Impact of Shunt Placement on CSF Dynamics.

BACKGROUND: CSF dynamics are disturbed in chronic hydrocephalus (NPH). We hypothesise that these alterations reflect a disturbance of intracranial compliance. The aim of our study is to investigate the variations in intracranial hydrodynamics in NPH after ventricular shunt surgery. PATIENTS AND METHOD: We included 14 patients with definite NPH. All patients improved after ventriculoperitoneal shunting. The patients underwent an analysis of intracranial haemodynamics by phase-contrast MRI (pcMRI) preoperatively, at 6 months postoperatively, and at 1 year postoperatively. We analysed the dynamics of intraventricular CSF at the level of the aqueduct of Sylvius (SVAQU) and CSF at the level of the high cervical subarachnoid spaces (SVCERV). We calculated the ratio between SVAQU and SVCERV, called CSFRATIO, which reflects the participation of intraventricular pulsatility in overall intracranial CSF pulsatility. RESULTS: SVAQU significantly (p = 0.003) decreased from 240 ± 114 µL/cc to 214 ± 157 µL/cc 6 months after shunt placement. Six months after shunt placement, SVCERV significantly (p = 0.007) decreased from 627 ± 229 µL/cc to 557 ± 234 µL/cc. Twelve months after shunt placement, SVCERV continued to significantly (p = 0.001) decrease to 496 ± 234 µL/cc. CSFRATIO was not changed by surgery. CONCLUSIONS: CSF dynamics are altered by shunt placement and might be a useful marker of the shunt's effectiveness-especially if pressure values start to rise again. The detection of changes in CSF dynamics would require a reference postoperative pcMRI measurement for each patient.

Insights on the Hydrodynamics of Chiari Malformation.

BACKGROUND: We propose that the appearance of a ptosis of the cerebellar tonsils and syringomyelia is linked to its own hemohydrodynamic mechanisms. We aimed to quantify cerebrospinal fluid (CSF) and cerebral blood flow to highlight how neurofluid is affected by Chiari malformations type 1(CMI) and its surgery. METHODS: We retrospectively included 21 adult patients with CMI who underwent pre- and postoperative phase contrast MRI (PCMRI) during the period from 2001 to 2017. We analyzed intraventricular CSF, subarachnoid spaces CSF, blood, and tonsils pulsatilities. RESULTS: In preoperative period, jugular venous drainage seems to be less preponderant in patients with syringomyelia than other patients (venous correction factor: 1.49 ± 0.4 vs. 1.19 ± 0.1, p = 0.05). After surgery, tonsils pulsatility decreased significantly (323 ± 175 µL/cardiac cycle (CC) vs. 194 ± 130 µL/CC, p = 0.008) and subarachnoid CSF pulsatility at the foramen magnum increased significantly (201 ± 124 µL/CC vs. 363 ± 231 µL/CC, p = 0.02). After surgery, we found a decrease in venous flow amplitude (5578 ± 2469 mm3/s vs. 4576 ± 2084 mm3/s, p = 0.008) and venous correction factor (1.98 ± 0.3 vs. 1.20 ± 0.3 mm3/s, p = 0.004). CONCLUSIONS: Phase-contrast MRI could be a useful additional tool for postoperative evaluation and follow-up, and is complementary to morphological imaging.

Diffusion and Flow MR Imaging to Investigate Hydrocephalus Patients Before and After Endoscopic Third Ventriculostomy.

INTRODUCTION: In patients with noncommunicating hydrocephalus, dilation of the ventricles stresses white matter fibers and alters the cerebral blood flow (CBF) and cerebrospinal fluid (CSF) dynamics. The purpose of this work was to investigate, non-invasively, how endoscopic third ventriculostomy (ETV) impacts white matter, CSF oscillations, and CBF. METHODS: Eleven patients presenting with chronic headaches and noncommunicating hydrocephalus due to aqueductal stenosis were treated by ETV. Phase Contrast-MRI (PCMRI) and Diffusion Tensor Imaging (DTI) were performed before and after surgery to evaluate CSF and CBF as well as white matter stresses in the Corpus Callosum (CC) and Corona Radiata (CR). ETV success was confirmed by quantification of the CSF oscillations through the aperture in the third ventricle. RESULTS: All patients improved after surgery. CSF stroke volume was five times greater than normal ventricular stroke volume. Decrease in cervical CSF oscillations and increase in CBF were observed after ETV. In CR, fiber anisotropy decreased, while water diffusion increased. In CC, anisotropy did not vary, while water diffusion also increased. CONCLUSION: Even if static ICP typically do not increase, CSF and blood flow are impacted. PCMRI and DTI can provide useful information to help neurosurgeons select patients with good chance to improve after ETV.

Dosimetric and volumetric outcomes of combining cyst puncture through an Ommaya reservoir with index-optimized hypofractionated stereotactic radiotherapy in the treatment of craniopharyngioma.

Large cystic craniopharyngioma management combining cyst puncture through an Ommaya reservoir with hypofractionated stereotactic radiotherapy was evaluated. The planning optimization was focused on the gradient and selectivity. Punctured and filled cyst treatment plans were compared with a retrospective analysis of volumetric and functional outcomes.

Robot-assisted intravertebral augmentation corrects local kyphosis more effectively than a conventional fluoroscopy-guided technique.

OBJECTIVEIntravertebral augmentation (IVA) is a reliable minimally invasive technique for treating Magerl type A vertebral body fractures. However, poor correction of kyphotic angulation, the risk of cement leakage, and significant exposure to radiation (for the surgeon, the operating room staff, and the patient) remain significant issues. The authors conducted a study to assess the value of robot-assisted IVA (RA-IVA) for thoracolumbar vertebral body fractures.METHODSThe authors performed a retrospective, single-center study of patients who had undergone RA-IVA or conventional fluoroscopy-guided IVA (F-IVA) for thoracolumbar vertebral body fractures. Installation and operating times, guidance accuracy, residual local kyphosis, degree of restoration of vertebral body height, incidence of cement leakage, rate of morbidity, length of hospital stay, and radiation-related data were recorded.RESULTSData obtained in 30 patients who underwent RA-IVA were compared with those obtained in 30 patients who underwent F-IVA during the same period (the surgical indications were identical, but the surgeons were different). The mean ± SD installation time in the RA-IVA group (24 ± 7.5 minutes) was significantly shorter (p = 0.005) than that in the F-IVA group (26 ± 8 minutes). The mean operating time for the RA-IVA group (52 ± 11 minutes) was significantly longer (p = 0.026) than that for the F-IVA group (30 ± 11 minutes). All RA-IVAs and F-IVAs were Ravi's scale grade A (no pedicle breach). The mean degree of residual local kyphosis (4.7° ± 3.15°) and the percentage of vertebral body height restoration (63.6% ± 21.4%) were significantly better after RA-IVA than after F-IVA (8.4° ± 5.4° and 30% ± 34%, respectively). The incidence of cement leakage was significantly lower in the RA-IVA group (p < 0.05). The mean length of hospital stay after surgery was 3.2 days for both groups. No surgery-related complications occurred in either group. With RA-IVA, the mean radiation exposure was 438 ± 147 mGy × cm for the patient and 30 ± 17 mGy for the surgeon.CONCLUSIONSRA-IVA provided better vertebral body fracture correction than the conventional F-IVA. However, RA-IVA requires more time than F-IVA.

Robot-Assisted Radiofrequency Ablation of a Sacral S1-S2 Aggressive Hemangioma.

BACKGROUND: Aggressive vertebral hemangiomas are rare tumors of the spine. The treatment management strategy usually consists of vertebroplasty, radiation therapy, or, in rare cases of surgical strategy. CASE DESCRIPTION: We present a case of a bulging sacral S1-S2 hemangioma in the spinal canal that could not be managed in the usual manner. CONCLUSION: Here we demonstrate the usefulness of radiofrequency ablation technique as an alternative treatment, as well as robotic assistance for optimal placement of the ablation probe within the lesion.

Cerebrospinal Fluid and Cerebral Blood Flows in Idiopathic Intracranial Hypertension.

OBJECTIVES: Cerebrospinal fluid (CSF) and blood flows have a strong relationship during a cardiac cycle. Idiopathic intracranial hypertension (IIH) is a pathology that seems to present hemodynamic and hydrodynamic disturbance. The aim of this study was to establish CSF and blood interaction in IIH. MATERIAL AND METHODS: We retrospectively studied cerebral hydrodynamic and hemodynamic flows by phase-contrast MRI (PCMRI) in 13 IIH subjects (according Dandy's criteria) and 16 controls. We analyzed arterial peak flow, pulsatility index, and resistive index in arterial and venous compartments (PFart, PIart, RIart, PFvein, PIvein, RIvein) and measured arteriovenous and CSF peak flow and stroke volume (PFav, SVVASC, PFCSF, SVCSF). RESULTS: We found no significant difference between IIH and control groups in arterial and venous parameters. Arteriovenous flow analysis showed higher PFav and SVVASC in the IIH group than in the control group (respectively 369 ± 27 mL/min and 286 ± 47 mL/min, p = 0.02; and 1085 ± 265 µL/cardiac cycle and 801 ± 226 µL/cardiac cycle, p = 0.007). PFCSF and SVCSF were higher in the IIH group than in the control group (respectively 206 ± 50 mL/min and 126.6 ± 24.8 mL/min, p = 0.04; and 570 ± 190 µL/cardiac cycle and 430 ± 100 µL/cardiac cycle, p = 0.0007). CONCLUSION: Although no significant change was found in arterial and venous flows, we showed that a small phase shift of venous outflow might cause an increase in the arteriovenous pulsatility and an increasing brain expansion during the cardiac cycle. This arteriovenous flow increase would result in an increase of CSF flushing through the foramen magnum and an increased ICP.

Evaluation of Screw Placement Accuracy in Circumferential Lumbar Arthrodesis Using Robotic Assistance and Intraoperative Flat-Panel Computed Tomography.

BACKGROUND: Neuronavigation has become a common means of placing pedicle screws in vertebral arthrodesis, because it reduces the incidence of complications related to poor screw positioning. OBJECTIVE: The To evaluate the accuracy of pedicle screw placement during lumbar arthrodesis performed with the new ROSA Spine robot and intraoperative flat-panel computed tomography (fpCT) guidance. METHODS: We performed a descriptive, observational, retrospective, single-center study of patients having undergone transforaminal lumbar interbody fusion (TLIF) for degenerative pathologies with the ROSA Spine robot and intraoperative fpCT guidance. The primary endpoint was the presence or absence of pedicle wall breach, as assessed from the fpCT scan. Screw placement was graded according to Ravi's classification. RESULTS: Twenty-five patients were operated on between November 2014 and July 2016; 21 underwent minimally invasive TLIF, and 4 underwent open TLIF. The mean ± standard deviation operating time was 241 ± 49.8 minutes. Of the 110 screws placed, 101 (91.8%) were completely within the pedicle (Ravi grade A), 5 (4.5%) had a pedicle wall breach <2 mm (grade B), 2 (1.8%) had a pedicle wall breach of 2-4 mm (grade C), and 2 had pedicle wall breach >4 mm (grade D) (1.8%). One screw (a grade D) was replaced during surgery. None of the breaches were symptomatic. CONCLUSIONS: When coupled with fpCT, the ROSA Spine robot is a reliable, accurate means of performing lumbar pedicle screwing.

Interactions between Flow Oscillations and Biochemical Parameters in the Cerebrospinal Fluid.

The equilibrium between the ventricular and lumbar cerebrospinal fluid (CSF) compartments may be disturbed (in terms of flow and biochemistry) in patients with chronic hydrocephalus (CH). Using flow magnetic resonance imaging (MRI) and CSF assays, we sought to determine whether changes in CSF were associated with biochemical alterations. Nine elderly patients with CH underwent phase-contrast MRI. An index of CSF dynamics (Idyn) was defined as the product of the lumbar and ventricular CSF flows. During surgery, samples of CSF were collected from the lumbar and ventricular compartments and assayed for chloride, glucose and total protein. The lumbar/ventricular (L/V) ratio was calculated for each analyte. The ratio between measured and expected levels (Ibioch) was calculated for each analyte and compared with Idyn. Idyn varied from 0 to 100.10(3)µl(2).s(2). In contrast to the L/V ratios for chloride and glucose, the L/V ratio for total protein varied markedly from one patient to another (mean ± standard deviation (SD): 2.63 ± 1.24). The Ibioch for total protein was strongly correlated with the corresponding Idyn (Spearman's R: 0.98; p < 5 × 10(-5)).We observed correlated alterations in CSF flow and biochemical parameters in patients with CH. Our findings also highlight the value of dynamic flow analysis in the interpretation of data on CSF biochemistry.

Frameless robotic stereotactic biopsies: a consecutive series of 100 cases.

OBJECT: Stereotactic biopsy procedures are an everyday part of neurosurgery. The procedure provides an accurate histological diagnosis with the least possible morbidity. Robotic stereotactic biopsy needs to be an accurate, safe, frameless, and rapid technique. This article reports the clinical results of a series of 100 frameless robotic biopsies using a Medtech ROSA device. METHODS: The authors retrospectively analyzed their first 100 frameless stereotactic biopsies performed with the robotic ROSA device: 84 biopsies were performed by frameless robotic surface registration, 7 were performed by robotic bone fiducial marker registration, and 9 were performed by scalp fiducial marker registration. Intraoperative flat-panel CT scanning was performed concomitantly in 25 cases. The operative details of the robotic biopsies, the diagnostic yield, and mortality and morbidity data observed in this series are reported. RESULTS: A histological diagnosis was established in 97 patients. No deaths or permanent morbidity related to surgery were observed. Six patients experienced transient neurological worsening. Six cases of bleeding within the lesion or along the biopsy trajectory were observed on postoperative CT scans but were associated with transient clinical symptoms in only 2 cases. Stereotactic surgery was performed with patients in the supine position in 93 cases and in the prone position in 7 cases. The use of fiducial markers was reserved for posterior fossa biopsy via a transcerebellar approach, via an occipital approach, or for pediatric biopsy. CONCLUSIONS: ROSA frameless stereotactic biopsies appear to be accurate and safe robotized frameless procedures.

Effect of surgery on periventricular white matter in normal pressure hydrocephalus patients: comparison of two methods of DTI analysis.

BACKGROUND: Diffusion tensor imaging (DTI) is a useful tool for assessing changes that occur in microstructures. We have developed a novel method for region of interest (ROI) delineation in the assessment of DTI parameters in patients with normal pressure hydrocephalus (NPH). PURPOSE: To compare the standard method and our novel method in an evaluation of the impact of surgery on periventricular white matter in patients with NPH. MATERIAL AND METHODS: Ten patients with NPH underwent 3T magnetic resonance imaging (MRI; including 12-direction DTI sequences) before and after surgery. We recorded diffusion parameters (λi, the fractional anisotropy [FA], the apparent diffusion coefficient, and Dr) in the internal capsule (IC) and the body of the corpus callosum (BCC). Using the standard delineation technique, regions of interest (ROIs) were positioned according to anatomical and functional considerations and then filled with several sub-ROIs. The ROIs delineated with our novel technique (extracted as the six sub-ROIs with the lowest standard deviation for the FA) were arranged in two rows (medial and lateral), from the ventricle to the brain surface. RESULTS: The within-ROI homogeneity was higher with the novel method than with the conventional method (P<10(-4)). When the conventional delineation method was applied to the IC data, only λ2 was found to be significantly greater after surgery; in contrast, application of our novel method evidenced a significant decrease in FA and λ1 and a significant increase in λ2 (P<0.05). Both before and after surgery, the FA in the medial row of ROIs was greater than the FA in the lateral row (P<0.01). In the BCC, only λ2 and Dr varied significantly (when evaluated with the novel method). CONCLUSION: Our results show that use of a novel method of DTI data analysis may be more sensitive to local changes induced by surgical procedures. Furthermore, this novel method was able to detect the transmantle pressure gradient related to the regional stress distribution.