Efficacy of ultrasound-assisted pterygopalatine block using a posterior-to-anterior subzygomatic approach in eye enucleation: a prospective randomized comparative study

Background: Pterygopalatine block (PPB) is widely indicated in ophthalmology due to its simultaneous impact on sympathetic, parasympathetic, and nociceptive innervation. Ultrasound (US) guidance enhances block accuracy; however, clinical data on the efficacy of US-assisted PPB using different approaches remain limited. Aim: To compare the efficacy of US-guided PPB using posterior-to-anterior subzygomatic and suprazygomatic approaches in patients undergoing eye enucleation. Materials and methods: A prospective randomized study was conducted. For postoperative analgesia, PPB was performed in Group 1 (n=30) using the posterior-to-anterior subzygomatic approach and in Group 2 (n=30) using the suprazygomatic approach. The time required to perform the block, onset of analgesia, changes in arterial blood pressure (BP) and heart rate (HR), and technical aspects of block execution were evaluated. Results: The interval between block administration and the onset of analgesia was significantly shorter in Group 1 (5.3±1.0 minutes) compared to Group 2 (10.1±1.4 minutes, p=0.041). Significant differences were also observed in the time to decreased skin sensitivity in the infraorbital area and time to pain relief: 8.9±0.9 and 13.5±0.7 minutes in Group 1 versus 14.4±1.2 and 19.6±1.7 minutes in Group 2 (p=0.037 and p=0.034, respectively). Mean arterial pressure and HR were lower in Group 1 (91.2±6.5 mmHg and 88.5±5.2 bpm) compared to Group 2 (101.1±6.6 mmHg and 105.3 ± 8.4 bpm, p=0.001). During the suprazygomatic PPB (Group 2), 53.3% (n=16) of patients reported discomfort, with a mean pain score of 2.3±0.5 on the numeric rating scale. Conclusion: For managing pain after eye enucleation, ultrasound-assisted PPB using the posterior-to-anterior subzygomatic approach is the method of choice. Compared to the suprazygomatic approach, it provides faster onset of effective analgesia, greater patient comfort, and improved safety.