Decompressive craniectomy in patients with malignant stroke with additional vascular territory.

INTRODUCTION: Decompressive craniectomy substantially reduces mortality and disability rates following a malignant stroke. This procedure remains a life-saving option, especially in contexts with little access to mechanical thrombectomy despite downward trends in the performance of decompressive craniectomy due to discussions on the acceptance of living with severe disabilities. However, the outcomes of the surgery in cases involving concomitant occlusion of anterior or posterior cerebral arteries have not been extensively studied. METHODS: In this retrospective cohort study, spanning January 2010 to December 2022 and including patients who underwent decompressive craniectomy, we compared outcomes between patients with and without additional vascular territory involvement. Independent variables included age, sex, comorbidities, admission National Institutes of Health Stroke Scale (NIHSS) and Glasgow Coma Scale (GCS) scores, time elapsed between stroke and surgery, laterality of the stroke, midline shift, and postoperative infarction volume. Outcomes included mortality and Modified Rankin Score at the 3-month follow-up. RESULTS: Of the 86 patients analyzed, 61 (70.9%) and 25 (29.1%) demonstrated no territory and additional territory involvement, respectively. Patients with involvement of additional territories exhibited lower admission GCS scores, higher NIHSS scores, and larger postoperative infarction volumes. However, these variables were not associated with poor outcomes. Univariate analyses revealed no differences in mortality or severe disability. Even after adjustment, the differences remained insignificant for mortality and severe disability. Age emerged as the sole variable linked to increased mortality. CONCLUSION: Our data suggest that, for patients with malignant stroke undergoing decompressive craniectomy, the outcomes for patients with and without involvement of additional vascular territory are similar.

Survival in patients undergoing surgical resection for brain metastasis from lung cancer and utility of different prognostic scales.

Brain metastases (BM) from lung cancer are among the most common intracranial tumors. Several studies have published scales to estimate the survival of patients with BM. Routine access to molecular diagnostics and modern oncologic treatments, including targeted therapy and immunotherapy, is limited in low- and middle-income countries (LMICs); therefore, incorporating them into recent prognostic scales may diminish the reliability of the scales in LMICs. This retrospective study aimed to determine the survival of 55 patients who were surgically treated for BM from lung cancer at a Brazilian public tertiary teaching hospital between 2012 and 2022. We determined clinical factors associated with survival, and compared observed survival rates with the estimated survival on prognostic scales. The mean overall survival (OS) was 9.3 months (range:0.2-76.5). At univariate analysis, female sex and improved postoperative Karnofsky performance status (KPS) score were associated with longer survival. The median survival did not differ between groups when classified using the Graded Prognostic Assessment (GPA)-2008, Lung-molecular GPA-2017, and Lung-GPA-2021 scales. According to the Diagnosis-Specific (DS)-GPA-2012 scale, there was a significant difference between the groups. In the multivariate Cox regression survival analysis, a higher DS-GPA-2012 and improved postoperative KPS score remained significantly associated with longer survival. In conclusion, this cohort showed a mean OS of < 1 year. Improved KPS score after surgery was associated with increased survival. This cohort DS-GPA scale demonstrated the highest concordance with observed survival, indicating its potential as a valuable tool for patient stratification in surgical treatment decision-making in LMICs.

A Piezoelectric MEMS Microgripper for Arbitrary XY Trajectory.

In this paper, a piezoelectric microgripper for arbitrary 2D trajectory is proposed. The desired trajectory of the specimen under consideration was obtained by the deformability of a structure consisting of 16 straight beams and 12 C-structures. The mechanical action that deforms the structure was obtained by an electrical voltage supplied to piezoelectric plates. In order to verify the proposed model a FEM software (COMSOL) was used and some of the most commonly used trajectories for medical applications, micropositioning, micro-object manipulation, etc., were examined. The results showed that the proposed microgripper was capable of generating any parametrizable trajectory. Parametric studies were also carried out by examining the most relevant parameters highlighting their influence on specimen trajectories.

A Cantilever-Based Piezoelectric MEMS for Arbitrary XY Path Generation.

This work pertains to the design of a cantilever-based piezoelectric MEMS device that is capable of generating arbitrary paths of its tip. The conceived device consists of a pair of rigidly coupled piezoelectric bimorph cantilevers, and a theoretical model is developed for the analytical evaluation of the proper voltage distribution to be supplied to the inner and outer electrodes of each piezoelectric actuator, in order to drive the tip along any desired trajectory. Such a device could be appealing in some microsurgical operations, i.e., the unclogging of arteries, endoluminal treatment of obstructive lesions, but also as a 2D micropositioning stage, etc. Theoretical predictions of voltage versus time that allow several pathways such as circles, ellipses, spirals, etc., to be accomplished have been verified with multiphysics FEM simulations and the numerical outcomes seem to corroborate the proposed model.

Analytical Modeling of a New Compliant Microsystem for Atherectomy Operations.

This work offers a new alternative tool for atherectomy operations, with the purpose of minimizing the risks for the patients and maximizing the number of clinical cases for which the system can be used, thanks to the possibility of scaling its size down to lumen reduced to a few tenths of mm. The development of this microsystem has presented a certain theoretical work during the kinematic synthesis and the design stages. In the first stage a new multi-loop mechanism with a Stephenson's kinematic chain (KC) was found and then adopted as the so-called pseudo-rigid body mechanism (PRBM). Analytical modeling was necessary to verify the synthesis requirements. In the second stage, the joint replacement method was applied to the PRBM to obtain a corresponding and equivalent compliant mechanism with lumped compliance. The latter presents two loops and six elastic joints and so the evaluation of the microsystem mechanical advantage (MA) had to be calculated by taking into account the accumulation of elastic energy in the elastic joints. Hence, a new closed form expression of the microsystem MA was found with a method that presents some new aspects in the approach. The results obtained with Finite Element Analysis (FEA) were compared to those obtained with the analytical model. Finally, it is worth noting that a microsystem prototype can be fabricated by using MEMS Technology classical methods, while the microsystem packaging could be a further development for the present investigation.

Occipital Interhemispheric Transtentorial Approach for a Pineal Region Meningioma with Pseudobulbar Palsy.

Meningiomas represent 8%-10% of all pineal region (PR) tumors. When they arise from the falx, tentorium, or tentorial incisura, they are not always considered a true PR tumor, as they do not originate from it but instead only grow toward the region. The true meningioma of PR must be originated from the arachnoid envelope of the pineal gland or from the 2 leaflets of the velum interpositum. In both conditions there are no dural attachments.1,2 Occipital interhemispheric transtentorial and supracerebellar infratentorial are the 2 main approaches for tumors within this region. Aside from the surgeon's preference, the position of the venous system and the direction of the tumor growth guide the approach choice. Endoscope assistance can help reach areas unable to be visualized under the microscope.3-5 We report the case of a 37-year-old female with a large PR meningioma (velum interpositum) presenting with intense dysphagia, dysphonia, and bilateral tongue palsy. Given the affected bilateral upper motor tracts associated with bulbar symptoms, a diagnosis of pseudobulbar palsy was considered.6,7 Preoperative imaging also showed compression of the deep venous system. The patient underwent a total resection of the tumor via an occipital interhemispheric transtentorial approach and exhibited a dramatic recovery of neurologic symptoms after the surgery (Video 1). Postoperative venogram showed restoration of the usual deep venous system pattern, which may be associated with significant neurologic improvement. Careful management of the deep veins is mandatory during the resection of PR meningiomas. The venous system improvement after the surgery may be associated with the dramatic recovery seen in this unique case. The patient consented to publication of her images.

Microscopic resection of a giant epidermoid tumor of the pineal region via supracerebellar infra and transtentorial approach with endoscope assistance.

The authors present a case of a 22-year-old male who developed hydrocephalus symptoms related to a giant epidermoid tumor at the pineal region. The surgical approach and technique for a large epidermoid tumor in this area are extensively discussed. A paramedian contralateral supracerebellar infratentorial and transtentorial approach was performed, with the patient in a semisitting position. The tumor was removed using a microscopic technique, and endoscope assistance was used in order to reach the areas unable to be visualized under the microscope. The patient was neurologically intact at his 2-year follow-up, and postoperative MRI showed a significant decrease in the tumoral volume. The video can be found here: https://stream.cadmore.media/r10.3171/2021.4.FOCVID2128.

New MEMS Tweezers for the Viscoelastic Characterization of Soft Materials at the Microscale.

As many studies show, there is a relation between the tissue's mechanical characteristics and some specific diseases. Knowing this relationship would help early diagnosis or microsurgery. In this paper, a new method for measuring the viscoelastic properties of soft materials at the microscale is proposed. This approach is based on the adoption of a microsystem whose mechanical structure can be reduced to a compliant four bar linkage where the connecting rod is substituted by the tissue sample. A procedure to identify both stiffness and damping coefficients of the tissue is then applied to the developed hardware. Particularly, stiffness is calculated solving the static equations of the mechanism in a desired configuration, while the damping coefficient is inferred from the dynamic equations, which are written under the hypothesis that the sample tissue is excited by a variable compression force characterized by a suitable wave form. The whole procedure is implemented by making use of a control system.

Development of an experimental model of neurocysticercosis-induced hydrocephalus. Pilot study

ABSTRACT PURPOSE: To develop an experimental model of neurocysticercosis-induced hydrocephalus METHODS: There were used 17 rats. Ten animals were inoculated with Taenia crassiceps cysts into the subarachnoid. Five animals were injected with 0.1ml of 25% kaolin (a standard solution for the development of experimental hydrocephalus) and two animals were injected with saline. Magnetic resonance imaging (MRI) was used to evaluate enlargement of the ventricles after one or three months of inoculation. Volumetric study was used to quantify the ventricle enlargement. RESULTS: Seven of the 10 animals in the cyst group developed hydrocephalus, two of them within one month and five within three months after inoculation. Three of the five animals in the kaolin group had hydrocephalus and none in the saline group. Ventricle volumes were significantly higher in the 3-months MRI cyst subgroup than in the 1-month cyst subgroup. Differences between cyst subgroups and kaolin group did not reach statistical significance. CONCLUSION: The developed model may reproduce the human condition of neurocysticercosis-related hydrocephalus, which exhibits a slowly progressive chronic course.

Development of an experimental model of neurocysticercosis-induced hydrocephalus. Pilot study.

PURPOSE: To develop an experimental model of neurocysticercosis-induced hydrocephalus METHODS: There were used 17 rats. Ten animals were inoculated with Taenia crassiceps cysts into the subarachnoid. Five animals were injected with 0. ml of 25% kaolin (a standard solution for the development of experimental hydrocephalus) and two animals were injected with saline. Magnetic resonance imaging (MRI) was used to evaluate enlargement of the ventricles after one or three months of inoculation. Volumetric study was used to quantify the ventricle enlargement. RESULTS: Seven of the 10 animals in the cyst group developed hydrocephalus, two of them within one month and five within three months after inoculation. Three of the five animals in the kaolin group had hydrocephalus and none in the saline group. Ventricle volumes were significantly higher in the 3-months MRI cyst subgroup than in the 1-month cyst subgroup. Differences between cyst subgroups and kaolin group did not reach statistical significance. CONCLUSION: The developed model may reproduce the human condition of neurocysticercosis-related hydrocephalus, which exhibits a slowly progressive chronic course.