Abstract
Introduction: High-resolution postmortem magnetic resonance imaging (MRI) is increasingly used to assess anomalies and can serve as a complementary tool to conventional autopsy. The main aim of this study was to detect and measure the diameter of cranial nerves across gestation. Methods: This observational study was conducted at a tertiary referral hospital and included 150 fetuses from 14 to 28 weeks of gestation with normal brain findings. Results: The optic nerve was identified the earliest at 15 weeks, with a mean diameter of 0.62 mm at 15 weeks and 1.49 mm at 27 weeks. The oculomotor nerve was identified earliest at 21 weeks, with a mean diameter of 0.94 mm at 21 weeks and 1.21 mm at 27 weeks. The trigeminal nerve was seen earliest at 21 weeks, with a mean diameter of 0.9 mm at 21 weeks and 1.2 mm at 27 weeks. The cranial nerve VII-VIII complex was seen earliest at 18 weeks, with a mean diameter 0.9 mm at 18 weeks and 1.14 mm at 27 weeks. Cranial nerve IX-X-XI was identified earliest at 24 weeks, with a mean diameter of 1.03 mm at 24 weeks and 1.15 mm at 27 weeks. Conclusion: High-resolution postmortem MRI enables visualization and measurement of fetal cranial nerves II, III, V, VII-VIII, and IX-X-XI, whereas cranial nerves I, IV, VI, and XII were not identifiable in our cohort. These findings provide normative reference data for the assessment of fetal cranial nerves in postmortem studies.