Meningiomas

Background information

Meningiomas are tumors that originate from the arachnoidea, i.e. the middle leaf of the three meninges, and account for about 20 - 30 % of all tumors of the central nervous system. Since they originate from the meninges, they are strictly speaking not "brain tumors" but actually "meningeal tumors". In most cases they are therefore located on the surface of the brain or at the base of the skull. Very rarely they develop from scattered meninges in the depth of the brain. The vast majority of meningiomas are benign tumors (WHO grade I), i.e. they grow very slowly and initially displace brain tissue without destroying it by infiltration. This allows them to reach a considerable size before symptoms set in.

7% of all menigeomas show somewhat faster growth and the recurrence rate is increased. They are called atypical menigeomas with WHO grade II. Malignant, fast and infiltrative growing anaplastic menigeomas (WHO grade III) are very rare (2%).

Most meningiomas are singular tumors based on spontaneous gene alterations (mutations) and histologically they can be divided into 15 subclasses. They can also occur as late effects of a previous radiotherapy.

It is not uncommon for meningiomas to be discovered purely coincidental, for example during a headache examination or an accident. In such asymptomatic cases, it must be carefully decided whether surgery is necessary or whether the tumour can be controlled in regular MRI examinations. In several observational studies the rule of thumb has been established that about one third of all randomly discovered meningiomas do not grow over an observation period of 3 years. 

Symptoms

The symptoms of meningiomas can vary greatly depending on their localization. Among other things, the following should be mentioned:

• Headache, caused by local irritation of the meninges or, in the case of large meningiomas, by increased intracranial pressure
• visual disturbances and/or double images in meningiomas at the base of the skull, which press on the optic nerves or the nerves that control the eye muscles
• Smell disorders in case of pressure on the olfactory nerves
• hearing problems, balance problems, facial pain or facial paralysis, difficulty swallowing, dizziness or nausea due to pressure on cranial nerves at the base of the skull
• Paralysis of the body, speech and movement disorders, visual disorders, personality changes when pressure is applied to the corresponding areas of the brain
• Epileptic seizures

Diagnostics

The imaging method of first choice is magnetic resonance imaging (MRI, MRI) as this method provides the best tissue differentiation and in most cases allows the reliable diagnosis of a meningioma. Especially before surgery, an additional computer tomography (CT) is performed to show tumor calcifications and the detailed spatial relationship to neighbouring skull base structures.

Therapy

For symptomatic meningiomas or meningiomas that have been shown to enlarge under observation, microsurgical removal of the tumor is the therapy of choice. This means that in over 90% of cases a definitive cure can be achieved without relapse. In the case of large menigeomas with a good blood supply, it may be advisable to carry out an angiography and embolization before the operation in order to stop the blood flow in parts of the tumour. In certain cases, this method can greatly simplify tumour resection and significantly reduce the risk of surgery.

The operation is always planned in detail pre-operatively using the latest 3D methods. During the operation, finely tuned microsurgical methods and instruments are used depending on the location of the tumour. Especially at the base of the skull, endoscopic surgery is performed to identify and expose small vessels and nerves at angles that are difficult to see. The aim is always to remove the meningioma completely and to resect the part of the meninges from which the meningioma originates, i.e. the "root of the meningioma" and replace it with artificial meninges (duraplasty).

If during the operation it turns out that a complete resection is not possible, a targeted radiation treatment (Cyber-Knife) of the tumour remnants can be performed after the operation. In the vast majority of cases, this can prevent further tumour growth.

The management of meningiomas at the Hirslanden Clinic is always interdisciplinary and each individual case is discussed in our Tumour Board before and after an operation. This guarantees the best possible therapeutic method, whether with or without surgery, in accordance with international guidelines.

41 y. old patient presenting with headaches, fatigue and repeated vomiting. MRI-imaging showed a contrast-enhancing tumor, measuring 5.3 x 4.5 x 4.6 cm – a meningioma of the tentorium. The tentorium separates the cerebrum from the cerebellum. Because of its size, the tumor compressed the fourth chamber (the 4^th ventricle) of the inner cerebrospinal fluid spaces, resulting in an impaired CSF-flow (occlusive hydrocephalus), that explained the patient’s symptoms. The tumor was completely resected without complications and the patient was able to leave the hospital a few days later without having any symptoms. The second MRI shows the postoperative MRI-findings a few years later without any signs of a tumor remnant or recurrence. The patient is fully active at work and without any neurological deficits.

Equivalent MRI-planes to the preoperative MRI-scans on pictures 1 – 3 a few years after surgery without any signs of tumor remnants or tumor recurrence: