Somatosensory evoked potential monitoring during intracranial surgery

In the neurosurgical approach to intracranial aneurysms which are often accompanied by arterial spasm and cortical ischaemia, monitoring procedures aim to obtain useful information on cerebral function. SEPs evoked by stimulation of the median nerve at the wrist and of the tibial nerve at the medial malleolus were registered in 45 patients with intracranial aneurysms during neurosurgical procedures. Our results show SEP abnormalities during different stages of neurosurgical procedures in 36 patients out of the monitored 45. Significant abnormalities of SEPs with respect to the control group were decrease of the amplitude of N 20-P 25 complex, lengthening of the absolute latency of the waves N 20- and P 25 and lengthening of the central conduction time (CCT) (N 13-N 20). The greatest SEP abnormalities were registered during the neurosurgical approach to aneurysm and during the clipping procedure. However, the changes were reversible in the majority of the patients. The aim of this paper was to focus on early detection of some cerebral function disturbances during the neurosurgical procedure as well as the prevention of possible brain damage.     

Nuclear magnetic resonance relaxation in experimental brain edema: effects of water concentration, protein concentration, and temperature

Proton relaxation times T1 and T2 of macromolecular solutions, bovine brain tissues, and experimental cat brain edema tissues were studied as a function of water concentration, protein concentration, and temperature. A linear relation was found between the inverse of the weight fraction of tissue water and the spin-lattice relaxation rate, R1, based on a fast proton exchange model for relaxation. This correlation was also found for the spin-spin relaxation rate, R2, of gray matter samples and macromolecular solutions at low concentrations. Concentrated solutions of protein-water samples showed an enhanced relaxation due to viscosity effects. The T2 of white matter was considerably lengthened with elevated water concentration, but showed no straightforward relation with the total tissue water content. The relaxation times of all samples increased with temperature, supporting the assumption of fast proton exchange in the model for relaxation. This was not found for white matter, in which T2 decreased with increasing temperature, which indicated that intermediate or even slow exchange was present. The relation found between relaxation times and tissue water content can be used to predict the amount of and/or increase in tissue water due to water-elevating processes such as edema.     

Subhepatic collections complicating laparoscopic cholecystectomy: Percutaneous management

Ten patients with subhepatic fluid collections complicating laparoscopic Cholecystectomy were successfully treated by interventional radiological procedures. The series included five abscesses, three hematomas, one biloma, and one serous collection. Abdominal pain or fever developed from 3 to 21 days after the laparoscopic intervention. All patients were asymptomatic 72 h after percutaneous drainage and there were no complications related to the procedure. Subhepatic fluid accumulations are common findings after laparoscopic cholecystectomies and have been considered an unreliable indicator of infection or other postoperative complications. However, the significance of these collections should not be underestimated in symptomatic patients. In such cases we propose diagnostic aspiration and drainage, when necessary, to safely and promptly establish the precise diagnosis and treatment. More serious complications can be avoided by early percutaneous intervention.     

Case report: myocardial ischemia: an overlooked substrate in syncope of aortic stenosis.

The cause of the syncope in aortic stenosis has been the subject of controversy partly because only a few patients have been monitored during their syncopal episodes. Among the mechanisms proposed are hypersensitive carotid sinus, complete A-V block, ventricular arrhythmias, and ischemic myocardial depression. It is now accepted that the syncope is caused by a vasodepressor response from stimulation of left ventricular baroceptors, resulting in reflex hypotension and bradycardia. This case report describes a patient who developed a syncopal episode during stress testing. Although the mechanism for the syncope is consistent with the vasodepressor response, ischemic changes were observed in the electrocardiogram before the development of syncope. Review of literature shows that, although different mechanisms for syncope have been described, all reported patients manifested myocardial ischemia before the development of their syncopal episodes even when the syncope was nonexertional and clearly caused by a vasodepressor response. The authors conclude that, independent of the mechanism proposed, myocardial ischemia is overlooked as an important substrate in which the syncopes are precipitated in aortic stenosis.     

Ocular symptoms in internal carotid artery occlusion]

The internal carotid artery occlusion causing an insufficiency of the cerebral circulation manifests itself--besides the neurological symptoms--by disorders of the visual organ. One can distinguish among them early, functional symptoms in the form of transient unilateral hemianopia on the side opposite to the occluded carotid artery and the attacks of transient amblyopia. Signs of fixed ischaemia of the eye ball appear afterwards in the form of oculomotor and pupillary disturbances, neovascularization of the iris, disturbances of the IOP, central retinal artery occlusion, ischaemic optic atrophy. The authors emphasize the value of Doppler's diagnostic ultrasonography, a fast and non-invasive method of direct evaluation of the blood flow in the internal carotid artery system.     

Progressive motor syndrome in a welder with pallidal T1 hyperintensity on MRI: A two-year follow-up.

Chronic exposure to manganese (Mn) fume during welding may lead to mainly extrapyramidal syndrome that is resistant to treatment. We present a 32-year-old patient who developed severe postural instability, Parkinsonism, dystonia, and pyramidal signs in the 10th year of welding. The neurological condition of the patient worsened markedly in the following 3 years, resulting in severe disability rendering him to be assisted in all his daily activities and he did not benefit from any dopaminergic agent. T1 sequences of the MRI of the brain showed pallidal hyperintensity symmetrically. Welders in our country often protect their eyes but ignore to use tools that protect them from inhalation of the fume. Since chronic Mn toxicity may cause serious disability and irreversible neurological disturbances, we strongly believe that it is necessary to inform welders and their employers about this potential hazard.     

Carcinoma of the papilla of vater: Are endoscopic appearance and endoscopic biopsy discordant?

Carcinoma of the papilla of Vater is classified as periampullary cancer representing 5% of all gastrointestinal tract malignancies. Early and accurate diagnosis is important for those patients with a tumor of the papilla, as the prognosis is more favorable than in other periampullary neoplasms. Endoscopically obtained biopsies from suspicious papillae can detect an early tumor, although even for skilled pathologists it is often difficult to differentiate carcinomas from noninvasive lesions on the basis of forceps biopsies. The purpose of this study was to assess the preoperative diagnostic accuracy of duodenoscopy appearance and biopsy in all cases with suspicion of tumor. Thirty patients with suspicion of carcinoma of the papilla of Vater and with final diagnosis established by pancreatoduodenectomy were included in this retrospective study. In each case, a comparison was made between endoscopic biopsy and duodenoscopic appearance. Duodenoscopic appearance sensitivity and accuracy for malignancy were 86% and 83%, respectively, whereas endoscopic biopsy sensitivity and accuracy were 65% and 67%, respectively. Although preoperative diagnosis of carcinoma of the papilla of Vater is useful for making therapeutic decisions, the diagnostic value of the endoscopic appearance was superior to endoscopic biopsy in this series. Presented at the 2003 American Hepato-Pancreato-Biliary Association Congress, Miami, Florida, February 27-March 3, 2003. Supported by FADA-CAPES/PROP 200J (M.L.D.).     

Balloon occlusion of the internal carotid artery in 40 cases of giant intracavernous aneurysm: technical aspects,cerebral monitoring,and results

Summary We have studied the results of carotid occlusion in the treatment of giant intracavernous carotid artery (ICA) aneurysms in 40 patients. Clinical, angiographic, Doppler and cerebral blood flow (CBF) criteria for tolerance of occlusion are discussed. The patients had headaches (47.5%), cranial nerve compression (87.5%), decreased visual acuity (20%), ruptured aneurysm (15%) and 5% were asymptomatic. Balloon occlusion tests were performed under light sedation anaesthesia: a successful test required perfect clinical tolerance and adequate angiographic collateral circulation in arterial, parenchymatous, and venous phases. Additional criteria include xenon 133 CBF measurements, and transcranial Doppler sonography of the middle cerebral artery. According to these criteria, 5 patients did not tolerate test occlusion and required an extra-intracranial (EC-IC) bypass. Mean follow-up was 4.7 years. All patients were radiologically cured of their ancurysm, and in 35 the symptoms resolved, although 3 had persistent ocular motor nerve palsies, and in 4 visual defects were unchanged. Complications were 1 permanent and 3 transient neurological deficits. Balloon occlusion of the ICA is an effective, reliable form of treatment for intracavernous giant aneurysm and should replace surgical ligation of the cervical carotid artery. With CBF or Doppler monitoring, the risk of neurological deficit is diminished. EC-IC bypass prior to ICA occlusion is indicated if test occlusion is not tolerated.