Masaki Niiro

Natural history of elderly patients with asymptomatic meningiomas

OBJECTIVE For the treatment of elderly patients with asymptomatic meningiomas, it is important to determine their natural history. Based on results of follow up examinations, the natural history of such patients was clarified and prognostic factors concerning the potential of tumour growth in the aged were identified. METHODS The clinical records and imaging studies of 40 elderly (over 70 years) patients with asymptomatic meningiomas were analysed. The patients were followed up with repeated imaging studies, and changes in tumour size, clinical signs, and outcomes were evaluated. RESULTS There were 32 women and eight men with a mean age of 76.1 years. The mean follow up period was 38.4 months, ranging from 6 to 97 months. Six patients died during the follow up period from disorders other than the tumours, and one patient died as a result of the tumour. Twenty six patients (mean follow up period 41.8 months, range 10–97 months) showed no tumour growth. Fourteen patients showed tumour growth (mean follow up period 32.1 months, range 6–88 months). Five (four men and one woman) of these patients became symptomatic. Based on imaging analysis (1) calcification of the tumour was associated with no tumour growth (p=0.036), and (2) the tumour size at the initial diagnosis was related to subsequent tumour growth (p=0.016). Other possible factors related to tumour growth included sex and hyperintensity on MRI T2 weighted images. CONCLUSION In elderly patients with asymptomatic meningiomas, careful clinical follow up with imaging studies is important. The imaging features mentioned may contribute to prediction of tumour growth.

Dural congestion accompanying meningioma invasion into vessels : the dural tail sign

Abstract Our purpose was to verify the histological appearance of the dural tail accompanying meningiomas on MRI. We studied seven patients such a dural tale. We examined the point of attachment of the tumour and the adjacent dura mater histologically. In all patients, rich vascularity and dilated vessels were observed in the dura mater at the point of attachment of the tumour; tumour cells invaded the dura mater and vessels, packing the latter. In the adjacent dura mater, showing as a dural tail on MRI, there was tumour-cell invasion in only one patient. Vascular congestion around the vessels compacted by the tumour cells in the dura mater and dilated vessels were seen in all patients. We therefore suggest that the mechanism of the dural tail sign is as follows. First, tumour cells invade vessels and pack them at the point of tumour attachment. Then, vessel congestion is induced in the adjacent dura mater, as a result of which it enhances markedly, giving rise to the dural tail sign.

Clinico-pathological study of meningiomas with haemorrhagic onset.

Summary¶Background. Haemorrhage from meningiomas is rare and the underlying pathophysiological mechanisms remain to be determined. We sought to identify these mechanisms by studying clinical and histological records of 6 meningioma patients treated at our institution.Patients and methods. We retrospectively studied 6 patients with meningiomas whose acute onset was due to haemorrhage. We evaluated clinical features and imaging studies. The vascularity and proliferative nature of these tumours were examined immunohistochemically and tissue factor (TF) immunoreactivity was assessed. For comparison we evaluated 25 non-haemorrhagic meningiomas.Findings. At onset, the haemorrhages mimicked stroke in all 6 patients. On imaging studies, 3 of the haemorrhages were intra- and extratumoural, the other 3 were extratumoural only. Hyperintensity on T2-weighted MRI was a characteristic of these meningiomas. Histologically, they were of 3 subtypes, meningothelial (n=3), transitional (n=2), and anaplastic (n=1). The MIB-1 labelling index of the 5 WHO Grade I meningiomas was 5.8±2.2. The mean number of CD31-positive blood vessels did not differ in haemorrhagic and non-haemorrhagic meningiomas. The TF-positivity rate of haemorrhagic meningiomas was higher than of non-haemorrhagic meningiomas.Interpretation. The proliferative nature of the meningiomas and TF expression in tumour cells may have contributed to the eventual haemorrhage of the meningiomas in our series.

MRI of a cerebral cryptococcal granuloma

Abstract We report a patient with a cerebral cryptococcal granuloma who presented with recent memory disturbance and deteriorating mental status followed by temporary loss of consciousness. To our knowledge, this is the first report of a cerebral cryptococcal granuloma examined by a combination of conventional MRI, fluid-attenuated inversion recovery and diffusion-weighted imaging and in which the surgical specimen was analysed histochemically.

Huge Arachnoid Cyst of the Posterior Fossa with Cerebellar Tentorium Dysplasia Associated with Juvenile Polyposis

We report an infant with a huge arachnoid cyst of the posterior fossa with dysplasia of the cerebellar tentorium and meningeal sinus and associated juvenile polyposis. Neuroimaging studies disclosed a huge median cystic lesion extending posterosuperiorly over the cerebellum. The cerebellar tentorium was raised to the parietal area; the vermis was normoplastic. Cystography showed no direct communication with the 4th ventricle or subarachnoid space. We discuss the differential diagnosis of median cysts of the posterior fossa and the association of juvenile polyposis.

MRI demonstration of intracerebral cryptococcal granuloma

Abstract We report an intracerebral cryptococcal granuloma in a patient who presented with recent memory disturbance and deteriorating mental status followed by temporary loss of consciousness. To our knowledge, this is the first reported case of an intracerebral cryptococcal granuloma examined by a combination of conventional MRI, fluid-attenuated inversion-recovery and diffusion-weighted imaging and in which the surgical specimen was analysed histochemically.

31P and 1H Magnetic Resonance Spectroscopy of Epileptic Brain.

poral structures, basal ganglia, thalamus, lateral temporal cortex, cingulate gyrus, and cerebellum. Cases were divided in two groups, mesial and lateral, according to the epileptic focus identified by intracranial EEG monitoring. There were 12 cases in the mesial group. The mesial temporal structures on the focus side were activated in all of them, but none showed activated lateral temporal cortex. Basal ganglia were activated in eight on the focus side, and five also showed activated ipsilateral thalamus. In four, the cingulate gyrus was activated. In three, secondarily generalized seizure developed during the SPECT examination. All of these were included among the cases with cingulate activation. In the lateral group, the lateral temporal cortex on the focus side was activated in four of the five cases, as were medial temporal structures. In three, ipsilateral activation of the basal ganglia was noted, including two with thalamus activation. In two, cingulate activation was noted. Two cases developed a secondarily generalized seizure in the SPECT examination, and both of these were included among the cases with cingulate activation. In 60% of studied cases, cerebellar activation wirs noted, but the side was not related significantly to the focus. The mesial temporal structures and basal ganglia were activated on the focus side, the most reliable indication of focus side. Activation of the lateral temporal cortex is highly suggestive of a lateral focus because it never occurred in the mesial group, whereas it was frequently (80%) seen in the lateral group. For secondarily generalized seizures, activation of the cingulate gyrus was seen in six cases. In five, a secondarily generalized seizure was noted during the SPECT trials, which suggests a close relation between seizure generalization and the cingulate gyrus. . Early ictal SPECT is suggestive of the focus laterality and location in the temporal cortex along with suggesting the pathways of seizure spreads and generalization.

31P-Magnetic Resonance Spectroscopic Study on the Effect of Glycerol on Cold-Induced Brain Edema

The aim of the present study was to determine the effects of a hyperosmotic agent, 10% glycerol, on both brain energy metabolism and intracellular pH (pHi) in experimental vasogenic brain edema. Vasogenic brain edema was induced by cold injury applied to bilateral parietal portions in 13 mongrel dogs (7 glycerol, 6 control) while, 3 dogs were used as control. Before and at 24 hours after the injury, sequential phosphorous-31 magnetic resonance spectroscopy (31P-MRS) was performed for 2 hours in order to determine phosphocreatine (PCr), beta-adenosine triphosphate (beta-ATP), inorganic phosphate (Pi) levels and pHi. At 24 hours following cold injury, both PCr/Pi and ATP/Pi ratios significantly decreased from 7.75 to 3.97 and from 2.26 to 1.25, respectively. Furthermore, a moderate decrease in pHi of 7.16 to 7.01 was significantly demonstrated during the same experimental period. Administration of glycerol for 30 minutes significantly increased PCr/Pi from 3.97 to 5.06 and ATP/Pi from 1.25 to 1.72, respectively. Also, glycerol administration caused a significant increase in pHi from 7.01 to 7.11. This study indicates that cryogenic injury, in which formation and expansion of vasogenic brain edema a known to occur, results in disturbed brain energy metabolism and in intracellular acidosis; moreover, the administration of glycerol can ameliorate either or both of these derangements.

C-Type Natriuretic Peptide Is Specifically Augmented by Pituitary Adenylate Cyclase-Activating Polypeptide in Rat Astrocytes

Abstract:  In rat‐cultured astrocytes, pituitary adenylate cyclase‐activating polypeptide (PACAP) activates gene expression and secretion of C‐type natriuretic peptide (CNP) in a dose‐ and time‐dependent manner. These results suggest that PACAP might be involved in the regulation of CNP biosynthesis in astrocytes.

Magnetic Resonance Study of Brain Oedema Induced by Cold Injury — Changes in Relaxation Times Before and After the Administration of Glycerol

Experiments were carried out to determine the ability of magnetic resonance systems to assess change in relaxation times following the induction of experimental brain oedema and subsequent administration of hypertonic glycerol. Nine small mongrel dogs were used for these experiments. Twenty-four hours after producing a cold lesion, magnetic resonance (MR) studies were performed and physiological data were measured. Thirty min after beginning the administration of glycerol, serum osmotic pressure was raised 88 mOsm/l. After administering glycerol a small reduction in long spin echo images was observed in the periventricular high intensity area. The T1 and T2 values appeared to be decreased from 30 min after glycerol administration. This decrease continued until the period of observation ended. Statistically significant changes in the T2 values, especially in the white matter of the opposite side, were seen. The changes in T1 were generally not statistically significant. We conclude that the changes in water content of the oedematous brain following the administration of glycerol can be detected by magnetic resonance systems, that these changes become appreciable 30 min after administration of glycerol and continue at least two more hours, and that the changes in T2 were larger than those in T1.