Takeo Baba

Novel epidemiological features of moyamoya disease

Background: Many clinical features that are specific to moyamoya disease have been reported and cited in textbooks based on previous data. The purpose of this study is to investigate the present epidemiological features of moyamoya disease based on recently obtained regional all-inclusive data. Methods: The authors performed an all-inclusive survey of moyamoya disease in Hokkaido, one of the major islands in Japan that has a population of 5.63 million. The epidemiological features were analysed based on the data from 267 newly registered patients with moyamoya disease in Hokkaido from 2002 to 2006. These analysed data were adjusted to the whole Japanese population at 2005. Results: The detection rate of the disease per year was 0.94 patients per 100 000 people, and prevalence was 10.5 patients per 100 000 people. The incidence of ischaemia concerned with the disease was 0.53 patients per 100 000 people-years and haemorrhage was 0.2 patients per 100 000 people-years. The ratio of female to male patients was 2.18. The ratio of patients aged 10 years and above to under 10 years of age at onset was 6.18. Two peaks for age of onset were seen: the highest was observed between 45 and 49 years, and the second between 5 and 9 years. Asymptomatic patients comprised 17.8% of the total number of patients. Conclusion: The epidemiological features of moyamoya disease determined by this survey varied considerably from previous data. The detection rate and prevalence of the disease were higher than those reported previously. The highest peak of onset age was older than those reported previously. In addition, it was revealed that asymptomatic moyamoya patients are not always rare in Japan.

Quantitative analysis of adverse events in neurosurgery.

OBJECTIVE:It is well recognized that the occurrence rate of adverse events related to surgical procedures is considerably high in neurosurgery compared with other specialties. The purpose of this study was to quantitatively determine the occurrence rate of adverse events related to surgery and endovascular intervention in neurosurgery. METHODSA conference on adverse events related to treatments (morbidity and mortality conference) has been held every month for the past 2 years in our department. At these conferences, all adverse events are evaluated and discussed. Adverse events include not only the unexpected complications, but also the neurological and general deterioration predicted before surgery. All the adverse events are discussed in terms of the conceivable causes, their association with the procedures, and the possibility of prediction and avoidance. RESULTSOne hundred eighty-two events (28.3%) among 643 neurosurgical interventions over 2 years were recognized as adverse events. Among these 182 adverse events, 165 (90.7%) were closely related to procedures and 125 events (68.7%) were predictable before or during the procedures. However, even when retrospectively reviewed, only 6 (3.3%) of events were deemed avoidable. Of these 6 avoidable events, there were only 2 (1.1%) that were considered to have been caused by error. CONCLUSIONAdverse events are not invariably rare in neurosurgery. Most of them are predictable; however, their avoidance is not necessarily easy. Avoidable adverse events caused by medical errors were observed in only 1.1% of cases.

Interstitial spinal-cord oedema in syringomyelia associated with Chiari type 1 malformations

Object: The pathophysiology of syringomyelia in Chiari type 1 malformations has not been clarified. Oedema-like spinal-cord swelling was recently reported in several pathological conditions, including Chiari type 1 malformations as a pre-syrinx state. However, the role of the pre-syrinx state in the development of syringomyelia is unknown. The purpose of this study is to investigate the parenchymal changes of the spinal cord in syringomyelia associated with Chiari type 1 malformations. Methods: Pre- and postoperative MRI findings in 14 patients who underwent foramen magnum decompression in our institute were reviewed. The analysis was focused on differences in visualisation of the syrinx between T1- and T2-weighted images and abnormal parenchymal signal changes. There were 6 men and 8 women, aged from 6 to 79 years. No patients showed hydrocephalus. Results: Twelve patients had large and expansive syrinx, whereas 2 patients showed small syrinx confined to the centre of the spinal cord. T2-weighted images displayed significantly larger intramedullary abnormal signal areas. Nine patients showed parenchymal hyperintensity areas around the enlarged central canal or base of the posterior white columns adjacent to the syringomyelic cavity. Such parenchymal hyperintensity areas markedly diminished with reduction of the syrinx after surgery and were considered to be interstitial oedema. Conclusions: From this study, the interstitial oedema of the spinal cord commonly accompanies syringomyelia with Chiari type 1 malformations. Accumulation of the extracellular fluid due to disturbed absorption mechanisms may play an important role in the pathophysiology of syringomyelia associated with Chiari type 1 malformations.

Rapid induction of 7H6 tight junction-associated protein and paracellular barrier function in capillary endothelial cells of porcine brain in vitro by treatment with astrocyte conditioned medium and cAMP

The capillary endothelium of the central nervous system functions as a highly selective permeability barrier, corresponding to the blood-brain barrier (BBB). In the present study, we assessed the roles of the tight junction-associated proteins ZO-1 and 7H6 in the development of brain endothelial barrier function. Capillary endothelial cells (ECs) of porcine brain were cultured and treated with a combination of astrocyte conditioned medium (CM), 8-(4-chlorophenylthio) cyclic AMP (cAMP), and phosphodiesterase inhibitor. Barrier function induced within 10h was more than 10 fold higher in terms of transendothelial electrical resistance (TER) and permeability to inulin and mannitol. Concomitantly, 7H6 antigen was significantly induced at the cell border, but the expression of ZO-1 did not change significantly between the control and treated cells. These results showed the importance of astrocyte CM and cAMP for the induction of the BBB and suggested that astrocyte CM and cAMP may function differently in the induction of 7H6 antigen in brain capillary ECs.

Reversible hyperintense lesion after balloon occlusion test.

We report a unique case of a reversible high signal intensity lesion observed on a magnetic resonance (MR) image accompanied by transient neurological deficits related to a balloon occlusion test. This abnormality was considered to be vasogenic edema caused by the disruption of the blood‐brain barrier (BBB) due to a long history of uncontrolled hypertension and transient ischemia induced by the balloon occlusion test.

Spinal cord herniation is one of the important differential diagnoses of spinal arachnoid cyst

We greatly appreciate the comment by Drs. Groen and Coopes on our recent article, “Pulsatile wall movement of spinal arachnoid cyst deteriorates spinal cord symptoms: report of three cases”. Spinal cord herniation is one of the important differential diagnoses of spinal arachnoid cyst. From our experience, spinal cord herniation can be visualized by thin slice MRI or CT myelography. The spinal cord is attached to the ventral dura mater with localized cord deformity. Clinically, the patients with spinal cord herniation often showed the Brown-Sequard syndrome with several years of history. In our three cases, the patients presented with a rather rapid progression of symptoms, and MRI showed mild ventral displacement of the spinal cord. Thin slice axial scans did not disclose the localized cord deformity (herniated part of the spinal cord). In our patients, the pulsatile cerebrospinal fluid movement, especially rostral flow during the diastolic phase of the cardiac cycle, caused spinal cord compression by the parachute-like expansion of the arachnoid cyst. Such dynamic pathophysiology could be appreciated with cine-mode MRI and intraoperative ultrasonography. During surgery, we confirmed the absence of the ventral dural defect in all three cases. We quite agree with Drs. Groen and Coopes that clinicians should be aware of the possibility of spinal cord herniation in cases of ventral spinal cord displacement. However, the possibility of the arachnoid cyst with a dynamic compressive pathomechanism will also be important when MRI shows only mild spinal cord displacement.