Observational Study of the Differences in Characteristics of the Spontaneous Electroencephalogram, Derived From the Left and Right Hemisphere in Patients With Unilateral Intracranial Tumor During Routine Anesthesia. Comparison With a Control Group Without Intracranial Pathology.

Inclusion Criteria:

- Adult ≥ 18 - 80 years old

- Able to comprehend, sign, and date the written informed consent document to
participate in the clinical trial

- Scheduled for "procedure"

- ASA Class I, II or III as assigned by the anaesthesiologist

Exclusion Criteria:

- Allergy or inability to tolerate "product"

- Body weight less than 70% or more than 130% of ideal body weight

- Pregnant or nursing females

- Participation in a clinical trial within the past 30 days

- Congenital mental disability or congenital anatomical brain abnormality

- A medical history of cerebrovascular accident or thrombosis

- A medical history of carotic artery occlusive pathology

- A medical history of degenerative cerebral pathology (MS, Dementia, ALS, para-or
tetraplegia due to a traumatic disruption of the spinal cord)

- A medical history of severe psychiatric pathology (Schizophrenia, severe depression,
alcoholism, drug abuse) Mild depression evoked by coping with the diagnosis of cancer
is not excluded

- Patients with a history of epileptic insults. Patients receiving preventive
anti-epileptic treatment due to the tumoral process are not excluded.

- Patients with low cardiac output conditions due to pre-existing cardiac pathology
(Cardiac insufficiency, valve pathology, dysrhythmia, myocardial infarction).
Patients presenting with stable coronary artery disease with a normal myocardial
function are not excluded)

- Arterial hypertension is not an exclusion criteria, nor is the use of
antihypertensive medication, except beta blockers for their potential interfering
effects on spontaneous EEG.