Motoyuki Iwasaki

Clinical Characteristics and Outcomes in Carotid Endarterectomy for Internal Carotid Artery Stenosis in a Japanese Population: 10-Year Microsurgical Experience

Few studies have explored the significance of carotid endarterectomy (CEA) in long-term prognosis in Japanese patients. In the present study, we precisely elucidated the demographic and radiologic data, surgical morbidity and mortality, and long-term outcome in 135 Japanese patients who underwent a total of 142 CEAs due to 70%-99% stenosis of the internal carotid artery at our hospitals over a 10-year period. The prevalence of risk factors was similar to those found in previous studies in Western countries. Surgical mortality (0.7%) and morbidity (2.8%) were relatively low. Blood flow studies done immediately after CEA revealed postoperative hyperperfusion in 8 patients (5.6%), but none of these patients exhibited related symptoms. Over the mean follow-up period of 38.7 months, a total of 9 patients died (6.7%), due mainly to malignancies. Cerebrovascular events occurred in 12 patients (8.5%), including ipsilateral ischemic stroke in 2 (1.4%). In addition, 11 patients (8.2%) developed vascular disorders in other organs, including coronary artery disease and chronic renal failure. Follow-up radiologic examination revealed restenosis of >50% in 3 carotid arteries (2.1%). Stenosis of the contralateral carotid arteries progressed to >70% in 12 patients (9.2%). This study strongly suggests that microsurgical CEA is feasible and effective in preventing subsequent ipsilateral ischemic stroke in Japanese patients; however, long-term medical and radiologic surveillance is essential to reduce the incidence of ischemic stroke in other areas and of vascular disorders in other organs to improve prognosis.

Ruptured aneurysms of the choroidal branches of the posterior inferior cerebellar artery: a review of the literature and a case report

Aneurysms of the choroidal branches of the posterior inferior cerebellar artery (PICA) are quite rare; only seven such cases have been reported thus far. In this study, we present a very rare case of a ruptured aneurysm of a choroidal branch of the PICA; the aneurysm was exposed by splitting the vermis and resected after proximal arterial ligation. We have also undertaken a thorough review of the literature on aneurysms in choroidal branches of the PICA, focusing on the clinical presentation, etiology, radiological findings, and surgical strategies. We found that the aneurysms in our patient and the aneurysms in seven published case reports were small, and frequently associated with vascular anomalies. Intraventricular hemorrhage (IVH) in the fourth ventricle was detected in all eight cases. The outcomes of surgical treatment were generally favorable, notwithstanding the high incidence of rebleeding after rupture of distal PICA aneurysms. The recognition of predominant fourth ventricular hemorrhage should raise the suspicion of the presence of an underlying aneurysm, and digital subtraction angiograms (DSAs) should be immediately obtained in order to detect small aneurysms of the choroidal branches of the PICA.

The Reliability of Reduced Field-of-view DTI for Highly Accurate Quantitative Assessment of Cervical Spinal Cord Tracts

Purpose: To compare the accuracy of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values between reduced FOV or so-called zonally oblique multislice (ZOOM) and conventional diffusion tensor imaging (DTI) in the cervical spinal cord. Methods: Both ZOOM and conventional DTI were performed on 10 healthy volunteers. Intraclass correlation coefficient (ICC) was used to evaluate the reliability of the measurements obtained. Four radiologists evaluated the FA and ADC values at each cervical cord level and classified the visibility by 4 ranks. The geometric distortion ratios of the long axis and short axis were compared between ZOOM and conventional DTI. The imaging parameters were as follows: b-value = 600 s/mm2; TR = 4500 ms; TE = 81 ms; FOV = 70 × 47 mm2 / 200 × 200 mm2; matrix = 80 × 51 / 128 × 126 (ZOOM and conventional DTI, respectively). The region of interest was carefully drawn inside the spinal cord margin to exclude the spinal cord component, without excluding the white matter fiber tracts. Results: The average FA value decreased in both ZOOM and conventional DTI in lower spinal cord levels; in contrast, the ADC value increased in lower spinal cord levels. Zonally oblique multislice DTI was superior to conventional DTI with regard to inter-rater and intra-rater reliability; further, visibility was better and the standard deviation was smaller in ZOOM DTI. On both the long and short axis, the geometric distortion ratio was lower in ZOOM DTI at all cervical spinal cord levels compared with the conventional DTI. There was a significant difference in the distortion ratios of the long and short axis between ZOOM and conventional DTI. Conclusion: Conventional DTI is unreliable owing to its susceptibility to the surrounding magnetic field. ZOOM DTI is reliable for performing highly accurate evaluations.

Characteristics of Symptomatic Intracerebral Hemorrhage in Patient Receiving Direct Oral Anticoagulants: Comparison with Warfarin

BACKGROUND Direct oral coagulants (DOAC) have been shown to decrease the frequency of intracerebral hemorrhage (ICH) compared with warfarin. However, the precise characteristics, such as the size and locations of the hemorrhage, and outcome and onset time of ICH in patient taking DOAC are not fully elucidated. METHODS We retrospectively analyzed the characteristics of symptomatic patients with ICH taking either DOAC or warfarin between January 2012 and December 2015. RESULTS Out of 400 consecutive patients with ICH, 15 patients were DOAC-ICH and 24 patients were warfarin-ICH. DOAC-ICH was observed in 6 patients with 10 mg of rivaroxaban, 5 patients with 15 mg of rivaroxaban, and 1 patient with 10 mg of apixaban, 5 mg of apixaban, 30 mg of edoxaban, and 60 mg of edoxaban. Prothrombin time was well controlled in most of the warfarin-ICH patients (83.3%). The locations of ICH were similar in both groups; however, median ICH volume was significantly smaller in DOAC-ICH patients than in warfarin-ICH patients (P < .01) and ICH around basal ganglia seemed to show great difference between the groups. DOAC-ICH patients showed better neurological outcome at the time of discharge than warfarin patients (P < .01), and the ratio of good prognosis was significantly higher in the DOAC-ICH patients than in the warfarin-ICH patients (P < .01). The onset of warfarin-ICH was frequently observed in the morning and evening, whereas DOAC-ICH did not show any specific onset time. CONCLUSIONS Patients with DOAC-ICH showed smaller ICH volume and better clinical outcomes than patients with warfarin-ICH, and DOAC-ICH did not show any specific onset peak.

A case of midbrain infarction with acute bilateral cerebellar ataxia visualized by diffusion tensor imaging.

An 85-year-old woman with hypertension was admitted with a sudden onset of gait disturbance and dysarthria. On admission, the patient showed severe bilateral cerebellar ataxia with moderate right medial longitudinal fasciculus (MLF) syndrome. Magnetic resonance (MR) imaging showed an acute infarction in the lower and medial part of midbrain. Diffusion tensor imaging (DTI) started from both cerebellar peduncles revealed that the lesion of the acute infarction matched the decussation of superior cerebellar peduncle where crossing of tract was seen and a part of its tract was interrupted at the site. Interruption of the cerebellum red nuclear path at the medial part of midbrain was considered to be the reason for bilateral cerebellar ataxia and visualization of cerebellum red nuclear path by DTI can give better understanding of the neurological symptom.

Highly Accurate Analysis of the Cervical Neural Tract of the Elderly Using ZOOM DTI

Background/Aims To investigate the fractional anisotropy (FA) values of the cervical spinal cord in elderly individuals using zonally magnified oblique multislice (ZOOM) diffusion tensor imaging (DTI). Methods Fourteen healthy elderly volunteers (group E) and 10 young volunteers (group Y) were enrolled. We assessed the FA, apparent diffusion coefficient (ADC), and λ1–λ3 values using 3-T magnetic resonance imaging. The region of interest was contoured entirely inside the spinal cord, with no gray/white matter distinction, in order to avoid including the cerebrospinal fluid. Results As lower cervical levels were approached, the FA values gradually decreased, while the ADC values increased. The mean FA values at each cervical level were as follows in groups E and Y: 0.71 and 0.70 at the C2/3 level, 0.66 and 0.66 at the C3/4 level, 0.63 and 0.62 at the C4/5 level, 0.57 and 0.57 at the C5/6 level, and 0.58 and 0.57 at the C6/7 level, respectively. The mean ADC values in groups E and Y were 1.06 and 0.99 at the C2/3 level, 1.05 and 1.06 at the C3/4 level, 1.14 and 1.06 at the C4/5 level, 1.18 and 1.21 at the C5/6 level, and 1.39 and 1.46 at the C6/7 level, respectively. There were no significant differences between the elderly and young participants. Conclusion In both asymptomatic elderly and young individuals, the FA values gradually decreased and the ADC values increased moving towards lower cervical levels. Age did not affect the FA values, even though mild cord compression was evident due to spondylotic changes. ZOOM DTI has the potential to provide more information than conventional DTI.

Serial Arterial Spin Labeling May Be Useful in Assessing the Therapeutic Course of Cerebral Venous Thrombosis : Case Reports

We report two cases of cerebral venous thrombosis (CVT) which serial arterial spin labeling (ASL) was useful in evaluating the clinical course of the disease. A 48-year-old female presented with acute seizure, and was diagnosed as transverse-sigmoid sinus thrombosis. ASL imaging revealed low signal intensity in the right temporal lobe, suggesting the decreased perfusion by elevated venous pressure. Soon after the treatment, while the development of venous collateral has not fully observed by magnetic resonance (MR) angiography, low ASL signal within the right temporal lobe have shown remarkable improvement. A 65-year-old female presented with vomiting and subsequent seizure was diagnosed as superior sagittal sinus thrombosis. The low ASL signal within the right frontal lobe seen in the acute stage improved to the normal level by the course of time, before the good collateral can be seen by MR angiography. This is the first report to assess the sequential change of the cerebral perfusion of CVT by ASL, and ASL may provide additional useful information in combination with conventional modalities.

Double Crush of L5 Spinal Nerve Root due to L4/5 Lateral Recess Stenosis and Bony Spur Formation of Lumbosacral Transitional Vertebra Pseudoarticulation: A Case Report and Review

We present a case of double-crushed L5 nerve root symptoms caused by inside and outside of the spinal canal with spur formation of the lumbosacral transitional vertebra (LSTV). A 78-year-old man presented with 7-year history of moderate paresis of his toe and left leg pain when walking. Magnetic resonance imaging (MRI) revealed spinal stenosis at the L3/4 and 4/5 spinal levels and he underwent wide fenestration of both levels. Leg pain disappeared and 6-min walk distance (6MWD) improved after surgery, however, the numbness in his toes increased and 6MWD decreased 9 months after surgery. Repeated MR and 3D multiplanar reconstructed computed tomography (CT) images showed extraforaminal impingement of the L5 root by bony spur of the left LSTV. He underwent second decompression surgery of the L5/S via the left sided Wiltse approach, resulting in the improvement of his symptoms. The impingement of L5 spinal nerve root between the transverse process of the fifth lumbar vertebra and the sacral ala is a rare entity of the pathology called “far-out syndrome (FOS)”. Especially, the bony spur formation secondary to the anomalous articulation of the LSTV (LSPA) has not been reported. These articulations could be due to severe disc degeneration, following closer distance and contact between the transverse process and the sacral ala. To our knowledge, this is the first report describing a case with this pathology and may be considered in cases of failed back surgery syndromes (FBSS) of the L5 root symptoms.

Lateral Position of the External Carotid Artery: A Rare Variation to Be Recognized During Carotid Endarterectomy

BACKGROUND External carotid artery (ECA) positioned laterally to the internal carotid artery (ICA) at the level of the common carotid artery (CCA) bifurcation is occasionally encountered during carotid endarterectomy (CEA). This study aimed to determine the frequency of this phenomenon and provide technical tips for performing CEA. METHODS The study included 199 consecutive patients (209 carotid arteries) who underwent CEA at Otaru Municipal Medical Center in 2007-2014. The position of the ECA with respect to the ICA at the CCA bifurcation was preoperatively rated as either lateral or normal, using three-dimensional computerized tomographic angiography (3-D CTA) anteroposterior projections. Postoperative diffusion-weighted images (DWIs), and postoperative 3-D CTA images were reviewed. RESULTS Among the 209 carotid arteries with atherosclerosis, 11 instances (5.3 %) of lateral position of the ECA were detected in 11 patients. Ten of these arteries (91 %) were right-sided (odds ratio 11.1; 95 % confidence interval 1.38-88.9). Wider longitudinal exposure of the arteries was used during CEA, and the CCA and ECA were rotated clockwise or counter clockwise. The ICA lying behind the ECA along the surgical access route was then pulled out laterally and moved to the shallow surgical field. Cross-clamping, arteriotomy, plaque removal, and wall suturing were performed as usual. No cerebral infarcts were detected on postoperative DWIs, and 3-D CTA revealed no CCA and ICA kinking. CONCLUSIONS Lateral position of the ECA is not extremely rare in patients undergoing CEA for atherosclerosis and may be a congenital variation, although this is still controversial. CEA can be performed safely if the arteries from the CCA to the ICA are rotated, and the ICA is moved to the shallow surgical field under wider longitudinal exposure. Although no postoperative cerebral infarcts were detected, the risk of artery-to-artery embolism resulting from artery repositioning prior to plaque removal should be taken into consideration.

[Radiotherapy for Alleviation of Paraparesis due to Leptomeningeal and Cauda Equina Metastasis of HER2-Positive Breast Cancer: A Case Report].

Leptomeningeal metastasis is a rare entity and its diagnosis is often difficult. Moreover, evidence-based therapeutic strategies have not yet been established. A 52-year-old woman presented with high fever and was diagnosed with bacterial meningitis at first examination;although her fever was alleviated, she experienced motor weakness in both of her lower extremities. Ga scintigraphy highlighted the hot-spot areas of the disease in the cranial bone. She was then transferred to our department. Open biopsy of the skull showed metastasis of the cancer. Chest CT results indicated right breast cancer and Gd-DTPA imaging showed obvious enhancement of the pia mater around the conus medullaris and cauda equina. However, cerebrospinal fluid(CSF)cytological examination did not show the presence of any positive cells;consequently, mastectomy was performed in the thoracic surgical department. The severity of paraparesis and pain in her legs increased;however, repeat MRI 1 month later showed no evidence of any change. Therefore, we performed biopsy of the cauda equina and arachnoid lesions. The pathological diagnosis was metastasis of breast cancer with positive human epidermal growth factor receptor 2(HER2)immunological staining. The results of a repeat cytological examination of the CSF during the surgery were negative. Local radiotherapy(25 Gy/5 Fr)as a monotherapy was selected for the patient, because her family did not approve of the combination of radiotherapy and chemotherapy. The severity of both paraparesis and limb pain decreased immediately after the radiotherapy.