Hideaki Shigematsu

Neuroradiologic Diagnosis of Minor Leak prior to Major SAH: Diagnosis by T1-FLAIR Mismatch

BACKGROUND AND PURPOSE: In major SAH, the only method to diagnose a preceding minor leak is to ascertain the presence of a warning headache by interview; however, poor clinical condition and recall bias can cause inaccuracy. We devised a neuroradiologic method to diagnose previous minor leak in patients with SAH and attempted to determine whether warning (sentinel) headaches were associated with minor leaks before major SAH. MATERIALS AND METHODS: We retrospectively evaluated 127 patients who were admitted with SAH within 48 hours of ictus. Previous minor leak before major SAH was defined as T1WI-detected clearly bright hyperintense subarachnoid blood accompanied by SAH blood on FLAIR images that was distributed over a larger area than bright hyperintense subarachnoid blood on T1WI (T1-FLAIR mismatch). RESULTS: The incidence of warning headache before SAH was 11.0% (14 of 127 patients, determined by interview). The incidence of T1-FLAIR mismatch (neuroradiologic diagnosis of minor leak before major SAH) was 33.9% (43 of 127 patients). Of the 14 patients with warning headache, 13 had a minor leak diagnosed by T1-FLAIR mismatch at the time of admission. Variables identified by multivariate analysis as significantly associated with minor leak diagnosed by T1-FLAIR mismatch included 80 years of age or older, rebleeding after admission, intracerebral hemorrhage on CT, and mRS scores of 3–6. CONCLUSIONS: We conclude that warning headaches diagnosed by interview are not a product of recall bias but are the result of actual leaks from aneurysms.

Centripetal Propagation of Vasoconstriction at the Time of Headache Resolution in Patients with Reversible Cerebral Vasoconstriction Syndrome

In this retrospective cohort study, the authors evaluated 16 patients diagnosed with reversible cerebral vasoconstriction syndrome who underwent MR imaging, including MRA, within 72 hours of RCVS onset (initial MRA) and within 48 hours of thunderclap headache remission. In 14 of the 16 patients (87.5%), centripetal propagation of vasoconstriction occurred from the initial MRA to remission of thunderclap headache, with typical segmental vasoconstriction of major vessels (M1, P1, A1). The authors conclude that there is evidence of centripetal propagation of vasoconstriction on MRA performed at the time of remission of the thunderclap headache, and this time point may represent a useful opportunity to diagnose RCVS with greater confidence. BACKGROUND AND PURPOSE: Reversible cerebral vasoconstriction syndrome is characterized by thunderclap headache and diffuse segmental vasoconstriction that resolves spontaneously within 3 months. Previous reports have proposed that vasoconstriction first involves small distal arteries and then progresses toward major vessels at the time of thunderclap headache remission. The purpose of this study was to confirm centripetal propagation of vasoconstriction on MRA at the time of thunderclap headache remission compared with MRA at the time of reversible cerebral vasoconstriction syndrome onset. MATERIALS AND METHODS: Of the 39 patients diagnosed with reversible cerebral vasoconstriction syndrome at our hospital during the study period, participants comprised the 16 patients who underwent MR imaging, including MRA, within 72 hours of reversible cerebral vasoconstriction syndrome onset (initial MRA) and within 48 hours of thunderclap headache remission. RESULTS: In 14 of the 16 patients (87.5%), centripetal propagation of vasoconstriction occurred from the initial MRA to remission of thunderclap headache, with typical segmental vasoconstriction of major vessels. These mainly involved the M1 portion of the MCA (10 cases), P1 portion of the posterior cerebral artery (10 cases), and A1 portion of the anterior cerebral artery (5 cases). CONCLUSIONS: This study found evidence of centripetal propagation of vasoconstriction on MRA obtained at the time of thunderclap headache remission, compared with MRA obtained at the time of reversible cerebral vasoconstriction syndrome onset. If clinicians remain unsure of the diagnosis during early-stage reversible cerebral vasoconstriction syndrome, this time point represents the best opportunity to diagnose reversible cerebral vasoconstriction syndrome with confidence.

Endoscopic Endonasal Approach to the Middle Cranial Fossa through the Cavernous Sinus Triangles: Anatomical Considerations

The lateral limit of endoscopic endonasal surgery has yet to be defined. The aim of this study was to investigate the lateral limit of endoscopic endonasal surgery at the level of the sphenoid sinus. Access from the sphenoid sinus to the middle cranial fossa through the cavernous sinus triangles was evaluated by cadaver dissection. Anatomical analysis demonstrated that the medial temporal dura mater was exposed through the anterior area of the clinoidal triangle, anteromedial triangle, and superior area of the anterolateral triangle, indicating potential corridors to the middle cranial fossa. This study suggests that the cavernous sinus triangles are applicable in selected cases to manage middle cranial fossa lesions by endoscopic endonasal surgery.

Identification of the internal carotid artery at the superior part of the cavernous sinus during endoscopic endonasal cavernous sinus tumor surgery

BackgroundIdentification of the internal carotid artery (ICA) is essential for successful endoscopic endonasal cavernous sinus tumor surgery. This study aimed to develop a method for identifying the ICA in cavernous sinus tumors at the superior part of the cavernous sinus.MethodsTen fresh cadavers were studied with a 4-mm 0° and 30° endoscope to identify surgical landmarks of the ICA in the cavernous sinus. Clinical cases of cavernous sinus tumors were surgically treated using an endoscopic transpterygoid approach.ResultsAnatomical study indicated the ICA at the superior part of the cavernous sinus can be identified using three steps: 1) exposure of the optic nerve sheath by drilling the optic canal; 2) identification of the proximal orifice of the optic nerve sheath at the transition of the optic nerve sheath and dura mater of the tuberculum sellae; and 3) identification of the clinoid segment of the ICA at the distal dural ring just below the proximal orifice of the optic nerve sheath. Although the ICA was encased and transposed by tumors in preliminary surgical cases, the clinoid segment of the ICA was safely exposed at the superior part of the cavernous sinus using this method.ConclusionsDural structures around the cavernous sinus are key to identifying the ICA at the superior part of the cavernous sinus. This method is expected to reduce the risk of ICA injury during endoscopic endonasal surgery for cavernous sinus tumors.

Predictors of early vs. late permanent shunt insertion after aneurysmal subarachnoid hemorrhage

Objective: Numerous studies have identified different predictors for secondary hydrocephalus after aneurysmal subarachnoid hemorrhage (SAH), although predictors regarding timing of the shunt operation have never been reported. Predictors for an early shunt, which was defined as a shunt operation performed ≤30 days after SAH onset, and for a late shunt, performed at >40 days, were investigated. Methods: A total of 735 consecutive SAH patients admitted to our hospital between 2003 and 2014 who underwent surgery for ruptured aneurysms within five days of onset were retrospectively assessed. Results: Secondary hydrocephalus developed in 225 patients, including 70 with an early shunt and 96 with a late shunt. Multivariate analysis showed that predictors for secondary hydrocephalus were age ≥70 years, World Federation of Neurosurgical Society (WFNS) grade IV-V, Fisher grade 3–4, intraventricular hemorrhage, anterior cerebral artery aneurysms, and external drainage for acute hydrocephalus (p < 0.05). In the early and late shunt groups, multivariate analysis indicated that early shunt was significantly associated with coil embolization, and late shunt was correlated with middle cerebral artery aneurysms and cerebral infarction due to vasospasm (p < 0.05). Discussion: The difference in the predictors between the early and late shunts implied that the mechanisms of secondary hydrocephalus differed between the early and late shunt groups. Knowledge of the associated risk factors might help to predict the timing of the shunt operation for early rehabilitation planning in the future.

Retrospective review of previous minor leak before major subarachnoid hemorrhage diagnosed by MRI as a predictor of occurrence of symptomatic delayed cerebral ischemia

OBJECTIVE This study attempted to determine whether a previous minor leak correlated with the occurrence of symptomatic delayed cerebral ischemia (sDCI). METHODS The authors retrospectively evaluated sDCI-related clinical features and findings from MRI, including T1-weighted imaging (T1WI)-FLAIR mismatch at the time of admission, in 151 patients admitted with subarachnoid hemorrhage (SAH) within 48 hours of ictus. RESULTS The overall incidence of sDCI was 23% (35 of 151 patients). In all subjects, multivariate analysis revealed that World Federation of Neurosurgical Societies Grades II-V, age 70 years or older, presence of rebleeding after admission, a previous minor leak before the major SAH attack as diagnosed by T1WI-FLAIR mismatch, acute infarction on diffusion-weighted imaging, and CT SAH score were significantly associated with occurrence of sDCI. In patients with no previous minor leak before major SAH as diagnosed by T1WI-FLAIR mismatch, the incidence of sDCI was only 7% (7 of 97 patients). CONCLUSIONS A previous minor leak before major SAH as diagnosed by T1WI-FLAIR mismatch represents an important sDCI-related factor. When the analysis was restricted to patients with true acute SAH without a previous minor leak diagnosed by T1WI-FLAIR mismatch, the incidence of sDCI was extremely low.

Hemiparesis without Responsible Hematomas in Patients with Subarachnoid Hemorrhage Undergoing Early Aneurysmal Repair

OBJECTIVE The presence of hemiparesis on arrival in patients with subarachnoid hemorrhage (SAH) is presumed to affect prognosis; intracranial hematomas with mass effect responsible for hemiparesis are frequently observed in these patients. The aim of this study was to clarify characteristics and outcomes of patients who presented with hemiparesis on arrival with no responsible hematomas (hemiparesis without hematoma) having mass effect demonstrated on computed tomography. METHODS Consecutive patients with SAH treated with surgery for ruptured cerebral aneurysms within 5 days of onset between 2003 and 2015 were retrospectively reviewed. RESULTS Hemiparesis without hematoma was present in 25 of 858 surgically treated patients (2.9%). Internal carotid artery aneurysms were significantly more common in patients with hemiparesis without hematoma than in the other patients (P < 0.05). In 19 of 21 surviving patients (90.5%) with hemiparesis without hematoma on arrival, the hemiparesis improved at discharge. Favorable outcomes were achieved in 16 of 25 patients with hemiparesis without hematoma (64%) and in 13 of 59 patients with hemiparesis with hematomas (22.0%); this difference was significant (P < 0.05). CONCLUSIONS Hemiparesis can be expected to improve in patients with SAH with hemiparesis without hematoma, and such patients appear to have a better prognosis than patients with SAH with hemiparesis and responsible hematomas. A possible major mechanism of hemiparesis without hematoma based on the characteristics identified is a combination of transient ipsilateral hemispheric functional failure caused by the impact of aneurysmal rupture and transient ischemia of the perforators originating from the internal carotid artery.

Clinical significance of centripetal propagation of vasoconstriction in patients with reversible cerebral vasoconstriction syndrome: A retrospective case-control study

Introduction We previously reported centripetal propagation of vasoconstriction at the time of thunderclap headache remission in patients with reversible cerebral vasoconstriction syndrome. Here we examine the clinical significance of centripetal propagation of vasoconstriction. Methods Participants comprised 48 patients who underwent magnetic resonance angiography within 72 h of reversible cerebral vasoconstriction syndrome onset and within 48 h of thunderclap headache remission. Results In 24 of the 48 patients (50%), centripetal propagation of vasoconstriction occurred on magnetic resonance angiography at the time of thunderclap headache remission. The interval from first to last thunderclap headache in patients with centripetal propagation of vasoconstriction (14 ± 10 days) was significantly longer than that of patients without centripetal propagation of vasoconstriction (4 ± 2 days). In the patients with centripetal propagation of vasoconstriction at the time of thunderclap headache remission, the incidence of another cerebral lesion (38%, 9 of 24 cases) was significantly higher than in patients without centripetal propagation of vasoconstriction (0%). From findings of sequential magnetic resonance angiography before and after thunderclap headache remission, we observed tendencies in which centripetal propagation of vasoconstriction gradually progressed after the onset of reversible cerebral vasoconstriction syndrome and peaked at the time of thunderclap headache remission. The progress of centripetal propagation of vasoconstriction concluded with thunderclap headache remission. Conclusions Centripetal propagation of vasoconstriction has clinical significance as an indicator of the severity of reversible cerebral vasoconstriction syndrome. The presence of centripetal propagation of vasoconstriction is associated with an increased risk of brain lesions and a longer interval from first to last thunderclap headache. Moreover, repeat magnetic resonance angiography to assess centripetal propagation of vasoconstriction during the time from onset to thunderclap headache remission can help diagnose reversible cerebral vasoconstriction syndrome.

Reply: To PMID 25977479.

We appreciate the comments from Joswig et al. In our article, we reported that the true incidence of warning headache is challenging to establish because it is difficult to obtain complete information from patients in poor clinical condition. Therefore, the diagnosis of a minor leak by interview has poor accuracy, and it is difficult to grasp the clinical implications of an interviewdiagnosed minor leak. Thus, we investigated the clinical features of patients with minor leak diagnosed by T1-FLAIR mismatch at the time of admission. In our report, the incidence of patients whose history of warning headache was unknown by interview was high (46.5%, 59 of 127 cases). If we excluded these 59 patients whose history of warning headache was unknown by interview, warning headache determined by interview was 20.6% (14/68 patients). This is statistically similar to the percentage in the data of the letter by Joswig et al (24.2%) by the Fisher exact test (P .424). Furthermore, the patients with warning headache diagnosed by interview had the same clinical features (elderly age, higher rate of rebleeding, intracerebral hemorrhage, and poor outcome) as patients diagnosed with minor leak by T1-FLAIR mismatch. The reasons for this discrepancy in clinical features between patients with warning headache diagnosed by interview in our data and patients with sentinel headache (SH) diagnosed by interview in the Joswig et al data are unknown. One reason may be the extremely low incidence of World Federation of Neurosurgical Societies (WFNS) grade I in patients with warning headache diagnosed by interview (43% [6 of 14] versus 81% [44 of 54] in patients without warning headache diagnosed by interview) in our data. The overall percentage of WFNS grade I in patients who were able to confirm the presence or absence of a warning headache in an interview was high (74%, 50 of 68 patients), in contrast to that in patients whose history of warning headache was unknown by interview (36%, 21 of 59 patients). Thus, patients who could confirm the presence or absence of a warning headache in an interview had good status at admission, with patients presenting without a warning headache having the best prognosis. We think that the difference in clinical features of patients with warning headache between the 2 studies results from the low number of cases with poor clinical condition and the low number of the patients whose history of warning headache was unknown by interview in the data of Joswig et al. Furthermore, we think that there are too few cases in their data to examine the clinical features of patients with a warning headache. However, these opinions are speculative. We agree with Joswig et al that SH preceding aneurysmal subarachnoid hemorrhage is not a rare phenomenon. We understand the importance of diagnosis at the time of SH preceding major attack. We expect further investigation by Joswig et al.