Dural Opening Research Articles

Ectopic cerebellar tissue in the occipital bone: a case report

BackgroundEctopic cerebellar tissue located distantly from the normal cerebellum is very rare, and its pathophysiology remains to be elucidated.Case presentationWe report an extremely rare case of intraosseous ectopic cerebellum detected incidentally at suboccipital craniotomy in a 46-year-old Japanese woman with hemifacial spasm. She had a small bone defect in the occipital bone, which contained a tiny area of soft tissue surrounded by cerebrospinal fluid connecting to the normal subarachnoid space through a dural opening. Histopathology demonstrated cerebellar cortex tissue consisting of molecular and granular cell layers.ConclusionsThis is the first report of glioneuronal ectopia within the skull bone separated from normal brain tissue, and it is important to distinguish this entity from other osteolytic lesions.

Transorbital endoscopic approach for exposure of the sylvian fissure, middle cerebral artery and crural cistern: an anatomical study.

The availability of minimal access instrumentation and endoscopic visualization has revolutionized the field of minimally invasive skull base surgery. The transorbital endoscopic approach using an eyelid incision has been proposed as a new minimally invasive technique for the treatment of skull base pathology, mostly extradural tumors. Our study aims to evaluate the anatomical aspects and potential role of the transorbital endoscopic approach for exposure of the sylvian fissure, middle cerebral artery and crural cistern. An anatomical dissection was performed in four freshly injected cadaver heads (8 orbits) using 0- and 30-degree endoscopes. First, an endoscopic endonasal medial orbital decompression was done to facilitate medial retraction of the orbit. An endoscopic transorbital approach through an eyelid incision, with drilling of the posterior wall of the orbit and lesser sphenoidal wing, was then performed to expose the sylvian fissure and crural cisterns. A stepwise anatomical description of the approach and visualized anatomy is detailed. A superior eyelid incision followed by orbital retraction provided a surgical window of approximately 1.2cm (range 1.0-1.5cm) for endoscopic transorbital dissection. The superior (SOF) and inferior (IOF) orbital fissures represent the medial limits of the approach and are identified in the initial part of the procedure. Drilling of the orbital roof (lateral and superior to the SOF), greater sphenoidal wing (lateral to the SOF and IOF) and lesser sphenoidal wing exposed the anterior and middle fossa dura. A square-shaped dural opening provided visualization of the posterior orbital gyri, sylvian fissure and temporal pole. Intradural dissection allowed exposure of the sphenoidal portion of the sylvian fissure, M1, MCA bifurcation and M2 branches and lenticulostriate perforators. Dissection of the medial aspect of the sylvian and carotid cisterns with a 30-degree endoscope allowed exposure of the mesial temporal lobe and crural cistern. The transorbital endoscopic approach allows successful exposure of the sphenoidal portion of the sylvian fissure and M1 and M2 segments of the middle cerebral artery. Angled endoscopes may provide visualization of the mesial temporal lobe and crural cistern. Although our anatomical study demonstrates the feasibility of intradural dissection and closure via an endoscopic transorbital approach, further studies are necessary to evaluate its role in the clinical scenario.

Impact of direct epispinal stimulation on bladder and bowel functions in pigs: A feasibility study.

This study assesses the potential of epispinal (subdural) stimulation application in the treatment of urinary and bowel neurological disorders. Acute experiments were performed on a large animal model - the domestic pig - to develop a new methodology facilitating future results and technology transfers to human. After rectal and bladder catheterization, four Landrace pigs (45-50 kg) underwent spinal cord surgery - that is, lumbosacral incision, laminectomy [L4-S4], dural opening and microsurgical arachnoid dissection. Three successive electrical stimulation sessions were carried out: 1) nerve roots stimulation, 2) epispinal stimulation with a matrix electrode, 3) epispinal stimulation with a small diameter needle electrode. Changes in rectal and bladder pressures were monitored throughout the various procedures to identify spinal areas inducing responses while evaluating the influence of electrode contacts size in the measured responses amplitudes. An interesting area was identified in the upper portion of the spinal myelomeres (ie, spinal cord segment delimited by two successive pairs of spinal roots) directly adjoining root with best pressures (either rectal or vesical). Significant responses (up to 40 cmH2 O) were also obtained with a needle electrode. Furthermore, bowel evacuation was triggered in one of the animals. Despite the use of smaller electrode contacts, no detrusor or rectum selective responses were observed in none of the sessions. This study showed, for the first time, that epispinal stimulation causes significant detrusor and rectal responses in pigs and allows considering further studies with the objective of treating urinary and rectal disorders in spinal cord injury patients.

Supracerebellar Infratentorial Paramedian Approach in Helsinki Neurosurgery: Cornerstones of a Safe and Effective Route to the Pineal Region.

The supracerebellar infratentorial (SCIT) paramedian approach in sitting position represents one of the most used surgical routes for dealing with pineal region lesions. The purpose of this study is to determine the cornerstones to perform this approach in a simple, safe, and effective way, so that it could be easily reproduced in other neurosurgical centers, particularly in those with modest resources. We reviewed and analyzed the surgical videos of 24 pineal region lesions that were operated on through an SCIT approach between June 2012 and October 2015. The SCIT approach may be divided into 3 main steps: 1) skin-muscle incision; 2) craniotomy; and 3) dura opening and access to the pineal region. Complete lesion removal was accomplished in 23 cases, and subtotal removal was accomplished in 1 case. The pineal region was effectively and safely reached through the SCIT approach in the sitting position with a mean time of 14 minutes, using a basic set of microsurgical instruments. Cornerstones and potential delaying events were carefully recorded for each of the 3 main steps of the approach. Moreover, we present in a short video a step-by-step guide to perform the SCIT approach in a fast and safe way. A correct application of microsurgical principles may allow to safely and rapidly perform the SCIT approach, therefore offering an effective and relatively atraumatic route for dealing with pineal region lesions.

How I do it: surgical ligation of craniocervical junction dural AV fistulas.

Dural arteriovenous fistulas (DAVFs) of the craniocervical junction are uncommon vascular lesions, which often require surgical treatment even in the endovascular era. Most commonly, the fistula is placed laterally, and surgical ligation is performed through a lateral suboccipital craniotomy. After dural opening, the area is inspected, and the arterialized vein is identified emerging from the dura, often adjacent to the entry point of the vertebral artery, and ligated. A far lateral craniotomy is the authors' preferred surgical approach for accessing and treating dural arteriovenous fistulas of the craniocervical junction that cannot be reached endovascularly.

Effects of colloid pre-loading on thromboelastography during elective intracranial tumor surgery in pediatric patients: hydroxyethyl starch 130/0.4 versus 5% human albumin

BackgroundVolume replacement therapy with colloid is still worth studying in major pediatric surgery with potential risk of bleeding. This study assessed the effects of 6% hydroxyethyl starch (HES) 130/0.4 and 5% Human Albumin (HA) on coagulation tested by thromboelastography (TEG) during elective intracranial tumor surgery in pediatric patients.MethodsIn this randomized controlled trial, 60 patients undergoing intracranial tumor resection under general anesthesia were assigned to HES and HA groups (n = 30), and administered preloads of 20 mL · kg−1 HES 130/0.4 and 5% HA, respectively, prior to dura opening. Primary outcomes were perioperative thromboelastography findings, and hemodynamic and hematological parameters. Blood transfusion, perioperative fluid balance, intracranial pressure, mortality, intensive care unit stay, and hospital stay were also assessed.ResultsTEG parameters did not differ after preloading compared to baseline values in either group, except for a decrease in maximum amplitude immediately after infusion (HES group, 57.6 ± 6.0 mm vs. 50.9 ± 9.2 mm; HA group, 60.1 ± 7.9 mm vs. 56.6 ± 7.1 mm; p < 0.01), which was restored to preoperative levels 1 h after fluid infusion. Total perioperative fluid balance, blood loss or transfusion, intracranial pressure, and hematological and hemodynamic variables were similar between both groups (p > 0.05). Mortality, length of hospital stay, and clinical complications were similar between both groups.ConclusionThese findings suggest that HES and HA might have no significant differences regarding coagulation as assessed by TEG during pediatric intracranial tumor surgery with 20 ml/kg volume pre-loading, which can maintain stable hemodynamics and may represent a new avenue for volume therapy during brain tumor resection in pediatrics.Trial registrationChiCTR-IPR-16009333, retrospectively registered October 8, 2016

Optimization of Microelectrode Recording in Deep Brain Stimulation Surgery Using Intraoperative Computed Tomography.

Microelectrode recording (MER) is used to confirm targeting accuracy during deep brain stimulation (DBS) surgery. We describe a technique using intraoperative computed tomography (CT) extrapolation (iCTE) to predetermine and adjust the trajectory of the guide tube to improve microelectrode targeting accuracy. We hypothesized that this technique would decrease the number of MER tracks and operative time, while increasing the recorded length of the subthalamic nucleus (STN). Thirty-nine patients with Parkinson's disease who underwent STN DBS before the iCTE method were compared with 33 patients undergoing STN DBS using iCTE. Before dural opening, a guide tube was inserted and rested on dura. Intraoperative computed tomography (iCT) was performed, and a trajectory was created along the guide tube and extrapolated to the target using targeting software. If necessary, headstage adjustments were made to correct for error. The guide tube was inserted, and MER was performed. iCT was performed with the microelectrode tip at the target. Coordinates were compared with planned/adjusted track coordinates. Radial error between the MER track and the planned/adjusted track was calculated. Cases before and after implementation of iCTE were compared to determine the impact of iCTE on operative time, number of MER tracks and recorded STN length. The use of iCTE reduced the average radial MER track error from 1.90 ± 0.12 mm (n= 54) to 0.84 ± 0.09 mm (n= 49) (P < 0.001) while reducing the operative time for bilateral lead placement from 272 ± 9 minutes (n= 30) to 233 ± 10 minutes (n= 24) (P < 0.001). The average MER tracks per hemisphere was reduced from 2.24 ± 0.13 mm (n= 66) to 1.75 ± 0.09 mm (n= 63) (P<0.001), whereas the percentage of hemispheres requiring a single MER track for localization increased from 29% (n= 66) to 43% (n= 63). The average length of recorded STN increased from 4.01 ± 0.3 mm (n= 64) to 4.75 ± 0.28 mm (n= 56) (P < 0.05). iCTE improves microelectrode accuracy and increases the first-pass recorded length of STN, while reducing operative time. Further studies are needed to determine whether this technique leads to less morbidity and improved clinical outcomes.

3D intra-operative ultrasound and MR image guidance: pursuing an ultrasound-based management of brainshift to enhance neuronavigation.

Brainshift is still a major issue in neuronavigation. Incorporating intra-operative ultrasound (iUS) with advanced registration algorithms within the surgical workflow is regarded as a promising approach for a better understanding and management of brainshift. This work is intended to (1) provide three-dimensional (3D) ultrasound reconstructions specifically for brain imaging in order to detect brainshift observed intra-operatively, (2) evaluate a novel iterative intra-operative ultrasound-based deformation correction framework, and (3) validate the performance of the proposed image-registration-based deformation estimation in a clinical environment. Eight patients with brain tumors undergoing surgical resection are enrolled in this study. For each patient, a 3D freehand iUS system is employed in combination with an intra-operative navigation (iNav) system, and intra-operative ultrasound data are acquired at three timepoints during surgery. On this foundation, we present a novel resolution-preserving 3D ultrasound reconstruction, as well as a framework to detect brainshift through iterative registration of iUS images. To validate the system, the target registration error (TRE) is evaluated for each patient, and both rigid and elastic registration algorithms are analyzed. The mean TRE based on 3D-iUS improves significantly using the proposed brainshift compensation compared to neuronavigation (iNav) before (2.7 vs. 5.9mm; [Formula: see text]) and after dural opening (4.2 vs. 6.2mm, [Formula: see text]), but not after resection (6.7 vs. 7.5mm; [Formula: see text]). iUS depicts a significant ([Formula: see text]) dynamic spatial brainshift throughout the three timepoints. Accuracy of registration can be improved through rigid and elastic registrations by 29.2 and 33.3%, respectively, after dural opening, and by 5.2 and 0.4%, after resection. 3D-iUS systems can improve the detection of brainshift and significantly increase the accuracy of the navigation in a real scenario. 3D-iUS can thus be regarded as a robust, reliable, and feasible technology to enhance neuronavigation.

Minimally invasive medial supraorbital, combined subfrontal-interhemispheric approach to the anterior communicating artery complex-a cadaveric study.

In selected cases, microsurgical clipping remains a valuable treatment alternative to endovascular occlusion of anterior communicating artery (AComA) aneurysms. Their clipping is challenging and carries a risk of postsurgical cognitive impairment. We evaluate the microsurgical anatomy of a new, minimally invasive combined interhemispheric-subfrontal approach to the AComA complex via a medial supraorbital craniotomy. In this descriptive anatomic study, four alcohol-embedded, silicon-injected human cadaver heads were used. In each of the two cadavers, the AComA complex was approached from either the right or left side. An operating microscope and standard microsurgical instruments were used. After a medial eyebrow incision, a medial supraorbital minicraniotomy was performed. The frontal sinus was opened and cranialized. Following the dural opening, a subfrontal arachnoid dissection was performed to identify the optico-carotid complex. By following the A1 segment, a low-lying AComA complex could be visualized. Shifting the corridor towards the midline enabled an interhemispheric dissection. This dissection resulted in a wide superior-inferior corridor. Higher-lying AComA complexes could also be visualized. The achieved exposure of the AComA complex would allow safe dissection and clipping of low- and high-lying AComA aneurysms, with minimal retraction and preservation of the surrounding anatomical structures, in particular the perforators. We demonstrate the anatomy of a novel approach for surgical clipping of AComA aneurysms. Our study suggests that this approach provides good exposure without concomitant structural and vascular injury and thus might reduce the risk of procedure-related morbidity.

Preoperative Magnetic Resonance and Intraoperative Computed Tomography Fusion for Real-Time Neuronavigation in Intramedullary Lesion Surgery

Image-guided surgery techniques in spinal surgery are usually based upon fluoroscopy or computed tomography (CT) scan, which allow for a real-time navigation of bony structures, though not of neural structures and soft tissue remains. To verify the effectiveness and efficacy of a novel technique of imaging merging between preoperative magnetic resonance imaging (MRI) and intraoperative CT scan during removal of intramedullary lesions. Ten consecutive patients were treated for intramedullary lesions using a navigation system aid. Preoperative contrast-enhanced MRI was merged in the navigation software, with an intraoperative CT acquisition, performed using the O-arm TM system (Medtronic Sofamor Danek, Minneapolis, Minnesota). Dosimetric and timing data were also acquired for each patient. The fusion process was achieved in all cases and was uneventful. The merged imaging information was useful in all cases for defining the exact area of laminectomy, dural opening, and the eventual extension of cordotomy, without requiring exposition corrections. The radiation dose for the patients was 0.78 mSv. Using the authors' protocol, it was possible to merge a preoperative MRI with navigation based on intraoperative CT scanning in all cases. Information gained with this technique was useful during the different surgical steps. However, there were some drawbacks, such as the merging process, which still remains partially manual. In this initial experience, MRI and CT merging and its feasibility were tested, and we appreciated its safety, precision, and ease.

Combined intra-extradural approach for posterolateral thoracic disk herniations. Preliminary study and technical note.

We performed a combined extra-intra dural approach in two preliminary cases. We performed bilateral laminectomy of adjacent vertebrae and unilateral partial medial arthrectomy of the involved segment. After a lateral extradural diskectomy, we, subsequently, performed a median longitudinal durotomy. The conflict between disk herniation and spinal cord was identified. We removed disk herniation moving disk fragments in the extradural compartment without ventral spinal dura opening. We solved spinal cord compression in both cases. Postoperative neurological improvement was observed in both cases. No major complications were observed. Our preliminary results are probably insufficient to establish surgical criteria but offer another surgical perspective to especially treat patients with contraindication to anterior approaches.

Improving the accuracy of microelectrode recording in deep brain stimulation surgery with intraoperative CT

Microelectrode recording (MER) is used to confirm electrophysiological signals within intended anatomic targets during deep brain stimulation (DBS) surgery. We describe a novel technique called intraoperative CT-guided extrapolation (iCTE) to predict the intended microelectrode trajectory and, if necessary, make corrections in real-time before dural opening. Prior to dural opening, a guide tube was inserted through the headstage and rested on dura. Intraoperative CT (iCT) was obtained, and a trajectory was extrapolated along the path of the guide tube to target depth using targeting software. The coordinates were recorded and compared to initial plan coordinates. If needed, adjustments were made using the headstage to correct for error. The guide tube was then inserted and MER ensued. At target, iCT was performed and microelectrode tip coordinates were compared with planned/adjusted track coordinates. Radial error between MER track and planned/adjusted track was calculated. For comparison, MER track error prior to the iCTE technique was assessed retrospectively in patients who underwent MER using iCT, whereby iCT was performed following completion of the first MER track. Forty-seven MER tracks were analyzed prior to iCTE (pre-iCTE), and 90 tracks were performed using the iCTE technique. There was no difference between radial error of pre-iCTE MER track and planned trajectory (2.1±0.12mm) compared to iCTE predicted trajectory and planned trajectory (1.76±0.13mm, p>0.05). iCTE was used to make trajectory adjustments which reduced radial error between the newly corrected and final microelectrode tip coordinates to 0.84±0.08mm (p<0.001). Inter-rater reliability was also tested using a second blinded measurement reviewer which showed no difference between predicted and planned MER track error (p=0.53). iCTE can predict and reduce trajectory error for microelectrode placement compared with the traditional use of iCT post MER.

Intraoperative Ultrasonography for Definition of Less Invasive Surgical Technique in Patients with Chiari Type I Malformation.

Chiari malformation type I (CM) is the main congenital malformation disease of the craniovertebral junction. The ideal surgical treatment is still controversial. Invasive procedures inside the cerebrospinal fluid (CSF) space and associated with dural repair are considered the gold standard; however, less invasive surgery with isolated bone decompression without dural opening may be possible in selected patients. Our study evaluates the efficacy of intraoperative CSF flow measurement with ultrasonography (USG) as a determining parameter in the selection of these patients. We analyzed prospectively 49 patients with CM operated on at the Hospital das Clínicas, College of Medicine, University of São Paulo. Patients underwent decompressive surgery with or without opening of the dura mater after intraoperative USG measuring flow rate. Avalue of 3 cm/second was considered a cutoff. Quality of life before and after surgery and the improvement of neck pain and headache were evaluated. Among 49 patients enrolled, 36 patients (73%) had CSF flow >3 cm/second and did not undergo duraplasty. In 13 patients (27%) with initial flow <3 cm/second, dural opening was performed together with duraplasty. All patients improved when preoperative and postoperative scores were compared, and all clinical parameters evaluated did not differ between both surgical groups. Patients submitted to bone decompression alone had a lower complication rate. Intraoperative USG with measurement of CSF allows the proper selection of patients with CM for less invasive surgery with bone decompression without duraplasty.

Usefulness of dural surface tracing of the cortical vessels with indocyanine green videoangiography just prior to dural opening for various cerebrovascular diseases.

Background:Indocyanine green (ICG) videoangiography can be used to delineate the locations of the cortical vessels just prior to dural opening, allowing safe and optimal dural opening. The present clinical series demonstrates the adjunct use of ICG videoangiography to optimize dural opening for the treatment of various cerebrovascular diseases.Methods:A total of 45 patients underwent surgery for superficial temporal artery-middle cerebral artery bypass (40), arteriovenous malformation (2), and dural arteriovenous fistula (3) between January 2012 and December 2016. After the dura had been exposed, ICG (0.25 mg/kg) was administered intravenously from the peripheral vein as a bolus just prior to dural opening. The operating microscope equipped with a fluorescent filter was used to examine the illuminated field of interest, and real-time flow assessment of the underlying cortical vessels and/or dural sinus was performed. The target recipient arteries for anastomosis or vascular malformations were visualized through the dura and marked using a pyoktanin pen on the dura mater.Results:The optimal dural opening was performed for anastomosis, and safety was ensured by locating the vascular malformations through the dura mater in all cases. The cortical vessel injury was avoided in all cases. No complication was related to this procedure.Conclusions:Dural surface tracing of the cortical vessels with ICG videoangiography just prior to dural opening is a useful technique, which allows optimal and safe dural opening for treatment of various cerebrovascular diseases.

Parasagittal meningiomas: Our surgical experience and the reconstruction technique of the superior sagittal sinus.

Background:The radical resection of parasagittal meningiomas without complications and recurrences is the goal of the neurosurgeon. Nowadays, different managements are proposed. This study describes our surgical technique during the lesional excision and the reconstruction of the superior sagittal sinus (SSS).Methods:The total removal (Simpson I and II) of parasagittal meningiomas (WHO grade I and II) was obtained in 75 patients from September 2000 to January 2010. The indocyanine green videoangiography was used before the dural opening and, when necessary, to identify and preserve the cortical veins. The surgery of the SSS was performed in accordance with Sindou's classification, and its reconstruction was achieved through the use of a patch of galea capitis.Results:We had no cases of recurrence and thrombotic occlusion of the SSS in 5 years after the reconstruction. No complications were observed in 65 patients, and no cases of mortality were reported. Neurological focal deficits were observed in 5 patients. A brain swelling and a venous infarction were observed in 1 patient. Only one case of thrombotic occlusion was observed. A cerebrospinal fluid leak was observed in 2 patients, and a systemic complication was found in 1 patient.Conclusion:Several factors contribute to the success of the parasagittal meningioma surgery. We consider the preservation of the cortical veins to be important, and, when possible, we recommend the reconstruction of the anterior third of the SSS. Our experience has led us to believe that until now surgery is a winning choice if practiced by expert hands.

Chapter 30 - Spinal cavernous malformations

Spinal cavernous malformations are rare intramedullary vascular lesions of the central nervous system. Most are located in the thoracic spine. Patients present with either acute neurologic deficit or gradual deterioration. Weakness is the most common presenting symptom. The annual hemorrhage risk is 2.1%. Diagnosis is made by magnetic resonance imaging as these lesions are occult on angiography. Surgical removal is indicated in patients with hemorrhage and neurologic deficit. All lesions are approached posteriorly by laminectomy. Dorsal cavernous malformations are exposed by focused laminectomy of the level or levels overlying the lesion with minimally facet violation. Ventral and lateral lesions are approached by laminectomy including a level above and level below as well as unilateral radical facetectomy. After midline dural opening, the dentate ligament is divided and retracted to allow up to 90° of rotation of the spinal cord. Microsurgical treatment is associated with 42% symptom improvement and 50% symptom stabilization. Postoperative worsening is associated with longer preoperative duration of symptoms. Therefore we recommend consideration of early surgery for cavernous malformation removal in patients with symptoms attributable to the lesion.

Cranial migration of ventriculoperitoneal shunt

We report a rare case of an 11-month male infant with cranial migration of ventriculoperitoneal (VP) shunt assembly. The shunt chamber was lying inside the ventricles. At the time of shunt revision, outsized burr hole and wide dural opening were observed. The ventricular migrated chamber of VP shunt was first retrieved from the ventricle followed by the removal of whole shunt assembly. A new VP shunt was placed on the other side with the chamber firmly anchored to the pericranium. The diagnosis was timely done and prevented complete shunt migration into the ventricles. We attribute factors such as outsized burr hole, wide dural opening, and poor anchoring of the straight connector of shunt chamber to periosteum because of poor tissue preservation (redo operation). Repeated flushing of the shunt chamber by cranial direction pressing on it by the mother might be a contributing factor for loosening of anchor sutures and cranial migration. Patients undergoing VP shunt procedure must be under regular follow-up for early recognition of this potential complication. Cranial migration of VP shunt is usually not a fatal complication.

Early permanent disappearance of abnormal muscle response during microvascular decompression for hemifacial spasm: a retrospective clinical study.

The objective of this study is to explore the cause of early abnormal muscle response (AMR) disappearance during microvascular decompression for hemifacial spasm and the clinical outcomes of these patients. Three hundred seventy-two patients received microvascular decompression (MVD) under intraoperative electrophysiological monitoring in Nanjing Drum Tower Hospital in 2014; the characteristic AMR of HFS was observed in 359 patients during the operation. And the 359 patients were divided into two groups based on whether AMR had remained before the beginning of the decompression procedure for offending vessels. Thirty-three patients who showed a permanent disappearance of AMR before the beginning of decompression were regarded as group I. Dural opening and the succeeding CSF drainage produced a permanent disappearance of AMR in 13. During the dissection of lateral cerebellomedullary cistern, a permanent disappearance of AMR was found in 20 patients. Thirty-two patients were cured immediately; delayed resolution (7days after surgery) was found in one patient. No complications were observed and no recurrence was found during the follow-up period in the 33 patients. In the other 326 patients (group II), AMR disappeared temporarily before the beginning of the decompression procedure for offending vessels in 42 patients. After decompression, AMR disappeared completely in 305 patients. Two hundred sixty-seven patients were cured immediately and 57 patients got a delayed resolution (2days to 45weeks after surgery). The two left did not get a complete abolition of spasm. Three cases of hearing loss, one hoarseness, and nine delayed facial paralysis were observed. The reason of early abnormal muscle response disappearance may be that the degree of neurovascular compression was not serious; these patients were more likely to get an immediate cure. Continuous intraoperative electrophysiological monitoring of AMR is necessary.

Pathological changes of the hippocampus and cognitive dysfunction following frontal lobe surgery in a rat model.

Postoperative cognitive dysfunction (POCD) is a known complication after intracranial surgery. Impaired hippocampal neurogenesis has been associated with cognitive dysfunction in animal models. In order to assess hippocampal changes after brain surgery, a frontal lobe corticectomy was performed in ten adult Wistar rats (group 4). Three different control groups (n = 10 each) included no treatment (G1), general anesthesia alone (G2), and craniectomy without dural opening (G3). Twenty-four hours after surgery, half of the animals were killed, and the mRNA levels for IL-6, TNF-α, and brain-derived growth factor (BDNF) in the contralateral hippocampus were assessed by qPCR. Seven days later, the remaining animals underwent anxiety and memory testing. Afterwards, the number of immature neurons in the hippocampal cortex was measured by doublecortin (DCX) staining. Twenty-four hours after surgery, mRNA levels of IL-6 and TNF-α increased and BDNF decreased in both surgical groups G3 and G4 (p = 0.012). Cognitive tests demonstrated an increase in anxiety levels and memory impairment in surgical groups compared with non-surgical animals. These changes correlated with an inhibition of hippocampal neurogenesis evidenced by a decreased number of new neurons (mean ± SD for G1-4: 66.4 ± 24; 57.6 ± 22.2; 21.3 ± 3.78; 5.7 ± 1.05, p < 0.001, non-parametric ANOVA). Intracranial surgery was demonstrated to induce an inflammatory reaction within the hippocampus that compromised neurogenesis and impaired normal cognitive processing. Corticectomy had a greater effect than craniotomy alone, indicating a central trigger for hippocampal inflammatory changes. POCD after craniotomy may originate from a central inflammatory response resulting from surgical trauma to the brain parenchyma.

Intraoperative image updating for brain shift following dural opening.

OBJECTIVE Preoperative magnetic resonance images (pMR) are typically coregistered to provide intraoperative navigation, the accuracy of which can be significantly compromised by brain deformation. In this study, the authors generated updated MR images (uMR) in the operating room (OR) to compensate for brain shift due to dural opening, and evaluated the accuracy and computational efficiency of the process. METHODS In 20 open cranial neurosurgical cases, a pair of intraoperative stereovision (iSV) images was acquired after dural opening to reconstruct a 3D profile of the exposed cortical surface. The iSV surface was registered with pMR to detect cortical displacements that were assimilated by a biomechanical model to estimate whole-brain nonrigid deformation and produce uMR in the OR. The uMR views were displayed on a commercial navigation system and compared side by side with the corresponding coregistered pMR. A tracked stylus was used to acquire coordinate locations of features on the cortical surface that served as independent positions for calculating target registration errors (TREs) for the coregistered uMR and pMR image volumes. RESULTS The uMR views were visually more accurate and well aligned with the iSV surface in terms of both geometry and texture compared with pMR where misalignment was evident. The average misfit between model estimates and measured displacements was 1.80 ± 0.35 mm, compared with the average initial misfit of 7.10 ± 2.78 mm between iSV and pMR, and the average TRE was 1.60 ± 0.43 mm across the 20 patients in the uMR image volume, compared with 7.31 ± 2.82 mm on average in the pMR cases. The iSV also proved to be accurate with an average error of 1.20 ± 0.37 mm. The overall computational time required to generate the uMR views was 7-8 minutes. CONCLUSIONS This study compensated for brain deformation caused by intraoperative dural opening using computational model-based assimilation of iSV cortical surface displacements. The uMR proved to be more accurate in terms of model-data misfit and TRE in the 20 patient cases evaluated relative to pMR. The computational time was acceptable (7-8 minutes) and the process caused minimal interruption of surgical workflow.