Sodium Lactate and Brain Relaxation (LSD)

Resection surgery of brain tumors by craniotomy requires efficient brain relaxation intraoperatively in order to avoid injuries caused by the brain retractors (such as ischemic-reperfusion and cerebral oedema). The gold standard for the brain relaxation during a surgery is Mannitol 20%.

Molar sodium lactate is now used to induce brain relaxation in patients with traumatic brain injury and intracranial hypertension due to its osmotic effect. Furthermore, the injection of sodium lactate may lead to better neuronal metabolism during cerebral aggression, and may participate to the reduction of cerebral oedema and secondary injuries.

LSD is a pilot randomised trial which tries to assess the interest of intravenous administration of molar Sodium Lactate on the quality of brain relaxation in surgical resection of supratentorial brain tumors by craniotomy.

The primary outcome measure is the quality of brain relaxation, evaluated by neurosurgeon at the opening of the dura, by a validated brain relaxation scale.

It's a prospective, comparative, randomised, double blinded study. It will enroll 50 patients undergoing resection surgery of supratentorial brain tumor. They will be randomly divided in 2 groups of 25 patients each : Mannitol 20% and molar Sodium Lactate. The only difference between the 2 groups is the drug used for brain relaxation at the surgical incision : Mannitol or Sodium lactate.

The outcome measures include quality of brain relaxation, need of "rescue" therapy to get an adequate brain relaxation, electrolytes alterations, change in lactate serum level, quantification of post operative brain swelling by MRI, time of extubation, Glasgow Coma Scale, neuropsychological evaluation, blood levels of Protein S100-β, NSE (Neuron-Specific Enolase) and GFAP Glial Fibrillary Acid Protein), morbidity and mortality during 30 days after surgery.

Eligibility Criteria:
Inclusion Criteria:

* Patients with ASA 1, ASA 2 ou ASA 3, meaning they don't have any unstable comorbidities which could be a threat to life.
* Scheduled surgery for resection of supratentorial brain tumors by craniotomy under general anesthesia
* Unilateral brain tumor
* Deviation of the falx cerebri \> 3mm on the preoperative imaging
* Pharmacological brain relaxation required by the neurosurgeon in charge of the patient.
* Patient who has been informed and who signed the free informed consent to participate to the study. Meaning the patient understood the purpose and the procedures required by the study and agreed to participate and obey the requirements and restrictions of this study.
* Affiliation to a social security system or recipient of a such system.

Exclusion Criteria:

* Emergency surgery
* Age \< 18 years old or \> 75 years old
* ASA score IV-V
* Legal incapability or limited legal capacity
* Patient who will unlikely cooperate to the study and/or poor cooperation foreseen by the investigator
* Preoperative Glasgow score \< 13
* Pregnant woman and/or breastfeeding
* Body index masse\< 18 kg.m-2 ou \> 30 kg.m-2
* Preoperative hyponatremia \< 130mmol/l or hypernatremia \> 145 mmol/l
* Osmotherapy in the 24 hours prior to the surgery (Mannitol, Hypertonic saline, Sodium lactate)
* Congestive heart failure
* Moderate ou severe chronic kidney disease, defined by a creatinine clearance (MDRD) \< 60 ml/min
* End-stage liver disease (Child Pugh ≥ B7)
* Myasthenia gravis
* External ventricular drain or ventriculoperitoneal shunt of cerebrospinal fluid
* Allergy to Mannitol 20% or one of his excipients
* Allergy to Sodium Lactate or one of his excipients
* Contraindication for propofol
* Allergy to anesthetic agents (propofol, remifentanil, cisatracurium)
* Refusal of consent
* Patient within the exclusion period of another study or planned by the "national file of volunteers"
* Medical history of cognitive disorders or demencia