Reversible Cerebral Metabolism Changes Using Proton Magnetic Resonance Spectroscopy in a Patient with Intracranial Dural Arteriovenous Fistula: A Case Report

Background

Cerebral metabolism can be disrupted by venous congestion in patients with intracranial dural arteriovenous fistula (DAVF), which may lead to adverse neurological outcomes. However, there are no clear indicators to guide cerebral evaluation and treatment selection in cases of DAVF. We describe a patient with a DAVF whose proton magnetic resonance spectroscopy (¹H-MRS) findings were associated with improvements in clinical status.

Case Description

An elderly woman with a history of myocardial infarction presented with progressive dementia, aphasia, and a severe headache. We detected a transverse-sigmoid sinus DAVF, as well as abnormal levels of lactate and N-acetylaspartic acid (NAA) in the ¹H-MRS, and successfully treated the patient using surgical sinus skeletonization. However, follow-up ¹H-MRS revealed inconsistent reversals in the levels of lactate and NAA. In addition, we calculated the NAA/creatinine ratios from before and after surgery, which revealed postoperative increases in the ratios for the left temporal, right parietal, and left parietal regions. These increases occurred concurrently with improvements in the patient's cognitive function.

Conclusions

¹H-MRS may be useful for pretreatment detection of increased lactate levels, decreased NAA levels, and/or decreased NAA/creatinine ratios. These findings may indicate poorer cerebral metabolism, and show a need for more aggressive treatment. Furthermore, ¹H-MRS may be useful for evaluating the effect of conservative treatment and for indicating conversion to a more aggressive treatment.

Introduction

Intracranial dural arteriovenous fistulas (DAVFs) are generally classified using criteria that were proposed by Borden et al¹ or Cognard et al,² based on the pattern of venous drainage. Cases with cortical venous drainage (CVD) have a high risk of an aggressive clinical course, which includes the possibility of intracranial hemorrhage.1, 2, 3, 4, 5, 6 Furthermore, venous congestion causes nonhemorrhagic neurological deficits (NHND), which can include dementia, cerebral ischemia, and several other symptoms. In addition, cerebral metabolism is impaired by venous congestion in patients with DAVF. The severe impairment of cerebral metabolism can lead to several symptoms, although it is difficult to quantitatively evaluate these symptoms. Thus, a decrease in the apparent diffusion coefficient (ADC), hemodynamic insufficiency as detected using positron emission tomography (PET), and a reduction of regional cerebral blood flow (rCBF) or loss of cerebral vascular reserve as detected using ¹²³I-iodoamphetamine single photon emission computed tomography have been proposed as indicators of venous congestion severity in cases of DAVF.7, 8, 9, 10 However, there are no clear indicators for clinical evaluations, and the treatment strategy in clinical practice is typically based on the presence or absence of CVD. Therefore, a more accurate evaluation method is urgently needed. Thus, we report a case of transverse sigmoid sinus (TSS) DAVF that we treated successfully, with before and after treatment evaluations of cerebral metabolism using proton magnetic resonance spectroscopy (¹H-MRS). To our knowledge, this is the first report evaluating the use of 3-Tesla (3-T) ¹H-MRS in a case of DAVF, and our findings from this case indicate that ¹H-MRS may be useful for selecting and evaluating therapies in cases of DAVF.