It is a type of anterior skull base meningioma.
These intracranial meningiomas may be associated with hyperostosis of the sphenoid ridge and may be very invasive, spreading to the dura of the frontal, temporal, orbital, and sphenoidal regions. Medially, this tumor may expand into the wall of the cavernous sinus, anteriorly into the orbit, and laterally into the temporal bone.
The relative incidence of meningiomas of the sphenoid ridge is 17%. This tumor usually arises from the lesser wing of the sphenoid bone. Sphenoid wing meningiomas, or ridge meningiomas, are the most common of the basal meningiomas.
Tumors found in the external third of the sphenoid are of two types: en-plaque and globoid meningiomas.
En plaque meningiomas characteristically lead to slowly increasing proptosis with the eye angled downward. Much of this is due to reactive orbital hyperostosis. With invasion of the tumor into the orbit, diplopia is common.
Patients with globoid meningiomas often present only with signs of increased intracranial pressure. This leads to various other symptoms including headache and a swollen optic disc.
Tumors growing in the inner wing (clinoidal) most often cause direct damage to the optic nerve leading especially to a decrease in visual acuity, progressive loss of color vision, defects in the field of vision (especially cecocentral), and an afferent pupillary defect.
If the tumor continues to grow and push on the optic nerve, all vision will be lost in that eye as the nerve atrophies.
Proptosis, or anterior displacement of the eye, and palpebral swelling may also occur when the tumor impinges on the cavernous sinus by blocking venous return and leading to congestion. Damage to cranial nerves in the cavernous sinus leads to diplopia.
The Ophthalmic nerve (is often the first affected, leading to diplopia with lateral gaze. The patient will have pain and altered sensation over the front and top of the head.
Horner syndrome may occur if nearby sympathetic fibers are involved.
Endocrine testing is important because pituitary insufficiency has been reported to occur in 22% of patients with anterior skull base meningiomas, including thyroid stimulating hormone (TSH), follicle stimulating hormone (FSH), and luteinizing hormone (LH).
Following the physical exam, the diagnosis is confirmed with neuro-imaging. Either a head CT or MRI with contrast such as gadolinium is useful, as meningiomas often show homogenous enhancement. Angiography looking for signs like stretched arteries may be used to supplement evaluation of vascular involvement and to determine whether embolization would be helpful if surgery is being considered.
On MRI imaging, T1- and T2-weighted sequences have variable signal intensity, but they enhance intensely and homogeneously after injection of gadolinium. They also tend to exhibit hyperostosis and calcifications which can be seen on either CT or MRI imaging. Additionally, the presence of a dural extension (also known as a dural tail) is helpful in distinguishing a meningioma from fibrous dysplasia
The differential diagnosis for sphenoid wing meningioma includes other types of tumors such as optic nerve sheath meningioma, cranial osteosarcoma, metastases, and also sarcoidosis.
Large and giant medial sphenoid wing meningiomas that are located deeply in the skull base where they are closely bounded by cavernous sinus, optic nerve, and internal carotid artery make the gross resection hard to achieve. Also, this kind of meningiomas is often accompanied by a series of severe complications.
For medial sphenoid wing meningiomas, visual loss and abnormalities of cranial nerves III, IV, VI, V1, and V2 may occur because the meningioma may have some degree of encasement of these structures as they ride through the cavernous sinus.
Seizures, paresis, and sensory loss may result depending on potential damage to adjacent brain parenchyma for patients with lateral sphenoid wing meningiomas.
Sphenoid wing meningiomas (SWMs) can encase arteries of the circle of Willis, increasing their susceptibility to intraoperative vascular injury and severe ischemic complications.
A retrospective review of 75 patients surgically treated for SWM from 2009 to 2015 was undertaken to determine the degree of circumferential vascular encasement (0°-360°) as assessed by preoperative magnetic resonance imaging (MRI). A novel grading system describing “maximum” and “total” arterial encasement scores was created. Postoperative MRIs were reviewed for total ischemia volume measured on sequential diffusion-weighted images.
Of the 75 patients, 89.3% had some degree of vascular involvement with a median maximum encasement score of 3.0 (2.0-3.0) in the internal carotid artery (ICA), M1, M2, and A1 segments; 76% of patients had some degree of ischemia with median infarct volume of 3.75 cm 3 (0.81-9.3 cm 3 ). Univariate analysis determined risk factors associated with larger infarction volume, which were encasement of the supraclinoid ICA ( P < .001), M1 segment ( P < .001), A1 segment ( P = .015), and diabetes ( P = .019). As the maximum encasement score increased from 1 to 5 in each of the significant arterial segments, so did mean and median infarction volume ( P < .001). Risk for devastating ischemic injury >62 cm 3 was found when the ICA, M1, and A1 vessels all had ≥360° involvement ( P = .001). Residual tumor was associated with smaller infarct volumes ( P = .022). As infarction volume increased, so did modified Rankin Score at discharge ( P = .025).
Subtotal resection should be considered in SWM with significant vascular encasement of proximal arteries to limit postoperative ischemic complications 1).
The clinical materials of 53 patients with sphenoid wing meningiomas treated microsurgically between January 2008 and January 2012 were analyzed retrospectively. Follow-up period ranged from 6 to 62 months (median, 34 months). Clinical outcomes including postoperative quality of life and recurrence rate were evaluated. Univariate and multivariate statistical analysis were performed among factors that might influence postoperative quality of life.
The mean age of patients was 49 years. Mean tumor size was 3.9cm. Total tumor resection was achieved in 38 cases (71.7%), subtotal in 10 cases (18.9%) and partial resection in 5 cases (9.4%). Within the follow-up period, ten patients (18.9%) had recurrence and three patients (5.7%) died. In univariate analysis, we found the postoperative Karnofshky Performance Score (KPS) improvement was determined by various factors, including extent of tumor resection, peritumoral edema, tumor blood supply, size, adhesion, encasement and preoperative KPS. However, multivariate analysis showed that complete resection, rich blood supply, adhesion to adjacent structure, encasement of neurovascular were independent predictive factors for worse postoperative KPS.
With the improved requirement of postoperative quality of life in patients, intentional incomplete resection should be considered as an acceptable treatment option. Multivariate analysis confirmed that incomplete resection, poor blood supply, lack of adhesion or encasement of adjacent structure were independent predictive factors for favorable postoperative quality of life. An individual treatment strategy could help improved quality of life 2).
Endo et al. report the utility of a pulsed water jet device in meningioma surgery. The presented case is that of a 61-year-old woman with left visual disturbance. MRI demonstrated heterogeneously enhanced mass with intratumoral hemorrhage, indicating sphenoid ridge meningioma on her left side. The tumor invaded the cavernous sinus and left optic canal, engulfing the internal carotid artery in the carotid cistern and encased middle cerebral arteries. During the operation, the pulsed water jet device was useful for dissecting the tumor away from the arteries since it was safe in light of preserving parent arteries. The jet did not cause any vascular injury and did not induce vasospasm as shown by postoperative symptomatology and MRIs. With the aid of pulsed water jet, we could achieve total resection of the tumor except for the piece within the cavernous sinus. The patient had no new neurological deficits after the operation 3).