# Medial tentorial dural arteriovenous fistula: A rare cause of bithalamic oedema

Cyril Dargazanli, Anais Lippi, Nicolas Gaillard

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Cyril Dargazanli, Anais Lippi, Nicolas Gaillard. Medial tentorial dural arteriovenous fistula: A rare cause of bithalamic oedema. Radiology Case Reports, 2022, 17 (6), pp.2111-2114. 10.1016/j.radcr.2022.03.072. hal-03653204

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Submitted on 31 May 2022

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<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_2.png" /><figcaption>Fig. 1 – Noninvasive Imaging A: Plain CT scan showing bithalamic symmetrical hypodensities B: Baseline MRI showing bithalamic FLAIR hyperintensities C: Diffusion MRI depicting increased bithalamic apparent diffusion coefficient (ADC) D: Punctuate hemorrhage in right thalamus on T2* E: Gadolinium enhanced sequence showing small foci of bithalamic patchy enhancement F: Arterialized superior vermian vein (white arrow) draining into vein of Galen (dotted white arrow) and subsequently into internal cerebral vein (black arrow).</figcaption></figure>

fistula (dAVF). Arterial supply was mainly from both falx cerebelli branches of the posterior meningeal arteries coming from the neuromeningeal trunks of the anterior pharyngeal arteries (APA, Fig. 2A, B), with a faint accessory supply from the medial tentorial branch of the left middle meningeal artery (Fig. 2C, D).

Anterior segment of the straight sinus was thrombosed (Fig. 2E), explaining the venous drainage into the superior vermian vein and the vein of Galen.

Complete embolization was performed using liquid embolic agent (ethylene-vinyl copolymer suspended in dimethyl sulfoxide and opacified with tantalum [Onyx, eV3]) through the left APA route (Fig. 2F).

Patient's cognition improved over the next month, with spontaneous mobilization 8 days after the embolization and complete normalization of vigilance.

However, patient was discharged in a rehabilitation center regarding persistence of severe comprehension disorders and aphasia.

MRI performed at 3 months showed complete resolution of thalamic anomalies.

## Discussion

A broad list of conditions (vascular, metabolic, infectious or neoplastic) is associated with bithalamic oedema. Although tentorial dural fistulas have already been described as a cause of bithalamic oedema and subacute dementia [1,2], they are not generally included in pathologies implied in this classical radiologic pattern [3]. Diagnostic may be difficult on noninvasive imaging, and these rare dAVF are potentially overlooked. Moreover, non-hemorrhagic presentation (thalamic dementia) may delay angiographic diagnosis, with a mean duration of symptoms at the time of diagnosis around 3 months [1]. Right diagnostic is of paramount importance, and may avoid inadequate brain biopsy.
<figure><img src="image_3.png" /><figcaption>Fig. 2 – Digital Subtraction Angiography (DSA) A and B: Lateral (A) and anteroposterior (B) arterial phase showing the fistulous plaque (white arrow), the arterialized superior vermian vein (dotted white arrow) and vein of Galen (black arrow) C and D: Small contribution of the medial tentorial branch from the left middle meningeal artery (white arrow) E: Lateral venous phase of left vertebral artery injection showing filling defect of the anterior part of straight sinus, related to deep venous thrombosis F: Post embolization non-subtracted image showing liquid-embolic cast in the arterial feeders, in the fistulous plaque, but away from the vein of Galen.</figcaption></figure>
Tentorial dural arteriovenous fistulas may be classified into 6 types on the basis of shunt location, associated sinus and direction of venous outflow [4]. Arterial feeders for the straight sinus/medial falcotentorial subtype are mainly the posterior meningeal artery, occipital artery or tentorial artery. Both endovascular and surgical procedures may be efficiently performed to cure these aDVF.

In conclusion, medial tentorial dAVF should be evocated in patients with unexplained rapidly progressive cognitive impairment and bithalamic oedema, and complete DSA should be performed in these situations.

## Patient consent

Informed consent for publication of this case was obtained from the patient.

## REFERENCES

[1] Holekamp TF, Mollman ME, Murphy RKJ, Kolar GR, Kramer NM, Derdeyn CP, et al. Dural arteriovenous fistula-induced thalamic dementia: report of 4 cases. J Neurosurg 2016;124(6):1752–65. doi:10.3171/2015.5.JNS15473.

[2] Cox M, Rodriguez P, Mohan S, Sedora-Roman NI, Pukenas B, Choudhri O, et al. Tentorial dural arteriovenous fistulas as a cause of thalamic edema: 2 cases of an important differential diagnosis to consider. The Neurohospitalist 2021;11(1):33–9. doi:10.1177/1941874420944333.

[3] Hegde AN, Mohan S, Lath N, Lim CCT. Differential diagnosis for bilateral abnormalities of the basal ganglia and thalamus. RadioGraphics 2011;31(1):5–30. doi:10.1148/rg.311105041.

[4] Lawton MT, Sanchez-Mejia RO, Pham D, Tan J, Halbach VV. Tentorial dural arteriovenous fistulae: operative strategies and microsurgical results for six types. Oper Neurosurg 2008;62(suppl_1) ONS110-ONS125. doi:10.1227/01.neu.0000317381.68561.b0.