Different aquaporin-4 expression in glioblastoma multiforme patients with and without seizures.

Aquaporin-4 (AQP-4), the most important water channel in the brain, is expressed by astrocyte end feet abutting microvessels. Altered expression levels of AQP-4 and redistribution of the protein throughout the membranes of cells found in glioblastoma multiforme (GBM) lead to development of the edema often found surrounding the tumor mass. Dysregulation of AQP-4 also occurs in hippocampal sclerosis and cortical dysplasia in patients with refractory partial epilepsy. This work reports on analysis of the relationship between AQP-4 expression and the incidence of epileptic seizures in patients with GBM. Immunohistochemical and polymerase chain reaction techniques were used to evaluate AQP-4 in biopsy specimens from 19 patients with GBM, 10 of who had a history of seizures before surgery. AQP-4 mRNA levels were identical in the two groups of patients, but AQP-4 expression was more frequently detected on the GBM membranes from specimens of patients with seizures than from individuals without (10 versus 2, P < 0.001). We conclude that reduced expression of cell surface AQP-4 is characteristic of GBM patients without seizures, likely attributable to a posttranslational mechanism.

Endoscopic third ventriculostomy in idiopathic normal pressure hydrocephalus: an Italian multicenter study.

OBJECTIVES: The aim of the report is to define the indications and results of endoscopic third ventriculostomy (ETV) in idiopathic normal pressure hydrocephalus and to discuss the physiopathological mechanism of this procedure. METHODS: The cases of 110 patients with idiopathic normal pressure hydrocephalus who underwent ETV in four Italian neurosurgical centers were retrospectively reviewed. The postoperative outcome was correlated with patient age, length of clinical history, preoperative clinical score, symptoms of clinical onset, type of hydrocephalus, and intraoperative findings. RESULTS: The follow-up period ranged from 2 to 12 years (average, 6.5 yr). The outcome evaluation was made 2 years after the procedure. Postoperative clinical improvement occurred in 76 (69.1%) of 110 patients. There was no correlation between success rate and patient age or type of ventricular enlargement (normal or enlarged fourth ventricle). Conversely, the rate of neurological improvement was higher in patients with shorter clinical history, better preoperative neurological score, and clinical onset with gait disturbances. Moreover, the intraoperative finding of the sudden reappearance of normal cerebral pulsations and significant downward and upward movements of the third ventricular floor after ETV was also correlated with a good outcome. CONCLUSION: ETV results in a relatively high rate of clinical improvement and a low complication rate in patients with idiopathic normal pressure hydrocephalus. Therefore, it may be easily performed with the same approach used for intracranial pressure monitoring with low morbidity. However, our data must be confirmed by additional studies.