Although several risk factors for stroke have been identified, one-third remain unexplained. Here we show that infection with Streptococcus mutans expressing collagen-binding protein (CBP) is a potential risk factor for haemorrhagic stroke. Infection with serotype k S. mutans, but not a standard strain, aggravates cerebral haemorrhage in mice. Serotype k S. mutans accumulates in the damaged, but not the contralateral hemisphere, indicating an interaction of bacteria with injured blood vessels. The most important factor for high-virulence is expression of CBP, which is a common property of most serotype k strains. The detection frequency of CBP-expressing S. mutans in haemorrhagic stroke patients is significantly higher than in control subjects. Strains isolated from haemorrhagic stroke patients aggravate haemorrhage in a mouse model, indicating that they are haemorrhagic stroke-associated. Administration of recombinant CBP causes aggravation of haemorrhage. Our data suggest that CBP of S. mutans is directly involved in haemorrhagic stroke.

Cerebral microbleeds (CMBs) are an important risk factor for stroke and dementia. We have shown that the collagen binding surface Cnm protein expressed on cnm-positive Streptococcus mutans is involved in the development of CMBs. However, whether the collagen binding activity of cnm-positive S. mutans is related to the nature of the CMBs or to cognitive impairment is unclear. Two-hundred seventy nine community residents (70.0 years) were examined for the presence or absence of cnm-positive S. mutans in the saliva by PCR and collagen binding activity, CMBs, and cognitive function were evaluated. Cnm-positive S. mutans was detected more often among subjects with CMBs (p < 0.01) than those without. The risk of CMBs was significantly higher (odds ratio = 14.3) in the group with S. mutans expressing collagen binding activity, as compared to the group without that finding. Deep CMBs were more frequent (67%) and cognitive function was lower among subjects with cnm-positive S. mutans expressing collagen binding activity. This work supports the role of oral health in stroke and dementia and proposes a molecular mechanism for the interaction.

To study the asymmetry in signal intensity of the sigmoid sinuses, internal jugular veins (IJVs), or both sets of structures on magnetic resonance (MR) images, the authors reviewed 226 serial sets of routine MR imaging studies. Cerebral digital subtraction angiography was performed in 20 patients with a markedly higher intensity and/or enhancement on the left; 15 of them also underwent venography. With every sequence, the left sigmoid sinus, IJV, or both were higher in signal intensity significantly more often than the right (range, P = .0001 to .0129). Angiography revealed hemostasis in the left IJV in 16 patients that disappeared during full inspiration in 14. In 13, venography revealed that the left brachiocephalic vein was compressed to occlusion between the aortic arch and the sternum during tidal volume ventilation. The occlusion disappeared at full inspiration, when the distance between the aortic arch and the sternum increased. This hemostasis could be the major cause of the frequent increased signal intensity of the left sigmoid sinus and IJV on MR images.

Dynamic magnetic resonance (MR) imaging for pituitary adenomas is usually performed in a coronal direction; however, small lesions between slices, or lesions located at the anterior or posterior aspect of the pituitary gland might be overlooked on MR images in only the coronal direction. The purpose of our study was to evaluate whether consecutive dynamic MR images in the coronal and sagittal planes improve detection of pituitary adenomas. Eighteen patients with pituitary microadenomas and nine with healthy pituitary glands were included in this study. MR images were performed with 1.5 T superconductive units and commercially-available head coils. After a 5 ml gadolinium contrast injection, eight serial dynamic sagittal images were obtained. Within 3 or 6 min, this was followed by a 10-15 ml gadolinium injection and acquisition of eight serial dynamic coronal images. Dynamic MR images and conventional noncontrast- and contrast-enhanced sagittal and coronal T1-weighted images were evaluated independently in a blind fashion by two neuroradiologists regarding the depiction of pituitary microadenomas. The sensitivities of dynamic enhanced MR imaging in the detection of microadenomas were 61.1% in sagittal direction, 72.2% in coronal direction respectively, and were superior to those of conventional noncontrast- and contrast-enhanced T1-weighted imaging (22.2-50%). The sensitivity of a combination of sagittal and coronal dynamic enhanced MR imaging for the detection of microadenomas was 88.9% and was superior to those of conventional noncontrast- and contrast-enhanced T1-weighted imaging combining sagittal and coronal directions (61.1%, 61.1%) (P<0.05, P<0.05, respectively). The specificity and accuracy of dynamic enhanced MR imaging with combination of sagittal and coronal images was 88.9% respectively. Dynamic gadolinium-enhanced MR imaging, especially using both sagittal and coronal planes, was concluded to be useful for the detection of pituitary microadenomas.

No abstract

Software-triggered contrast-enhanced 3D MR angiography with centric K-space ordering is a promising technique for viewing intracranial arteries.

The operative findings and outcomes of neurovascular decompression for trigeminal neuralgia were compared between patients aged 75 years and older (elderly group, 17 patients) and patients aged under 75 years (nonelderly group, 115 patients). There were no statistically significant differences in the operative findings or outcomes between the two groups, except in the percentage of patients who had been treated with carbamazepine.Neurovascular decompression for trigeminal neuralgia can be performed in elderly patients with the same operative results as in nonelderly patients. If other treatments (especially carbamazepine treatment) prove ineffective, neurovascular decompression should be considered in elderly patients before they become too old to undergo surgery. However, neurovascular decompression in elderly patients requires great care, as the venous system, including the superior petrosal vein, should be preserved and retraction of the cerebellum should be avoided whenever possible to maintain correct blood circulation in the cerebellum and brainstem.

It is more accurate to describe the CN and IVN as coursing beneath the SVN in either the IAC or cerebellopontine cistern, rather than stating that the three components rotate, as reported in cadaver studies. The MR cisternography studies provided quite detailed information about the topography of the four components and the relationship between the blood vessels and cranial nerves in the IAC and the cerebellopontine cistern.