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The patient came to the clinic 25-February-2004 complaining of severe headache for several months and blurred vision lat month with anosmia.


MRI brain with  contrast done 14-February-2004 showing huge olfactory groove meningioma more to the left with massive edema over the left cerebral hemisphere.


On examination: The patient has anosmia with decreased visual functions more the left eye with scatomas. She had episodes of vomiting the last 2 weeks. The patient has epiattacks and she felt down in the bathroom one week ago.


Modified left bifrontal craniotomy done with reflection of the bone flap to the left ear. The brain is severely swollen and all measures to decrease the swelling failed. Trying to minimize the traction injury, the tumor was approached and piece-meal resection was achieved. Total resection of the mass was done, but the brain swelling persisted. The wound was closed, so that the dura was not pushing the brain. The patient was extubated and sent to the ICU. The patient still drowsy and she was sent for control CT-scan of the brain, which revealed very huge occipital hematoma. The patient was taken to the operating room and the hematoma was evacuated, after what good recovery was achieved.


Clinical Features
These tumors arise from the midline of the anterior fossa between the crista galli and the tuberculum sellae. They are usually bilateral but may be asymmetric and attain a large size before causing symptoms. The most common presenting symptom is a subtle change in mental function or headache alone or in combination with mental function change, but a disturbance in vision or a seizure disorder may also be the initial manifestation. Loss of the sense of smell was recorded as "possibly" the primary symptom in only 3 of 28 patients in Cushing's series, and he questioned the reliability of this finding.
MRI clearly defines the extent of the tumor, the edema in the surrounding brain, the relationship of the tumor to the optic nerves and anterior cerebral arteries, and any extension into the ethmoid sinus. Angiography is rarely needed.
Surgical Management
In planning the operation, it is important to remember that the blood supply comes into the tumor through the bone in the midline of the anterior fossa from branches of the ethmoidal, middle meningeal, and ophthalmic arteries; the posterior capsules may be attached to the optic nerves, chiasm, and anterior cerebral arteries. For patients with a large tumor, It is preferable to perform a bifrontal craniotomy. This approach is associated with the least amount of retraction on the frontal lobes, gives direct access to all sides of the tumor, and allows the surgeon to decompress the tumor while working along the base of the skull to interrupt the blood supply. For smaller tumors, a right subfrontal approach coming from laterally over the orbital roof, as for tuberculum sellae meningioma, may be used. Some uses a pterional approach. Others use either exposure and may resect part of the frontal lobe. The patient is placed carefully in the supine position with the head elevated and slightly extended. Using a coronal incision, the skin flap and underlying tissue, including pericranial tissue, are turned down together. Burr holes are placed just below the end of the anterior temporal line and on each side of the sagittal sinus at the level of the skin incision. The cut just above the supraorbital ridge is made from each side as far medially as possible. Usually this leaves a centimeter or less of bone in the midline. Because of the irregular bone projecting from the inner table of the skull in this area, it is often not possible to cut completely across the area, but the external table can be cut with a fine drill attachment and the bone can be broken at this point. The frontal sinuses are almost always entered. The mucosa is removed and the sinuses are packed with bacitracin-soaked Gelfoam. A flap of pericranial tissue from the back of the skin flap is turned down over the sinuses and sewn to the adjacent dura. The dural incision is made over each medial inferior frontal lobe just above the edge of the craniotomy opening. While the frontal lobes are retracted carefully, the superior sagittal sinus is divided between two silk sutures and the falx is cut. The frontal lobes are then retracted carefully laterally and slightly posteriorly. The tumor will come into view in the midline; at times it is found to have grown into the region of the crista galli and falx. The anterior capsule of the tumor is exposed, and then an extensive internal decompression is done. The base of the tumor in the midline is gradually divided, interrupting the blood supply that is coming in through numerous openings in the bone. These are occluded with coagulation and bone wax. The capsule can now be reflected into the area of the decompression without undue pressure on the frontal lobes. Great care is taken during the dissection of the posterior portion of the capsule. The surgeon reflects it anteriorly and is careful to look for the pericallosal branch of each anterior cerebral artery. The frontal polar branch will often be adherent to the tumor and may need to be divided. It is usually possible to follow the capsule back to the sphenoid wing and then, working medially, to identify the anterior clinoid processes and the optic nerves. At times it may be difficult to see the nerves because of the posterior and inferior compression and the thickened arachnoid. However, under magnification, the tumor can be reflected off the optic nerve(s). Once the bulk of the tumor is removed, the dural attachment is totally excised and any bone hyperostosis removed, with care taken to avoid entering the ethmoid sinus unless it is known that the tumor extends into the sinus. The region of the cribriform plate is covered with a graft of pericranial tissue and Gelfoam to prevent a cerebrospinal fluid (CSF) leak.
Complete removal can be achieved in 90% of cases and 5% with a radical subtotal removal with a small fragment left on the internal carotid artery or other vitally important structures. In 90% of patients a good result can be achieved. Postoperative death due to various causes is around 5%.
The incidence of complications is low and do not interfere with eventual recovery. CSF leak through the ethmoid sinus that required transethmoidal repair can be in 5% of cases. A wound infection also 5%, A subdural hygroma requiring a subdural-peritoneal shunt in 5%. Disturbance in mental function and personality changes when present preoperatively or transiently in the postoperative period usually recover completely. Preoperative visual symptoms usually recover and headache is relieved.
A systematic investigation of long-term follow-up results after microsurgical treatment of patients harbouring an olfactory groove meningioma, particularly with regard to postoperative olfactory and mental function, has rarely been performed. We reassessed a series of patients treated microsurgically for an olfactory groove meningioma in regard to clinical presentation, surgical approaches and long-term functional outcome. Method. Clinical, radiological and surgical data in a consecutive series of 56 patients suffering from olfactory groove meningioma were retrospectively reviewed.
Findings. Presenting symptoms of the 41 women and 15 men (mean age 51 years) were mental changes in 39.3%, visual impairment in 16.1% and anosmia in 14.3% of the patients. Preoperative neurological examination revealed deficits in olfaction in 71.7%, mental disturbances in 55.4% and reduced vision in 21.4% of the cases. The tumour was resected via a bifrontal craniotomy in 36, a pterional route in 13, a unilateral frontal approach in 4 and via a supraorbital approach in 3 patients. Extent of tumour resection according to Simpson’s classification system was grade I in 42.9% and grade II in 57.1% of the cases. After a mean followup period of 5.6 years (range 1–13 years) by clinical examination and magnetic resonance imaging (MRI), 86.8% of the patients resumed normal life activity. Olfaction was preserved in 24.4% of patients in whom pre- and postoperative data were available. Mental and visual disturbances improved in 88 and 83.3% of cases, respectively. Five recurrences (8.9%) were observed and had to be reoperated.

Frontal approaches allowed better resection of tumours with gross infiltration of the anterior cranial base, tumours extending into the ethmoids or nasal cavity and in cases with deep olfactory grooves. Preservation of olfaction should be attempted in patients with normal or reduced smelling preoperatively.
Meningiomas of the midline anterior skull base include tumours originating from the dura of the cribriform plate, planum sphenoidale and tuberculum sellae and account for about 10% of all intracranial meningiomas [41]. For clinical, radiological and surgical purposes true olfactory groove meningiomas, i.e. tumours originating from the dura between the crista galli and the frontosphenoid suture should be differentiated from planum sphenoidale and tuberculum sellae meningiomas [8, 32]. Tumours arising from the latter sites usually come to clinical attention at an early stage with visual deterioration, while this is a late feature in olfactory groove meningiomas which usually remain clinically quiescent during the early phase of growth. Anatomically, olfactory groove meningiomas arise from the weakest part of the skull base, the cribriform plate, which makes them prone to infiltrate the underlying bone and extend into the paranasal sinuses and nasal cavity. This is a rare feature in planum sphenoidale or tuberculum sellae meningiomas.
A systematic assessment of functional outcome after resection of olfactory groove meningiomas, particularly in respect to olfactory function, has rarely been performed [3, 30, 46]. We retrospectively analyzed meningiomas with a predominant origin from the dura of the cribriform plate with regard to clinical presentation, different surgical approaches and follow-up results which were treated microsurgically in our institution.
Patients and methods
From June 1990 till June 2003, an olfactory groove meningioma was microsurgically resected in 56 consecutive patients in our department. The medical charts, surgical records and radiological studies were retrospectively reviewed in these patients. Only tumours with a primary origin from the dura of the cribriform plate were included in this report. Lesions with a predominant dural origin from the planum sphenoidale, tuberculum sellae, anterior clinoidal process or orbital roof were not considered in this series.
Radiological studies
Magnetic resonance imaging (MRI) was obtained preoperatively in all patients and clearly demonstrated the relationship of the tumour with the optic nerves, chiasm and the anterior cerebral arteries (ACA). These vessels were encased by the tumour in three patients. A significant bifrontal or unilateral edema was displayed on MRI in 34 patients. CT with bone algorithms, performed preoperatively in 23 patients revealed a hyperostosis of the crista galli or the cribriform plate in six and erosion of the cribriform plate in four cases. Cerebral angiography was performed regularly early in the study period to demonstrate tumour vascularity, provide information regarding ACA displacement and to evaluate the possibility of preoperative embolization. In all 23 cases studied angiographically, the tumour was predominantly supplied by the anterior or posterior ethmoidal branches of the ophthalmic artery and preoperative partial embolization was performed in two patients with occlusion of the anterior branch of the middle meningeal artery. Angiography is no longer performed in these tumours in our institution. Mean maximal diameter of the tumours as depicted from preoperative MRI was 5.2 cm (range: 2.5–7.5 cm).
Tumour extension and dural attachment
As shown by preoperative MRI and confirmed intraoperatively, the tumour was attached to the cribriform plate, adjoining part of the planum sphenoidale, crista galli and medial orbital roofs on both sides in 24 patients. Tumours in these cases were broad-based, were larger than 5.5 cm in maximal diameter and had an almost symmetric growth on both sides. The tumour attachment area was restricted to the cribriform plate and adjacent part of the orbital roofs on both sides in 19 patients.
A pure unilateral dural origin from the cribriform plate and adjoining anterior cranial base was observed in 13 patients, on the left side in six and on the right side in seven cases. Bilateral extension of the tumour into the ethmoidal cells was disclosed on preoperative coronal MRI in two cases and unilateral extension in one. The tumour reached the nasal cavity in two additional cases. The meningioma extended into the optic canal on one or both sides in five patients, all of whom had visual disturbances preoperatively.
Surgical approaches
Thirty-six patients with a bilateral tumour were operated via a bifrontal craniotomy with opening of the frontal sinus, double ligation and division of the anterior end of the superior sagittal sinus with subsequent subfrontal Fig. 3. Artist’s sketch showing dural attachment of olfactory groove meningiomas. (A) Bilateral attachment to the cribriform plate, planum sphenoidale and orbital roofs (24 cases), (B) tumours attached to the cribriform plate and medial orbital roofs bilaterally (19 cases), (C) Unilateral attachment to the cribriform plate and medial orbital roof (13 cases). Posterior extension over the tuberculum sellae (straight arrow) was observed in four, encroachment into the optic canal (curved arrow) in five cases removal of the meningioma. This approach has been described in detail [27, 28, 36]. Additionally, a bilateral tumour was extirpated via a pterional approach in seven patients. The contralateral tumour part was removed after partial resection of the falx cerebri and crista galli [15, 47]. Tumours restricted to one side were resected through a unilateral frontal approach in four cases, via a pterional approach in six and a lateral supraorbital (‘key-hole’) craniotomy in three patients [35]. The latter approach was used in small tumours up to 3.5 cm in diameter and was endoscopically-assisted in one case with a deep olfactory groove. In all but three patients were the tumour had been removed via a frontal craniotomy the floor of the anterior cranial base was covered with a vascularized galea-periosteal flap reinforced with sutures and fibrin glue. A hyperostosis of the crista galli and, or cribriform plate was removed by drilling in 16 patients. Tumours that had invaded into the ethmoidals or nasal cavity were removed via a bifrontal craniotomy. This was combined with a lateral rhinotomy performed by members of the otolaryngology department in two cases.
Patient’s follow-up
All patients were followed-up with clinical examination and MRI studies six months and one year after surgery. Thereafter, patients were re-examined at one or two year intervals based on each follow-up result. Postoperative assessment of mental function was available in 25 of 31 patients with preoperative personality changes. Olfactory function was tested semi-quantitatively before surgery and on each follow-up examination with different odours for each nostril separately. Preoperatively, test results were reliably obtained in 46 patients. In the remainder mental changes allowed only a gross differentiation between smelling and not smelling at best. Postoperative results of olfactory tests were available for analysis in 41 patients. All patients with visual disturbances had detailed pre- and postoperative ophthalmological investigations, including visual acuity, visual fields, fundoscopy and intraocular pressure measurement.
The 41 women and 15 men had a mean age of 51 years (range 30–74 years). The most common presenting symptoms were mental disturbances in 22 patients (39.3%), headache in 11 (19.6%), visual deterioration in nine (16.1%) and anosmia in eight cases (14.3%).

Tab-1. Preoperative  symptoms and neurological signs

Symptoms Patients (%)
Mental changes 39.3
Headache 19.6
Visual disturbance 16.1
Disturbance of olfaction 14.3
Dizziness 10.7
Siezurew 8.9
Hemiparesis 1.8

The duration of symptoms was longest for mental changes (mean 3.2 years, range 3 months to 12 years), medium in duration for anosmia and headache (mean 10 months, range 4–18 months and mean 8.3 months, range 3 weeks to 2 years, respectively) and shortest for visual disturbances and seizures (mean 2 months, range 1 week and 6 months and 3 weeks, range 1–7 weeks, respectively). The neurological examination revealed, in order of frequency, disturbance of olfaction in 33 of 46 patients (71.7%) that could be reliably tested, personality changes in 31 (55.4%), and decreased vision in 12 patients (21.4%) (Table 1).
Surgical aspects
The meningioma was completely resected in all patients irrespective of the surgical approach applied. A Simpson [39] grade I resection was achieved in 24 patients, 23 had been operated through a frontal craniotomy and one via a pterional approach. This group included all patients with tumour invasion into the ethmoids and nasal cavities. The dural attachment area of the tumour was coagulated in 32 patients (Simpson grade II removal). In five cases where the tumour had encroached into the optic canal these tumour extensions could simply be pulled out in two but necessitated opening of the optic canal in three patients. The optic nerves and chiasm were posteriorly and inferiorly dislocated by the tumour in 20 cases. A nodular posterior growth of the tumour pushing both optic nerves laterally was removed in three patients.
In all cases with intimate relationship of the meningioma to the optic nerve, chiasm or ACA there was a clear separating arachnoid membrane facilitating tumour removal from these structures. Intraoperative data regarding preservation of the olfactory nerves were available in 40 patients. The nerves were grossly distorted or infiltrated by the tumour in 26 patients. However, the nerves were protected by an arachnoid sheath bilateral in 5 and unilateral in 9 cases. At the end of the surgical procedure the nerve was in anatomic continuity in 12 patients on one side and in four cases bilaterally. In patients with gross tumour extension into the ethmoids and nasal cavities, the skull base defect was subsequently covered with a titanium mesh and periosteal flap in two cases and with a double layer of galea-periosteal in three patients.
Postoperative olfactory function
All patients with preoperative anosmia remained anosmic although one olfactory tract could anatomically be preserved in three patients and both tracts in one case. Olfaction was preserved on one side in three patients who were hyposmic before surgery and who were treated via a unilateral approach for a unilateral meningioma. A normal sense of smelling was maintained in five cases with normal olfaction preoperatively (three operated via a bifrontal and two via a pterional route). A postoperative deterioration of olfaction was found in 15 patients. Two patients with a normal preoperative sense of smell were rendered hyposmic and six anosmic. Seven patients who could smell on one nostril preoperatively became anosmic. Loss of olfaction was usually noted immediately after surgery. However, one patient became anosmic three months after surgery and later suffered from cacosmia. Three patients with reduced olfaction before surgery reported an amelioration in smelling postoperatively. Two of these patients had preserved olfaction on one side. The third in whom both olfactory tracts could not be preserved intraoperatively was actually anosmic on testing (Table 2).
Mental disturbances
Thirty-one patients (55.4%) had mental and personality disturbances preoperatively. In order of frequency, short-memory deficits were present in all, inability to concentrate in 25, lethargy and apathy in five, confusion in four and dementia in three patients. An uninhibited frontal behaviour (‘Witzelsucht’) was observed in two cases. Four patients had a characteristic evolution with aggressiveness and irascibility in the early stages of disease which later developed into apathy. Mental disturbances correlated with the presence and extent of edema on preoperative MRI, as 27 of 31 cases presenting with mental disturbances had moderate or extensive peritumoural edema. None of the patients with a normal mental status preoperatively deteriorated after surgery. Postoperative psychometric assessment was available in 25 out of 31 patients with preoperative mental deficits. After surgery mental disturbances improved in all but one patient with an uncomplicated postoperative course. Nineteen patients had normal mental function, two had slight memory and attention deficits and one patient who had been operated for recurrent tumour suffered from moderate short-memory and attention deficits. All these patients regained normal daily activity. One patient with presenile dementia did not improve. Recovery from mental disturbances correlated with resolution of edema on follow-up MRI. Two patients with major complications had a deterioration of their mental function.
A cerebrospinal fluid (CSF) leak through the ethmoids occurred in three patients, all being operated via a bifrontal craniotomy. The CSF leakage was successfully treated by lumbar drainage in two patients but necessitated surgical repair in one case. In this patient the site of CSF leak was found in the middle ethmoidal cells. The dural attachment of the tumour had been coagulated and the anterior cranial fossa had not been covered with a periosteal flap. The fistula was repaired with a galeaperiosteal flap reinforced with sutures and fibrin glue and further postoperative course was uneventful. Three patients had major complications. Two patients operated via a bifrontal approach had intraoperative injury of the ACA. One of these patients was rendered dependent due to mental deterioration and a moderate hemiparesis and the other died in the rehabilitation clinic two months after surgery due to pneumonia. The third patient had hemorrhagic infarction of the left basal ganglia that produced a profound hemiparesis and mental deterioration three days after an otherwise uneventful surgery. The permanent morbidity rate, other than olfactory dysfunction, was 17.9%. There were three postoperative deaths (Mortality rate: 5.4%). Beside the patient mentioned above, another one had a fulminant pulmonary embolism 25 days after an otherwise uneventful postoperative course and one patient had rebleeding after one-stage resection of a large olfactory groove meningioma and a left-sided frontal falx meningioma. Despite immediate surgical exploration she did not regain consciousness and died six days after surgery.
Follow-up results
All patients in this series had a follow-up with clinical and MRI assessment of at least one year after surgery (mean follow-up 5.6 years, range 1–13 years). Of the 53 surviving patients, 46 (86.8%) had resumed a normal life with either no or minor symptoms (Karnofsky et al. [16] score: 90–100). Five patients (9.4%) returned to their previous level of activity but had major symptoms, i.e. decreased vision and short memory deficits (Karnofsky score: 70–80). Two patients were severely disabled and required permanent assistance (Karnofsky score: 40). Vision was improved in all but two patients with preoperative visual disturbances. One of these patients had progressive visual loss due to glaucoma. Four recurrences of de novo meningiomas were observed, 1.5–8 years after the first surgery (Table 4). All tumours were progressive in growth and had to be reoperated. In addition, one patient who had been operated 33 years ago had a recurrent bifrontal tumour infiltrating the entire frontal cranial base and extending into the nasal cavity. The tumour was resected including the dura and infiltrated bone (Simpson grade I) but a second recurrence was observed on routine MRI follow-up in the ethmoidal air cells and nasal cavity four years later. This tumour was radically removed by members of the otolaryngology department via a lateral rhinotomy approach.
Histological examination
The meningioma was of the meningothelial subtype in 31 patients, fibroblastic in 14, transitional in 6, psammomatous in 4 and atypical in one case. The histological subtype did not correlate with the invasiveness of the tumour.
From June 1990 to June 2003, 1011 intracranial meningiomas have been microsurgically treated in our institution, among them 56 meningiomas with predominant origin from the olfactory groove. The incidence of these tumours was thus 5.5% of all intracranial meningiomas which is comparable to a figure of 5.4–10% given in the literature.
Clinical presentation
Mental and personality changes were the most common presenting symptoms in our study (39.3%) and were found in 55.4% of the patients on clinical examination. Changes of the mental status are reported as a primary symptom in 20.7–71% of patients harbouring an olfactory groove meningioma [3, 8, 28, 36, 40, 43]. Euphoria was seen in 59.1% of patients in the series of Solero et al. but was seldom seen in other investigations including our own [3, 40]. However, an early phase of aggressiveness which later developed into apathy has been reported and was observed in four of our cases [3]. As pointed out by Cushing and Eisenhardt [8], impaired sense of smell is rarely a reason to consult medical advise. Decreased olfaction was appreciated by 14 of his 29 patients, being possibly the primary symptom in only three of them. Bakay did not observe decreased olfaction as a presenting symptom in his series [2]. Preoperative anosmia was noted on clinical examination in 53.8–100% of patients in previous studies [2, 15, 23, 40, 43]. Disturbance of olfaction was the presenting symptom in 14.3% of our patients and was found in 71.7% of the cases on clinical examination. Visual impairment is a common finding, being present in 15.3– 58.1% of the patients preoperatively [3, 8, 15, 23, 40, 41, 43, 44]. It was found in 21.4% of our patients on admission and was either caused by tumour encroachment into the optic canals, direct compression of the optic nerves and chiasm by a large tumour or increased intracranial pressure due to a sizeable tumour causing bilateral papilloedema. Classical Foster–Kennedy Syndrome, described in 1911 in a patient with a bilateral olfactory groove meningioma was not observed in this study [18]. It is reported to occur in 0–5.5% in more recent series.
Surgical approach
The first successful resection of an olfactory groove meningioma was performed by Francesco Durante in 1885 via a left frontal craniotomy in a 35 year old woman [12]. This patient had left-sided anosmia and exophthalmus as well as memory deficits prior to surgery. Although displaying temporary rhinorrhea she remained in good condition for twelve years after the operation [8, 12]. A unilateral frontal approach and uncapping of the tumour by wedge excision of part of the frontal lobe was preferentially performed by Cushing and Eisenhardt [8], Dandy [9], Olivecrona [29], Poppen [32], Solero et al. [40] and Symon [41]. In 1938, Teonnis recommended a bifrontal bone flap without resection of frontal lobe tissue. The frontal sinus was not opened during craniotomy and the tumour was resected via an interhemispheric route after ligation of the superior sagittal sinus and after incising the attachment of the falx to the crista galli [42]. Bifrontal craniotomy with opening of the frontal nasal sinus and a subfrontal route to the meningioma has been used with success by several investigators [13, 14, 20, 26, 28, 36]. This approach provides a good overview of the anterior skull base for resection of bilateral, broadbased tumours including their dural attachment and infiltrated bone. It gives the surgeon access to the ethmoidal air cells or nasal cavities when these sites are involved. This approach can be combined with a lateral rhinotomy for radical tumour resection as performed in two of our patients and described by others [5, 21, 31]. The large galea-periosteal flap obtained with this approach can be used for reconstruction of the anterior skull base to prevent CSF leakage [26]. However, ligation of the anterior end of the superior sagittal sinus, usually routinely performed using this approach seems to have an infrequent but significant risk of producing venous infarction [1]. To reduce this risk it is important to ligate the sinus immediate beneath the foramen caecum. Seeger has proposed a unilateral basal approach with preservation of the superior sagittal sinus [37]. However, complications related to frontal bridging veins are not eliminated in his exposure. Kempe [17] in 1968 has extended a unilateral frontal craniotomy to the temporal region for tumours with predominant posterior extension. To anticipate complications from the frontal venous system and from opening of the frontal sinus, Hassler in 1989 has proposed the pterional approach for these tumours, which was also routinely used by Yasargil [15, 47]. All 11 tumours in Hassler’s series could be completely removed and no surgical complications were encountered. Release of CSF from the optic and carotid basal cisterns decreases intracranial pressure and facilitates tumour removal by this approach. Early control of the optic nerve and carotid artery and its branches at the posterior pole of the tumour helps preserving these structures [15, 44]. This is an important aspect because most fatal complications reported in the literature are caused by injury of the ACA which is masked behind the main bulk of the tumour and is encountered late during the frontal approach [3, 34, 40]. This complication was seen in two of our patients with unsatisfying outcome. No permanent complications were observed in 13 cases in our series treated via the pterional approach. This approach, however, has limitations in tumours with gross infiltration of the anterior skull base and tumours extending into the ethmoids and nasal cavity. Adequate fronto-basal repair and removal of tumour in a deep olfactory groove is difficult without significant frontal lobe retraction. It has to be noted, that the depth of the cribriform plate has varied anteriorly between 1 and 16mm and posteriorly between 1 and 10 mm, in anatomic studies [19]. Sekhar and Tzortzidis recommends an extended fronto-temporal craniotomy and orbital osteotomy (one-and-a-half approach) to minimize frontal lobe retraction and to secure the ACA and optic nerve early during operation [38]. Following this approach, the anterior and posterior ethmoidal arteries can be ligated to interrupt the main blood supply to the tumour. Division of these vessels after subperiorbital dissection of the supero-medial wall of the orbit has been described without orbital osteotomy and from our experience an orbitotomy is not necessary in these tumours [24]. Different surgical approaches have been used in our patients and the tumour could be resected completely and successfully with each of them. A Simpson Grade I resection, however, was achieved almost exclusively via the frontal route. Also, repair of the anterior cranial fossa and removal of subbasal tumour extensions were facilitated using this approach. Retraction of the frontal lobes is minimized provided that the lower craniotomy border is flash with the anterior cranial floor. It has to be noted that all recurrences observed in this series, had a prior bifrontal approach and two of these had a Simpson Grade I resection. Also, most complications encountered in this series were recorded in patients who had a subfrontal resection of their meningioma. It has to be taken into account that tumours which were resected via a bifrontal craniotomy were usually large and always bilateral. The bifrontal craniotomy group also included all cases with extensive drilling of the anterior cranial base and tumours invading the ethmoids and nasal cavity. Interestingly however, none of the CSF fistulas observed in this series have occurred in these latter patients supporting the view that this complication can largely be prevented by meticulous covering of the frontal cranial base after tumour resection [10, 11, 26, 36].
Olfactory function
Olfaction is an important sense with regard to life-quality and it has rarely been systematically investigated after resection of olfactory groove meningiomas [45, 46]. Preservation of olfaction has generally been disappointing in these tumours [30, 41]. Indeed, all patients in our series with preoperative anosmia remained anosmic on postoperative follow-up even though the olfactory tract was in anatomic continuity after tumour removal in some cases. This included all patients with gross infiltration of the skull base or tumour extension into the ethmoids or nasal cavities. Anosmia may be caused by ischemia due to deprivation of the blood supply to the olfactory nerves or transection of the fila olfactoria during surgical manipulation. Other reasons might be degeneration of the olfactory nerve cells by long standing compression of a slowly evolving mass lesion or frank tumour infiltration of the structures subserving olfaction. Nonetheless, preservation of olfaction is worth attempting in patients with normal or reduced olfaction preoperatively. In these cases an intact arachnoid layer and viable olfactory structures may be identified intraoperatively at least on one side and thus protected. Although the olfactory system and its arachnoid cistern can usually be delineated on coronal MRI in normal subjects these structures are obscured in patients with olfactory groove meningiomas [6]. The presence of viable olfactory structures can therefore only be appreciated during surgical exposure. In this series, the sense of smelling was fully or partly preserved in ten patients. Two patients even reported an amelioration of their sense of smelling postoperatively which was confirmed on semiquantitative testing. Frontal lobe retraction should be kept to a minimum to prevent tearing of the fila olfactoria at the level of the cribriform plate. No difference in the rate of preserving olfaction was observed with the various surgical approaches in our patients. Nonetheless, a unilateral surgical approach is preferable leaving the contralateral olfactory system undisturbed.
Mental disturbances
In the series of Bakay and Cares 8 of 17 patients with preoperative mental disturbances showed definitive improvement on postoperative follow-up [3]. Solero and coworkers reported that only 38.3% of their patients were mentally normal before surgery. This figure increased to 81.6% postoperatively [40]. Ojeman, in reviewing his series of 19 patients harbouring an olfactory groove meningioma found that preoperative mental disturbances and personality changes usually completely recovered after tumour removal [27]. These results are confirmed by others and in the present study [15]. In our series the severity of mental deficits was related to tumour size and the extend of bifrontal edema on T2-weighted preoperative MRI. Improvement of the mental status was observed in all but one of our patients with an uncomplicated postoperative course. Amelioration of mental function correlated well to the disappearance of perifocal edema on follow-up MRI.
A complete removal of the olfactory groove meningioma was achieved in 67–100% in different series [3, 15, 26, 27, 34, 40, 41, 43]. Data on the recurrence rate of these tumours give conflicting results. Several authors have reported a very low recurrence rate [7, 27, 34, 41, 44]. Ojeman had no recurrences in his 19 patients after an average follow-up period of 4.4 years [27]. Chan and Thompson observed no recurrence with a Simpson grade I and II resection after a mean follow-up of 9 years [7]. Other series, however, have reported a high recurrence rate of up to 41% at 10-years follow-up in these tumours [25, 43]. The rate of recurrence seems to be proportional to the time period of follow-up [22, 25, 26]. We found a higher propensity of these tumours to recur when compared to other skull base meningiomas treated in the same institution and with a comparable follow-up period [4]. Two of five recurrences observed in this series had a Simpson grade I resection at first surgery and appeared in the ethmoidal cells or nasal cavity without evidence of intracranial tumour regrowth. Tumour in these cases has probably invaded into the paranasal mucosa and had not been removed at first surgery although extensive drilling of the anterior floor had been performed in at least one of these cases. These ‘en plaque’ tumour extensions may not be recognised even on high-quality preoperative MRI because they are obscured by the brightly enhancing mucosa after contrast administration. Recurrences may appear after a long interval after an apparent radical removal, as illustrated by one of our cases and observed in other series [3, 21, 43]. Cushing described invasion of the cranial base in four patients and has covered a large opening in the ethmoids with facia from the leg in one patient (Case 15) with an uneventful postoperative course [8]. Poppen, in 1964 has recommended to remove any enostosis found at the attachment area of the tumour [32]. Derome and Guiot [11] have found that 15% of olfactory groove meningiomas had invaded into the paranasal sinuses and introduced a transbasal extension of the frontal approach for these tumours in 1972. As pointed out by these authors extensive basal resection of involved bone will invariably result in anosmia. In our experience all patients with obvious tumour infiltration (hyperostosis or destruction) of the anterior cranial fossa were already anosmic before surgery. Therefore, removal of infiltrated bone does not interfere with functional outcome in these cases. The follow-up period in most series, including our own, is short for this tumour entity and data on the rate of recurrence have to be regarded as preliminary [3, 22, 26, 27].




The patient had huge extradural hematoma, which was the case of the swelling and made the first operation difficult. Usually after resection of the tumor. the brain  becoming lax and regain good pulsation, but here was not the case.


In retrospective analysis, the hematoma must be diagnosed first and removed and then remove the tumor. But for several reasons the hematoma was missed and the first surgery was very difficult.


In the future do the MRI investigations immediately before surgery.


The patient came to the clinic 09-April-2007 to discontinue Epanutin. She is convulsion free for three years. On examination, the right eye still having decreased vision with bilateral anosmia.


1. Intraoperative navigation will ameliorate such events, and confirm the necessity for such technology. Real-time intraoperative navigation is costly and commercially inapplicable for private sector, and must be modified to be used for all surgical disciplines and to have neurophysiologic monitoring added to the navigation system merged with the visual data in real time.

2. MRI of the brain done 01-January-2005 confirming the total resection of the tumor with mild malacia of the left frontal lobe due to to pressure effect of the missed right occipito-parietal extradural hematoma.


T1W MRI transverse sections
T2W transverse sections
T1W sagittal sections
T2W sagittal sections
Postoperative MRI after 3 years showing complete resection and no recurrence.


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