Hiroshi Inui

Four cases of vertebrobasilar insufficiency.

Four cases of vertebrobasilar insufficiency are reported. Case 1 was a 38-year-old man who felt a sudden onset of dizziness when he turned his head to the back. An abnormal positional nystagmus was observed when he rotated his head to the left. A magnetic resonance angiogram (MRA) demonstrated total occlusion of the left vertebral artery (VA). Case 2 was a 31-year-old woman who had a total occlusion of her left VA as observed in the MRA. Case 3 was a 68-year-old man who noted dizziness. The systolic blood pressure change on his Schellong test was 28 mmHg. On his MRA, severe displacement of the basilar and the vertebral arteries was visible. Case 4 was a 76-year-old woman who noted a blackout-like sensation. Optokinetic nystagmus was noted with a hyponystagmus pattern, and an eye tracking test showed a saccadic pattern. On her MRA, the vertebrobasilar system was narrowed. The arterial architecture and any stenosis of the blood vessels could be detected non-invasively by MRA.

Auditory brainstem response findings in brainstem ischemia following selective occlusion of the anterior inferior cerebellar artery in the rat

Auditory brainstem responses (ABRs) were measured ipsilaterally (n = 13) or contralaterally (n = 5) after inducing permanent right or left anterior inferior cerebellar artery (AICA) occlusion. Three types of wave patterns were classified when ABRs were recorded ipsilaterally. In type 1 (n = 4) all components disappeared; in type 2 (n = 2) all components disappeared transiently and then reappeared; and in type 3 (n = 7) only the latency difference between components I and IV increased. These findings indicate that all components reappeared in type 2 responses because cochlear blood flow was re-established quickly by collateral circulation, while type 3 changes reflected the relative sensitivity of the cochlea to ischemic damage when compared with the rest of the auditory pathways. When the ABRs were recorded contralaterally, characteristic findings included a delay in latency of component IV and a significant increase in inter-peak latency in components I–IV and IIb–IV.

Brainstem ischemic damage following occlusion of the blood vessels in the rat's posterior cerebral circulation.

Progression of ischemic damage was investigated immunohistochemically in neural dendrites using microtubule-associated protein 2 (MAP2) as a dendritic marker in the rats brainstem. Neuronal soma and dendrites were clearly stained by this protein but some structures such as axonal bundles, glia and endothelial cells were not visualized. When the anterior inferior cerebellar artery (AICA) was occluded unilaterally for 30 min, a wide ischemic lesion was detected in the occluded side of the brainstem and was observed as a loss of reaction to MAP2. After ischemia for 2 h, loss of reaction in the perikarya and dendrites was seen to expand to the ipsilateral (occluded side) cochlear nucleus. When the basilar artery was blocked, ischemic damage in the vestibular nucleus was more intense than that in the cochlear nucleus. In all specimens studied, differences in anatomical blood supply demonstrated selective tissue vulnerability for ischemic damage.

Autoradiographic measurement of regional brainstem blood flow: occlusion of the anterior inferior cerebellar artery

Autoradiography was used to measure regional brainstem blood flow in Wistar rats following permanent left anterior inferior cerebellar artery (AICA) occlusion. With the AICA occluded, blood flow to the left vestibular nucleus decreased 31 % while flow to the left cochlear nucleus decreased 47% when compared to the right (unobstructed) side. In the rat, the median pontine branch of the basilar artery was found to provide the principal blood supply to the vestibular nucleus. Electrocochleography was also used to measure the action potential (AP), summating potential (SP) and cochlear microphonics (CM) during left AICA occlusion. The AP disappeared completely after at least 7 min, while the SP polarity changed from negative to positive. Findings also showed that CM2 did not disappear completely in pre-mortem animals.

MR-angiographic Findings of Patients with Central Vestibular Disorders

Magnetic resonance angiography (MRA) is a new, noninvasive, and useful method to estimate the posterior circulation in patients with vertigo. From June 1995 to May 1997, 180 patients were examined by magnetic resonance imaging (MRI) and MRA in our department. One hundred and forty-seven patients were vertiginous patients. We measured the displacement angle of the basilar artery with MRA, and examined the relationship between the findings from some neurological examinations and MRA findings in patients with vertigo and dizziness. One hundred and forty-seven patients with vertigo or dizziness were examined by MRI and MRA. They were diagnosed with MRI images in addition to several neurological examinations. MRA was not used for the diagnosis but rather for measuring the displacement angle of the basilar artery. Eighty-six cases with central vestibular disorders, 11 cases with vertebrobasilar insufficiency, and 26 cases with autonomic nerve disorders were recognized. In the cases of central vestibular disorders, the incidences of hyperlipidemia and hypotension were higher than the incidence of anemia. The average displacement angle of the basilar artery (n = 180) was 153.4 degrees +/- 39.4 degrees (mean +/- S.D.). MRA findings were classified into five categories. Ten patients were classified as category III, which represented unilateral partial vertebral artery stenosis. The detection rate for category III and IV abnormalities by neurological examination was higher than that for the other categories. MRI and MRA are important methods to examine patients with central nervous disorders. Distal vertebral artery stenosis may carry a higher risk of a stroke than brainstem infarction.

Endolymphatic space size in patients with Meniere’s disease and healthy controls

Abstract Conclusions: The incident ratios of cochlear and/or vestibular endolymphatic hydrops (EH) were significantly higher in the affected ears of patients with Meniere’s disease (MD) than in the ears of healthy controls. There were no significant differences between controls and the contralateral ears of MDs. Objectives: The aim was to compare the incidence ratios of EH between unilateral/bilateral MD and controls using 3T magnetic resonance imaging (MRI) with intravenous gadolinium. Methods: A total of 41 patients were diagnosed with MD: 32 with unilateral MD (uMD) and nine with bilateral MD (bMD). Fifteen healthy volunteers were enrolled as controls. The patients underwent 3T MRI 4 h after intravenous injection of gadolinium. Results: Cochlear EH was present in 3.3% of 30 ears of 15 controls, 6.3% of 32 contralateral (contra) ears of 32 uMDs, 62.5% of 32 affected ears of 32 uMDs, and 55.6% of 18 affected ears of nine bMDs. Vestibular EH was observed in 6.7% of control ears, 3.1% of contra-uMD ears, 65.6% of affected uMD ears, and in 55.6% of affected bMD ears. Either cochlear or vestibular EH was present in 10.0% of control ears, 6.3% of contra-uMD ears, 81.3% of affected uMD ears, and 44.4% of affected bMD ears.

Volumetric measurements of the inner ear in patients with Meniere’s disease using three-dimensional magnetic resonance imaging

Abstract Conclusion: This study described the lateralities of axial length of inner ear (ALIE), of the volume of inner ear (VIE) and age-related differences of the volume of inner ear components in patients with chronic rhinosinusitis (CRS). Age-related differences were found in ALIE and the positive correlation in ALIE and the volume of the cochlea (VC) of the affected ear in patients with Meniere’s disease (MD). Objective: To identify side or sex-related differences in the ALIE, the length of the spiral canal of cochlea (LSCC), and the volume of components of the inner ear in MD and CRS. Methods: Thirty-two with unilateral MD and 14 with CRS were included. Images were acquired with a 3.0-tesla unit using SPACE sequences. The ALIE was measured and the VIE, VC, the volume of the vestibule (VV), and of the semi-circular canals (VSC) were also measured. Results: In CRS, ALIE of the right ear in males was significantly longer than in females. Patients younger than 60 years old with CRS had a significantly larger VIE, VC, and VSC than older than 60. In MD, the ALIE in older than 60 was longer than below 60.

Autoradiographic measurement of regional brainstem blood flow. Findings after 2 hours of occlusion of the unilateral anterior inferior cerebellar artery and 30 minutes' occlusion of the unilateral vertebral artery.

Using [14C]iodoantipyrine, regional brainstem blood flow was measured in the rat 2 h after occlusion of the left anterior inferior cerebellar artery (AICA) and 30 min after occlusion of the left vertebral artery (VA). Two hours after occluding the left AICA, the mean +/- SEM value of blood flow in 6 animals in the right superior olive was 2.13 +/- 0.13 ml/g/min and in the left side, 1.13 +/- 0.11. Thirty minutes after occlusion of the left VA, there were no significant differences between the right and left sides. Blood flow changes were assessed in the hindbrain structures between the control group, 30 min after occlusion of the left VA and 2 h after occlusion of the left AICA. Changes observed in the blood flow in the hindbrain structures suggest that the extra volume of the blood flow might be concealed in the brainstem. However, whether the recovery of the blood flow rate indicates the recovery of the brainstem function remains unclear.

Magnetic resonance volumetric measurement of endolymphatic space in patients without vertiginous or cochlear symptoms

Abstract Conclusion: Magnetic resonance volumetric measurement of inner ear endolymphatic space (ELS) was performed in patients without vertiginous or cochlear symptoms. The existence of the ELS in patients with chronic rhinosinusitis (CRS) was shown. The ELS in the cochlea and vestibule was classified into four categories. These findings could be useful as a standard reference for further research. Objectives: To identify normal values of the ELS in the cochlea and vestibule. Methods: Twenty-four patients with CRS were enrolled. Inner ear fluid space images and positive perilymph/positive endolymph images were acquired using a 3.0-tesla unit. Three-dimensional (3-D) images were constructed semi-automatically using both anatomical and tissue information by fusing the 3-D images of the inner ear fluid space and the ELS. Results: Among all patients, the mean ELS/the total fluid space (TFS) ratio in the cochlea was 8.8% and that in the vestibule was 16.2%. The ELS in the cochlea and vestibule was classified into four categories. Age-related differences were found in the TFS, ELS, and ELS/TFS ratio in the inner ear and the ELS and ELS/TFS ratio in the vestibule.

Hemodynamics of a Simulation of the Vertebrobasilar System Using Silicone Tube

We investigated the hemodynamics of the vertebrobasilar system (VBS) using a simulation model tube made of silicone which had different diameters between the bilateral vertebral artery (VA) ducts (stenotic and normal VA ducts). Using the ultrasonic Doppler method. the laterality index (L.I.) of the flow velocity in the VA duct was 32.88%. The flow volume of the anterior inferior cerebellar artery duct and the posterior inferior cerebellar artery duct also had significant laterality. By investigating the effects of the rotatory pulse rate and fluid viscosity, a maximal decrease to below 40-50% of the flow volume of the branches, and to below 71.93% in the mean flow velocity of the basilar artery (BA) duct (BA duct) were observed. and the maximum L.I. increased to 43.15%. When the unilateral stenotic VA duct was occluded by clamping (clamping occlusion), the flow volume profiles of the branches were the same as without clamping occlusion. The L.I. showed no significant changes and the maximal decrease in the mean flow velocity of the BA duct was 68.61%. Using the laser Doppler method, the flow velocity distribution of the BA duct was shifted towards the side of the stenotic VA duct. These results suggest that the rheological dynamics in the main vessels can certainly reflect the posterior circulatory dynamics, and that modulating factors also aggravate the hemodynamics of the VBS with this disorder.