Early Magnesium Treatment After Aneurysmal Subarachnoid Hemorrhage: Individual Patient Data Meta-Analysis.

BACKGROUND AND PURPOSE: Delayed cerebral ischemia (DCI) is an important cause of poor outcome after aneurysmal subarachnoid hemorrhage (SAH). Trials of magnesium treatment starting <4 days after symptom onset found no effect on poor outcome or DCI in SAH. Earlier installment of treatment might be more effective, but individual trials had not enough power for such a subanalysis. We performed an individual patient data meta-analysis to study whether magnesium is effective when given within different time frames within 24 hours after the SAH. METHODS: Patients were divided into categories according to the delay between symptom onset and start of the study medication: <6, 6 to 12, 12 to 24, and >24 hours. We calculated adjusted risk ratios with corresponding 95% confidence intervals for magnesium versus placebo treatment for poor outcome and DCI. RESULTS: We included 5 trials totaling 1981 patients; 83 patients started treatment<6 hours. For poor outcome, the adjusted risk ratios of magnesium treatment for start <6 hours were 1.44 (95% confidence interval, 0.83-2.51); for 6 to 12 hours 1.03 (0.65-1.63), for 12 to 24 hours 0.84 (0.65-1.09), and for >24 hours 1.06 (0.87-1.31), and for DCI, <6 hours 1.76 (0.68-4.58), for 6 to 12 hours 2.09 (0.99-4.39), for 12 to 24 hours 0.80 (0.56-1.16), and for >24 hours 1.08 (0.88-1.32). CONCLUSIONS: This meta-analysis suggests no beneficial effect of magnesium treatment on poor outcome or DCI when started early after SAH onset. Although the number of patients was small and a beneficial effect cannot be definitively excluded, we found no justification for a new trial with early magnesium treatment after SAH.

Rapid and sequential desensitization to both aspirin and clopidogrel.

Hypersensitivity reactions to aspirin and clopidogrel are 2.5% and 1%, respectively. Dual anti-platelet therapy with these drugs is effective in preventing thrombosis following deployment of stents for cerebrovascular and cardiovascular syndromes. Desensitization therapy with both aspirin and clopidogrel may be required for patients undergoing stent implantation that have experienced hypersensitivity to these agents. We report the case of a 58-year-old woman who developed urticaria and angioedema following aspirin therapy for ischaemic cerebrovascular disease. She developed an identical reaction after clopidogrel was subsequently administered. Investigations revealed the presence of an internal carotid artery aneurysm that required deployment of a stent. Rapid desensitization to aspirin over 5.5 h followed 3 days later by rapid desensitization to clopidogrel over 2.5 h was successfully performed prior to stenting. After 4 months she has tolerated this dual anti-platelet therapy without any adverse reaction. Rapid and sequential desensitization to both aspirin and clopidogrel can be successfully performed for patients who require stent deployment but have hypersensitivity to both these anti-platelet agents.

Survival of patients following neurosurgical treatment of colorectal adenocarcinoma metastasis in the Northern Sydney-Central Coast area.

Cerebral metastases from gastrointestinal primaries constitute about 3-5% of surgically resected brain secondaries. There has been a paucity of regional and worldwide data concerning the survival and clinical course of patients undergoing neurosurgical treatment of cerebral metastases from colorectal origin. The clinical course and survival of 32 patients undergoing neurosurgical intervention for colorectal carcinoma metastases between 1999 and 2007 was examined. The 21 male and 11 female patients examined had a median age of 61.8 years at diagnosis of colorectal cancer; median interval between colorectal cancer diagnosis and cerebral metastatic disease was 27.6 months; and 88% of patients underwent microsurgical resection. Median survival from neurosurgical intervention was 7.5 months. Perioperative mortality was 3%. Age, gender and infratentorial location of lesions had no significant impact on survival. Patients undergoing whole brain radiotherapy (WBRT) had a significantly longer survival than those not undertaking this treatment (median survival 10.6 vs. 5.2 months, p = 0.018). A randomised, controlled trial of the utility of WBRT following surgical resection in this tumour subtype seems appropriate.

Cranial venous outflow obstruction in the pseudotumour syndrome: incidence, nature and relevance.

This study reports a retrospective analysis of the evidence of cranial venous outflow pathology in 188 patients with pseudotumour syndrome (PTS) investigated over the period 1968-1999. Standard methods of investigation appropriate to the period were used, i.e. cerebral angiography, CT and MR scanning. Recently, some patients had specific venous studies including intraluminal cranial venous sinus pressure measurements. A sub-group (25 patients) was investigated for haematological abnormalities. The overall incidence of cranial venous outflow abnormality was 19.7% (37 cases). In decades, related to the predominant investigative method, the figures were: to 1979, 4.2% (2 cases); to 1989, 15.0% (8 cases); to 1999, 31.0% (27 cases). A cause of the venous abnormality was identified in 20 cases, most commonly haematological and iatrogenic. In 17 patients (all females) no cause was identified. Fifteen of the 25 patients (60%) tested specifically were found to have a haematological abnormality, although no correlation was shown between this and a demonstrable venous outflow abnormality. The conclusion was drawn that there is a high incidence (close to one-third) of venous outflow abnormalities in PTS with detailed investigation. Issues of mechanism and therapy are discussed.

Excitatory convergence of Y and non-Y channels onto single neurons in the anterior ectosylvian visual area of the cat.

Numerous functional and hodological studies of the anterior ectosylvian visual area (AEV) of the cerebral cortex of the cat suggest that this area plays an important role in processing information about visual motion. In the present study, in cats with selective conduction block of Y fibres in one optic nerve, we have examined the extent of the excitatory convergence of Y (presumed 'motion channel') and non-Y information channels on single neurons in AEV, as well as the contribution of the Y channel to the receptive field properties of AEV neurons. While in normal cats all neurons recorded from AEV were binocular, i.e. could be photically activated via either eye, in cats with selective conduction block of Y fibres in one optic nerve, a significant proportion (about 15%) of AEV cells could be photically activated only via the normal eye. In comparison to those in normal cats, the peak discharge rates of AEV neurons in the Y-blocked cats were drastically reduced not only when photic stimuli were presented via the Y-blocked eye, but also when they were presented via the normal eye. Selective block of Y input also resulted in a significant shift in velocity preferences towards the lower velocities. However, the direction selectivity indices of AEV neurons were not affected by selective Y block. Thus: (i) the responses of AEV neurons to a high velocity of motion are dependent on the integrity of the Y input; (ii) the 'spontaneous' (i.e. not photically evoked) discharges of Y retinal ganglion cells exert a facilitatory influence on the responses of AEV cells to photic stimuli; (iii) although the responses of AEV neurons are dominated by the Y inputs, AEV neurons also receive significant non-Y excitatory inputs; and (iv) the strong direction selectivity revealed in most AEV neurons does not dependent on the integrity of Y input.