Abstract
Aim: The present study aimed to find range of fourth ventricle indices, their variation with age and gender and to correlate these indices with the cerebrum dimensions in apparently normal patients.
Material And Methods: With the Institutional ethical committee clearance, soft copies of head CT scans of hundred patients (50 males, mean age 33.77+/-15.06 yrs; and 50 females, mean age 36.22 +/- 11.4 yrs) were subjected to morphometric analysis of fourth ventricle’s length (AP-4) and width (W-4) using dicom image software. Mean, standard deviation, ranges and 95% confidence intervals were calculated. Two sample independent student t -test, Pearson’s correlation coefficient and Regression analysis were applied to find the gender variation, correlation with diameters of cerebrum and correlation with age respectively at 0.05 significance level.
Results : Mean AP-4 was 7.24 +/- 2.18 mm with 95% CI being 6.81 to 7.67 mm. Mean W-4 was 13.70+/- 2.26 mm with 95% CI being 13.25 to 15.15 mm. Length showed non-significant correlation with AP (r=0.087, p=0.54) and with TD (R=0.18, P=0.21). Width showed negative correlation with anteroposterior diameter (r= -0.08, p=0.54) but positive correlation with transverse diameter of cerebrum (r=0.25, p= 0.08). Length showed almost nil correlation with age whereas width showed negative correlation with age (t stat = -1.68, p = 0.09).
Conclusion: Diameters of cerebrum and 4th ventricle width were significantly higher in males. 4th ventricle width showed maximum correlation with transverse diameter of cerebrum. 4th ventricle length does not depend upon age but width decreases with age.

Key words: 4th ventricle indices, AP-4, W-4, cerebrum diameters.