Abstract
Introduction: Cavum septi pellucidi (CSP) describes a septum pellucidum that has a separation between its two leaflets and contains cerebrospinal fluid. Multiple studies was held previously to evaluate the CSP and some of those studies consider it as a normal variant while the other consider it as a sign of midline brain developmental abnormality. The objective of our study was to assess the relation of CSP to other brain abnormalities and correlate this to its size and form of presentation.
Methods: We reviewed the neuroimaging studies of 1840 patients in our cross sectional study. A CSP was found in 85 (4.6%) of these patients. We graded CSP into three grades: I <1 cm3, II 1-2 cm3, III >2 cm3.
Results: Headache was the main presenting symptom in 44.7% of our patients sample (P<0.001). Patients less than 20 years old tend to have grade I CSP while grades II and III occurred more in patients older than 20 (P<0.001). 67.8% of patients with grade I show no associated brain abnormality
Conclusion: There is no significant predominance of one sex over the other to have CSP. Grade I was noted more in patients less than 20, some of them presented with developmental delay and seizures. Grades II and III were more common in patients older than 20, some of them presented with past history of tumors. Most of grade I patients show no other abnormality while most of patients with grades II and III show other abnormalities in their brain imaging.

Key words: Cavum septi pellucid, brain imaging, MDCT, MRI