Butterfly glioma is a rare and aggressive type of brain tumor, a specific subgroup of glioblastoma, the most common primary brain cancer. It is characterized by its distinct growth pattern, spreading across the corpus callosum, the large bundle of nerve fibers connecting the two brain hemispheres. This bihemispheric involvement gives it a “butterfly-like” appearance on imaging scans. Its aggressive infiltration impacts various neurological functions, leading to a range of symptoms and a generally poor prognosis.
What is Butterfly Glioma
Butterfly glioma is classified as a high-grade astrocytoma. Its defining characteristic is its ability to cross the midline of the brain, typically through the corpus callosum, affecting both cerebral hemispheres. This unique spread distinguishes it from other brain tumors, as it infiltrates widely rather than remaining localized.
The tumor’s aggressive nature stems from its rapid growth and diffuse infiltration into surrounding brain tissue. On Magnetic Resonance Imaging (MRI) scans, this tumor often presents with a distinctive “butterfly-shaped” pattern, a result of its bihemispheric involvement. Common imaging features also include internal necrotic or hemorrhagic areas and irregular peripheral contrast enhancement, highlighting its aggressive pathology.
Common Symptoms
The symptoms of butterfly glioma arise from the tumor’s pressure on brain tissue and its widespread infiltration across both hemispheres. Headaches are common, often worsening in the morning. Patients may also experience nausea and vomiting as the tumor grows and increases pressure within the skull.
Seizures are a frequent clinical presentation. Cognitive changes, such as confusion, memory loss, or a decline in overall brain function, can also manifest due to the tumor’s diffuse spread. Motor deficits, including weakness on one side of the body, and changes in personality or increased irritability may also occur, depending on the specific brain regions affected by the tumor’s infiltration.
How Butterfly Glioma is Diagnosed
The diagnosis of butterfly glioma relies heavily on advanced imaging techniques, primarily Magnetic Resonance Imaging (MRI). MRI scans visualize the tumor’s characteristic spread across the corpus callosum and its involvement of both brain hemispheres, creating the distinctive “butterfly” pattern. These images reveal features such as ill-defined, heterogeneous masses that are typically hypointense on T1-weighted scans and hyperintense on T2 and FLAIR images, often showing marked contrast enhancement.
Despite clear imaging findings, a definitive diagnosis requires a biopsy. This procedure, which can be stereotactic or open, involves obtaining a tissue sample from the tumor for neuropathological examination. Microscopic analysis confirms the presence of glioblastoma and helps differentiate it from other conditions that can mimic a “butterfly” pattern on MRI, such as primary CNS lymphoma or tumefactive multiple sclerosis.
Treatment Options
Treatment for butterfly glioma typically involves a combination of therapies due to its aggressive and infiltrative nature. Surgical resection, while a standard approach for many brain tumors, is often limited in butterfly gliomas because of the tumor’s diffuse spread across both hemispheres via the corpus callosum. Complete removal of the tumor is usually not feasible, as microscopic tumor cells often remain after surgery. The aim of surgery is primarily to reduce tumor volume, alleviate symptoms, and obtain tissue for diagnosis.
Radiation therapy is a key part of treatment for butterfly glioma, often administered after surgery to target any remaining tumor cells. This can involve standard fractionated radiation, given in daily doses over several weeks, or hypofractionated approaches, which deliver higher doses over a shorter period. Radiation is designed to damage and destroy cancer cells, helping to slow tumor growth.
Chemotherapy, particularly with temozolomide (TMZ), is commonly used in conjunction with radiation therapy. Temozolomide is an oral chemotherapy drug that works by alkylating DNA, leading to cell death. It is often given concurrently with radiation and then in cycles following radiation, a regimen known as the Stupp protocol for glioblastoma. This multimodal approach aims to improve survival outcomes and manage the aggressive progression of the disease.
Prognosis and Guiding Factors
Butterfly glioma is associated with a poor prognosis due to its aggressive nature and bihemispheric spread. Median overall survival rates for patients are generally low, often ranging from less than 6 months to around 8.5 months, although some studies report ranges of 12-15 months. Despite this challenging outlook, multimodal treatment approaches, including surgery, radiation therapy, and chemotherapy, have been associated with longer survival compared to supportive care alone.
Molecular characteristics of the tumor can offer additional insights into prognosis and influence treatment decisions. The isocitrate dehydrogenase (IDH) mutation status is a significant prognostic factor; IDH-mutant gliomas generally have a more favorable prognosis than IDH-wildtype glioblastomas, which are more common in butterfly gliomas. Another important biomarker is the O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status. Tumors with MGMT promoter methylation tend to respond better to temozolomide chemotherapy, leading to improved survival outcomes. These molecular markers help personalize the understanding of the disease’s likely course and guide therapeutic strategies.