Meningiomas: clinical correlates, skull x-ray, CT and pathological evaluations.

Objective: To assess the frequency and the diagnostic performance of plain skull x-ray and and CT of meningiomas.

Methods: All pathologically diagnosed intracranial meningiomas in patients seen at Tikur Anbessa Hospitals were reviewed.

Results: Between December 1999 and July 2004 there were 25 histologically diagnosed cases of meningioma at the Tikur Anbessa Hospital (TAH). The duration of symptoms was ranging from 0.5-10 yrs. (mean 2.4 +/- 2.1 yrs) and age ranging from 21-57 yrs (mean age of 49.3 +/- 10 yrs.) with M:F ratio of 1.2:1. Blurring of vision was the commonest clinical presentation. Clinical correlates, skull x-rays, computerized tomographic results and pathology are evaluated. Plain skull x-ray findings were normal in 12/23 (52%); 10/23(43%) of the cases had non-specific sellar changes of raised intra-cranial pressure. Twenty-three of the 25 meningiomas had CT scanning done, and CT diagnosed 17/23 (74%) meningiomas correctly. Two meningiomas were unusual in location: one was intranasal and the other was intra-ventricular. Parasellar tumors were frequent sites of misdiagnosis. The commonest locations were parasellar and cerebral convexity, each accounting for 6/25 (24%) of the cases. The commonest CT observation was intense and homogeneous enhancement 15/23 (65%). Meningothelial meningioma was the commonest cellular type accounting for 11/25 (46%) of the pathologies followed by the transitional 4/25 (16%) and the atypical and psammomatous types, each with equalfrequency, 3/25 (12%).

Conclusion: CT scan had a diagnostic accuracy of 83%, sensitivity of 74%, specificity of 95%, positive predictive value (PPV) of 95%, and negative predictive value (NPV) of 75%. Statistical analysis verifies the pre-operative reliability for diagnosing meningiomas by CT scanning.