4 Left Temporal Arteriovenous Malformation

Left Temporal Arteriovenous Malformation

Clinical Presentation

A 45-year-old man presented with recurrent episodes of impaired consciousness followed by a confusional state lasting for several minutes. On hospital admission his neurologic examination was normal.

Initial Neuroradiologic Findings

Cerebral MRI showed a lesion (30 × 25 mm) with numerous flow voids in the left temporal region extending temporomesially and showing intense enhancement on postgadolinium MRI. There were no signs of recurrent bleeding. An enlarged draining vein running along the left midbrain was interpreted as a dilated basal vein of Rosenthal (Fig. B4.1). MR angiography (MRA) was not performed.

Suspected Diagnosis

Repeated complex partial seizures caused by an arteriovenous malformation (AVM) in the left temporal lobe.

Questions to Answer by Ultrasound Techniques

Detection of the nidus.
Detection of the feeding arteries.
Detection and identification of the draining veins.

Initial Neurosonologic Findings

Extracranial Duplex Sonography

Comparison of the right and left sides revealed increased flow velocity in the left internal carotid artery (ICA) and reduced pulsatility (flow velocity / pulsatility index (PI): left ICA 81/48 cm/s / 0.6; right ICA 59/24 cm/s / 0.95). Assessment of both vertebral arteries (VAs) was normal (Fig. B4.2 and Fig. B4.3).

Transcranial Duplex Sonography

Color-mode imaging revealed atypical flow signals of multiple vessels (25 × 25 mm) between the main stem of the left middle cerebral artery (MCA) and posterior cerebral artery (PCA) considered to be the nidus of the AVM. Clear identification of the terminal ICA and the proximal MCA was not possible. An arterial vessel signal away from the probe with turbulent flow, increased flow velocity, and reduced PI related to the vessel conglomerate was thought to represent a major feeder originating from the distal ICA (flow velocity 155/84 cm/s). More posteriorly, a similar feeder signal with a marked turbulent flow and musical murmurs toward the probe and a reduced PI was found in the projection of the left proximal P2-PCA segment (flow velocity 150/78 cm/s). The distal left M1-MCA as well as the distal left P2- and P3-PCA segments revealed normal flow velocities and PI. Raised flow velocities with an increased PI were observed in the enlarged left basal vein of Rosenthal (flow velocity 52/30 cm/s) but not in the contralateral corresponding vein (flow velocity 13/10 cm/s; Figs. B4.4–B4.11; Videos B4.1–B4.3). Duplex sonographic measurement of the global cerebral circulation time between the left ICA and the left internal jugular vein (IJV) after intravenous administration of an echo contrast agent (Levovist) was significantly shortened (3.4 seconds compared with the normal published value of 7 ± 1.3 seconds; see Video B4.4). For further discussion, see Chapter 3, “Cerebral Circulation Time” under “Parameter s of Cerebral Hemodynamics.”

Conclusion

Large left temporal AVM. Blood supply via feeding arteries from the left distal ICA or proximal M1-MCA and left proximal P2-PCA segments. Main drainage via the left basal vein of Rosenthal. Significant shortening of the global cerebral circulation time.

Conventional Angiography

Digital subtraction angiography (DSA) was performed which confirmed an AVM with a nidus of 30 × 25 × 15 mm visible on selective left ICA injection. The main feeder was the anterior choroidal artery. AVM supply during vertebral contrast injection was seen via the posterior choroidal artery from the proximal PCA. Extensive filling of the dilated left basal vein of Rosenthal, followed by the straight sinus, was seen even in the early arterial phase of the carotid and vertebral angiograms (Fig. B4.12, Fig. B4.13, Fig. B4.14).

Fig. B4.1 MR T2-weighted image, axial plane. Multiple flow voids in the left temporal lobe corresponding to the nidus of the AVM. Note the enlarged basal vein of Rosenthal as a major AVM draining vein (arrowhead).

Fig. B4.2 Extracranial duplex, longitudinal plane. Left ICA with slight increase of blood volume flow (330 mL/min) and flow velocity (81/48 cm/s) and reduced pulsatility in comparison to the contralateral side (PI = 0.6).

Fig. B4.3 Extracranial duplex, longitudinal plane. Right ICA with lower blood volume flow (220 mL/min). Normal flow velocity (59/24 cm/s) and pulsatility (PI = 0.95).

Fig. B4.4 TCCS (transtemporal approach), left-sided insonation, midbrain plane. AVM nidus in the left temporal lobe reflected by the multicolored signals indicating different flow directions (arrowhead). Note the course of the M1-MCA (arrows) as well as the A1-ACA (arrow).

Clinical Course

Because of the reported recurrent complex partial seizures, anticonvulsive therapy was started. Opinions were obtained from our neurosurgeons, interventional neuroradiologists, and radiotherapists. Microsurgical resection was considered to be of high risk because of the eloquent localization of the malformation. Radiosurgery was not indicated because of the large size of the AVM. Partial embolization was considered to be possible via the endovascular approach; however, the patient decided against any intervention. Repeated clinical and ultrasound follow-up over an observational period of 12 years showed no further changes. No further seizures have occurred to date.

Final Diagnosis

Symptomatic epilepsy with complex partial seizures caused by a left temporal AVM.

Fig. B4.5 TCCS (transtemporal approach), left-sided insonation, thalamic plane. The AVM nidus (arrowhead) appears larger in the thalamic plane and the draining basal vein of Rosenthal becomes visible (arrow).

Fig. B4.6 TCCS (transtemporal approach), left-sided insonation, midbrain plane. Increased velocity and turbulent flow away from the probe in projection of the terminal ICA corresponding to an AVM feeder (flow velocity 155/84 cm/s, reduced PI = 0.66).

Fig. B4.7 TCCS (transtemporal approach), left-sided insonation, midbrain plane. Normal flow signal in the distal left M1-MCA (flow velocity 109/40 cm/s, normal PI =1.1).

Fig. B4.8 TCCS (transtemporal approach), left-sided insonation, midbrain plane. Increased flow velocity in the proximal left P2-PCA toward the probe corresponding to an AVM feeder (flow velocity 150/78 cm/s, reduced PI = 0.71).

Fig. B4.9 TCCS (transtemporal approach), left-sided insonation, thalamic plane. Normal flow velocity in the distal left P2-PCA (flow velocity 66/29 cm/s, normal PI = 0.9). Note the hidden flow signal of the basal vein of Rosenthal within the spectrum of the PCA.