Transcranial Sonographic Alterations of Substantia Nigra and Third Ventricle in Parkinson＆#39;s Disease with or without Dementia

Background： Numerous studies have demonstrated that patients with Parkinson＆#39;s disease （PD） have a higher prevalence of substantia nigra （SN） hyperechogenicity compared with controls. Our aim was to explore the neuroimaging characteristics of transcranial sonography （TCS） of patients with PD and those with PD with dementia （PDD）. The correlation between the echogenicity of the SN and clinical symptoms in Chinese patients with PDD was also assessed. Methods： The ratios of SN hyperechogenicity （SN＋）, maximum sizes of SN＋, and widths of third ventricle （TV） were measured using TCS for all the recruited patients. Data were analyzed using one-way analysis of variance, rank-sum test, Chi-square test, and receiver-operating characteristic （ROC） curve analysis. Results： The final statistical analysis included 46 PDD patients, 52 PD patients, and 40 controls. There were no significant differences in ratios of SN＋ and maximum sizes of SN＋ between PDD and PD groups （P 〉 0.05）. TV widths were significantly larger in PDD group （7.1± 1.9 mm） than in PD group （6.0± 2.0 mm） and controls （5.9 ± 1.5 mm, P 〈 0.05）; however, the ratios of enlarged TV did not differ among the three groups （P = 0.059）. When cutoff value was set at 6.8 mm, the TV width had a relatively high sensitivity and specificity in discriminating between PDD and PD groups （P = 0.030） and between PDD group and controls （P = 0.003）, based on ROC curve analysis. In PDD patients, SN＋ was more frequently detected in akinetic-rigid subgroup, and patients with SN＋ showed significantly higher Hoehn and Yahr stage and Nonmotor Symptoms Questionnaire scores （P 〈 0.05）. Conclusions： Compared to Chinese patients with PD, patients with PDD had a wider TV, altered SN sonographic features, and more severe clinical symptoms. Our findings suggest that TCS can be used to assess brain atrophy in PD and may be useful in discriminating between PD with and without dementia.

Minimally invasive keyhole approaches for removal of tumors of the third ventricle

Background In recent years, keyhole microsurgery has become an important subject of modern minimally invasive neurosurgery. In this study, minimally invasive techniques avoiding unnecessary tissue injuries were applied to refine traditional approaches for the removal of third ventricular tumors within a limited operative filed. Methods Individualized keyhole approaches were designed according to the characteristics of third ventricular tumors and their growth patterns. A series of keyhole approaches such as supraorbital subfrontal approach, infratentorial supracerebellar approach, interhemispheric transcallosal approach, pterional approach were taken to enter the third ventricle anteriorly, posteriorly, superiorly or laterally, respectively. A total of 34 removed tumors in or extended into the third ventricle included 11 craniopharyngiomas, 10 pituitary adenomas, 2 pinealomas, 1 cholesteatoma, 3 germinomas, and 7 gliomas. Results Total tumor resection was done in 27 （79.4%） of the patients, and subtotal resection in 7 patients （20.6%）. Residual tumor was due to tight adherence of germinoma to the vein of Galen （1 patient）, craniopharyngioma to the pituitary stalk （3）, supratentorial extension of pineal region gliomas （1）, suprasellar extension of gliomas （1） and giant pituitary adenoma （1）. Complications such as brain contusion, postoperative hemorrhage and infection were not associated with keyhole approaches. Extended incision or enlarged bone flap was not made because of episode during operation or inadequate exposure. Conclusions Keyhole approaches are safe, effective and minimally invasive in the surgical treatment of tumors deeply seated in the third ventricle. Individualized keyhole approach ensures a successful treatment. Tumors in the upper middle part of the third ventricle can be exposed by the interhemispheric transcallosal keyhole approach. Tumors of the posterior third ventricle may be well exposed by the infratentorial supracerebellar keyhole approach. Tumors of the anterior third ventricle can be entered by either a supraorbital subfrontal keyhole approach or a pterional keyhole approach.

Neural progenitor cells but not astrocytes respond distally to thoracic spinal cord injury in rat models

Traumatic spinal cord injury （SCI） is a detrimental condition that causes loss of sensory and motor function in an individual. Many complex secondary injury cascades occur after SCI and they offer great potential for therapeutic targeting. In this study, we investigated the response of endogenous neural progenitor cells, astrocytes, and microglia to a localized thoracic SCI throughout the neuroaxis. Twenty-five adult female Sprague-Dawley rats underwent mild-contusion thoracic SCI （n = 9）, sham surgery （n = 8）, or no surgery （n = 8）. Spinal cord and brain tissues were fixed and cut at six regions of the neuroaxis. Immunohistochem- istry showed increased reactivity of neural progenitor cell marker nestin in the central canal at all levels of the spinal cord. Increased reactivity of astrocyte-specific marker glial fibrillary acidic protein was found only at the lesion epicenter. The number of activated microglia was significantly increased at the lesion site, and activated microglia extended to the lumbar enlargement. Phagocytic microglia and macrophages were significantly increased only at the lesion site. There were no changes in nestin, glial fibrillary acidic protein, microglia and macrophage response in the third ventricle of rats subjected to mild-contusion thoracic SCI compared to the sham surgery or no surgery. These findings indicate that neural progenitor cells, astrocytes and microglia respond differently to a localized SCI, presumably due to differences in inflammatory signaling. These different cellular responses may have implications in the way that neural progenitor cells can be manipulated for neuroregeneration after SCI. This needs to be further investigated.

Temporal-spatial Generation of Astrocytes in the Developing Diencephalon

tAstrocytes are the largest glial population in the mammalian brain.However,we have a minimal understanding of astrocyte development,especially fate specification in different regions of the brain.Through lineage tracing of the progenitors of the third ventricle(3V)wall via in-utero electroporation in the embryonic mouse brain,we show the fate specification and migration pattern of astrocytes derived from radial glia along the 3V wall.Unexpectedly,radial glia located in different regions along the 3V wall of the diencephalon produce distinct cell types:radial glia in the upper region produce astrocytes and those in the lower region produce neurons in the diencephalon.With genetic fate mapping analysis,we reveal that the first population of astrocytes appears along the zona incerta in the diencephalon.Astrogenesis occurs at an early time point in the dorsal region relative to that in the ventral region of the developing diencephalon.With transcriptomic analysis of the region-specific 3V wall and lateral ventricle(LV)wall,we identified cohorts of differentially-expressed genes in the dorsal 3V wall compared to the ventral 3V wall and LV wall that may regulate astrogenesis in the dorsal diencephalon.Together,these results demonstrate that the generation of astrocytes shows a spatiotemporal pattern in the developing mouse diencephalon.