Isolated developmental venous anomaly of the pons with transpontine drainage: case report

Hemifacial spasm caused by the brainstem developmental venous anomaly: A case report and review of the literature

Background:

Hemifacial spasm (HFS) is usually caused by vascular compression of the root exit zone (REZ) of the facial nerve. Dual compression of the REZ by veins and arteries is also associated with HFS, but venous origin alone is rarely reported. We present a rare case of HFS caused by the brainstem developmental venous anomaly (DVA) treated with microvascular decompression (MVD).

Case Description:

A 30-year-old women presented with the left-sided HFS since the age of 18 years. The brainstem DVA was diagnosed by magnetic resonance imaging (MRI) and followed by two attempts of MVD at some other clinics without any improvement. At our hospital, MVD was performed through a left retromastoid craniotomy. Intraoperatively, after detaching the strong adhesions between the cerebellar hemisphere, petrosal dura and lower cranial nerves, and removing the Teflon sponge inserted during the previous operations, the compressing large vein was found, separated from facial nerve REZ and MVD was completed. The postoperative computed tomography angiography and MRI showed the thrombosis of the main trunk of DVA and decompression of the facial nerve REZ. Complete cessation of HFS with hearing preservation was observed with only slight weakness of mimic muscles which disappeared within 3 months after surgery.

Conclusion:

HFS associated with brainstem DVA is a very rare condition. MVD of the facial nerve REZ with transposition of the large draining vein should be considered as an effective treatment option.

Isolated hemorrhagic arterialized DVAs: revisiting symptomatic DVAs

We aim to present here a small case series of symptomatic isolated hemorrhagic arterialized developmental venous anomalies (sDVAs) with a larger goal of revisiting the classification based on patho-mechanisms plus emphasizing angiographic features coupled with CT and MRI. Typically, DVA is an incidental and silent abnormality on neuroimaging. Understanding its morphology in terms of arterialization and relationship with other entities is crucial for management. One adult and two pediatric cases presented with acute or sub-acute hemorrhage in the cerebellum or thalamus. Morphologic characterization on cross-sectional imaging and catheter angiography confirmed the integrated diagnosis of "symptomatic isolated hemorrhagic arterialized DVAs with deeper or superficial venous drainage". Conservative management was adopted in all cases. We emphasize the following classification and approach for symptomatic DVAs: (1) congestive isolated arterialized sDVAs, (2) congestive isolated resistive sDVAs, (3) coexisting sDVAs (with AVM or cavernous malformation), (4) compressive sDVAs (compressive effects), and (5) idiopathic DVAs. Like our three cases, ganglionic and infratentorial DVAs have higher propensity of hemorrhage, compressive effects, and usually harbor deeper venous drainage. Typical "caput medusae" as dominant collector vein on cross-sectional imaging is crucial to complement and even confirm the diagnosis of DVA before catheter angiography in sDVAs. Capillary stain or early opacification of DVAs is a marker of arteriovenous shunting in arterialized sDVAs. Recognition of this entity is crucial as treatment is usually conservative.

Developmental Venous Anomaly: Benign or Not Benign

Developmental venous anomalies (DVAs), previously called venous angiomas, are the most frequently encountered cerebral vascular malformations. However, DVA is considered to be rather an extreme developmental anatomical variation of medullary veins than true malformation. DVAs are composed of dilated medullary veins converging centripetally into a large collecting venous system that drains into the superficial or deep venous system. Their etiology and mechanism are generally accepted that DVAs result from the focal arrest of the normal parenchymal vein development or occlusion of the medullary veins as a compensatory venous system. DVAs per se are benign and asymptomatic except for under certain unusual conditions. The pathomechanisms of symptomatic DVAs are divided into mechanical, flow-related causes, and idiopathic. However, in cases of DVAs associated with hemorrhage, cavernous malformations (CMs) are most often the cause rather than DVAs themselves. The coexistence of CM and DVA is common. There are some possibilities that DVA affects the formation and clinical course of CM because CM related to DVA is generally located within the drainage territory of DVA and is more aggressive than isolated CM in the literature. Brain parenchymal abnormalities surrounding DVA and cerebral varix have also been reported. These phenomena are considered to be the result of venous hypertension associated with DVAs. With the advance of diagnostic imagings, perfusion study supports this hypothesis demonstrating that some DVAs have venous congestion pattern. Although DVAs should be considered benign and clinically silent, they can have potential venous hypertension and can be vulnerable to hemodynamic changes.