الفهرس 
Anterior Skull Base AnatomyOnly 14 pages are availabe for public view
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Abstract
This study included 30 patients with anterior skull base meningiomas operated in the period between October 2004 to March 2008 in the neurosurgery departments of Ain Shams University Hospitals.
There were 14 patients of olfactory groove meningiomas, 4 cases of planum sphenoidale meningiomas, 5 patients of tuberculum sellae meningiomas, and 7 patients of sphenoid wing meningiomas, (2 cases of clinoidal meningiomas, 3 patients with middle & outer thirds sphenoid wing meningiomas, and 2 patients with en-plaque sphenoid wing meningiomas).
The highest incidence of these tumors was found in the 5th and 6th decades of life and were more common in females than males in ratio of 3.3/1.
Headache was the most common clinical manifestation followed by visual deterioration, 50% patients of olfactory groove meningioma presented with frontal manifestations. Anosmia was another important clinical manifestation unique to olfactory groove meningioma and it passed unnoticed in some patients. Less common clinical manifestations were; seizures, diplopia, proptosis, unilateral motor weakness and amenorrhea.
MRI & CT scan were mandatory for proper diagnosis and visualization of these meningiomas and their relation to the neurovascular structures allowing planning of the best approach and follow up of the patients. CT scan was superior to MRI in delineating the bony anatomy and the pathological reaction in the skull such as hyperostosis and bony erosion. MRI was the diagnostic modality of choice in this study, it was helpful in delineating the relationship of the tumor to the neurovascular structures and it was very helpful in delineating the exact anatomical location of the tumor and its extent into different compartments .Preoperative angiography & MRA are important in delineating the position and the state of the neighboring vessels.
The average tumor size was significantly large 5.8 cm in olfactory groove meningiomas and significantly small in tuberculum sellae meningiomas 2.5 cm due to the proximity of the later to the optic nerve.
Four different surgical approaches were used. The choice of surgical approach depended on the tumor location, size and also the surgeon’s preference. The most common surgical approach used is the unilateral subfrontal approach used in (10 patients) followed by the pterional approach (8 patients), bilateral subfrontal approach (6 patients) & frontolateral approach (6patients).
Simpson grading system was used to assess the degree of tumor removal. Total removal was defined as Simpson grades (I or II). Subtotal removal was defined as Simpson grades (III or IV). Total removal was achieved in 23 patients (76.6%), and subtotal removal in 7 patients (23.3%), one of them died post operatively, the remaining 6 patients with subtotal excision still having a good chance of a good outcome due to the slow growth of these skull base meningiomas especially with the adjuvant use of the radiosurgery provided by gamma knife and linear accelerator. The use of microsurgical techniques considerably widens the possibilities for total surgical excision with decompression of the vital neurovascular structures.
There were statistically significant relations between the tumor size, vascular encasement and the severity of the brain edema to extent of tumor removal while there were no significant relation between the locations, the Histopathological types & surgical approaches to the extent of tumor removal.
Pathological examinations revealed: WHO grade I (benign) in 28 patients, grade II (atypical) in one patient, and grade III (malignant) in one patient.
Visual acuity improved in 66.7% of the patients and only one patient had post operative visual deterioration. There was significant relation between the degree of preoperative visual acuity and the rate of visual improvement, with better rates of improvement reported among those with good preoperative visual conditions. And there was significant relation between the visual outcome and the duration of visual complaint, patients with visual complaint less than one year had better visual outcome.
CSF rhinorrhea, diabetes insipidus, seizures, brain swelling, wound infection, pulmonary embolism, and intracerebral hematomas, anosmia were the complications encountered post-operatively in the patients. 2 patients died after surgery due to extensive cerebral infarction.
Karnofsky scale was used to evaluate the functional outcome. The median preoperative Karnofsky scale was 80, which improved to 90 postoperatively.
The patients were regularly followed up by neurological, ophthalmological and radiological examinations (CT& MRI). During the follow up, 2 patients had tumor recurrence one of them with atypical meningioma and the other one with malignant meningioma subjected to reoperation followed by fractionated radiotherapy.