الفهرس 
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Abstract
Meningioma is the most common benign intracranial tumor. It is an extra-axial tumor that arises from the arachnoid cap cells. It has a gradual onset of symptoms related to mass effect. It has different locations including parasagittal, olfactory groove, convexity, falcine and posterior fossa locations.
Olfactory groove meningiomas (OGMs) account for 8 to 13 % of all intracranial meningiomas. It arises in the midline over the cribriform plate and frontosphenoid suture and occupies the floor of the anterior cranial fossa extending all the way from the crista galli to the tuberculum sella.
Olfactory groove meningiomas can grow insidiously large and present as one of the largest intracranial tumors. Tumor size has been categorized by neuroimaging evaluation. The classification includes small (0–2 cm in diameter), medium (2–4 cm diameter) large (4–6 cm diameter) and giant (>6 cm in diameter).
According to the WHO classification, meningioma can be of type I, which is the benign form, type II usually referred to as the atypical meningioma and type III, which is the malignant meningioma. Meningioma is mostly a benign tumor that can be cured completely with surgical resection. The extent of surgical resection is classified according to the Simpson grading system
Several surgical approaches can be applied for resection of olfactory groove meningiomas including the traditional frontal or bifrontal approach, the pterional approach and transnasal endoscopic approach. More aggressive approaches have been proposed for resection of OGMs expanding into the paranasal sinuses and orbits, including transbasal, subcranial, and fronto-orbital approaches, frontal or bifrontal craniotomy combined with orbital or nasal osteotomies, and craniofacial resection.
The classic subfrontal approach for olfactory groove meningiomas, introduced by Seeger, is one of the most commonly used approaches, the craniotomy usually large enough to accommodate the occurrence of brain edema, it facilitates the harvesting of a large fascia graft for frontal skull base reconstruction, and early devascularization of the tumor however, a disadvantage of this approach is the late visualization of the optic nerves and the anterior cerebral complex.
The aim of the study is to assess the bilateral subfrontal approach in the surgical management of olfactory groove meningioma as regard the degree of surgical exposure (bounders of the tumor and its relation to the adjacent neurovascular structures), the extent of tumor removal and the incidence of perioperative complications.
This prospective study included forty patients with olfactory groove meningioma. These patients were operated upon in Alexandria University Hospital, via the bilateral sub-frontal approach in the period between 2015 and 2018 with follow up period of one year after surgery.
This study was done on 40 patients, 28 were females (70%) and 12 were males (30%). Ten patients (25%) there ages between 21-40 years, 24 patients (60%) there ages between 41-60 years and 6 patients (15%) there ages ≥ 61 years with the mean age (49.78 years).
The youngest patient was 26 years old female and oldest was a female as well 68 years old.
The most common compliant on admission was headache which was seen in 36 patients (90%). The duration of headache according to patient’s history ranged from 1 month to 6 years. The second most common complaint was anosmia in 32 patients (80%), 18 patients had papillodema (45%), 12 patients (30%) had visual impairment, 10 patients (25%) had behavioral changes, 7 patients (17.5%) had seizures and 5 patients (12.5%) had foster kennedy syndrome.
Three patients (7.5%) the tumor diameter was between 2-4 cm, 26 patients (65%) the tumor diameter was between 4-6 cm and 11 patients (27.5%) the tumor diameter was >6 cm with the mean diameter 5.42 cm. The minimum tumor diameter is 3.5 cm and the maximum tumor diameter is 6.8 cm.
Four patients (10%) had postoperative tumor bed hematoma, one patient needed surgical evacuation to the hematoma and the others managed conservatively. Two patients (5%) had postoperative behavioral changes which improved spontaneously within two months. Three patients (7.5%) had postoperative CSF rhinorrhea which stopped in all after repeated lumbar drainage. Four patients (10%) had postoperative anosmia. Two patients (5%) had postoperative seizure which controlled with antiepileptic drugs. Three patients (7.5%) had postoperative optic nerve injury. Four patients (10%) had postoperative infection which responded well to appropriate antibiotic treatment.
One patient died in this study was female having large OGMs (6.8 cm) with massive edema. She had postoperative seizure and large tumor bed hematoma which needed surgical evacuation and stayed in ICU for 10 days during which had infection, CSF rhinorrhea and died.
The bilateral subfrontal approach is a simple, safe and wide approach for OGMs. This approach provides excellent opportunity for radical resection of large OGMs and drilling of hyperostosis in the cribriform plate area. Reconstruction of the cranial base is ideal through this approach which minimizes the risk of CSF leak.