Nanoparticles exploit biological pathways to achieve payload delivery of small molecules to cellular and intracellular targets. Synthetic strategies, including surface, porosity, stealthing, and size ...modifications, can be utilized to refine the pharmacokinetic properties of nanoparticles and allow for efficient delivery.
This review highlights the properties of nanoparticles used in targeted drug delivery, including delivery to cells as well as organelle targets, some of the known pharmacokinetic properties of nanoparticles, and their typical modifications to allow for therapeutic delivery. Nanoparticles exploit biological pathways to achieve payload delivery to cellular and intracellular targets, including transport past the blood-brain barrier. As illustrative examples of their utility, the evaluation of targeted nanoparticles in the treatment of cancers and diseases of the central nervous system, such as glioblastoma multiforme, neurovascular disorders, and neurodegenerative diseases, is discussed.
Background
Stereotactic radiosurgery (SRS) has become a primary option for management for both newly diagnosed vestibular schwannomas (VS), as well as VS that enlarge after initial observation.
...Methods
A retrospective review of our prospectively maintained data base found 871 patients who underwent Gamma knife® SRS as their initial (primary) management between 1987 and 2008. Follow-up ranged from 1–25 years (median = 5.2 years) Median tumor volume was 0.9 cc (0.02–36) and median margin dose was 13 Gy (12–25).
Results
Progression free survival (PFS) after SRS was 97% at 3 years, 95% at 5 years, and 94% at 10 years. Freedom from delayed surgical resection was found in 98.7% of patients. Smaller tumor volume was significantly associated with improved PFS. There were 326 patients with serviceable hearing (Gardner–Robertson 1 or 2) at the time of SRS with audiological follow-up of ≥ 1 year. Serviceable hearing preservation rates after SRS were 89.8% at 1 year, 76.9% at 3 years, 68.4% at 5 years, 62.5% at 7 years, and 51.4% at 10 years. Factors associated with improved serviceable hearing preservation included younger age, Gardner-Robertson grade 1 at SRS, and absence of subjective complaints of dysequilibrium or vertigo (vestibulopathy). Fifty-one patients (5.8%) developed trigeminal neuropathy. Fourteen (1.6%) developed a transient House-Brackmann grade 2 or 3 facial neuropathy.
Conclusions
In this report with extended follow-up, primary SRS achieved tumor growth control in 94% of patients. Optimization of long- term cranial nerve outcomes remains an important achievement of this management strategy for VS.
The stereoelectroencephalography (SEEG) procedure provides a unique 3D overview of the seizure-onset zone. Although the success of SEEG relies on the accuracy of depth electrode implantation, few ...studies have investigated how different implantation techniques and operative variables affect accuracy. This study examined the effect of two different electrode implantation techniques (external vs internal stylet) on implantation accuracy while controlling for other operative variables.
The implantation accuracy of 508 depth electrodes from 39 SEEG cases was measured after coregistration of postimplantation CT or MR images with planned trajectories. Two different implantation techniques were compared: preset length with internal stylet use and measured length with external stylet use. Correlations between implantation accuracy and technique type, entry angle, intended implantation depth, and other operative variables were determined statistically using multiple regression analysis.
Multiple regression analysis showed that the internal stylet technique exhibited a larger target radial error (p = 0.046) and angular deviation (p = 0.039) with a smaller depth error (p < 0.001) than the external stylet technique. Entry angle and implantation depth were positively correlated with target radial error (p = 0.007 and < 0.001, respectively) only for the internal stylet technique.
Better target radial accuracy was achieved when an external stylet was used to open the intraparenchymal pathway for the depth electrode. In addition, more oblique trajectories were equally accurate to orthogonal ones with the usage of an external stylet, while more oblique trajectories were associated with larger target radial errors with the usage of an internal stylet (without an external stylet).
Vestibular schwannomas (VS) are increasingly diagnosed in patients with normal hearing because of advances in magnetic resonance imaging. We sought to evaluate whether stereotactic radiosurgery (SRS) ...performed earlier after diagnosis improved long-term hearing preservation in this population.
We queried our quality assessment registry and found the records of 1134 acoustic neuroma patients who underwent SRS during a 15-year period (1997-2011). We identified 88 patients who had VS but normal hearing with no subjective hearing loss at the time of diagnosis. All patients were Gardner-Robertson (GR) class I at the time of SRS. Fifty-seven patients underwent early (≤2 years from diagnosis) SRS and 31 patients underwent late (>2 years after diagnosis) SRS. At a median follow-up time of 75 months, we evaluated patient outcomes.
Tumor control rates (decreased or stable in size) were similar in the early (95%) and late (90%) treatment groups (P=.73). Patients in the early treatment group retained serviceable (GR class I/II) hearing and normal (GR class I) hearing longer than did patients in the late treatment group (serviceable hearing, P=.006; normal hearing, P<.0001, respectively). At 5 years after SRS, an estimated 88% of the early treatment group retained serviceable hearing and 77% retained normal hearing, compared with 55% with serviceable hearing and 33% with normal hearing in the late treatment group.
SRS within 2 years after diagnosis of VS in normal hearing patients resulted in improved retention of all hearing measures compared with later SRS.
The purpose of this review is to provide a discussion of the history and utility of robotics in invasive monitoring for epilepsy surgery using stereoelectroencephalography (sEEG). The authors ...conducted a literature review of available sources to describe how the advent of surgical robotics has improved the efficacy and ease of performing sEEG surgery. The sEEG method integrates anatomic, electrographic, and clinical information to test hypotheses regarding the localization of the epileptogenic zone (EZ) and has been used in Europe since the 1950s. One of the primary benefits of robot-assisted sEEG implantation techniques is the ability to seamlessly transition between both orthogonal and oblique trajectory types using a single technique. Based on available information, it is our view that, when applied appropriately, robotic sEEG can have a low rate of complications and many advantages over both non-robotic sEEG implantation and traditional craniotomy-based invasive monitoring methods.
Near-infrared (NIR) light is commonly used to map venous anatomy in the upper extremities to gain intravenous access for line placement. In this report, the authors describe the use of a common and ...commercially available NIR vein finder to delineate the cortical venous anatomy prior to dural opening.During a variety of cranial approaches, the dura was directly visualized using an NIR vein finder. The NIR light source allowed for recognition of the underlying cortical venous anatomy, dural sinuses, and underlying pathology before the dura was opened. This information was considered when tailoring the dural opening. When the dura was illuminated with the NIR vein finder, the underlying cortical and sinus venous anatomy was evident and correlated with the observed cortical anatomy. The vein finder was also accurate in locating superficial lesions and pathological dural veins. A complete accordance in the findings on the pre- and post-dural opening images was observed in all cases.This simple, inexpensive procedure is readily compatible with operative room workflow, necessitates no head fixation, and offers a real-time image independent of brain shift.
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