Temporal Lobe Arteriovenous Malformations Research Articles

Temporal Lobe Arteriovenous Malformations

Temporal lobe arteriovenous malformations (AVMs) represent a subgroup of intracranial AVMs with particular characteristics and management issues. To characterize the surgical outcomes of temporal lobe AVMs with emphasis on visual field deficits (VFDs) and seizures. Between 1992 and 2008, 29 patients were operated on for temporal lobe AVMs. Patient data were retrospectively collected and analyzed. Twelve of 29 patients (41.4%) presented with seizures and 4 (13.7%) presented with VFDs. Postoperatively, 6 patients (24%) showed new VFDs and 2 improved, with a rate of preservation of full visual fields of 84%. Larger AVMs (> 3 cm) were significantly associated with postoperative VFD (P = .008). Epilepsy outcomes assessed by the Engel scale were as follows: 9 patients (75%) were in class I (seizure free), 1 patient (8.3%) was in class III, and 2 patients (16.6%) were in class IV (no change or worsening). Postoperative modified Rankin Scale outcomes were excellent (grade 0-1) in 18 patients, good (grade 2) in 7, and poor (grade 3-4) in 4. Older age at diagnosis correlated with a worse functional outcome (Spearman ρ = 0.369; P = .049). AVMs were totally removed in 27 of 29 patients (93.1%). Complete surgical excision was confirmed with angiography. Two patients needed reoperation for AVM remnant. Three patients had persistent hemiparesis (10.3% permanent morbidity). There was no mortality. Seizure control is usually underappreciated in the surgical management of AVMs. However, in temporal lobe AVMs, good outcomes with low morbidity and good visual field preservation can be accomplished.

Temporal lobe arteriovenous malformations: anatomical subtypes, surgical strategy, and outcomes

Descriptions of temporal lobe arteriovenous malformations (AVMs) are inconsistent. To standardize reporting, the authors blended existing descriptions in the literature into an intuitive classification with 5 anatomical subtypes: lateral, medial, basal, sylvian, and ventricular. The authors' surgical experience with temporal lobe AVMs was reviewed according to these subtypes. Eighty-eight patients with temporal lobe AVMs were treated surgically. Lateral temporal lobe AVMs were the most common (58 AVMs, 66%). Thirteen AVMs (15%) were medial, 9 (10%) were basal, and 5 (6%) were sylvian. Ventricular AVMs were least common (3 AVMs, 3%). A temporal craniotomy based over the ear was used in 64%. Complete AVM resection was achieved in 82 patients (93%). Four patients (5%) died in the perioperative period (6 in all were lost to follow-up); 71 (87%) of the remaining 82 patients had good outcomes (modified Rankin Scale scores 0-2); and 68 (83%) were unchanged or improved after surgery. Categorization of temporal AVMs into subtypes can assist with surgical planning and also standardize reporting. Lateral AVMs are the easiest to expose surgically, with circumferential access to feeding arteries and draining veins at the AVM margins. Basal AVMs require a subtemporal approach, often with some transcortical dissection through the inferior temporal gyrus. Medial AVMs are exposed tangentially with an orbitozygomatic craniotomy and transsylvian dissection of anterior choroidal artery and posterior cerebral artery feeders in the medial cisterns. Medial AVMs posterior to the cerebral peduncle require transcortical approaches through the temporo-occipital gyrus. Sylvian AVMs require a wide sylvian fissure split and differentiation of normal arteries, terminal feeding arteries, and transit arteries. Ventricular AVMs require a transcortical approach through the inferior temporal gyrus that avoids the Meyer loop. Surgical results with temporal lobe AVMs are generally good, and classifying them does not offer any prediction of surgical risk.

Spontaneous thrombosis of congenital cerebral arteriovenous malformation complicated by subdural collection:in uterodetection with disappearance in infancy

We report a case of congenital left temporal lobe arteriovenous malformation (AVM) detected by cranial ultrasound in utero and confirmed immediately after birth by cranial Doppler ultrasound and cranial MRI. The AVM disappeared on follow-up cranial MRI 4 months later. A small left frontal subdural collection was present on these follow-up MR images, which subsequently resolved by the 7 month MRI study. The cause of the spontaneous thrombosis of the AVM is uncertain. The frontal subdural collection may be secondary to volume loss. This case documents the perinatal presence of AVM. The baby was neurologically intact before, during and after the thrombosis of the AVM.

Retrospective analysis of the surgically treated temporal lobe arteriovenous malformations with focus on the visual field defects and epilepsy

Background Authors investigate the surgical outcomes of the temporal lobe arteriovenous malformation (AVM) with focus on the visual field deficit and seizure. Methods Between 1981 and 2004, we experienced 294 cases of intracranial AVMs. Among the 294 cases, 45 (15.3%) were located in the temporal lobe. Twenty-six of the 45 cases underwent microsurgical excisions of the AVMs. Results The male-female ratio of 26 surgically treated temporal lobe AVMs was 15:11. The mean age was 34.2 years, ranging from 7 to 63 years. The sites of lesion were classified as polar in 1, dorsal in 2, laterobasal in 15, and mediobasal in 8. The initial symptoms were hemorrhage in 22 and epilepsy in 4 cases. Arteriovenous malformations were totally removed in all 26 patients and there was no surgical mortality. The visual field deficits were identified in 17 of 22 patients with hemorrhage. Massive hematoma cases that needed emergency operation were 5. Visual field deficits improved in only 2 of the 5 patients after surgery. Among the 7 quadrantanopia patients, 3 resulted in hemianopia after surgery. Seven of 22 hemorrhage patients had history of epilepsy. Although one patient had new postoperative epilepsy, the medical controls of the seizure were good in all 8 patients. Four patients underwent AVM excision for epilepsy without hemorrhage. In two patients, seizures disappeared after surgery. The other two patients had typical psychomotor seizures after the total excision of AVMs. Conclusions Improvement of visual field deficit due to hematoma was difficult in most cases. Emergency craniotomy for global neurological deterioration due to massive hematoma had improved the visual field deficit in two cases. Although the outcome of seizure associated with hemorrhage was acceptable, the postoperative intractable seizures would remain in cases with epilepsy without hemorrhage. Intraoperative electrocorticography might be requisite for nonruptured temporal lobe AVM cases with epilepsy.

Temporal lobe arteriovenous malformations: Surgical management and outcome

Temporal lobe arteriovenous malformations (AVMs) represent a subgroup of intracranial AVMs with particular characteristics and management issues. We performed a retrospective analysis of 24 consecutive patients with temporal lobe AVMs treated with surgical excision. Factors such as location, size, arterial feeders, venous drainage, and clinical follow-up were recorded for each. Results were compared with those of 132 patients with nontemporal lobe AVMs surgically treated over the same time period. Sixteen of the temporal AVMs were located in the convexity, six in the mesotemporal region, and two were predominantly intraventricular. The mode of presentation was seizure in 11 patients, hemorrhage in 7, headache in 4, and 2 were asymptomatic. Patients with convexity AVMs more commonly presented with seizures, whereas patients with mesotemporal or intraventricular AVMs were more likely to present with hemorrhage. One patient with subarachnoid hemorrhage from a basilar artery aneurysm died. Postoperatively, 2 patients (8.3%) had a new hemiparesis and dysphasia, 1 (4%) had a new dysphasia and hemianopsia, and 3 others (13%) were left with an isolated superior quadrant field deficit. Lasting surgical morbidity other than isolated field deficit was 13% for patients with temporal AVMs and 15% for those with nontemporal AVMs. Temporal lobe AVMs may be successfully resected using a direct microsurgical approach with limited morbidity and excellent prognosis for recovery. Most of the deficits relating to AVM hemorrhage and those of the immediate postoperative period improved significantly over the subsequent few months.

Magnetoencephalographic localization of a language processing cortical area adjacent to a cerebral arteriovenous malformation

In order to accurately estimate the risk of surgery for dominant perisylvian arteriovenous malformations, the topographical relationship of the lesion to language cortex must be determined. A case is presented in which a magnetoencephalographic (MEG) study was used to map preoperatively and noninvasively an intracortical source of speech-receptive cortex in a 25-year-old right-handed man with a dominant left temporal lobe arteriovenous malformation. The speech-evoked magnetic field was analyzed at 36 positions over the left hemisphere in response to presentations of the consonant-vowel syllables "da" and "ga." A topographical map of the magnetic component evoked at 110 msec after stimulus onset, which was negative going to the vertex in concurrent electrical recordings, was congruent with a superficial cortical neuronal current source. This source was displaced from that usually observed in normal individuals to tonal or click stimuli, being superior to the probable location of auditory cortex, and superior and anterior to the probable location of Wernicke's area as conventionally described. The MEG results were in accord with the determination of position of a language-processing cortical area as assessed by direct electrical stimulation of the cortex during surgery under local anesthesia, and by superselective Amytal (amobarbital) injection during angiography. The MEG recordings and exposed brain stimulation sites were coordinated by cranial measurements, skull x-ray landmarks, and angiographic anatomy. Investigations such as this, which compare MEG findings with those from established clinical procedures, are an essential step in determining the physiological and anatomical utility of magnetoencephalography for noninvasive clinical functional localization.