Isolated Mega Cisterna Magna: A Preliminary Study from Eastern Iran

Background  The clinical significance and incidence of isolated mega cisterna magna (MCM) have been thoroughly investigated. While MCM has been reported in association with psychiatric disorders in adults, current study sought to report its incidence and relationship with gender and age in a consecutive series of patients without psychiatric comorbidities. Materials and Methods  We retrospectively reviewed 1,016 consecutive computed tomography scans of patients between the age of 1 and 80 with a history of minor head trauma, headache, or vertigo from April to August 2023. Two perpendicular diameters inside the MCM were measured: the first diameter (D ₁ ) was measured longitudinally on the midsagittal plane (anteroposterior diameter), whereas the second one (D ₂ ) was measured transeversely (transverse diameter). An MCM with D ₁ > 20 mm was defined as "huge MCM." The relationship between age, gender, and the two diameters were subsequently analyzed. Results  Over a course of 5 months, 92 cases with MCM, including 76 men, were evaluated. The mean age of MCM cases was 35.31 ± 26.14, with no significant relationship observed between age and MCM. No significant difference in D ₁ was found between genders, while D ₂ significantly differed between men and women ( p  < 0.029). "Huge MCM" was exclusively observed in 18 men ( p  < 0.035). There was also no significant correlation between D ₁ and D ₂ . Conclusion  MCM appears to be a normal variation in the general population with no clinical significance. Despite the small sample size, the current study can provide a foundation for further studies to investigate the correlation of isolated MCM with different aspects of cognitive functions and its potential clinical relevance.