The Effect of Head Position on the Optik Nerve Sheath Diameter in Patients During Thyroid Surgery

Aim: In thyroidectomy surgery, the patient's head is placed in hyperextension and the patient is placed in a semi-sitting position to facilitate access to the surgical site. This position of the head causes a decrease in venous return or partial obstruction of venous return due to stretching of the neck veins. The aim of our study is to demonstrate the effect of surgical position on intracranial pressure by measuring the optic nerve sheath diameter (OSSD) using ultrasonography in patients undergoing thyroid surgery and to determine its correlation with post-operative headaches.

Material And Method: Our study was conducted prospectively and randomly in patients undergoing elective total thyroidectomy. Patients aged 18-65 with an ASA score of 1-2 and an operation time of less than 4 hours were included in our study. Patients were positioned in the semi-Fowler position with a 30° extension of the head. Bilateral OSSD surgical positioning was applied, and after ensuring haemodynamic stability for 5 minutes and at the end of the operation, measurements were taken twice using ultrasound, and the average was recorded. The Visual Analogue Scale (VAS) was used to assess postoperative pain intensity. Headache was assessed and recorded at 15 minutes, 30 minutes, 1 hour, 24 hours, 3 days, and 7 days postoperatively.

Inclusion criteria

• Patients aged between 18 and 65, with an ASA score between 1 and 2 according to the American Society of Anesthesiologists (ASA) physical status classification system
• whose surgery duration was expected to be less than 4 hours were included in our study.

Exclusion criteria

• liver failure
• kidney failure
• intracranial masses
• history of hydrocephalus,
• migraine
• chronic hypoxemia or hypercarbic lung disease
• additional heart disease
• hemodynamic insufficiency
• neurological and psychiatric diseases,
• glaucoma
• patients in whom ocular USG could not provide adequate images
• patients with pathological problems involving the eyelid and its surrounding area
• patients with diseases such as periorbital cellulitis
• patients with preoperative headache complaints
• patients with known diseases that could cause increased intracranial pressure
• patients who refused to participate in the study were excluded from the study.