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The most common tumors of the ear and the base of the skull are acoustic neuroma, meningioma and glomus tumors. Acoustic neuroma is the most frequent, representing six to ten percent of both cancerous and nonmalignant brain tumors.
Tumor growth in these areas often leads to hearing loss, tinnitus, balance problems or unsteadiness. Treatment options for skull base tumors include microsurgical removal, radiation and, in some instances, observation.
Cranial Base Surgery
The cranial base is the complex region comprising the floor of the cranium, the ventral surface of the brain and brainstem, and the nerves, arteries and veins entering and exiting the skull. The practice of cranial base surgery includes diagnosis of tumors and conditions in this region, patient counseling regarding treatment options and timing, and surgical treatment if required. Benign intracranial tumors and aneurysms of the cerebral vasculature are the most common conditions treated by cranial base surgeons, and the treatment of these conditions is individualized to the patient’s symptoms, age, health status, and diagnosis. The University of Cincinnati Cranial Base team includes specialist in neurotology, neurosurgery, neuroanesthesiology and neurophysiology to provide comprehensive care in this anatomically challenging region.
Schwannoma
Schwannomas are benign nerve sheath tumors that occur on the sensory cranial nerves, and they represent 6-10% of intracranial tumors. The most common type is a vestibular schwannoma (often called acoustic neuroma) followed by the trigeminal schwannoma. These tumors may occur sporadically or may be hereditary, as seen in patients with neurofibromatosis type 1 and type 2. The sporadic form is usually solitary, while patients with neurofibromatosis frequently have multiple tumors.
Treatment of these benign tumors varies and is dependent on patient symptoms, tumor size and age. The presenting symptoms may include hearing loss, imbalance or vertigo, impairment of facial movement, or headaches. In large tumors, the mass may compress the brainstem, which if untreated may lead to severe ataxia and even death. The majority of these slow growing tumors are identified at a stage where treatment options include observation with MRI for tumor growth, stereotactic radiation therapy to halt tumor growth, or surgery for excision of the lesion or decompression of the brainstem.
Meningioma
Meningiomas arise from meningothelial cells from the covering of the brain and account for 22% of intracranial tumors. The majority of meningiomas occur on the convexities of the brain, but a subset of these tumors present in the cerebellopontine angle at the cranial base. Most meningiomas are benign or atypical,and malignant meningiomas are fortunately uncommon. Management of meningiomas depends primarily upon the size and location of the tumor, as patients may have a paucity of symptoms. Treatment options are highly individualized to the patient and may include observation, stereotactic radiation, or complete or partial resection of the tumor. When occurring at the cranial base, brainstem compression or involvement of the cranial nerves are the primary concerns and may necessitate surgical treatment.
Paraganglioma
Glomus jugulare is a type of paraganglioma, and is a benign neuroendocrine tumor arising in the temporal bone. The vast majority of these tumors are nonfunctional, but 1- 3% of tumors secrete active hormones and may cause symptoms of palpitations, tachycardia, flushing and anxiety. Glomus jugulare tumors are located at the jugular foramen of the skull base and often present with pulsatile tinnitus, hearing loss, or weakness of the lower cranial nerves. Lower cranial nerve weakness may manifest as dysphagia, dysphonia, and tongue or shoulder weakness. Paragangliomas are very vascular tumors and may be treated with radiation or with surgical excision after preoperative embolization.
For additional information:
The American Neurotology Society
Acoustic Neuroma Association
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