1. 2025;28;E191-E198Correlation Between Meckel’s Cave Size and lohexol Dosage in Percutaneous Microballoon Compression for Trigeminal Neuralgia of Aged Patients
   Retrospective Study
   Yong Yu, MM, Jing Wang, MD, Chuanxi Peng, MB, Chengxing Qian, MM, Renbo Shen, MM, Yanqing Zuo, MB, Weibang Liang, PhD, Jie Chen, MB, and Yulong Chong, MD.

BACKGROUND: Percutaneous microballoon compression (PMC) is a safe and effective method (1) for treating trigeminal neuralgia (TN). Though many surgeons have carried out this kind of surgery, practitioners who lack sufficient surgical experience may be unaware of this method of improving the clinical effectiveness of PMC for aged patients.

OBJECTIVE: To investigate the relationship among the success of the PMC method, the size of a patient’s Meckel’s cave (MC), and the iohexol dosage in a pear-shaped balloon and form a mathematical model for the effectiveness of the treatment.

STUDY DESIGN: Retrospective study.

SETTING: Neurosurgery Department of Tongling People’s Hospital, China.

METHODS: One hundred eighteen patients (34 men and 84 women) undergoing PMC, aged 72.07 ± 7.10 years old, were collected retrospectively in the study. Fifteen of the patients were in Tongling People’s Hospital from September 2022 to March 2024, and 103 were in Nanjing Drum Tower Hospital from January 2023 to October 2023, The sizes of all the patients’ MCs were measured by 3D-Slicer software with preoperative cranial magnetic resonance imaging (MRI); all balloons were of the standardized pear shape, and intraoperative iohexol dosages were recorded. The patient’s score on the Barrow Neurological Institute pain scale (BNI-P) was recorded at 3 time points: before the surgery (Pre_BNI), the first day after the surgery (BNI_1), and the seventh day after the surgery (BNI_7). Correlation analysis was carried out to determine the association between the intraoperative iohexol dosage and MC size.

RESULTS: The overall effective rate of PMC was 97.46% (115/118). During the first postoperative day, 3 patients reported feeling pain scores of V on the BNI-P scale. None of the other patients reported an experience of pain. At the 7th day of post-operation, those 3 patients still felt no pain relief, whereas the others continue not to experience pain. There was a significant correlation between iohexol dosage (unit: mL) and MC size (expressed as MC volume, unit: mm3): iohexol dosage (mL) = 0.54336 + 0.00060286 x MC Volume (mm3) - 0.05654 x BNI_1*. ( *The scores from 1 to 5 are equivalent to I to V on the BNI-P.)

LIMITATIONS: The study was retrospective, so we could not validate the accuracy of the model by analyzing the iohexol dosage used in the operation; additionally, the duration of the follow-up was short, and the sample size was relatively small.

CONCLUSIONS: The equation (iohexol dosage = 0.54336 + 0.00060286 x MC Volume - 0.05654 x BNI_1) yields a value at which operations have a very high success rate, regardless of whether the patients have received previous TN treatment. The equation can be used to guide the intraoperative usage of iohexol and to help surgeons without sufficient surgical experience for predicting patients’ prognoses.

KEY WORDS: Trigeminal neuralgia, percutaneous microballoon compression, iohexol dosage, 3D Slicer, Meckel’s cave