Thalamic Arteriovenous Malformations Research Articles

Recurrent late cerebral necrosis with aggressive characteristics after radiosurgical treatment of an arteriovenous malformation

/Late cerebral radiation necrosis usually occurs within 3 years of stereotactic radiosurgery. The authors report on a case of recurrent radiation necrosis with rapid clinical deterioration and imaging findings resembling those of a malignant glioma. This 68-year-old man, who had a history of a left posterior temporal and thalamic arteriovenous malformation (AVM) treated with linear accelerator radiosurgery 13 years before presentation and complicated by radiation necrosis 11 years before presentation, exhibited new-onset mixed aphasia, right hemiparesis, and right hemineglect. Imaging studies demonstrated hemorrhage and an enlarging, heterogeneously enhancing mass in the region of the previously treated AVM. The patient was treated medically with corticosteroid agents, and stabilized temporarily. Unfortunately, his condition worsened precipitously soon thereafter, requiring the placement of a shunt for relief of obstructive hydrocephalus. Further surgical intervention was offered, but the patient's family opted for hospice care instead. The patient died 10 weeks after initially presenting to the authors' institution, and the results of an autopsy demonstrated radiation necrosis. Symptomatic radiation necrosis can occur more than a decade after stereotactic radiosurgery, necessitating patient follow up during a longer period of time than currently practiced. Furthermore, there is a need for more careful reporting on the natural history of such cases to clarify the pathogenesis of very late and recurrent radiation necrosis after radiosurgery and to define patient groups with a higher risk for these entities.

Embolization of basal ganglia and thalamic arteriovenous malformations.

Basal ganglia and thalamic arteriovenous malformations (AVMs) show a poor natural history and have proven difficult to treat. We report the safety and efficacy of presurgical and preradiosurgical embolization of these deep central lesions and describe the contribution of embolization to multimodality treatment. Thirty-eight patients with basal ganglia and/or thalamic AVMs underwent embolization in a total of 69 sessions. Seven of the 38 patients (18.4%) presented with hemorrhage, and 23 of 38 (60.5%) exhibited neurological deficits before therapy. Thirty patients (78.9%) underwent embolization with a liquid adhesive (cyanoacrylate), and five of these patients also underwent embolization with polyvinyl alcohol. Five patients (13.2%) were treated with polyvinyl alcohol or polyvinyl alcohol and silk. One patient (2.6%) underwent embolization alone, 19 (50.0%) underwent embolization followed by radiosurgery, 5 (13.2%) underwent embolization plus microsurgical resection, and 13 (34.2%) patients were treated using all three modalities. Three patients did not undergo embolization because of the morphological features of the AVMs and poor endovascular access. The patients who underwent embolization achieved AVM volume reductions of 10 to 100% (mean, 49.7%). Fifteen patients (39.5%) achieved complete obliteration of their AVMs, one with embolization alone, three with embolization followed by radiosurgery, five with embolization plus microsurgical resection, and six with a combination of all three modalities. At the time of the last follow-up imaging session, embolization combined with radiosurgery (19 patients) yielded a mean volume reduction of 81.1%, and all three modalities (13 patients) yielded a mean reduction of 84.6%. Four permanent neurological deficits resulted from embolization (5.8% of procedures, 10.5% of patients). The embolization-related complication rate was higher in the earlier years (1984-1989) of this series. Endovascular embolization plays an important role in multimodality treatment of AVMs involving the basal ganglia and/or thalamus. Embolization can result in obliteration of a significant volume of the AVM and may allow complete obliteration of the AVM when combined with microsurgical resection and/or stereotactic radiosurgery.

Wyburn–Mason Syndrome Variant Treated with Stereotactic Radiosurgery

Classical Wyburn–Mason syndrome consists of unilateral arteriovenous malformations affecting the retina, midbrain, and visual pathways in the brain, and the facial structures. An unusual case of Wyburn–Mason syndrome with bilateral manifestations and without retinal involvement is described. A 19-year-old girl presented at the age of 5 with a left hemiparesis and aphasia following intracerebral hemorrhage in the right internal capsule and basal ganglia. Angiography demonstrated left sylvian, right frontoparietal, and right thalamic arteriovenous malformations (AVMs). In addition to multiple intracranial AVMs, she had multiple telangiectatic lesions scattered over her body. Ophthalmological examination was normal except for left orbital bruit. Two years later, with moderate clinical improvement, she had proton beam radiosurgery for her multiple AVMs. Due to lack of beneficial effect, repeat radiosurgery with more appropriate dose is under consideration. A review of the literature revealed that our presenting case represents one of the few reported cases of atypical Wyburn–Mason syndrome with bilateral manifestations and without retinal involvement. To our knowledge, ours represent the first reported case for which radiosurgery had been offered as a treatment modality.

Surgery for Deeply Seated Arteriovenous Malformation

Surgery for deeply seated arteriovenous malformation (AVM) is controversial because stereotactic irradiation is applicable to the lesion. We have, however, experienced 30 deeply seated AVMs treated by direct surgery and/or endovascular treatment. The present study shows profiles of those patients and results of surgery. They include AVM in the thalamus in 12 cases, striatum in four cases, paraventricular area in five cases, medial temporal lobe in three cases, intraventricular area in three cases, and other regions in three cases. They were treated by surgery alone in 23 cases, embolization followed by surgery in four cases, and embolization alone in three cases. AVM in the mediodorsal thalamus and fornix (5 cases) was best treated by transcallosal approach. Venous aneurysm was commonly found in the AVM of this region and was a good navigator to the AVM. Pulvinar AVM was accessible through posterior interhemispheric approach (2 cases). None of these cases had additional neurological deficits. Cadaver dissection was useful for acquisition of surgical approach. Striatal AVM was approached through hematoma cavity with minimal manipulation to the surrounding structures, yet two of four cases showed progression of their weakness. The present study indicates that thalamic AVM can be approached surgically with careful selection of the approach. On the other hand, striatal AVM is not a good candidate for direct surgery and better treated by stereotactic irradiation.

Lesions affecting the claustrum

MR imaging examinations of seven patients with a variety of claustral disorders and included in this study. The ages of the patients ranged from 4 to 65 years, and all of them were males. The lesions involving the claustrum comprised cases with asphyxia, Wilson's disease, ischemic white matter disease, thalamic arteriovenous malformation, MELAS syndrome, viral encephalitis and Parkinson's disease.

Total excision of a thalamic arteriovenous malformation using an orbito-fronto-malar approach: Case report

A 37-year-old woman was admitted to Osaka Neurological Institute after the sudden onset of left hemiplegia, hemihypesthesia, and ipsilateral hemianopia on February 4, 1992. Computed tomography (CT) disclosed the presence of hemorrhage in the right thalamus extending to the ipsilateral internal capsule. Cerebral angiography after CT scanning disclosed the presence of a cerebral arteriovenous malformation (AVM) fed by copsulothalamic and lateral geniculate body arteries originating from the right anterior choroidal artery. She was operated on with removal of the AVM using a right orbito-fronto-malar approach (OFM approach), which did not require transection of the cerebral parenchyma. The anterior choroidal artery could be followed distally from its origin and small feeding branches originating from the parent artery were easily identified, and the cerebral base could be examined in greater detail than with the conventional frontotemporal approach. The nidus could be excised in its entirety without difficulty. Postoperative angiography confirmed total excision of the AVM. She was transferred to another hospital for rehabilitation on April 13, 1992. Motor strength on the left side had improved to 3 / 5 by that time. The OFM approach appears to be potentially useful for the resection of inferolateral thalamic AVMs, because it does not require corticotomy and feeding branches can be identified and dealt with prior to other surgical manipulations.

Surgical Treatment of Thalamic Arteriovenous Malformations

The microsurgical excision of arteriovenous malformations located in the thalamic region in eight patients is reported. Six were located in the posterior aspect of the thalamus and two were located in the anterior. Hemorrhage occurred in all of the cases. Hemiparesis, hemianesthesia, and consciousness disturbance were the most typical clinical features. The supine position with the anterior transcallosal approach was used for anterior dorsal lesions, and the sitting position with the posterior interhemispheric approach was used for posterior dorsal lesions. Total removal was confirmed by angiography in seven patients, and incomplete removal was noted in one patient. There was one death in this group of patients. Memory disturbance was the most common postoperative complication. This complication showed considerable improvement with time. Other complications included homonymous hemianopsia (three patients), hemisensory loss (six patients), and transient hemiparesis (one patient). All survivors (seven patients) were able to return to their occupation after surgery. The vascular input, the location of the malformation, and clinical history are the contributory factors concerning operability. With the modern neurosurgical and anesthesiological facilities, surgical removal of thalamic malformations in selected cases is advisable.

視床部AVMの1治療例

視床部AVMの1治療例

Feeder に動脈瘤を伴った AVMの塞栓術

Two cases of ruptured cerebellar arteriovenous malformations (AVMs) and one case of ruptured thalamic AVM with a peripheral aneurysm in their main feeders of AVMs were treated by endovascular techniques. In the first case, the aneurysm was located in the midportion of the superior cerebellar artery (SCA) which fed the nidus; in the second case, the aneurysm was in the anterior inferior cerebellar artery (AICA); and in the third case, the aneurysm was in the medial posterior choroidal artery (MPCA). All aneurysms were thought to be the cause of bleeding from CT and MRI findings. A microcatheter was inserted very carefully just proximal to the aneurysm via the transfemoral route, and after negative results of a provocation test by amytal was confirmed, the aneurysm and nidus were embolized using ethylene-vinyl-alcohol copolymer (EVAL) simultaneously. In each cases disappearance of the aneurysms and reduction of nidus size were recognized after embolization without new neurological deficits. EVAL is a new liquid embolic agent which forms an ethylene-vinyl-alcohol copolymer upon contact with blood and is not adhesive and soft enough to resect after embolization. In cases of AVMs with the peripheral aneurysm in the feeding artery, it is ideal to embolize aneurysms and AVMs simultaneously to prevent a rupture of the aneurysm following the increase in the intraluminal arterial pressure after embolization of the pedicle of AVM. EVAL is an appropriate embolic agent in this type of cases, because it makes repeated injection, possible until the complete disappearance of an aneurysm.

視床AVMの手術

In this report, three operations for thalamic arteriovenous malformation (AVM) are discussed, mainly from the viewpoint of surgical approach and technique.Case 1 was a 20-year-old male with a history of three episodes of intracranial hemorrhage. Angiogram demonstrated a nidus 2cm in diameter at the anterior inferior site of the left thalamus. The malformation was fed by anterior and posterior choroidal arteries and the anterior thalamoperforating artery. First surgery was performed using a subtemporal approach. The left posterior communicating artery which mainly fed the nidus was trapped. Second surgery was performed via a bifrontal craniotomy. An anterior transcallosal approach was used to expose the AVM. Nidus was totally excised via the left lateral ventricle. Postoperatively, no new neurological deficit appeared.Case 2 was a 36-year-old female who experienced a sudden intraventricular hemorrhage. Angiogram demonstrated a nidus 2cm in diameter at the posterior superior site of the left thalamus. The malformation was fed by the anterior and posterior choroidal arteries. Surgery was performed via a left parietal craniotomy. A transparietal approach was used to expose the AVM and the nidus was totally excised. Although the patient exhibited Gerstmann syndrome and right homonymous hemianopsia, they were transient, and the patient was discharged with no deficit.Case 3 was a 51-year-old female with a history of three episodes of intracranial hemorrhage. Angiogram demonstrated a nidus 4cm in diameter at the right thalamus. The malformation was fed by the anterior and posterior choroidal arteries, the anterior thalamoperforating artery and the thalamogeniculate artery. Surgery was performed via a right fronto-temporo-parietal craniotomy. At first, the feeder was clipped using a subtemporal approach. And then the nidus was totally excised using a transparietal and transventricle approach. Postoperatively, impairment of consciousness appeared.It appeared to be important in surgery for AVM's in a critical area like the thalamus that management of the feeder be performed first, bleeding should be avoided as much as possible, and the normal brain tissue should not be damaged. Although the border between the nidus and the normal brain tissue should be ascertained, MRI was considered to be useful in determining these relationships. While it is reasonable to excise the thalamic AVM via the lateral ventricle, it is difficult to manage the feeder at first. Previous feeder clipping was useful in two cases. The trans parietal approach was used in two cases. Even at the dominant hemisphere, neurological deficit associated with this approach did not remain. Monitoring of SEP and using doppler sonography were also useful.

Technique of catheterization and embolization of the lenticulostriate arteries

✓ The technique of catheterization and embolization of the lateral and medial lenticulostriate arteries, using one or two balloon catheters of various designs, is described. A case of a bilateral thalamic arteriovenous malformation is presented and a further instance of an aneurysm of a striate artery is briefly discussed. Because of the high probability of proximal middle cerebral artery (MCA) thrombosis, care must be taken to determine tolerance to MCA occlusion prior to embolization.