The Challenging Clinical Management of Patients with Cranial Dural Arteriovenous Fistula and Secondary Parkinson’s Syndrome: Pathophysiology and Treatment Options

Cranial dural arteriovenous fistula (cDAVF) may rarely lead to parkinsonism and rapid cognitive decline. Dysfunction of the extrapyramidal system and the thalamus, due to venous congestion of the Galenic system with subsequent parenchymal edema, is likely to represent an important pathophysiological mechanism. Here, we report a case of a 57-year-old man with a cDAVF of the straight sinus (Borden type III; DES-Zurich bridging vein shunt [BVS] type with direct, exclusive, and strained leptomeningeal venous drainage [LVD]) and subsequent edema of both thalami, the internal capsule, the hippocampi, the pallidum, and the mesencephalon. Several attempts at venous embolization were unsuccessful, and the neurological condition of the patient further deteriorated with progressive parkinsonism and intermittent episodes of loss of consciousness (KPS 30). A suboccipital mini-craniotomy was performed and the culminal vein was disconnected from the medial tentorial sinus, achieving an immediate fistula occlusion. Three-month follow-up MRI revealed complete regression of the edema. Clinically, parkinsonism remitted completely, allowing for tapering of dopaminergic medication. His cognition markedly improved in further course. The purpose of this report is to highlight the importance of rapid and complete cDAVF occlusion to reverse venous hypertension and prevent progressive clinical impairment. The review of the literature underlines the high morbidity and mortality of these patients. Microsurgical disconnection of the fistula plays an important role in the management of these patients and, surprisingly, has not been reported so far.

Coexisting arachnoid cyst and tentorial sinus: A therapeutic dilemma

A 4-year-old male presented with a large arachnoid cyst over the left temporal region causing displacement of adjacent structures. Cerebral angiography showed dilatation of the tentorial sinus without other apparent vascular alterations. The association of these two anomalies raises a therapeutic dilemma as no information is available about how the variants of the venous system can modify cerebrospinal fluid hydrodynamics and thus affect arachnoid cyst’s prognosis. In this case, the patient was treated conservatively and has remained stable for 2 years.

Tentorial Dural Arteriovenous Fistulae: Operative Strategies and Microsurgical Results for Six Types

Objective: Tentorial dural arteriovenous fistulae (DAVF) are rare, have a high risk of hemorrhage, often cannot be obliterated endovascularly, and frequently require microsurgical interruption of the draining vein. We differentiated these fistulae into six types and developed specific operative strategies on the basis of these types. Methods: During a 9-year period, 31 patients underwent microsurgical treatment for tentorial fistulae: seven galenic DAVF, eight straight sinus DAVF, three torcular DAVF, three tentorial sinus DAVF, eight superior petrosal sinus DAVF, and two incisural DAVF. Results: The posterior interhemispheric approach was used with galenic DAVF; the supracerebellar-infratentorial approach was used with straight sinus DAVF; a torcular craniotomy was used with torcular DAVF; the supratentorial-infraoccipital approach was used with tentorial sinus DAVF; the extended retrosigmoid approach was used with superior petrosal sinus DAVF; and a pterional or subtemporal approach was used with incisural DAVF. Angiographically, 94% of the fistulae were obliterated completely. Four patients had transient neurological morbidity, none had permanent neurological morbidity; and there was no operative mortality (mean follow-up, 4.2 yr). Conclusion: Tentorial DAVF can be differentiated on the basis of fistula location, dural base, associated sinus, and direction of venous drainage. The operative strategy for each type is almost algorithmic, with each type having an optimum surgical approach and an optimum patient position that allows gravity to retract the brain, open subarachnoid planes, and shorten dissection times. No matter the type, the fistula is treated microsur-gically by simple interruption of the draining vein.

Anatomic Variations of the Deep Cerebral Veins, Tributaries of Basal Vein of Rosenthal: Embryologic Aspects of the Regressed Embryonic Tentorial Sinus

The embryonic tentorial sinus regresses at the 60–80 mm embryologic stage and most of the deep venous channels constitute the basal vein of Rosenthal (BVR). Persisting remnants of the embryonic tentorial sinus can be seen in the adult configuration of the BVR. We tried to explain the anatomic representations of the BVR associated with the remnant embryonic tentorial sinus. A total 41 patients and 82 hemispheres were included in this study. CT angiography was performed in all patients as screening for cerebrovascular disease or other intracranial disorders. A separate workstation and 3D software were used to evaluate the cranial deep venous systems with 3D volume rendering techniques, thin-slice MIP images, and MPR techniques for the analysis of complicated angioarchitecture. Variations of the BVR were classified according to the developmental alterations of efferent pathways into four groups: telencephalic group (A) including tributaries of the uncal vein, inferior frontal vein, anterior communicating vein, and inferior striatal vein; diencephalic group (B) of the interior ventricular vein and peduncular vein; tegmental bridging group (C) of the longitudinal LMV anastomosis; tectal group (D) of the superior vermian vein and internal occipital vein in relation to the Galenic connection. The BVR constituted from the embryonic tentorial sinus was also assessed and the developmental aspects reviewed. Remnant embryonic tentorial sinus was visualized in 12% (10/82) of hemispheres, all of them invariably connected with the telencephalic (A) and diencephalic (B) groups. Most of those connections (9/10) to basal venous tributaries originated from the medial tentorial sinus except one case from the lateral tentorial sinus. No Galenic connections of the BVR were identified in 10% (8/82). Various tributaries of the BVR were classified as: Telencephalic group (A) 43% (35/82), Diencephalic group (B) 35% (29/82), Bridging group (C) 11% (9/82), and Tectal group (D) 6% (5/82). Four cases (5%) were unclassified and revealed only small basal tributaries of the BVR without connection to the great vein of Galen. Anatomic variations of the BVR connected with persistent embryonic tentorial sinus could often be demonstrated in adult configurations considering the embryologic aspects of developmental regression and secondary cerebral venous adaptations.

Anatomic Variations of the Superficial Middle Cerebral Vein: Embryologic Aspects of the Regressed Embryonic Tentorial Sinus

The embryonic tentorial sinus usually regressses during postnatal development, but its typical prenatal drainage patterns and intradural anastomoses can be depicted as various developmental phenotypic representations. Here, we tried to clarify the variant types of the superficial middle cerebral vein (SMCV) associated with the embryonic tentorial sinus. Total 41 patients and 82 hemispheres were included in this study. CT angiography was performed in all patients as screening for cerebrovascular disease or other intracranial disorders. A separate workstation and 3D software were used to evaluate the cranial venous systems with 3D volume rendering techniques, thin-slice MIP images, and MPR techniques for the analysis of its complicated angioarchitecture. Variations of the SMCV were classified according to the developmental alterations of the embryonic tentorial sinus, including sphenoparietal sinus (cranial remnant of tentorial sinus), basal sinus (floor of middle cranial fossa), petrosal and caudal remnant of the tentorial sinus. Secondary intradural anastomoses of cavernous and superior petrosal sinuses were also evaluated for the efferent pathways. The most frequent type of remnant tentorial sinus, sphenoparietal sinus was present in 49% (40/82) of hemispheres examined. Other regressed patterns of embryonic tentorial sinus were also identified in 38% (31/82): nine caudal remnant type around the transverse sinus, 12 petrosal type, one basal type, five unclassified cases, and mixed type were found in four cases. Secondary intradural cavernous sinus anastomosis was seen in 44% (36/82), however the most prevalent pattern was no anastomosis (46/82) with cavernous sinus. Only one case of superior petrosal sinus anastomosis was found in this series associated with basal sinus type. Anatomic variations of SMCV can be clearly demonstrated with embryologic aspects of the tentorial sinus according to its developmental regression and postnatal secondary adaptations of cerebral venous drainage.

Microsurgical anatomy of the tentorial sinuses

✓ Variations of the tentorial sinus of cadaver cerebellar tentoria were examined under a surgical microscope. The tentorial sinuses were classified into four groups: Group I, in which the sinus receives venous blood from the cerebral hemisphere; Group II, in which the sinus drains the cerebellum; Group III, in which the sinus originates in the tentorium itself; and Group IV, in which the sinus originates from a vein bridging to the tentorial free edge. The tentorial sinuses of Groups I and II were frequently located in the posterior portion of the tentorium. The sinuses of Group I were short and most frequently present in the lateral portion of the tentorium. The tentorial sinuses of Group II, which were usually large and drained into the dural sinuses near the torcular, were separated into five subtypes according to the draining veins and direction of termination. The tentorial sinuses of Groups III and IV were located near the tentorial free edge or the straight sinus. The draining patterns of the tentorial sinuses and their draining veins (so-called “bridging veins”) were present in most cases. Knowledge of this anatomy can benefit the neurosurgeon carrying out repair near or on the cerebellar tentorium.