Postoperative hyperperfusion in dural arteriovenous fistula associated with venous ischemia: case report

Hemodynamic studies of intracranial dural arteriovenous fistulas using arterial spin-labeling MR imaging

Arterial spin-labeling (ASL) magnetic resonance imaging (MRI) enables non-invasive acquisition of the brain perfusion information in cerebrovascular disease. We investigated hemodynamic changes in intracranial dural arteriovenous fistulas (DAVFs) using ASL-MRI. ASL-MRI by a Q2TIPS sequence on a 3.0-Tesla MRI was performed for three patients with Cognard's IIa+b type of DAVFs before and after treatment. Perfusion images obtained by ASL-MRI (ASL images) before treatment were visually compared with those by single-photon emission computed tomography images (SPECT images). Increasing rates of temporal changes of regional perfusion values in ASL images (ASL values) before and after treatment were also calculated. In all three patients, ASL images before treatment demonstrated high perfusion in regions around the shunting areas, where normal or low perfusion were detected on SPECT images; thus, ASL images might have demonstrated the abundant arterial shunting flow via the fistulas. On days eight to 20 after treatment, ASL values around the shunt areas remained the same or decreased, and those in the regions other than the shunt areas increased in all three patients. This might have been due to a combination of the following: a decrease in shunt flow volume, an amelioration of venous congestion, and a sustained an upward shift in the autoregulation of the brain perfusion pressure. All regional ASL values decreased on days 112 and 120 after treatment in two patients, which possibly reflects a reduction in the upward shift in autoregulation. ASL-MRI might be useful for identifying the hemodynamic behavior of DAVFs before and after treatment.

Changes of brain perfusion after endovascular embolization of intracranial arteriovenous malformations visualized by 99mTc-ECD SPECT

OBJECTIVE

Published data describing scintigraphic evaluation of perfusion changes in patients with cerebral arteriovenous malformations (AVMs) after embolization are very scarce. The aim of our study was to evaluate these changes by using Tc-ethyl cysteinate dimer single photon emission computed tomography.

MATERIALS AND METHODS

The examinations were performed in 20 patients before and after the treatment. Voxel-based analysis was used for semiquantitative assessment of single photon emission computed tomography. Hypoperfusion in basal single photon emission computed tomography was diagnosed when asymmetry index was higher than 10% in a cluster volume (CV) greater than 10.0 ml. The change of perfusion between basal and control studies was considered significant when relative difference (RD) was higher than 10% in a CV greater than 10 ml.

RESULTS

Obliteration of AVMs was total or nearly total in 12 patients and partial in 8 patients, No serious complications were observed after the procedure. Before embolization hypoperfusion in the region of an AVM was seen in 17 cases, perfusion defects in areas distant from an AVM were found in 12 patients. After embolization, perfusion around an AVM deteriorated in 11 patients (CV=10.7-68.7 ml, mean 28.6+/-18.4, RD=14-26%, mean 17.8+/-4.5). Improvement was seen in three cases (CV=13.7-17.7 ml, mean 16+/-2, RD=16.5-20.1%, mean 18.2+/-1.8). Perfusion deterioration in areas distant from AVMs was found in nine cases, improvement in three cases.

CONCLUSION

The changes of perfusion caused by endovascular embolization of AVM can rely on both deterioration and improvement, and occur in the parenchyma surrounding the AVM and in the distant regions of the brain. Although deterioration of perfusion indicated that more frequent follow-up was necessary, it was not related with serious complications in our group of patients.

Cerebral venous ischemia by dural arteriovenous fistulas

Intracranial dural arteriovenous fistulas (AVFs) are potentially at risk for hemorrhage, and their symptoms and prognosis are highly variable. We present 7 surgical cases with the initial symptoms of venous ischemia by dural AVF. The series comprises 3 male and 4 female, ranging in age from 37 to 76 years (mean age, 61.1 years). Initial symptoms were dizziness in 3 cases, headache in 2 cases, unconsciousness in 1 case, and hemiparesis in 1 case. The locations included the superior sagittal sinus in 3 cases and the transverse-sigmoid sinus in 4 cases. Computed tomography with contrast media and magnetic resonance imaging revealed abnormal vessels. In all cases, retrograde feeding into the cortical veins was observed. On angiography, multiple retrograde venous drainage into the cortical veins were observed in all cases. Single photon emission computed tomography (SPECT) demonstrated apparent hypoperfusion in all 7 cases and further decrease by diamox challenging test in 4 cases. The dural AVFs were removed, and the symptoms disappeared in all cases, although transient aphasia was observed in a single case postoperatively. Postoperative SPECT showed improvement of cerebral blood flow in 4 and no change in 2 of 6 follow-up cases. Cerebral ischemia was induced by venous hypertension, and the hypoperfused brain improved immediately after the operation. Cerebral venous ischemia is a reversible condition that can be improved by appropriate early-stage treatment.

Cerebral hyperperfusion syndrome

Cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy is characterised by ipsilateral headache, hypertension, seizures, and focal neurological deficits. If not treated properly it can result in severe brain oedema, intracerebral or subarachnoid haemorrhage, and death. Knowledge of CHS among physicians is limited. Most studies report incidences of CHS of 0-3% after carotid endarterectomy. CHS is most common in patients with increases of more than 100% in perfusion compared with baseline after carotid endarterectomy and is rare in patients with increases in perfusion less than 100% compared with baseline. The most important risk factors in CHS are diminished cerebrovascular reserve, postoperative hypertension, and hyperperfusion lasting more than several hours after carotid endarterectomy. Impaired autoregulation as a result of endothelial dysfunction mediated by generation of free oxygen radicals is implicated in the pathogenesis of CHS. Treatment strategies are directed towards regulation of blood pressure and limitation of rises in cerebral perfusion. Complete recovery happens in mild cases, but disability and death can occur in more severe cases. More information about CHS and early institution of adequate treatment are of paramount importance in order to prevent these potentially severe complications.

Pretreatment and Posttreatment Evaluation of Hemodynamic and Metabolic Parameters in Intracranial Dural Arteriovenous Fistulae with Cortical Venous Reflux

OBJECTIVE

Retrograde drainage into the cortical veins results in poor outcome in patients with an intracranial dural arteriovenous fistula. However, the pathophysiological features of dural arteriovenous fistulae remain obscure. This study aimed to clarify hemodynamic and metabolic conditions in these patients using positron emission tomography.

METHODS

This study included eight patients with an intracranial dural arteriovenous fistula. All patients had cortical venous reflux, as demonstrated by angiography. Regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), regional cerebral metabolic rate for oxygen, and regional oxygen extraction fraction (rOEF) were measured before and after surgical or endovascular treatment using positron emission tomography.

RESULTS

Pretreatment positron emission tomographic studies revealed that all patients had abnormal hemodynamic and metabolic parameters in the area that was drained by the involved cortical veins. A severe increase in rCBV was noted in seven of the eight patients. A significant decrease in rCBF also was observed in all eight patients. A negative correlation was observed between rCBF and rCBV. Three patients had an elevated rOEF. Oxygen metabolism was impaired in seven patients. All patients underwent successful treatment. Follow-up studies demonstrated significant improvements in rCBF, rCBV, and regional cerebral metabolic rate for oxygen. The improvement in regional cerebral metabolic rate for oxygen varied among the patients. Normalization of rOEF also was confirmed in three patients who had increased rOEF before the treatment.

CONCLUSION

The present results suggest that hemodynamic and metabolic characteristics vary widely among patients with cortical venous reflux. It is essential to precisely evaluate hemodynamic and metabolic conditions to predict their outcomes and therapeutic effects.

Postoperative hyperperfusion in a patient with a dural arteriovenous fistula with retrograde leptomeningeal venous drainage: case report

OBJECTIVE AND IMPORTANCE

Hyperperfusion has been reported after carotid endarterectomy or stenting for stenosis of the internal carotid artery. Because few reports have examined postoperative hyperperfusion after treatment for dural arteriovenous fistulae (DAVFs), we present a case describing a patient who manifested this clinical entity.

CLINICAL PRESENTATION

The patient was a 63-year-old man with a DAVF in the left transverse sigmoid sinus with retrograde leptomeningeal venous drainage. He experienced slowly progressive disorientation lasting for several months. Preoperative single-photon emission computed tomography with (123)I-labeled N-isopropyl-p-iodoamphetamine revealed an area of hyperintensity on T2-weighted magnetic resonance imaging (MRI) scans that coincided with the hypoperfusion area; it was not increased after acetazolamide challenge. Complete DAVF obliteration was achieved by embolization, then sinus isolation. After treatment, he experienced frequent generalized convulsions that were terminated by 2-day barbiturate therapy.

INTERVENTION

On T2-weighted MRI scans obtained 3 days after surgery, the hyperintense area not only persisted but had expanded to the left parietal lobe. Moreover, a subcortical hyperintense lesion was recognized on T1-weighted MRI scans; this was considered to reflect cortical laminar necrosis. Single-photon emission computed tomography revealed hyperperfusion in the left parietal lobe; it changed to hypoperfusion a month after treatment.

CONCLUSION

In patients with DAVFs with preoperative findings of marked low perfusion and a poor perfusion reserve, postoperative study may reveal hyperperfusion on single-photon emission computed tomography or cortical laminar necrosis on MRI. This may be evidence of severe perfusion disturbance as a result of venous infarction. In these patients, careful blood pressure control and early treatment of seizures are important after DAVF treatment.

Early Intracerebral Hemorrhage Complicating the Successful Occlusion of a Carotid-Cavernous Fistula

A 74-year-old woman with a direct carotid-cavernous fistula secondary to aneurysm rupture was treated by endovascular balloon occlusion of the fistula. Two days later, she suffered an intracerebral hemorrhage ipsilateral to the treated carotid cavernous fistula, perhaps due to normal perfusion pressure breakthrough.

Normal perfusion pressure breakthrough has been described as a cause of hemorrhage following treatment of arteriovenous malformations and carotid stenosis. We report an unusual case of therapeutic endovascular occlusion of a direct carotid-cavernous fistula complicated by hemorrhage presumably caused by normal pressure perfusion breakthrough.