Effect of Optıc Nerve Dıameter ın Tymphanoplasty Surgery Performed ın Lateral Head Posıtıon Under General Anesthesia
Phase: NA
Conditions: Optic Nerve Diameter, Intracranial Pressure Increase
Sponsor: Bursa Yuksek Ihtisas Training and Research Hospital

OFFİCİAL TİTLE OF THE STUDY : 
EFFECT 
OF 
OPTİC 
NERVE 
DİAMETER 
İN 
TYMPANOPLASTY 
SURGERY PERFORMED İN LATERAL HEAD POSİTİON UNDER 
GENERAL ANESTHESİA 
 
NCT number (not  available) 
 
Document Date:      2020-01-12 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
RESEARCH PROTOCOL 
Official Title: 
 EFFECT OF OPTİC NERVE DİAMETER İN TYMPANOPLASTY SURGERY PERFORMED İN LATERAL HEAD 
POSİTİON UNDER GENERAL ANESTHESİA 
Research basis and rationale:  
Ultrasonography for optic nerve diameter (ONSD) measurement is a non-invasive, rapid, and easily 
applicable method for diagnosing intracranial pressure changes. In tympanoplasty surgery cases, the 
head and neck remain in a lateral position, and venous return can sometimes be compressed in the 
surgical field due to the procedure 
Research objective:  
The aim of this study is to determine the effect of lateral head position and variables such as 
demographic data and surgical duration on the increase in intracranial pressure. 
Research methodology: 
Patients over 18 years of age with ASA I and II who were to undergo tympanoplasty surgery in lateral 
head and neck position under general anesthesia(GA) were included. Patients' perioperative vital 
signs (arterial blood pressure, heart rate, sPO2, and EtCO2) were monitored routinely in the 
operating room. Demographic data (age, gender, weight, height), surgical duration, and 
perioperative complications were also recorded. Anesthesia was administered with propofol 2-4 
mg/kg, rocuronium 0.6 mg/kg, and fentanyl 1-2 mcg/kg for induction, and sevoflurane for 
maintenance. Following intubation, ONSD  measurements were taken in three time intervals by the 
anesthesiologist: transverse and sagittal planes. Both ONSDs were recorded by ultrasound at T1: 5 
min in supine position, T2: end of the procedure with head in lateral position, and T3: supine position 
before extubation. Postoperative headache and neck pain were questioned upon awakening, and at 
1, 6, and 24 hours.  
Statistical methodology: 
Data were analyzed using Jamovi software (version 2.6.24). Descriptive statistics are presented as 
mean ± standard deviation (SD) for continuous variables and as frequencies and percentages for 
categorical variables. 
For the primary outcome, optic nerve sheath diameter (ONSD) measurements obtained at three time 
points (T1: post-intubation, T2: lateral head position during surgery, T3: supine position before 
extubation) were analyzed using repeated measures analysis of variance (ANOVA). Post-hoc 
pairwise comparisons were conducted to identify specific differences between time points, with 

Bonferroni correction applied for multiple comparisons. 
To investigate factors affecting ONSD changes, the relationship between surgical duration and 
temporal ONSD variations was examined. Patient age, body mass index (BMI), and surgical side 
(right vs. left ear) were also evaluated for their effects on ONSD. 
To compare ONSD changes between ipsilateral and contralateral eyes relative to the surgical side, a 
mixed-design ANOVA was performed with Time (3 levels: T1, T2, T3) and Eye (2 levels: right, 
left) as within-subjects factors and Surgical Side (2 levels: right ear, left ear) as a between-subjects 
factor. 
Statistical significance was set at p &lt; 0.05 for all analyses. 
An a priori power analysis was performed using G*Power (version 3.1.9.7) for a repeated measures 
ANOVA with time as the within-subject factor (three measurements). Effect size estimation was 
based on pilot data (mean ONSD values: 5.27, 5.57, and 5.40 mm), yielding an estimated effect size 
of f = 0.45. Assuming an α level of 0.05, a power of %95, three repeated measurements, and a 
correlation among repeated measures of 0.5, the minimum required sample size was calculated as 
18 patients.