptoms are assumed to be non-organic, or at least not referrable to the specifics of craniocervical venous anatomy.

So, the reasoning is circular, and whilst this may not matter when frank venous thrombosis makes the diagnosis of venous disease clear, it might be frustrating attempts to understand the clinical expression of more subtle forms of cranial venous outflow compromise. Reassurance on this point, however, is only possible if it is inconceivable that the symptoms described by these patients could ever be referred back to the venous system, an assumption that has not been tested.

The purpose of this study was to test this assumption by examining the clinical profile of patients who, by default, make a significant contribution to perceptions of normal venous anatomy, that is patients with MRI brain scans reported to be normal.

Method
Cross-sectional: we recorded the symptoms and diagnoses in 100 consecutive patients with MRI brain scans reported as normal.

Results
26 % complained of headache, 25 % of focal neurological symptoms, 15 % of dizziness. 13 % had seizure/collapse. 46 % of patients had no final diagnosis. 18 % were diagnosed with migraine, 7 % with functional neurological disorder and 6 % with epilepsy.

Conclusions
The clinical overlap between patients with brain MRI reported as normal and patients with known venous sinus disease, as documented in the literature, raises strong concerns regarding their role in defining normal craniocervical venous anatomy. Current assumptions regarding this anatomy, therefore, are probably unsafe, this inviting a re-evaluation of the clinicopathological significance of hitherto almost ignored configurations of cranial venous outflow, such as jugular venous narrowing or outflow asymmetry, and giving encouragement to explore a pathological substrate in cranial venous outflow insufficiency for a range of otherwise unexplained symptoms.

Open access, https://www.sciencedirect.com/science/article/pii/S0967586824004211

 

"It has been proposed, for example, that chronic fatigue syndrome, IIH and spontaneous intracranial hypotension are all related, between them covering a spectrum of intracranial pressure disturbance caused by cranial venous outflow insufficiency [21]. In this scenario spontaneous intracranial hypotension represents a manifestation of IIH which develops following rupture of the dura under the stress of chronically raised pressure [22], [23], [24], and chronic fatigue syndrome (or fibromyalgia) represents the clinical manifestation of forms of IIH where papilloedema is absent, either because IIH is relatively mild [25], [26], or because it is modified by the presence of a CSF leak [21]. Thus, headache and fatigue are prominent in all, not necessarily with any distinguishing features [27]. In each, various combinations of the multiple symptoms described in the previous paragraph are frequent [27], [28], [29]. In none, are there reliably any clinical signs [27], [28], [29], [30], and in none, can the radiology be guaranteed to differentiate between them. All three conditions can be associated with elevated intracranial venous pressures with focal pressure gradients across intracranial or extracranial venous stenoses presenting targets for successful interventions [3], [14], [17], [18], [19], [20]."

 

Just for info :

IIH is "Idiopathic intracranial hypertension" according to wikipedia. I couldn't see anywhere it had been explained in the paper.

And reference to "venous sinus disease" is not obviously to do with the sinuses people are usually familiar with that can develop sinusitis it is a reference to various veins in the brain :

https://d45jl3w9libvn.cloudfront.net/jaypee/static/books/9789380704517/Chapters/images/313-1.jpg