Quantitative Susceptibility Mapping as a Possible Tool to Radiographically Diagnose Sentinel Headache Associated with Intracranial Aneurysm: Case Report

doi:10.1016/j.wneu.2017.04.151

World Neurosurgery

Volume 103, July 2017, Pages 954.e1-954.e4

https://doi.org/10.1016/j.wneu.2017.04.151 Get rights and content

Background

Sentinel headache (SH) occurs before aneurysm rupture in an estimated 15%–60% of cases of aneurysmal subarachnoid hemorrhage (aSAH). By definition, noncontrast computed tomography (CT) scan of the brain and lumbar puncture are both negative in patients presenting with SH. One of the theories explaining this phenomenon is that microhemorrhage (MH) from the aneurysm wall contribute to iron deposition in the interface between the aneurysm wall and brain parenchyma. Quantitative susceptibility mapping (QSM) is a recently introduced magnetic resonance imaging (MRI) technique that has proven capable of localizing the deposition of paramagnetic metals, particularly ferric iron. Thus, the QSM sequence may be able to detect iron deposition secondary to MH.

Case Description

A 76-year-old male presented with the “worst headache of my life.” Noncontrast head CT scan and lumbar puncture were negative. Magnetic resonance angiography (MRA) of the brain revealed an anterior communicating artery (A-com) aneurysm measuring 7 mm with a large bleb. T1-weighted imaging (WI), T2-WI, MRA, T2 star-weighted angiography (SWAN), and QSM sequences were obtained. T2-WI, SWAN, and QSM revealed isointense, hypointense, and hyperintense signals, respectively, at the interface of the aneurysm wall and brain tissue. These findings were consistent with deposition of ferric iron at this interface. The A-com aneurysm was treated with coil embolization, and the patient exhibited no postoperative deficits.

Conclusions

The MRI QSM sequence can localize iron deposition resulting from MH within an aneurysmal wall. This sequence may be a promising imaging tool for screening patients presenting with SH.

Introduction

Sentinel headache (SH) is characterized by sudden, intense, and persistent pain, and typically precedes aneurysmal subarachnoid hemorrhage (aSAH) by days or weeks. It can occur in 15%–60% of patients with aSAH, and its precise pathophysiological mechanism remains unknown. The current consensus is that structural changes in the aneurysm wall or microhemorrhage (MH) within aneurysmal walls through the internal layers (e.g., intima, media) could be responsible for the characteristic pain.1, 2, 3, 4, 5, 6, 7, 8 Beck et al.⁹ reported that patients with SH had 10-fold greater risk of rebleeding compared with patients without SH. Correct identification of SH is a key to preventing major aSAH, which is associated with high morbidity and mortality.

With progress in modern imaging technology, T2 star-weighted angiography (SWAN) has become sensitive to paramagnetic substances, and there is evidence that it is as sensitive to acute intracerebral hemorrhage as computed tomography (CT).10, 11 However, SWAN is not useful for determining the exact age of the subarachnoid blood and cannot differentiate subarachnoid blood in the acute and subacute phases.¹²

Quantitative susceptibility mapping (QSM) is one of the latest magnetic resonance imaging (MRI) sequences developed for quantifying tissue magnetic susceptibility.13, 14, 15 QSM can be used to quantitatively measure the iron content (in the ferric form) in brain structures.15, 16, 17, 18, 19 Thus, QSM potentially may be used to detect the accumulation of hemosiderin, and thus MH, within the aneurysmal wall.

Here we describe a case in which MRI QSM was successfully used to detect MH in a patient presenting with SH. The accurate diagnosis enabled correct identification of an aneurysm at increased risk for rupture and led to prompt treatment of the aneurysm. We then discuss the potential utility of this new sequence in identifying MH from aneurysms.

Section snippets

Case Presentation

A 76-year-old male presented with the “worst headache of my life.” This prompted evaluation for aSAH using noncontrast head CT, which was negative for aSAH. Lumbar puncture was also negative for xanthochromia. However, MRA of the brain revealed an anterior communicating artery (A-com) aneurysm measuring 7 mm.

MRI was performed immediately using a 7-T MRI scanner (MR950; GE Healthcare, Waukesha, Wisconsin, USA). The protocol included an anatomic T1 (BRAVO sequence) and SWAN. SWAN images were

Discussion

SH occurs before rupture of an aneurysm in an estimated 15%–60% of cases of aSAH. Proper identification of SH is a key to the prevention of aSAH, which carries high morbidity and mortality. MH as a cause of SH remains a subject of debate; regardless, reliably detecting MH using traditional imaging techniques is difficult. In this study, we have demonstrated that QSM can be a useful tool for identifying MH.

Several studies have demonstrated that fluid-attenuated inversion recovery and SWAN MRI

Conclusion

High-resolution MRI-QSM sequence has the potential to be a highly useful tool for detecting ferric iron deposits secondary to MH within the aneurysm wall.

Acknowledgment

We thank Faith L. Vaughn for her assistance with final editing of the manuscript.

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The headache preceding an intracranial aneurysm (AN) rupture is called sentinel headache (SH). According to the literature, SH is observed in 15%–60% of cases1,2 and is followed by the occurrence of subarachnoid hemorrhage (SAH) within several weeks. It is characterized by a sudden, intense, and persistent headache.2
The headache preceding an intracranial aneurysm rupture is called a sentinel headache (SH), and it is characterized by a sudden, intense, and persistent headache. As subarachnoid hemorrhage (SAH) often develops within several weeks of SH, its rapid diagnosis and treatment can improve the prognosis.
A 52-year-old woman with migraine in her medical history visited the outpatient clinic due to left orbital pain. There was no neurologic deficit. Although magnetic resonance imaging examination found no SAH, a left internal carotid artery–posterior communicating artery bifurcation aneurysm was detected by magnetic resonance angiography. Ten days after the onset of orbital pain, the patient consulted our hospital for a second opinion. We scheduled an elective clipping because the irregular shape of the aneurysm had a high risk of rupture. On the day before surgery, the aneurysm ruptured and led to SAH. Clipping was performed immediately. The patient was discharged with no neurologic deficit.
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Another recent study58 showed that quantitative susceptibility mapping, which is a novel MRI technique useful for localizing deposition of paramagnetic metals such as ferric iron, can be used to detect microhemorrhages from IAs. Microhemorrhages from aneurysms are believed to cause sentinel headache and could be a sign of wall instability and impending rupture.58 Therefore, using quantitative susceptibility mapping to detect microhemorrhage from an aneurysm wall could give a clue about the stability of the aneurysm and help clinical decision making.58
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Since the development and improvement of noninvasive diagnostic imaging (computed tomography angiography and magnetic resonance angiography), many prospective studies and meta-analyses have compared these tests with gold standard digital subtraction angiography (DSA). Although computed tomography angiography and magnetic resonance angiography have lower detection rates for UIAs, they are vital in the treatment and follow-up of UIAs. The reduction in ionizing radiation and lack of endovascular instrumentation with these modalities provide benefits compared with DSA. Novel molecular imaging techniques to detect inflammation within the aneurysmal wall with the goal of stratifying risk based on level of inflammation are under investigation.
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: Conflict of interest statement: This work was supported by funding from Nakatani Foundation. The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Case ReportQuantitative Susceptibility Mapping as a Possible Tool to Radiographically Diagnose Sentinel Headache Associated with Intracranial Aneurysm: Case Report

Background

Case Description

Conclusions

Introduction

Section snippets

Case Presentation

Discussion

Conclusion

Acknowledgment

Lancet Neurol

Surg Neurol

Lancet

Magn Reson Imaging

Magn Reson Imaging

Neuroimage

Subarachnoid haemorrhage: diagnosis, causes and management

Brain

Aneurysmal subarachnoid hemorrhage

N Engl J Med

Sentinel headaches in aneurysmal subarachnoid haemorrhage: what is the true incidence? A systematic review

Cephalalgia

Incidence of subarachnoid hemorrhage: role of region, year, and rate of computed tomography: a meta-analysis

Stroke

Case Report
Quantitative Susceptibility Mapping as a Possible Tool to Radiographically Diagnose Sentinel Headache Associated with Intracranial Aneurysm: Case Report