We all have a general idea about the skull that encases our brain. The skull is made of bone to protect the soft brain inside. The hard skull bones are made up of three tissue layers (meninges), to protect it from damage. The meninges are the dura mater (the outermost layer), the arachnoid mater (the middle layer), and the pia mater (the innermost layer). It is these meninges that cover and protect the central nervous system (the brain & spinal cord). There is also a cerebrospinal fluid that flows throughout the spaces in the meninges and the spaces (also called ventricles) in the brain, as well. The skull base consists of the lower part of the skull and consists of the following.
- Anterior Cranial Base (front part of the cranial base)
- Middle Cranial Base (middle part of the cranial base)
- Posterior Cranial Base (back part of the cranial base)
What is a skull base tumour ?
A skull base tumour is a tumour affecting the base of the skull.It could be of three types based on the area of the skull base they affect.
- Tumours affecting Anterior Cranial Base (front part of the cranial base)
- Tumours affecting Middle Cranial Base (middle part of the cranial base)
- Tumours affecting Posterior Cranial Base (back part of the cranial base)
What are the types of skull base tumours ?
These can vary from primary (originating in skull base) to secondary (originating elsewhere) neoplasms, as well as from benign to malignant neoplasms. The benign tumours include Meningiomas (tumour affecting meninges), Schwannomas (tumour affecting nerves), Pituitary Adenomas (tumour affecting the pituitary gland), Chondroblastomas (tumours of cartilage) and Haemangiomas (tumour affecting the blood vessels of skull). The malignant tumours include Carcinomas (malignant cancers of epithelial tissue), Sarcomas (malignant cancers of connective tissue, eg: bone- osteosarcoma & cartilage- chordoma & chondrosarcoma), lymphomas or myelomas.
What are the causes of skull base tumours ?
Each tumour of the skull base has its own cause. Most have changes in the cell’s gene make-up. Certain Oncogenes (tumour causing genes) get turned on, whilst Tumour Suppressor Genes get turned off. Some meningiomas have an anomalous chromosome 22. Meningiomas also frequently have over expression of growth factors and their receptors, which add to the growth and enlargement of these tumours. Other factors that can increase risk of skull base cancer include previous radiation therapy or radiation exposure to the head and a previous history of brain cancer or other cancers.
What are the clinical features of skull base tumours ?
Benign tumours are very slow-growing and can expand to quite a large size, before they cause any symptoms. As the tumour grows, it may hamper normal functioning of the brain. These symptoms occur based on the tumour’s location. The initial symptoms are generally due to increased intracranial pressure caused by the growing tumour. These include headache, nausea and weakness in an arm or leg, most commonly. Seizures, personality changes, or visual problems may also occur. Tumours of skull base may show cranial nerve symptoms like double vision, hearing or smelling loss or impaired swallowing functions.
How is a skull base tumour diagnosed ?
- A complete physical examination of the body is mandatory.
- Imaging Tests: Important diagnostic tests include MRI Scans or PET Scans. Magnetic Resonance Imaging (MRI), both with and without a contrast dye & Computed Tomography (CT) Scans are the imaging tests used most often for diagnosis of skull base tumours. CT scan and /or MRI should be carried out to provide the exact anatomical information of the tumour such as its extent and measurements. Doctors can then view, assess and judge the cancer and determine how far it has progressed or spread.
Magnetic resonance angiography (MRA): This specialized MRI is done to analyze the blood vessels in the brain. This is extremely useful before surgery to help the surgeon plan operations. - Biopsy : A histological study of the biopsy, under the microscope confirms the cancer diagnosis, but in this case, has to be combined with surgery as it can lead to complications.
How are skull base tumours treated ?
In general, we can classify and discuss the management of the cranial base tumours according to their histopathologic types. Since biologic aggressiveness directs decision on which mode of treatment is the best from an oncological standpoint, and the location of tumour and clinical presentation provide important information on the risks that could occur in treatment. In skull base tumours that are considered benign, observation is done, especially if the patient has negligible symptoms. These include skull base meningiomas and schwannomas. What is needed then is careful follow-up, physical examination as well as imaging studies. It detects changes and follows tumour progress. Whilst small tumours are treated with minimal risks, larger tumours are harder to treat and can cause considerable post-treatment problems.
- Surgery : Since cranial base tumours are situated deep and enclosed by critical structures, conventional neurosurgical approaches are not that helpful because of the requirement for significant brain retraction, reduced control of the lesion and adjacent structures. Earlier, such operations often caused partial removal of the lesion with increased morbidity. However, nowadays, modern skull base surgery gives far better exposure of deep-seated cranial base lesions with less need for cerebral retraction by removing non-critical bones (eg, petrous apex, clinoid) with focused operative maneuvers (eg, mobilization of neurovascular structures). With the introduction of these techniques, most skull base tumors can be safely approached, and many are radically resected. However, sometimes, the tumour may not be completely operable.
- Radiation therapy : a cancer treatment that utilizes high-energy x-rays or basically radiation to eradicate cancer cells. Radiation therapy has to be used post surgery to kill any remaining cancer cells.
Conventional fractionated radiotherapy has been used for malignant skull base tumours and radiosensitive tumours. Radiation therapy also reduces the growth and recurrence rates of some of the benign tumours like paragangliomas and meningiomas. - Chemotherapy and hormonal therapy : Chemotherapy is indicated in specific malignant tumours.
- Other therapies : To obtain the maximum effect of treatments, various combined treatment regimens are indicated for the management of certain skull base tumours. For incompletely resected tumours, radiotherapy is effective in delaying the rate of growth and symptomatic recurrences. The final therapeutic decision must take into account the patient’s condition, the natural history of the tumour, and the risks and benefit of each treatment option.
What is the care to be taken after the treatment of skull base tumour ?
Metastatic diagnostic workup and monitoring post-treatment for aggressive or disseminated tumours includes imaging and scanning of the skull and body with radiography, MRI or CT scans. The length of recovery time varies, based on how extensive the tumour was, patient’s age and general health and the type of treatment. There may be problems with muscle coordination or speech, following surgery depending on the tumour’s location; but these are often temporary. Many skull base tumour patients should go in for rehabilitative services to restore physical and psychological functions. These services consist of physical, occupational and speech therapy to alleviate the symptoms that are caused by the tumour or its treatment.
How to find and reach neurosurgeons for skull base tumour surgery ?
Now you can find and reach neurosurgeons for skull base tumour surgery from different hospitals and destinations on a single platform, Hinfoways. You can avail opinions and information from multiple neurosurgeons, cost estimates for skull base tumour surgery from different hospitals, compare things and then choose a neurosurgeon or a hospital for skull base tumour surgery.
Find, reach and choose a neurosurgeon for skull base tumour surgery on Hinfoways. Make an informed choice.
Disclaimer: The content provided here is meant for general informational purposes only and hence SHOULD NOT be relied upon as a substitute for sound professional medical advice, care or evaluation by a qualified doctor/physician or other relevantly qualified healthcare provider.
