Increased CSF glutamate may originate within the CNS and may play a pathogenetic role in HIV dementia, thus supporting the treatment of these patients with glutamate receptor antagonists.

Experimental studies have shown the role of excitotoxicity in the pathogenesis of ischemic brain lesions, and glutamate levels have been found to be elevated in CSF and plasma from patients, early after stroke. In this study, we investigated whether platelets could be involved in the mechanism of altered plasma glutamate levels after stroke. Forty four patients, from 6 hours to 9 months after ischemic stroke, 15 age-related healthy controls and 15 controls with stroke risk factors or previous transient ischemic attack were enrolled. Glutamate plasma levels, platelet glutamate release after aggregation and platelet glutamate uptake were assessed. Plasma glutamate levels were increased up to 15 days after the ischemic event in stroke patients, and the levels at day 3 were inversely correlated with the neurologic improvement between day 3 and 15. Ex vivo platelet glutamate release was decreased by 70% in stroke patients, suggesting previous in vivo platelet activation. Moreover, platelet glutamate uptake in these patients was decreased by 75% up to 15 days and was still reduced 90 days after stroke. Our data show a prolonged increase of glutamate in plasma after stroke, which might presumably be linked to altered platelet functions, such as excessive release of the amino acid or impaired uptake.

Glutamate may play an important role in the pathogenesis of migraine: glutamate release in the brain may be involved in the development of spreading depression and increased concentrations of this amino acid have been reported in plasma and platelets from migraine patients. Here we assessed platelet glutamate uptake and release in 25 patients affected by migraine with aura (MA) and 25 patients affected by migraine without aura (MoA), comparing the results with a group of 20 healthy matched controls. Both glutamate release from stimulated platelets and plasma concentrations of the amino acid were assessed by high-performance liquid chromatography, and were increased in both types of migraine, although more markedly in MA. Platelet glutamate uptake, assessed as 3H-glutamate intake, was increased in MA, while it was reduced in MoA with respect to the control group. These results support the view that MA might involve different pathophysiological mechanisms from MoA and, specifically, up-regulation of the glutamatergic metabolism. Understanding these dysfunctional pathways could lead to new, possibly more successful therapeutic approaches to the management of migraine.

Cerebral venous thrombosis (CVT) was formerly considered a rare disorder, associated with an unfavorable outcome. More recent data based on modern imaging techniques, however, have changed our perception of this disorder. The use of angiography and, especially, MRI have allowed an early diagnosis and have proved that the incidence of CVT is, in fact, higher than previously thought, approximately 3-4 cases per million people per year, and that the majority of patients have a favorable outcome. At present, the most frequent causes are oral contraceptives assumption and pregnancy/puerperium; as a consequence, 75% of patients are females. CVT may cause isolated intracranial hypertension or lead to an ischemic stroke, which does not follow the distribution of an arterial vessel and has a relevant vasogenic edema. Venous strokes often have a hemorrhagic component, ranging from small petechiae to an actual intracerebral hemorrhage; the latter is associated with a worse clinical course. The clinical presentation of CVT is highly variable and includes patients with just a mild headache, others with focal neurological deficits and a few with a dramatic syndrome with coma; seizures are a frequent presenting symptom. The best radiological examination to confirm the suspicion of CVT is MRI of the brain, which can both demonstrate parenchymal lesions and directly show evidence of sinus occlusions. The available evidence suggests that anticoagulants are effective in reducing mortality and dependency in CVT patients; the possible role of systemic or localized thrombolysis is still to be established.