Overview of meningioma of middle cranial fossa
Meningioma of middle cranial fossa, also known as meningioma of middle cranial fossa, refers to meningiomas originating from the middle cranial fossa, which mainly include meningioma of middle and lateral pterygoid crest, meningioma of medial pterygoid crest (saddle node meningioma), meningioma of anterior bedspace, cavernous sinus meningioma, and meningioma of Meckel’s cavity.
Etiology
The etiology of cranial fossa meningioma is still unclear, and may be related to a combination of factors, such as gene mutation, craniocerebral trauma, radiation exposure, and viral infection.
Classification
The middle cranial fossa is butterfly shaped and can be distinguished into a smaller central portion and two larger, concave lateral portions. The central part is the saddle area located above the body of the pterygoid, i.e. the pterygoid saddle and its surrounding structures, mainly the pituitary gland, pituitary fossa and cavernous sinus on both sides. The lateral portion consists mainly of the greater wing of the pterygoid and the rocky portion of the temporal bone, which houses the temporal lobe. Meningiomas of the base of the middle cranial fossa can be classified according to the common site of origin of the tumor:
1. mesial and lateral meningiomas of the pterygoid crest;
2. saddle node (medial pterygoid crest) meningiomas;
3. anterior bedsplit meningiomas;
4. cavernous sinus meningioma;
5. Meckel’s cavity meningioma.
Symptoms
1. Pterygoid crest meningioma
There are significantly more female than male patients. The most common signs and symptoms are headache and epilepsy. Medial pterygoid crest meningioma takes years of vision loss as the main symptom, and may present with monocular vision loss or blindness, visual field defect, monocular pain, ipsilateral optic nerve compression and atrophy, and contralateral fundus of the eye presents with optic papilloedema due to increased intracranial pressure (Foster-Kennedy syndrome); it may invade the cavernous sinus and present with bulbar conjunctival congestion, monocular vision loss, and pairs of cerebral nerve paralysis of the Ⅲ, Ⅳ, and Ⅵ pairs. Meningiomas in the middle and lateral part of the pterygoid crest are commonly associated with headache and cranial hypertension, epilepsy, aphasia, weakness of the contralateral limb, and cone-bundle sign; there are often bony warts at the base of the tumor, which may affect the orbital volume and result in protrusion of the eyeballs; it may compress the cavernous sinus and cause temporal bulging.
2. Saddle node meningioma (medial pterygoid crest meningioma)
The common clinical manifestations are monocular or binocular visual loss and bilateral temporal hemianopsia, optic nerve atrophy. There is often no papillary edema, olfactory and psychiatric disorders (differentiated from olfactory groove meningioma), and there may be endocrine disorders, but the pterygoid saddle is not enlarged (differentiated from pituitary tumor). Those with large tumors may have headache, epilepsy, mental changes, fundus optic papillae edema and other manifestations.
3. Meningioma of anterior syrinx (medial pterygoid crest type meninges)
Common clinical manifestations are more common in females, and pregnancy may worsen the condition. Headache or periorbital pain is the earliest symptom, which often lacks specificity. Progressive monocular visual impairment may occur after slow progression of the disease, which may be accompanied by primary optic nerve atrophy and visual field defects. Involvement of the supraorbital fissure and cavernous sinus can be cranial nerve palsy and the affected side of the eyeball protrudes, facial (mainly trigeminal nerve ophthalmic branch distribution area) sensory loss, conjunctival congestion and edema. In the late stage, there may be symptoms of cranial hypertension, frontal lobe symptoms, temporal lobe hook gyrus seizures, hypothalamic symptoms, epilepsy, personality changes, and olfactory disorders.
4. Meckel’s meningioma
The common clinical manifestations are sensory abnormality, pain or hyperalgesia in the distribution area of the trigeminal nerve on the affected side, with trigeminal neuralgia being the most common, which is intermittent at the beginning and persistent thereafter. There may be trigeminal motor function involvement and atrophy of masticatory muscles. Compression of cavernous sinus can have ophthalmic muscle paralysis, eyelid ptosis and unilateral eyeball protrusion and other cavernous sinus syndrome manifestations. Compression of the Eustachian tube may cause tinnitus, hearing impairment and inner ear fullness. Invasion of the posterior cranial fossa can cause cerebellar angle, cerebellum and brain stem symptoms.
5. Cavernous sinus meningioma
It is mainly characterized by frontal and orbital pain on the same side of the lesion, motor nerve palsy, eyeball protrusion and epilepsy.
Examination
The possibility of this disease should be considered in those who have the above typical clinical manifestations, or those who have prolonged headache, adult epilepsy, mental changes, limited mass in the skull, and fundus optic papillae edema.
1.CT
The manifestation is a homogeneous slightly high-density or isodense mass with clear boundaries, connected to the dura mater and/or the inner plate of the skull with a broad base, and there may be localized skull bone proliferation and destruction; the enhancement is mostly homogeneous and intensified.
2.MRI
T1WI is equal or slightly low signal, T2WI is high signal or equal signal; enhancement scans mostly show uniform enhancement, and the characteristic rat-tail sign or dural tail sign can be seen.
3. Cranial X-ray film
Bone hyperplasia (diffuse bone thickening, radiating bone needle-like changes, sclerotic bone hyperplasia), (can involve the inner plate, the whole layer and even reach the subcutaneous and submuscular), vascular indentation (a cluster of branching or radiating vascular indentation) and tumor calcification (calcium spots are dense and become snowflake-like or clump-like) can be seen.
4. Cerebral angiography
Characteristic manifestations include tumor staining in the capillary or venous phase, accelerated circulation, early appearance of draining veins but lack of continuous draining veins, early filling of the supplying arteries, enlargement and tortuosity in the form of ballooning of the supplying vessels, and thickening of the supplying arteries in the vicinity of the tumor segment.
Diagnosis
The diagnosis of meningioma of the middle cranial fossa can be basically confirmed according to the manifestations of CT, MRI and clinical symptoms, and X-ray film of the base of the skull is also helpful in the diagnosis of this disease.
Differential diagnosis
1. Pterygoid crest meningioma should be distinguished from dural metastatic carcinoma, which has history of primary tumor and metastasis to lungs, liver and other parts of the body, and is often combined with skull destruction and multiple metastatic foci of brain parenchyma, and may have extradural lipid signal on MRI.
2. The anterior bed synapse meningioma should be distinguished from olfactory groove meningioma, which is mainly psychiatric symptoms, often with euphoria, inattention, unilateral or bilateral loss of sense of smell, and about 30% of them have grand mal seizures. the volume of the lesion on MRI is larger, and the olfactory groove area is the main area.
3. Cavernous sinus meningioma should be distinguished from cavernous sinus thrombosis and carotid cavernous sinus:
(1) Cavernous sinus thrombosis has a history of infection. Clinically, the typical cavernous sinus syndrome appears in the short term. Cerebrospinal fluid examination may have elevated white blood cells, smear or culture can be clear pathogenic bacteria. Routine blood leukocytes and neutrophils are elevated, and the blood sedimentation is rapid. Head CT shows cavernous sinus swelling, irregular filling defects and dilated ophthalmic veins. MRI shows equal (high) signal in T1WI and low (equal) signal in T2WI in early stage, and after a few days, it can show “bull’s-eye” sign with equal signal in the center and high signal around it, and then in the second month, it shows equal signal in T1WI and high signal in T2WI, and contrast-enhanced T1WI shows equal signal and high signal in T2WI, and contrast-enhanced T1WI shows high filling defect in the cavernous sinus. A filling defect in the cavernous sinus is seen. The direct sign of head MRV is the absence of high signal in the normal development of cavernous sinus or low flow signal with blurred and irregular edges; the indirect sign is the formation of venous side branches at the obstruction and the abnormal expansion of draining veins in other ways.
(2) Carotid cavernous sinus leakage is often associated with a history of head trauma, edema and congestion of the conjunctiva at different periods after the injury, pulsatile proptosis, intracranial vascular murmur, progressive vision loss and other typical signs and symptoms, and the diagnosis can be confirmed with cerebral angiography.
4. Meckel’s meningioma should be distinguished from primary trigeminal neuralgia and secondary trigeminal neuralgia caused by other reasons.
Complications
Common postoperative complications include cerebrospinal fluid leakage, hematoma in the operative area, cranial nerve dysfunction, epilepsy, hydrocephalus, hydrocephalus, meningitis, deep vein thrombosis, and pulmonary embolism.
Treatment
1. Surgical resection
Surgical resection is the preferred treatment strategy, and the ideal surgical access should be selected according to the basal attachment site of the tumor, and intraoperative attention should be paid to the protection of blood vessels and nerves adjacent to and wrapped by the tumor. If the tumor infringes the dura mater of the base of the cranial fossa or the bone of the base of the cranial fossa, the tumor should be resected together, and reconstruction of the cranial base should be carried out by using autologous fat, muscle, artificial dura mater, etc., plus sealing adhesive with medical adhesive. If important blood vessels are involved or damaged, end-to-side or end-to-end anastomosis or saphenous artery bypass grafting can be done. If the cranial nerve is damaged, the peroneal nerve, auricular nerve or supraorbital nerve can be used for cranial nerve anastomosis reconstruction.
2.Radiotherapy
Stereotactic radiosurgery can be used for those who have residual or recurrent disease after surgery, those who are old or have difficulty in tolerating surgery, and those who are unwilling to undergo surgery for small anterior synostosis meningiomas.
Prognosis
1. Due to the deep location of meningioma in the middle fossa of the skull and its close relationship with important blood vessels at the base of the skull, cavernous sinus and multiple groups of cranial nerves, it is more difficult to perform surgery, and the mortality rate, disability rate and recurrence rate of the patients after operation are all higher.
2. The main factors affecting surgical total resection include tumor staging (origin of the tumor and whether there is arachnoid separation between the tumor and the internal carotid artery, whether it is a recurrence, invasiveness, size of the tumor, whether it involves the cavernous sinus, the relationship with the optic nerve, the internal carotid artery and its branches, the selection of surgical access and the texture of the tumor, etc.).
3. Factors affecting the prognosis include the degree of first surgical resection, intraoperative damage to important nerves and blood vessels, severity of preoperative symptoms, location of the tumor, size of the tumor, invasiveness, and choice of surgical approach.