Recruitment slow. Standard stroke patient management was changed (CT replacing MRI if NIHSS > 10). We closed the study to avoid bias (after 28 inclusions /out of 30 planned)

In this exploratory randomized double blind placebo controled trial, lactate solution or placebo will be administered to acute ischemic stroke patients selected for endovascular treatment (EVT) without intravenous thrombolysis. The treatment will be administered within one hour after EVT. Primary outcome measures will be lactate and metabolite concentrations in the ischemic lesion, in the penumbra and contralaterally, evaluated by magnetic resonance spectroscopy(MRS). Secondary outcome measures will be evolution of the ischemic penumbra, clinical outcome at 3 months.The trial will end when 10 patients per group have completed the study.

This is an exploratory randomized double blind placebo controled trial on acute ischemic stroke patients. Lactate solution or placebo will be administered to acute ischemic stroke patients selected for endovascular treatment (EVT) without intravenous thrombolysis. Magnetic resonance spectroscopy will be performed before EVT to measure metabolite concentrations in the ischemic core, penumbra and in the contralateral hemisphere. The treatment will be administered within one hour after EVT. As soon as the patient is stabilized, she/he will undergo an additional magnetic resonance imaging (MRI) with magnetic resonance spectroscopy (MRS). MRS will also be performed during the control MRI after 24 hours. Neurological deficits will be evaluated on admission, at 24 hours using the National Institute of Health Stroke Scale (NIHSS), and at 3 months, with both NIHSS and the modified Rankin scale. Primary outcome measures will be lactate and metabolite concentrations changes in the ischemic lesion, in the penumbra and the contralateral side, evaluated by magnetic resonance spectroscopy after intervention compared to baseline MRS values. Secondary outcome measures will be evolution of the ischemic penumbra and clinical outcome at 3 months. The trial will end when 10 patients per group have completed the study.

Inclusion Criteria:

• Acute ischemic stroke with arterial occlusion affecting middle cerebral artery (segment M1or segment 2) or internal carotid artery (T-type or L-type occlusion) selected for EVT
• not eligible for intravenous thrombolysis (IVT)
• Moderate to severe stroke (NIHSS > or = 4), and preadmission mRS > or = 3)
• Perfusion - diffusion mismatch
• Obtain consent from independent Doctor Randomisation criteria
• If possible oral consent from patient or relatives
• Treatment administration possible within 1h from EVT

Exclusion Criteria:

• Rapid neurological recovery
• Clinically unstable patient
• Contraindications to MRI
• Blood Na+ > 155 mmol/l or plasma osmolality > 320 mosmol/l
• Medical history of traumatic brain injury (TBI), neurodegenerative disease, intracranial hemorrhage, cerebral aneurysm, brain tumour
• Medical history of psychiatric disorders
• Liver insufficiency
• Heart failure
• Pregnancy (pregnancy test required in women aged under 50 unless patient or relatives indicate that the patient is not pregnant)
• Participation in another clinical trial in the last 30 days
• Lack of consent of an independent Doctor

Individual patient data will be made available 1 year after the end of the study to other investigators if the patient provides informed consent for further use of his/her data.

Numbered vials, prepared by hospital pharmacy