The study aims to show the effects of interscalene brachial plexus (ISBP) block on intracranial pressure by measuring optic nerve sheath diameter (ONSD) and internal vein collapsibility index (IJV-CI).

40 is the targeted number of patients who are going to have humerus fracture or opened rotator-cuff surgery. Single shot-ISBP block with 25 ml local anesthetic will be performed as anesthetic approach for surgery to all participants. Intraoperative ONSD and IJV-CI measurements will be performed before the ISBP block, 20 minutes and 60 minutes after the block. Hypothesis; external drug-volume effect on internal jugular vein causes decreasing maximum diameter of internal jugular vein (Dmax), venous return from cranium to heart decreases, intracranial pressure can increase.

Inclusion Criteria:

• Patients who had elective humeral fracture and open rotator-cuff surgery,
• Patients aged 18-85 years,
• Patients have ASA I-II anesthesia risk according to the American Society of Anesthesiologists (ASA) risk classification,
• Patients that gave consent for participation in the study will be included.

Exclusion Criteria:

• Patients who do not give consent to the study,
• Patients with infection and open wounds in the area of skin puncture and eyelids,
• Patients have any history of intracranial pathology,
• Patients have nerve blockade contraindications such as coagulation disorder and antithrombotic-anticoagulant use,
• Patients have a history of allergy to one of the study drugs,
• Patients have a body mass index over 35 kg/m2,
• Patients with contralateral pneumothorax,
• Patients with severe respiratory distress,
• Patients with uncontrolled hypertension,
• Patients with acute or chronic eye disease,
• Patients with previous eye surgery,
• Patients using a beta-blocker known to increase intraocular pressure,
• Patients using calcium channel blockers, statins and nitrates,
• Patients in need of intraoperative sedation,
• Patients who develope any complications (hoarseness, horner's syndrome, respiratory distress, local anesthetic toxicity) due to ISBP block will be excluded from the study.