Yuichiro Yoneoka

Growth of incidental meningiomas.

Summary¶ The aim of this study was to assess the growth of incidental meningiomas, to establish a strategy for dealing with these tumours. The cases of 37 patients with a meningioma revealed incidentally by computerized tomography or magnetic resonance imaging, who were followed at least once by an additional imaging study, were reviewed. The tumour volume was calculated, to estimate the annual growth rate of the incidental meningiomas. Nine of the 37 patients (24.3%) showed a considerable increase (the annual growth rate>1 cu cm/year) in their tumour volume (tumour growth). There was no significant difference in the follow-up period, age, or the volume of tumour between the patients with and without tumour growth. However, a multivariate analysis revealed that the likelihood of tumour growth independently and significantly increased according to a decrease in the age of the patients (Odds ratio 0.18 for one-standard-deviation change (1SD) 12.6 years, p=0.042) and according to an increase in the volume of the tumour (Odds ratio 3.64 for 1SD 4.46 cu cm, p=0.042). The majority of patients with incidental meningioma can be apparently observed without any surgical intervention, because their annual growth rates are generally less than 1 cu cm/year. However, clinical and radiological observations would be advisable for these patients (especially young patients and patients with a large tumour), in view of the presence of rapidly growing tumours in some of the patients.

Intrauterine methylmercury intoxication: Consequence of the inherent brain lesions and cognitive dysfunction in maturity

We studied the effects of intrauterine neurotoxicity by methylmercury (MeHg) on the postnatal developing and adult stages of rats. We used offspring delivered from dams that had been given 1 mg/kg/day methylmercury chloride for 5 pregestational days and throughout pregnancy. Histopathological examination of the brains of a proportion of the offspring on postnatal days 1 (P1) and P3 revealed degenerative neurons in the brain stem and the limbic system, including the hippocampus and the amygdala. At P7 and P14, degenerative neurons were indiscernible, but reactive astrocytosis remained in the brain stem. At P70 and P180, the brains seemed to have developed well. However, in behavioral analyses performed at 6 months of age, MeHg-exposed rats showed a significant learning disability in the passive avoidance response compared with controls, but no differences in water maze performance. Furthermore, morphometric analysis of the amygdala and hippocampus revealed significantly fewer neurons in both areas in the MeHg-exposed rats. Thus, chronic intrauterine exposure to low-dose MeHg induces a decrease in neuron population in the limbic system, and the offspring have impaired higher brain function.

Planum Temporale: Where Spoken and Written Language Meet

Functional magnetic resonance imaging studies on spoken versus written language processing were performed in 20 right-handed normal volunteers on a high-field (3.0-tesla) system. The areas activated in common by both auditory (listening) and visual (reading) language comprehension paradigms were mapped onto the planum temporale (20/20), primary auditory region (2/20), superior temporal sulcus area (2/20) and planum parietale (3/20). The study indicates that the planum temporale represents a common traffic area for cortical processing which needs to access the system of language comprehension. The destruction of this area can result in comprehension deficits in both spoken and written language, i.e. a classical case of Wernicke’s aphasia.

Cranial base chordoma – long term outcome and review of the literature

SummaryBackground. The purpose of this study is to clarify the latest long-term therapeutic result for cranial base chordomas. We are seeking an improvement of long term therapeutic outcome through a review of cranial base chordomas treated in our institute and of the published literature in the era of multimodality therapy. Materials and methods. We retrospectively reviewed 13 consecutive patients with cranial base chordoma, including ten males and three females with mean age of 39.5 years (range 5–76 years). Results. The method of initial treatment included surgery and post-operative conventional local irradiation (IR) in 9 patients, surgery and IR followed by post-operative stereotactic radiosurgery (SRS) in 2 patients, surgery as well as SRS in one patients, and surgery as well as SRS followed by IR in one patient. Subtotal removal (over 95%) was accomplished in eight patients. The mean follow-up period after completion of surgery and initial radiotherapy was 122 months (median 108 months). According to the Kaplan-Meier estimate method, the 5-year survival rate was 82.5%: 11 out of 13 patients survived longer than 5 years and five patients survived longer than 10 years. With a longer follow-up period than the previous reports, our series has provided a 5-year survival rate comparable to that of proton beam therapy. Although our series indicates a favourable outcome, surgical resection followed by IR or SRS failed to control tumour growth in five patients. Conclusions. IR and/or SRS provided results comparable with proton beam or heavy particle therapy in our series of cranial base chordomas probably because the radiation field must have covered the target of the tumour volume sufficiently, and reduction of gross tumour volume reduced the target size for radiotherapy. Pursuit of further effective combinations of IR and stereotactic radiotherapy (SRS, proton beam, heavy particle) after tangible resection, especially for residual and recurrent lesions, will be an acceptable framework to achieve a better therapeutic outcome for cranial base chordomas than at present.

Criteria for normalcy of cavities observed within the adult hippocampus: high-resolution magnetic resonance imaging study on a 3.0-T system.

Background and Purpose. Cavities occasionally found within the hippocampus during routine clinical magnetic resonance imaging (MRI) studies are believed to be a normal variant reflecting fluid collection within the vestigial hippocampal sulcus. However, the lack of systematic studies defining objective criteria for such cavities has hampered further assessment of potential abnormalities within the hippocampus. This study assessed the detailed characteristics of hippocampal cavities in normal subjects using a new high‐resolution MRI technique in an attempt to define objective criteria of normalcy. Methods. A new high‐resolution imaging technique, T2‐reversed MRI on a high‐field (3.0‐T) system was used to image the hippocampus in 74 normal volunteers in 3 age groups (28 young, 24 middle, and 22 senior). Results. Residual cavities in the vestigial hippocampal sulcus were resolved as single, crescent‐shaped structures along the deep aspect of the vestigial hippocampal sulcus. The size of the cavities did not vary with age and never exceeded 1 mm in width and 3 mm in length. The frequency of detection, however, increased with age (21.4% [5/28] in the young, 25.0% [6/24] in the middle, and 36.4 [8/22] in the senior age group). Conclusion. The study established clear objective criteria for normal cavities within the hippocampus. These cavities likely represent physiological fluid collection within the vestigial hippocampal sulcus. Any cavity that does not meet these defined criteria should be considered potentially abnormal.

MRA Demonstration of “Periarteritis” in Tolosa-Hunt Syndrome

Summary Background. Modern magnetic resonance imaging (MRI) diagnosis of Tolosa-Hunt syndrome rests upon demonstration of cavernous sinus abnormalities. We present a case of Tolosa-Hunt syndrome who has no abnormal mass lesion in the cavernous sinuses on MRI but with a diagnostic lesion on magnetic resonance angiography (MRA). Clinical Presentation. A 48-year-old woman developed acute periorbital pain and abducens palsy of the right side at the first episode, and subacute peri-orbital pain and rapidly deteriorating visual acuity on the left side at the second episode with a four months interval. MRI showed no soft-tissue abnormality in the cavernous sinuses. Findings. MRA demonstrated a narrowing of the right cavernous carotid artery at the first episode, and narrowings of the left clinoid carotid and ophthalmic arteries at the second episode. Based on these findings, the patient underwent urgent steroid therapy and the symptoms resolved dramatically in each episode. Follow-up MRA confirmed resolution of arterial narrowings. Interpretation. MRA may help prompt the noninvasive diagnosis in certain cases of Tolosa-Hunt syndrome with little inflammatory reaction in the cavernous sinus but with predominant intra- and juxta-cavernous periarteritis.

Preoperative depiction of cavernous sinus invasion by pituitary macroadenoma using three-dimensional anisotropy contrast periodically rotated overlapping parallel lines with enhanced reconstruction imaging on a 3-tesla system.

OBJECTIVES Three-dimensional anisotropy contrast (3DAC) magnetic resonance (MR) imaging provides clear depiction of neuronal fibers. The aim of this study was to identify intracavernous cranial nerves in patients with pituitary macro-adenoma and in healthy volunteers by using 3DAC MR imaging on a 3-tesla system and to preoperatively predict cavernous sinus invasion by pituitary macroadenoma. METHODS Thirty-three patients (cavernous sinuses in 66 sides) with pituitary macroadenomas and 25 healthy volunteers (50 sides) participated in this study. Coronal 3DAC MR images constructed from diffusion weighted images, acquired with periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) sequences, and T2-weighted reverse images were obtained at the same anatomical locations using a 3-tesla MR imaging system. Attempts were made to identify the cranial nerves. RESULTS The oculomotor and ophthalmic/maxillary nerves were preoperatively identified in all sides (66 sides in patients and 50 sides in healthy volunteers) on 3DAC MR images. In the 33 patients, cavernous sinus invasion was revealed in 10 (12 [18.2%] of 66 sides) by intraoperative endoscopic observation. Coronal 3DAC MR images revealed that the oculomotor nerves were half surrounded with adenoma in all 12 of these sides, and the ophthalmic/maxillary nerves were half encapsulated with tumor (sensitivity/specificity: 100%/100% and 83%/100%, respectively). CONCLUSIONS Preoperative evaluation of pituitary macroadenomas using 3DAC PROPELLER MR imaging on a 3-tesla system is likely to be a powerful noninvasive method of detecting cavernous sinus invasion, which can potentially dominate the therapeutic strategy for these lesions.

Early morphological recovery of the optic chiasm is associated with excellent visual outcome in patients with compressive chiasmal syndrome caused by pituitary tumors.

Abstract Objectives: The study objectives are (1) to identify factors predicting the excellent visual recovery after transsphenoidal removal of pituitary tumors and (2) to describe the association of excellent visual recovery and early restoration of symmetry of the decompressed optic chiasm. Methods: Thirty-five patients with visual symptoms due to pituitary tumors underwent endoscopic endonasal surgery. All patients received perioperative diagnostic magnetic resonance (MR) imaging and ophthalmological assessments within 2 weeks before surgery, within 2 weeks after surgery, and 3 months or later after surgery. Preoperative best-corrected visual acuity (BCVA ≧ 20/20), degree of visual field deficit (VFD, less than half of VF), thickness of retinal nerve fiber layer (RNFL) measured by optical coherence tomography (OCT), and thickness of ganglion cell complex (GCC) measured by OCT were considered for statistical analysis as predictive factors of VF outcome. Multivariate logistic regression models were used in statistical evaluation of data. Results: In the multivariate analysis, RNFL (odds ratio  =  62·137, P < 0·001) and preoperative VFD (odds ratio  =  8·244, P < 0·02) proved to be effective as factors predicting sufficient VF recovery. Postoperative restoration of symmetry of the optic chiasm was related to sufficient VF recovery (P < 0·0001, Fisher’s exact test) and RNFL (P < 0·0001, Fisher’s exact test). Discussion: Early decompression is crucial for sufficient VF recovery, in particular, while RNFL preserves normal or borderline thickness and while VFD keeps within hemianopia. Morphological reversibility is associated with functional reversibility in the optic chiasm compressed by a pituitary tumor. In particular, early morphological recovery suggests functional recovery, which indicates neurocyte reserve in the compressed optic pathway with functional recovery.

Pre-operative histopathological evaluation of meningiomas by 3 0T T2R MRI.

Summary. Background: To assess the potential of T2 reversed (T2R) magnetic resonance imaging (MRI) for the pre-operative histopathological assessment of meningiomas. Method: Twenty patients scheduled for meningioma resection were prospectively assessed using T2R MRI on a 3 tesla system. Image characteristics were compared with intra-operative findings and post-operative histopathological examination of excised meningioma tissues. Findings: The averaged T2 characteristics expressed as averaged grayscale levels of the tumour correlated highly with tumour consistency, in agreement with previous reports. Furthermore, detailed evaluation of the structural appearance of tumour on T2R images revealed brightness of tumour (shorter T2) was dependent on the degree of histopathological heterogeneity. Significantly shorter T2 value correlated with collagen-rich fibrous tissue. Interpretation: The study demonstrated the advantage of T2R imaging in pre-operative determination of histopathological characteristics of meningiomas. As a step towards MR microscopy and improved pre-operative treatment planning, T2R imaging on a 3.0T system appears to play an important role in the non-invasive pre-operative structural assessment of a tissue of interest.

Synchronized multiple regression of diagnostic radiation-induced rather than spontaneous: disseminated primary intracranial germinoma in a woman: a case report.

IntroductionExamples of the spontaneous regression of primary intracranial germinomas can be found in the literature. We present the case of a patient with disseminated lesions of primary intracranial germinoma which synchronously shrunk following diagnostic irradiation. We will discuss whether this regression was spontaneous or radiation-induced.Case presentationA 43-year-old Japanese woman presented to our hospital complaining of memory problems over a period of one year and blurred vision over a period of three months. Following magnetic resonance imaging, she was found to have a massive lesion in the third ventricle and small lesions in the pineal region, fourth ventricle, and in the anterior horn of the left lateral ventricle. Prior to an open biopsy to confirm the pathology of the lesions, she underwent a single cranial computed tomography scan and a single cranial digital subtraction angiography for a transcranial biopsy. Fourteen days after the first magnetic resonance image - 12 and eight days after the computed tomography scan and digital subtraction angiography, respectively - a pre-operative magnetic resonance image was taken, which showed a notable synchronous shrinkage of the third ventricle tumor, as well as shrinkage of the lesions in the pineal region and in the fourth ventricle. She did not undergo steroid administration until after a biopsy that confirmed the pathological diagnosis of pure germinoma. She then underwent whole craniospinal irradiation and went into a complete remission.ConclusionsIn our case report, we state that diagnostic radiation can induce the regression of germinomas; this is the most reasonable explanation for the synchronous multiple regression observed in this case of germinoma. Clinicians should keep this non-spontaneous regression in mind and monitor germinoma lesions with minimal exposure to diagnostic radiation before diagnostic confirmation, and also before radiation treatment with or without chemotherapy begins.