Meningiomas are the most common type of primary central nervous system (CNS) tumor, originating from the meninges, the protective membranes surrounding the brain and spinal cord. A “Grade 1” classification by the World Health Organization (WHO) signifies slow-growing tumor cells that appear close to normal under a microscope. These benign, or non-cancerous, tumors represent approximately 80% to 81% of all meningiomas. Their slow growth often means they can exist for years without causing noticeable problems.
Recognizing Symptoms
Symptoms associated with Grade 1 meningiomas vary widely, depending on the tumor’s size and location. Many individuals remain asymptomatic, meaning they experience no symptoms at all, with tumors discovered incidentally during imaging tests performed for other health concerns. When symptoms do emerge, they tend to develop gradually and can be subtle.
Common symptoms include headaches, which might worsen over time, and seizures. Depending on where the tumor presses on the brain or nerves, individuals might also experience changes in vision (e.g., blurriness, double vision), hearing loss, or ringing in the ears. Weakness or numbness in the arms or legs, speech difficulties, or changes in personality or memory can also occur. These symptoms are not unique to meningiomas and warrant a thorough medical evaluation.
Diagnosis and Evaluation
Diagnosis typically begins with a comprehensive neurological examination. A doctor assesses functions like vision, hearing, balance, coordination, strength, and reflexes to identify affected areas of the brain or spinal cord. This initial assessment provides clues but does not definitively diagnose a tumor.
If a meningioma is suspected, imaging techniques are the primary tools. Magnetic Resonance Imaging (MRI) is the gold standard, providing detailed images of the brain and spinal cord. A contrast dye is often injected before the MRI to make the tumor more visible.
Computed Tomography (CT) scans, which use X-rays, can also be used, especially if MRI is not feasible. While imaging strongly suggests a meningioma, a definitive diagnosis and grading of the tumor (determining if it is Grade 1, 2, or 3) require a biopsy. During a biopsy, a tissue sample is removed, often with a needle, and examined under a microscope by a neuropathologist to confirm the diagnosis and assess its characteristics.
Treatment Approaches
Treatment for Grade 1 meningiomas is highly individualized, considering the tumor’s size, location, growth rate, patient health, age, and symptoms. For small, slow-growing, asymptomatic tumors, a “watch-and-wait” approach, also known as active surveillance, is often recommended. This involves regular monitoring with MRI scans to track the tumor’s size and growth without immediate intervention. This strategy suits elderly patients or those with other significant health conditions.
When a Grade 1 meningioma causes symptoms, grows, or poses a risk to neurological structures, surgical removal is generally the primary treatment. The goal is to remove as much of the tumor as safely possible, ideally achieving complete resection to reduce recurrence. Surgical success depends on the tumor’s accessibility and proximity to delicate structures.
If complete surgical removal is not feasible due to location or critical structure involvement, or if residual tumor remains after surgery, radiation therapy may be considered. Radiation therapy uses high-intensity beams to damage tumor cell DNA, preventing growth. Techniques like stereotactic radiosurgery (SRS), delivering a high dose in a single session, or fractionated stereotactic radiotherapy (FSRT), delivering multiple smaller doses, can be employed. Radiation therapy can be a standalone treatment for inaccessible tumors or an adjuvant therapy after partial removal to control remaining cells.
Long-Term Outlook
The long-term outlook for individuals with Grade 1 meningiomas is favorable due to their benign nature and slow growth. After complete surgical removal, the recurrence rate is relatively low, typically ranging from 7% to 25%. Even with complete removal, there is an approximate 24% to 32% chance of recurrence over 15 years. When recurrence occurs, it is most often at the original tumor site.
Regular follow-up imaging, primarily with MRI scans, is important to monitor for recurrence or new tumor growth. For completely resected Grade 1 meningiomas, annual MRI scans are often recommended, with surveillance potentially discontinued after about 11 years if no recurrence is observed. This extended follow-up is due to the slow-growing nature of these tumors and the potential for late recurrence. Early detection of regrowth through consistent monitoring allows for timely intervention, which can involve further treatment like additional surgery or radiation therapy.