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Year : 2015  |  Volume : 28  |  Issue : 1  |  Page : 93-98

The outcome of bilateral subfrontal approach of large olfactory groove meningioma

1 Department of Neurosurgery, Faculty of Medicine, Menoufia, Egypt
2 Department of Neurosurgery, Faculty of Medicine, Zagazig, Egypt

Date of Submission12-Mar-2014
Date of Acceptance26-Apr-2014
Date of Web Publication29-Apr-2015

Correspondence Address:
Yasser Bahgat El-Sisi
Department of Neurosurgery, Faculty of Medicine, Kamal El Nagar Street, El Shohada, Menoufia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1110-2098.155954

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The aim of the study was to evaluate the value of bilateral subfrontal approach for management of olfactory groove meningioma focused on preoperative and postoperative investigations for ophthalmologic disturbance.
Olfactory groove meningiomas arise in the midline along the dura of the cribriform plate and may reach a large size before producing symptoms. There are many surgical approaches such as bilateral subfrontal, unilateral subfrontal, and pterional approaches for this lesion.
Patients and methods
Over a 3-year period, 20 patients with olfactory groove meningiomas more than 4.5 cm in diameter were operated upon using the bilateral subfrontal approach. Data related to clinical history, symptoms, signs, and outcome were obtained by review of the patient's clinical notes, operative reports, histopathological records, follow-up records, and radiological images. Operative and postoperative events were noted with a follow-up period of 6 months.
Twenty patients with olfactory groove meningiomas were approached by bilateral subfrontal approach. The most common presenting symptom was headache, which was seen in 16 patients (80%). On admission, five patients (25%) had mental status changes, nine patients (45%) presented with associated visual complaints, and two patients (20%) had epilepsy at presentation. Within the first month after surgery, the postoperative visual acuity was improved in two patients, whereas in seven patients it remained unchanged. In two patients, visual field defects improved and in one patient the defects resolved completely.
Visual deficits can be improved in patients with olfactory groove meningiomas after a bifrontal approach, after 6 months follow-up period without additional neurological deficits.

Keywords: Anterior skull base meningioma, bifrontal approach, meningiomas, olfactory groove meningiomas

How to cite this article:
El-Sisi YB, Rashed ME, Hanafy AM, Gaber Saleh EE, El Noomany HA, Sheha AF. The outcome of bilateral subfrontal approach of large olfactory groove meningioma. Menoufia Med J 2015;28:93-8

How to cite this URL:
El-Sisi YB, Rashed ME, Hanafy AM, Gaber Saleh EE, El Noomany HA, Sheha AF. The outcome of bilateral subfrontal approach of large olfactory groove meningioma. Menoufia Med J [serial online] 2015 [cited 2021 Apr 18];28:93-8. Available from: http://www.mmj.eg.net/text.asp?2015/28/1/93/155954

  Introduction Top

Olfactory groove meningiomas (OGM) arise from the midline of the anterior cranial fossa at ethmoidal cribriform plate and comprise ~9-12% of all intracranial meningiomas [1]. OGM have some particularities, which are slow-growing tumors, often bilateral rather than unilateral but asymmetrical, and they may produce progressive compression of the frontal lobes. There are intratumoral calcifications in up to 15-20% of patients [2]. OGM can project backward toward the sella, if large enough, and they can affect vision by compressing the optic nerve and chiasm. The most common presenting symptoms are headache alone or in combination with personality changes, anosmia, and visual impairment.

Intracranial hypertension or seizures are less common initial symptoms. The anatomic location of OGMs may cause prolonged psychiatric symptoms before the onset of more overt neurologic deficits. For these reasons, OGM are among the largest intracranial tumors we see [3]. Brain computer tomography (CT) scan and MRI show the usual characteristics of meningiomas in the mid-subfrontal region, the extent of the tumor, and the edema of the surrounding brain [4]. The MRI also defines the relationship of the tumor with the optic nerves and anterior cerebral arteries and its extension into the ethmoidal sinus [5]. Surgical resection is the treatment of choice for most OGMs, but the size of the tumor, the encasement of important vascular and neural structures, and their invasion into the paranasal sinuses raise major surgical challenges during these procedures [6]. Evaluation of bilateral subfrontal approach of large OGM and analysis of the clinical and radiological data, the operative techniques, and the outcome of 20 patients with OGM operated upon in the Neurosurgical Department of El Menoufia and Zagazig Universities between January 2009 and January 2012 were performed.

  Patients and methods Top

This prospective study included 20 patients. Information on clinical history, symptoms, signs, and outcome was obtained by review of the patient's clinical notes, operative reports, histopathological records, follow-up records, and radiological images.

All patients were studied preoperatively by contrast-enhanced MRI. OGM were defined as those having their point of origin in the midline anterior cranial fossa, along the dura of the cribriform plate and frontosphenoidal suture. Anterior frontal, tuberculum sellae, clinoidal, and diaphragma sellae meningiomas were excluded.

A tumor was considered giant when the equivalent diameter was greater than 4.5 cm [7].

All patients received perioperative dexamethasone and anticonvulsant therapy. Peritumoral edema was evaluated by both T2-weighted and proton-weighted MRI by a neuroradiologist graded according to the following scheme: grade 0, absent or minimal edema; grade I, moderate edema; and grade II, marked edema. All meningiomas were supplied by the anterior or posterior ethmoidal branches of the ophthalmic artery or the anterior branch of the middle meningeal artery or by all of these. Postoperative CT examinations were performed in all patients within 24 h. Preoperative hydrocephalus was not present in any patient. Microsurgical techniques were used for all patients.

Simpson's grade, complications, and intraoperative findings were recorded in the operative note for each patient, whereas surgical specimens were evaluated by a neuropathologist.

All histopathology results were analyzed according to the WHO grading criteria.

Ophthalmological assessments

Formal preoperative and postoperative ophthalmological examinations were performed by the Ophthalmology Department and included testing for visual acuity, fundoscopy, and Goldmann perimetry for visual fields. Visual acuity was tested with a Snellen chart at 6 m in all patients. The presence of concomitant eye pathology was also taken into account.

To evaluate the degree of visual loss quantitatively, Rosenstein and Symon (1984), adapted a point scoring system. Each eye was assessed individually with respect to the state of the visual fields and the visual acuity. The points were then totaled and a percentage of visual loss was calculated [Table 1].
Table 1: Visual score

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Olfactory function assessment

All patients were assessed according their olfactory function by the test of olfaction; the test substance chosen for evaluating the sense of smell was a mild perfume or aromatic substance such as peppermint and coffee. With the patient's eyes closed, the test odor is placed under one nostril, whereas the other is occluded. The patient is asked to sniff and indicate whether he or she can smell something and if so, to identify it, the test is repeated with the opposite nostril [8].

Operative management

The patient was positioned supine with slight flexion of the trunk and knees. The head was placed in a three-point fixation head holder and elevated above the heart 15° to help venous drainage. Eyes were protected. The vertex was tilted down 15-30° allowing the frontal lobes to fall away without traction. Bicoronal Scalp incision was performed. Scalp flap including the pericranium was sharply dissected from the bone. The temporal fascia and adipose tissue were elevated in one layer by establishing a plane between them and the deep temporalis fascia to avoid injury to the frontal branch of facial nerve. Dura was carefully separated from underlying bone, especially in the midline overlying the sagittal sinus. The dura was incised on both sides proximally; superior sagittal sinus was secured and divided. Falcine dura was detached from the crista galli, and the frontal lobes were gradually fallen back. At this time, the operating microscope was used to open basilar cisterns to allow drainage of cerebrospinal fluid as lumber drain was not used.

With respect to the arachnoid plan, gradual debulking and dissection of the tumor was initiated from the anterior to posterior direction, starting at the deepest level of the tumor in the 'anterior fossa' with care of early controlling feeders arteries. After complete intradural tumor removal, the procedure of extradural tumor excision can be followed.

Dura was closed watertight after repair (if needed), with dural hitching to the periosteum or to small holes in the bone edges. Additional dural defects were reconstructed with pericranium if needed or with artificial dura.

The bone flap was held with several sutures through small holes made in the bone edges.

Statistical analysis

Results were collected, tabulated, and statistically analyzed by an IBM compatible personal computer using SPSS statistical package version 20.

Two types of statistical analysis were performed:

(1) Descriptive statistics were expressed in number (N), percentage (%), mean (th X ), and SD.

(2) Analytic statistics

  1. Qualitative data were analyzed using the c2 -test.
  2. Normally distributed quantitative data were analyzed by Mann-Whitney's test (between two groups) and the Kruskal-Wallis test (for >2 groups), and Tamhane's test was used as a post-hoc test.
  3. P value of less than 0.05 was considered statistically significant.

  Results Top

From January 2009 to 2012, a total of 20 patients were treated for OGM at the Department of Neurosurgery at Menoufia and Zagazig universities. All patients were surgically operated upon by the senior author.

The mean patient age was 56.4 years (range 28-78), and 75% of the patients were women and 25% were men.

The most common presenting symptom was headache, which was seen in 16 patients (80%); on admission, five patients (25%) had mental status changes with intellectual deterioration, nine patients (45%) presented with associated visual complaints, and two patients (10%) had epilepsy at presentation. All patients were assessed by olfactory function test; nine patients had anosmia on presentation; and unilateral preservation of olfactory function was possible only in two of all patients postoperatively.

The size of the tumor was calculated on the basis of measurements obtained from CT scans or MRI. The tumor equivalent diameter varied from 5.6 to 8 cm, with a median of 6.4 cm. Meningiomas were broad on the basis of symmetrical bilateral growth in all but one patient; preoperative ethmoidal extension of the tumor was demonstrated in one patient. Peritumoral edema on preoperative MRI studies was absent in 14 (70%), moderate in four (20%), and severe in two (10%) patients.

Twenty patients were operated upon by a bifrontal approach; when the frontal sinus was entered, the mucus membranes were exenterated and the duct was tamponaded with iodine-soaked cottonoids and covered with pericranium.

Total macroscopic surgical resection of the mass lesion was achieved in 14 patients (Simpson grade I removal in one patient and Simpson grade II in 13 patients); four patients underwent a nonradical removal (Simpson grade III), whereas two patients underwent a subtotal resection (Simpson grade IV). Radical tumor removal was avoided in elderly patients.

In all patients, there was an intact arachnoidal plane between the tumor and the optic nerve, chiasm, and anterior cerebral artery complex, thus facilitating tumor dissection from these structures. Recurrence occurred in one patient who underwent subtotal resection and was reoperated 24 months after the first intervention. None of the other patients showed radiological progression of the tumor during their follow-up, and their clinical condition remained stable. The pathological finding was: 10 patients had meningothelial (50%), five patients had transitional (25%), two patients had fibroplastic (10%), two patients had aggressive (10%), and one patient had psammomatous (5%) meningioma.

Ophthalmological findings

Nine patients (45%) presented with visual deficits; the mean duration of visual symptoms was 27.4 months (range 3-125). Visual acuity was decreased bilaterally in three patients and unilaterally in six patients. Fundoscopy revealed optic disc pallor in 14 patients (five right eye, five left eye, and four bilateral) and disc swelling in three patients (two right eye, one left eye). A Foster-Kennedy syndrome was present in one patient. Visual field defects were found in seven patients. Chiasmal compression produced bitemporal hemianopia in four patients and a temporal hemianopia in one eye in three patients.

Within the first month after surgery, the postoperative visual acuity improved in two patients, whereas in seven patients it remained unchanged. In two patients, visual field defects improved and in one patient the defects resolved completely.

In three patients, visual field defects were unchanged and became worse in one patient. No patient had postoperative deterioration of visual acuity [Table 2].

Postoperative recovery of visual deficits was poor in five patients with a deficit of more than 24 months, and none of these patients had improvement in visual function.
Table 2: Postoperative visual function in 20 patients

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In general, vision improved rapidly within the first month, with little further improvement within the first year of follow-up [Table 3].
Table 3: Comparison between the mean values of visual scale preoperatively and postoperatively

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Complications were seen in six patients (16.6%). The most frequent postoperative complication was persistent rhinorrhea, which occurred in two patients (10%); all CSF leaks stopped after insertion of a lumbar drain. Persistent postoperative seizures were present in one patient. As discussed above, in one patient, there was postoperative visual field deterioration. One patient with symptomatic delayed frontal pneumocephalus had surgical repair 1 month after tumor resection, with subsequent resolution of the symptoms. Wound infection occurred in one patient (5%) and postoperative hematoma occurred in three patients (15%) [Table 4].
Table 4: Percentage distribution of the postoperative complications

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There was one mortality on the 17th postoperative day secondary to massive pulmonary embolism after an uneventful early postoperative course. No other clinical complications were observed. There was good outcome postoperatively and after 6 months according to the Karnofsky scale [Table 5].
Table 5: Percentage distribution of the Karnofsky scale at different stages for living 19 patients postoperatively

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  Discussion Top

The surgical principles of the management of OGM were first described by Cushing and Eisenhardt in 1938 [1]. He emphasized the importance of tumor decompression before capsule dissection, thus preserving the anterior cerebral arteries that may be adherent. Yet, the correct approach used in the resection of giant OGMs remains controversial [7].

Our study presents a homogeneous cohort of patients with giant olfactory meningiomas surgically treated by a bifrontal approach. The bifrontal approach has been described in detail in numerous studies [9], whereas the subfrontal route without resection of the frontal lobe tissue was first described by Tonnis in 1938 and later used by several authors [10]. This approach provides direct access to the tumor without excessive brain retraction, reaching the primary tumor attachment and the vascular feeders of the meningioma, thus first dividing the ethmoidal arteries and small meningeal feeding vessels, devascularizing, and debulking the tumors from the inferior aspect. In those with extensive bone involvement, it may be appropriate to drill the anterior cranial base and provide a secondary reconstruction with a vascularized pericranial flap [11]. Disadvantages are the inevitable opening of the frontal sinus with the risk for CSF leakage and meningitis.

We used pericranial flaps to cover the defect in the floor of the anterior fossa. Two patients had rhinorrhea without meningitis and both stopped after insertion of a lumbar drain.

Hemiparesis was present in one patient. This symptom may be caused by the pressure of the meningioma on the motor area [3].

Anosmia is an early symptom of OGM, but only few patients complain of it. The decline in olfactory function is gradual, similar to that seen in the elderly, and only one side is affected in the early stage. Lateralized testing of olfactoy function seems to be necessary to achieve an early diagnosis. Preservation of olfaction during surgery is difficult. Although the olfactory tract is in anatomical continuity after resection of the meningioma [1], postoperative anosmia may be induced by ischemia caused by loss of blood supply to the olfactory nerves or a functional lesion of the fila olfactoria during surgery. In the study by Bassiouni et al. [1] comparing various surgical approaches, there was no difference in the preservation of olfaction. To prevent further damage to the olfactory nerves, frontal lobe retraction should be minimal. Our findings indicate that 45% patients had anosmia on presentation. In those with preoperative unilateral normal olfactory function, only two of 11 patients had preserved olfaction after surgery.

The most common reason for seeking medical attention in patients with olfactory meningiomas is failing vision.

Vision deficits often progress asymmetrically; the commonest early visual complaint is blurred vision in one eye secondary to a central scotoma, but partial loss of vision in one eye proceeds almost unnoticed by the patient [12]. Preoperative visual deficits on clinical examination are reported in 15.3-58.1% of patients [13]. Visual impairment, including optic disc swelling and pallor, was found in 45% of our patients on clinical examination. Classical Foster-Kennedy syndrome was reported to occur in 5% of patients in recent studies [14] and was found in 5% of our patients. Patients with visual impairment longer than 1 year have a worse chance of improved vision [14]. In addition, our findings suggest that visual outcome was better in patients with symptoms shorter than 24 months. Postoperatively, visual function improved in 25% of our patients, whereas in 75% patients it was unchanged. There was no deterioration of visual acuity after bifrontal excision, but in one patient the visual field defect worsened.

The percentage of recovery of visual fields in our series was less than that reported by other authors in patients with frontal meningiomas [2]. Larger mean tumor diameter and longer duration of visual deterioration in our series compared with patients in other reports with tumors smaller than 3 cm and a shorter history of symptoms may have an influence on the differences in visual outcome. Nakamura et al. [2] reported worse improvement rates of postoperative visual outcome in tuberculum sellae meningiomas treated with a bifrontal approach than in those treated with a frontolateral approach.

However, in their series, clinical and radiological data were not matched in the two groups. Larger tumor diameter in the bifrontal group and the fact that this approach was performed in earlier years may have influenced the visual outcome.

Complete resection of olfactory meningiomas has been reported in 67-100% of patients [5]. Recurrence rates of these tumors range from 5 to 41%, although several authors have reported a very low or no recurrence rate after a mean follow-up period ranging from 4.4 to 9 years [15].

Recurrence of meningioma may be the result of incomplete resection or occur even after radical resection after a long follow-up [16]. The approach for tumor resection seems not to influence tumor recurrence [17].

Mortality rates vary from 0 to 17% [18] in the recent literature. In our series, we had one death after a massive pulmonary embolism on the 17th postoperative day but none directly related to surgery.

  Conclusion Top

Our results at the longest follow-up indicate that there is a good prospect that visual deficits will improve in patients with OGMs after a bifrontal approach, without additional neurological deficits. This approach may be considered the most appropriate for these tumors more than 4.5 cm in diameter [Figure 1] and [Figure 2].
Figure 1: (a– c) T1 MRI brain with preoperative contrast sagittal, axial, and coronal cuts; olfactory groove meningioma (d) postoperative CT brain, 1 week postoperative.

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Figure 2: (a, b) T1 MRI brain with preoperative axial and sagittal cuts; olfactory groove meningioma (c) CT axial cut postoperative shows complete removal 1 week postoperative.

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  Acknowledgements Top

Conflicts of interest

None declared.

  References Top

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  [Figure 1], [Figure 2]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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