Estimation of intracranial pressure by ultrasound of the optic nerve sheath in an animal model of intracranial hypertension

BackgroundUltrasound of the optic nerve sheath diameter (ONSD) has been used as a non-invasive and cost-effective bedside alternative to invasive intracranial pressure (ICP) monitoring. However, ONSD time-lapse behavior in intracranial hypertension (ICH) and its relief by means of either saline infusion or surgery are still unknown. The objective of this study was to correlate intracranial pressure (ICP) and ultrasonography of the optic nerve sheath (ONS) in an experimental animal model of ICH and determine the interval needed for ONSD to return to baseline levels.MethodsAn experimental study was conducted on 30 pigs. ONSD was evaluated by ultrasound at different ICPs generated by intracranial balloon inflation, saline infusion, and balloon deflation, and measured using an intraventricular catheter.ResultsAll variables obtained by ONS ultrasonography such as left, right, and average ONSD (AON) were statistically significant to estimate the ICP value. ONSD changed immediately after balloon inflation and returned to baseline after an average delay of 30 min after balloon deflation (p = 0.016). No statistical significance was observed in the ICP and ONSD values with hypertonic saline infusion. In this swine model, ICP and ONSD showed linear correlation and ICP could be estimated using the formula: −80.5 + 238.2 × AON.ConclusionIn the present study, ultrasound to measure ONSD showed a linear correlation with ICP, although a short delay in returning to baseline levels was observed in the case of sudden ICH relief.     

Cone Beam Computed Tomography Analysis of Sphenoid Sinus Pneumatization and Relationship with Neurovascular Structures

BackgroundThe sphenoid sinus is considered as the most variable pneumatized structure of the skull.PurposeThe aim of the present study was to determine the prevalence of the Onodi cell as well as to evaluate the relationship between the sphenoid sinus type of pneumatization and the presence of surrounding neurovascular protrusion using cone beam computed tomography (CBCT).MethodsThe CBCT images of 500 patients/996 sides [203 males (40.6%) and 297 females (59.4%)] were analyzed in this study. The type of sphenoid sinus pneumatization, prevalence of internal carotid artery (ICA) and optic nerve (ON) protrusion and dehiscence, and also the frequency of Onodi cell were assessed.ResultsThe percentages of the conchal, presellar, sellar, postsellar (a), and postsellar (b) types of pneumatization were 1%, 11.5%, 35.5%, 38.9%, and 13.1%, respectively. The more the sphenoid sinuses pneumatized, the greater the frequency of ON and ICA protrusion and dehiscence of their wall to the sinus. The prevalence of Onodi cell was 38.8%. A significant correlation was found between ON dehiscence and the presence of Onodi cells.ConclusionThe present study demonstrated a significant relationship between the sinus type and frequency of neurovascular protrusions. Therefore, the sphenoid sinus extent of pneumatization might be useful in predicting the risk of iatrogenic damage to the surrounding structures.     

锰离子增强MRI在显示大鼠视觉传导通路中的最佳时间

目的 探讨锰离子增强MRI在显示大鼠视觉传导通路中的最佳时间.方法 对24只SD大鼠的单侧眼球内注射氯化锰溶液(30 mmol/L)3 μl后,随机分为8组(注射后3、6、12、24、30、36、48、72 h组),在间隔不同时间后分别行MR T1W扫描.设定相同的ROI后,分别测量和计算视神经、外侧膝状体、上丘在各组图像中的CNR.结果 3~24 h视神经、外侧膝状体和上丘的MR强化信号逐渐增高,至24 h达峰值,持续至30 h后逐渐下降.大鼠视神经的信号强度除在注射后6 h组和72 h组、24 h组和30 h组差异无统计学意义外(P均 >0.05),其余各组间的差异均有统计学意义(P均 <0.05);外侧膝状体各组间两两比较、上丘各组间两两比较差异均有统计学意义(P均 <0.05).结论 锰离子增强MRI在显示大鼠视觉传导通路中的最佳时间是24~30 h.     

青光眼视神经保护治疗的研究进展

青光眼是以特征性视神经损伤和视功能损害为特点的一类疾病,病理性高眼压是主要危险因素。在青光眼治疗方面,既要降低眼压,又要保护视神经。视神经损伤的机制是神经节细胞的凋亡,能阻止或延缓神经节细胞凋亡的方法称为青光眼的视神经保护治疗。青光眼视神经保护治疗是目前研究的热点,主要包括抗青光眼药物、热激蛋白、神经干细胞、神经营养因子及基因治疗和中医药等研究。     

Tratamiento combinado de la maculopatía por foseta papilar secundaria a glaucoma

Case reportA 58-year-old man was referred to the retina specialist for evaluation of decreased vision in the left eye (LE). At the first visit, visual acuity was 0.9 in right eye (RE) and hands movement in LE, and the intraocular pressure (IOP) was 34 mmHg and 42 mmHg in right and left eye, respectively. Dilated funduscopic examination revealed papillary pallor, increased cup-to-disc ratio of the optic nerve in both eyes, and retinal posterior pole edema in the LE. Optical coherence tomography (OCT) and fluorescein angiography assessment confirmed the diagnosis of a macular serous retinal detachment (RD) caused by an optic disc pit secondary to glaucoma. Combined surgical treatment with ExPress drainage device implantation, pars plana vitrectomy (PPV), and juxtapapillar laser endophotocoagulation was performed. IOP normalization was achieved as well as complete anatomical resolution of macular RD.     

Grasping without vision: Time normalizing grip aperture profiles yields spurious grip scaling to target size

The analysis of normalized movement trajectories is a popular and informative technique used in investigations of visuomotor control during goal-directed acts like reaching and grasping. This technique typically involves standardizing measures against the amplitude of some other variable – most typically time. Here, we show that this normalizing technique can lead to some surprising results. In the first of two experiments, we asked participants to grasp target objects without ever seeing them from trial to trial. In the second experiment, participants were given a brief preview of the target and were then cued 3 s later to pick it up while vision was prevented. Critically, on some trials during the delay period and unbeknownst to the participants, the previewed target was swapped for a new unseen one. The results of both experiments show that time-normalized measures of grip aperture during the closing phase of the movement appear to be scaled to target size well before the fingers make contact with the target – even though participants had no idea what the size of the target was that they were grasping. In contrast, a classical measure of anticipatory grip scaling, maximum grip aperture, did not show scaling to target size. As we demonstrate, however, in both experiments, movement time was longer for the larger target than the smaller ones. Thus, the comparisons of time-normalized grip aperture, particularly during the closing phase of the movements, were made across different points in real time. Taken together, the results of these experiments highlight a need for caution when investigators interpret differences in time-normalized dependent measures – particularly when the effect of interest is correlated with the dependent measure and a third variable (e.g., movement time) that is used to standardize the dependent measure.     

Pre-chiasmatic transection of the optic nerve can save contralateral vision in patients with optic nerve sheath meningioms

Objectives

With respect to its characteristic pattern of growth from the orbit into the intracranial space toward the chiasm, patients with optic nerve sheath meningiomas (ONSM) are threatened to loose function of both optic nerves. Fortunately, in less than 5% both optic nerves are involved initially. Hence, prevention of vision of the contralateral eye is the foremost aim of any therapy. Performing pre-chiasmatic transection might offer a further treatment option to avoid further tumor growth toward the chiasm.

Patients and methods

In this retrospective study 12 patients with ONSM and blindness of the affected eye were included. The surgical approach was performed either from pterional intradural or as a combined approach from pterional extra- and intradural.

Results

Without any exceptions, vision of the contralateral eye could be preserved and did not show any deterioration after surgery or during the follow-up time of 50.6 months. Furthermore in 58.3% of patients gross total tumor resection could be achieved. During follow up observation in 67% of patients no further tumor progress or recurrences could be observed. 4 patients, however, showed delayed tumor progress or recurrences that were treated by radiotherapy.

Conclusion

Pre-chiasmatic transection of the optic nerve might offer a surgical treatment option to control tumor growth and to preserve vision of the contralateral eye.