Uncrossed corticospinal tracts presenting as transient tumor-related symptomatology.

Ipsilateral corticospinal innervation is rare. No prior cases have described ipsilateral tumor-associated symptoms as the presentation of an uncrossed corticospinal tract. Herein, we describe a case associated with a left frontal tumor, presenting with transient ipsilateral hemiparesis and aphasia. Due to the fluctuating symptomatology, we suspected a cerebrovascular cause and initially performed a workup for stroke. Ipsilateral motor innervation was discovered with intraoperative monitoring during the resection of the tumor, and confirmed with postoperative diffusion tensor imaging (DTI). Neurosurgeons should be aware of uncrossed motor system, and include it in the differential of ipsilateral deficit in patients with intracranial tumors.

An fMRI, DTI and Neurophysiological Examination of Atypical Organization of Motor Cortex in Ipsilesional Hemisphere Following Post-Stroke Recovery.

OBJECTIVES: We report a 61-year-old woman who developed left hemiparesis following a right frontal stroke. She underwent rehabilitation and regained function of the left side of her body. Three years after her first stroke, she developed a large left subdural hematoma and again presented with left hemiparesis. MATERIALS AND METHODS: Prior to the cranioplasty, an fMRI scan involving left and right hand movement, arm movement, and foot peddling were conducted in order to determine whether the patient showed ipsilateral activation for the motor tasks, thus explaining the left hemiparesis following the left subdural hematoma. Diffusion tensor imaging (DTI) tractography was also collected to visualize the motor and sensory tracts. RESULTS: The fMRI results revealed activation in the expected contralateral left primary motor cortex (M1) for the right-sided motor tasks, and bilateral M1 activation for the left-sided motor tasks. Intraoperative neurophysiology confirmed these findings, whereby electromyography revealed left-sided (i.e., ipsilateral) responses for four of the five electrode locations. The DTI results indicated that the corticospinal tracts and spinothalamic tracts were within normal limits and showed no displacement or disorganization. CONCLUSIONS: These results suggest that there may have been reorganization of the M1 following her initial stroke, and that the left hemisphere may have become involved in moving the left side of the body thereby leading to left hemiparesis following the left subdural hematoma. The findings suggest that cortical reorganization may occur in stroke patients recovering from hemiparesis, and specifically, that components of motor processing subserved by M1 may be taken over by ipsilateral regions.

Fourier transform infrared spectromicroscopy and hierarchical cluster analysis of human meningiomas.

Limitations of conventional light microscopy in pathological diagnosis of brain tumors include subjective bias in interpretation and discordance of nomenclature. A study using mid-infrared (IR) spectromicroscopy was undertaken to determine whether meningiomas, a group of brain tumors prone to recurrence, could be identified by the unique spectral 'fingerprints' of their chemical composition. Paired, thin (5-microm) cryosections of snap-frozen human meningioma tumor samples removed at elective surgery were mounted on glass (hematoxylin and eosin-stained tissue section) and infrared (unstained tissue section) reflectance slides, respectively. Concordance of the tumor-bearing areas identified in the stained section by a pathologist with the unstained IR tissue section was ensured using a novel digital grid and tumor-mapping system developed in our laboratory. Compared with the normal control, tumor samples from four meningioma patients revealed a marked decrease in bands associated with unsaturated fatty acids, particularly in the bands at 3010, 2920, 2850, and 1735 cm(-1). Spectral datasets were subjected to hierarchical cluster analyses (HCA) using Ward's algorithm for comparison and grouping of similar data groups, and were converted into color-coded digital maps for matching spectra with their respective clusters. False color images of 5 and 6 clusters obtained by HCA identified dominant clusters corresponding to tumor tissue. Corroboration of these findings in a larger number of meningiomas may allow for more precise identification of these and other types of brain tumors.

Phenomenology of neurophysiologic changes during surgical treatment of carotid stenosis using signal analysis.

OBJECTIVE: To describe the changes in the shape and topology of the somatosensory evoked potential (SSEP) during carotid endarterectomy, with particular reference to the time of clamping. METHODS: Routine intraoperative monitoring was performed on 30 patients undergoing carotid endarterectomy (15) or undergoing stenting (15) using median nerve SSEPs. Post-operatively the first and second derivatives of the potential were examined. Separate analysis of the SSEP using wavelets was also performed. RESULTS: In no instances did changes in the SSEP reach clinical significance. The first derivative showed significant changes that were temporally related to the clamp period. After clamping the 'velocity' was higher than baseline. There were changes in the wavelets related to the clamp period with more marked spectral edges at the conclusion of the procedure than baseline. In all instances the patient had a good clinical outcome. CONCLUSIONS: Wavelet and derivative analysis of evoked potentials show changes that are not apparent with measures of amplitude and latency. The clinical relevance of these changes remains uncertain and await larger studies. SIGNIFICANCE: Increased velocity and spectral edges may be markers of increased cerebral blood flow, at least in the setting of pre-existing carotid stenosis.

Synchrotron-based intravenous cerebral angiography in a small animal model.

K-edge digital subtraction angiography (KEDSA), a recently developed synchrotron-based technique, utilizes monochromatic radiation and allows acquisition of high-quality angiography images after intravenous administration of contrast agent. We tested KEDSA for its suitability for intravenous cerebral angiography in an animal model. Adult male New Zealand rabbits were subjected to either angiography with conventional x-ray equipment or synchrotron-based intravenous KEDSA, using an iodine-based contrast agent. Angiography with conventional x-ray equipment after intra-arterial administration of contrast agent demonstrated the major intracranial vessels but no smaller branches. KEDSA was able to visualize the major intracranial vessels as well as smaller branches in both radiography mode (planar images) and tomography mode. Visualization was achieved with as little as 0.5 ml kg-1 of iodinated contrast material. We were able to obtain excellent visualization of the cerebral vasculature in an animal model using intravenous injection of contrast material, using synchrotron-based KEDSA.

Spinal dural arteriovenous fistula: a case series and review of imaging findings.

INTRODUCTION: Spinal dural arteriovenous fistulae (sdAVF) are rare lesions. Patients typically present with slowly progressive myelopathy that is often mistaken for degenerative cervical or lumbar stenosis. On spinal magnetic resonance imaging (MRI), multisegmental T2 hyperintensities along with associated flow voids are pathognomonic of sdAVF. However, diagnosis can be difficult. Definitive diagnosis and localization is achieved with complete spinal angiography. Treatment options include open surgical ligation, endovascular embolization or multimodality treatment. The purpose of this study is to present a series of cases to aid in the assessment, diagnosis and treatment of this unusual pathology. CASE PRESENTATION: We present 10 cases of sdAVF treated at our center over an 8-year period. Seventy percent of patients were male. The mean age of presentation was 62.6 years. The most common lesion was a dorsal dural AVF with single feeder. All patients underwent open surgical ligation, six having preoperative coil embolization of the radicular artery to allow for intraoperative localization of the fistula. Eight patients showed improvement following treatment as graded by the Nurick system. Two patients failed to improve. None of the patients worsened. One patient had a radiation burn from the spinal angiogram requiring secondary closure and one patient had a pseudomeningocele at the site of surgery that resolved. DISCUSSION: The successful treatment of sdAVF requires a detailed understanding of clinical presentation and imaging findings to allow for precise treatment. Owing to the rarity of the condition, clinicians must continue to share their experiences to advance our knowledge.

Thrombolytic therapy for delayed, in-hospital stroke after cardiac surgery.

Five patients who had delayed stroke after cardiac surgery underwent intraarterial administration of a fibrinolytic agent for thromboembolism (n = 4) or thrombosis (n = 1) of the cerebral artery. Complete recanalization of the occluded artery was obtained in 3 patients and partial recanalization in 2. Additional angioplasty for basilar artery stenosis was performed in 1 patient. No patients exhibited rebleeding into the pericardial space or wound bleeding. All patients survived with moderate or full functional recovery. Immediate cerebral angiography and local thrombolysis may improve functional outcome and survival in patients with postcardiotomy cerebral thromboembolism.

Repair of a tear at the base of a blister-like aneurysm with suturing and an encircling clip: technical note.

OBJECTIVE: An aneurysm can produce large defects in the parent vessel if the aneurysm tears at the neck of the vessel. The authors present a technique to repair a tear at the base of a blister-like aneurysm encountered during microsurgical clipping of an anterior wall aneurysm of the internal carotid artery. METHODS: The repair technique involved suturing and covering the aneurysm with an encircling aneurysm clip. A large tear had destroyed the vessel's tubular structure, and repair was not sufficient using an encircling clip alone. Two microsuture stitches were placed on the tear, so that a split artery re-formed a tubular structure. The lesion was then covered with Surgicel (Ethicon, Inc., Somerville, NJ) and fibrin glue. When the Surgicel and fibrin glue were applied, the temporary clip on the distal internal carotid artery was removed for a moment, allowing retrograde blood flow to provide the counterforce necessary to maintain the vessel's tubular structure. An encircling clip was then applied to cover the entire circumference of the lesion. RESULTS: This method required only a short occlusion time for arterial repair, thus helping avoid ischemic complications. The patient awoke with transient hemiparesis, but recovery was prompt. CONCLUSION: This technique is useful for repairing an aneurysmal tear at its base, especially if the tear is large.

Spinal subdural empyema after a dural tear. Case report.

Spinal subdural empyema is an exceptionally rare and serious condition. Immediate surgery with complete exposure and drainage of the abscess is generally recommended. The authors present a patient in whom a Staphylococcus aureus septicemia related to nosocomial pneumonia developed after a thoracic laminectomy. The surgery was further complicated by an unintended durotomy (dural tear). Ten days postoperatively, the patient experienced back pain and lower-extremity symptoms caused by a subdural empyema. Cultures from the wound also grew S. aureus. This represents the first case of spinal subdural empyema in which the spread of infection into the subdural space is believed to have been facilitated by a dural tear. The patient had a favorable outcome despite an initial delay in surgical intervention because of a pulmonary embolus.

Intraoperative angiography evaluation of the microsurgical clipping of unruptured cerebral aneurysms.

Intraoperative angiography evaluation of the clippings of cerebral aneurysms was investigated in a series of 38 consecutive patients with unruptured cerebral aneurysms to determine any favorable impact on the outcome. Unexpected findings including major arterial occlusion or residual aneurysm were identified. Specific variables such as the size and site of aneurysm were analyzed to determine the impact on clinical outcome and the incidence of clip modification. There were 11 large and 27 small aneurysms in this series. Mortality and permanent morbidity after microsurgical clipping were 0.0% and 2.6%, respectively. Unexpected angiographic findings necessitating clip repositioning consisted of residual aneurysm in two cases and distal branch occlusion or parent vessel stenosis in four. The need for clip modification was significantly higher for large than for small aneurysms (p = 0.007), and the rate of clip adjustment increased with increasing aneurysm size (p = 0.008). Intraoperative assessment prior to wound closure allows for the recognition and correction of defects and decreases the risk of postoperative complications. Intraoperative angiography may become important in the microsurgical clipping of unruptured cerebral aneurysms, especially large aneurysms.

Intraoperative angiographic assessment of graft patency during extracranial-intracranial bypass procedures.

The use of intraoperative angiography to monitor graft patency was retrospectively reviewed in extracranial-intracranial bypass procedures. Forty-two patients underwent 43 extracranial-intracranial bypass procedures with the use of intraoperative angiography. Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass was performed in 41 patients (42 procedures) with ischemic cerebrovascular diseases, and vertebral artery-MCA bypass using radial artery graft for intentional ligation of the common carotid artery in one patient with nasopharyngeal carcinoma. Intraoperative angiography provided high-quality subtraction images in every case. There were no complications due to angiography. Graft occlusion was observed intraoperatively in three cases, but an additional procedure reopened the occluded graft in all three cases. Graft patency rate was 100% after surgery. Outcome was excellent in 40 patients and good in one patient who underwent STA-MCA bypass. Intraoperative angiography provides useful information regarding graft patency during bypass surgery. Intraoperative assessment prior to wound closure allows for the recognition and correction of technical failure and decreases the risk of postoperative complications.

Dual energy CT at the synchrotron: a piglet model for neurovascular research.

BACKGROUND: Although the quality of imaging techniques available for neurovascular angiography in the hospital environment has significantly improved over the last decades, the equipment used for clinical work is not always suited for neurovascular research in animal models. We have previously investigated the suitability of synchrotron-based K-edge digital subtraction angiography (KEDSA) after intravenous injection of iodinated contrast agent for neurovascular angiography in radiography mode in both rabbit and pig models. We now have used the KEDSA technique for the acquisition of three-dimensional images and dual energy CT. MATERIALS AND METHODS: All experiments were conducted at the biomedical beamline ID 17 of the European Synchrotron Radiation Facility (ESRF). A solid state germanium (Ge) detector was used for the acquisition of image pairs at 33.0 and 33.3 keV. Three-dimensional images were reconstructed from an image series containing 60 single images taken throughout a full rotation of 360°. CT images were reconstructed from two half-acquisitions with 720 projections each. RESULTS: The small detector field of view was a limiting factor in our experiments. Nevertheless, we were able to show that dual energy CT using the KEDSA technique available at ID 17 is suitable for neurovascular research in animal models.

Biomolecular diagnosis of human glioblastoma multiforme using Synchrotron mid-infrared spectromicroscopy.

Glioblastoma multiforme (GBM) is one of the most malignant human tumors, with a uniformly poor outcome. One obstacle in curing malignant brain tumors is the limitation of conventional light microscopy in detecting microscopic residual tumor in biopsy samples from the perimeter of the surgically resected tumor. We further refined the identification of GBM tumor tissue at the sub-cellular level, utilising the technique of Synchrotron, sourced mid-infrared (mid-IR) spectromicroscopy. Paired, thin (5 microm) cryosections of snap-frozen human GBM tumor samples removed at elective surgery were mounted on glass slides (hematoxylin and eosin-stained tissue section) and calcium fluoride (CaF2) windows (unstained tissue section for transmission spectromicroscopy), respectively. Concordance of tumor bearing areas identified in the stained section with the unstained IR tissue section was confirmed by the pathologist of the study. Compared with molecular signatures obtained from normal control brain tissue, unique spectroscopic patterns were detected in GBM tumor samples from 6 patients. The identifying features of GBM were: i) high protein-to-lipid ratios (amide I+II/CH2 symmetric stretch; amide I+II/CH2+CH3 symmetric and asymmetric stretch), and ii) considerable enhancement of the intensities of characteristic peaks at 2,957 and 2,871 cm(-1) representing CH3 asymmetric and symmetric stretch, respectively. Spectral data sets were subjected to Ward's algorithm for assignment to similar groups, and then subjected to hierarchical cluster analysis (HCA) by means of false color digital maps. False color images of 5 clusters obtained by HCA identified dominant clusters corresponding to tumor tissue. Corroboration of these findings in a larger number of GBM may allow for more precise identification of these and other types of brain tumors.

Synchrotron-based intra-venous K-edge digital subtraction angiography in a pig model: a feasibility study.

BACKGROUND: K-edge digital subtraction angiography (KEDSA) combined with the tunability of synchrotron beam yields an imaging technique that is highly sensitive to low concentrations of contrast agents. Thus, contrast agent can be administered intravenously, obviating the need for insertion of a guided catheter to deliver a bolus of contrast agent close to the target tissue. With the high-resolution detectors used at synchrotron facilities, images can be acquired at high spatial resolution. Thus, the KEDSA appears particularly suited for studies of neurovascular pathology in animal models, where the vascular diameters are significantly smaller than in human patients. MATERIALS AND METHODS: This feasibility study was designed to test the suitability of KEDSA after intravenous injection of iodine-based contrast agent for use in a pig model. Four adult male pigs were used for our experiments. Neurovascular angiographic images were acquired using KEDSA with a solid state Germanium (Ge) detector at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. RESULTS: After intravenous injection of 0.9 ml/kg iodinated contrast agent (Xenetix), the peak iodine concentrations in the internal carotid and middle cerebral arteries reached 35 mg/ml. KEDSA images in radiography mode allowed the visualization of intracranial arteries of less than 1.5mm diameter.

Expression of N-myristoyltransferase in human brain tumors.

N-myristoylation is a process of covalent irreversible protein modification that promotes association of proteins with membranes. Based on our previous findings of elevated N-myristoyltransferase (NMT) activity in colonic epithelial neoplasms that appears at an early stage in colonic carcinogenesis, together with elevated NMT expression in human colorectal and gallbladder carcinomas, we investigated NMT activity and protein expression of NMT1 and NMT2 in human brain tumors and documented elevated NMT activity and higher protein expressions. For the first time, we have demonstrated that NMT has the potential to be used as a marker of human brain tumors. However, further studies with larger number of patients are required to establish its role as a complementary diagnostic tool. This finding has significant implications for further understanding of biological mechanisms involved in tumorigenesis, as well as for diagnosis and therapy of human brain tumors.