DNET tumors are a type of benign brain tumor, often linked to long-standing epilepsy. They are slow-growing and most frequently diagnosed in children and young adults. Understanding their nature, symptoms, and treatment is important for managing the associated neurological effects.
Understanding DNET Tumors
Dysembryoplastic Neuroepithelial Tumors, or DNETs, are a low-grade brain tumor. These rare tumors account for less than 1-2% of all brain tumors. DNETs are composed of both glial cells, which provide support to the central nervous system, and neuronal cells, which are responsible for its functioning.
DNETs commonly develop in the cerebrum, the part of the brain controlling thought, movement, and sensation. Their most frequent location is the temporal lobe, although they can also appear in the frontal lobe and, less commonly, in other areas of the brain or spinal cord.
DNETs are often associated with epilepsy, particularly long-standing seizures. The tumors can make surrounding brain tissue more prone to seizure activity. They are frequently seen in children and adolescents, with an average diagnosis age of nine years, and are a common cause of epilepsy in children.
Recognizing the Signs
The most common symptom associated with DNET tumors is seizures. These seizures can be difficult to control with medication alone. Patients often experience partial or focal seizures, which originate in a specific brain area.
The type and severity of seizures vary depending on the tumor’s location and size. While seizures are the primary indicator, other less frequent symptoms may include headaches, especially with very large tumors. Other neurological impairments, such as weakness or vision changes, are uncommon unless the tumor affects those specific functions.
Diagnosis and Identification
Identification of a DNET tumor typically begins when a patient experiences seizures. A neurological examination assesses brain function. Imaging techniques play a central role in visualizing the tumor and determining its characteristics.
Magnetic Resonance Imaging (MRI) scans are particularly useful, as DNETs often have a distinct appearance on these images, appearing as well-defined lesions. They may show a “bubbly” or multicystic structure and are typically hypointense on T1-weighted images and hyperintense on T2-weighted images. A Computerized Tomography (CT) scan might also be used, revealing low-density masses that can sometimes have calcifications.
An electroencephalogram (EEG) is frequently conducted to evaluate the brain’s electrical activity and pinpoint the origin of seizure activity. While imaging studies can strongly suggest the presence of a DNET, a definitive diagnosis requires a biopsy. During a biopsy, a tissue sample from the tumor is taken and then examined by a pathologist under a microscope to confirm its specific features.
Treatment Approaches
The primary and most effective treatment for DNET tumors is surgical removal. The goal of surgery is to completely remove the tumor, which can lead to significant improvement or resolution of seizures. Complete tumor removal is associated with a high rate of cure and seizure freedom.
Neurosurgeons often use advanced tools, such as intraoperative MRI and neuronavigation, to achieve maximal safe resection, especially when the tumor is located near important brain areas. Even if the entire tumor cannot be removed, the prognosis remains favorable because DNETs are benign. In instances of partial removal, the remaining tumor often stays dormant for many years.
Anti-seizure medications are frequently used alongside surgery to manage symptoms. Their dosage might be gradually reduced or discontinued after surgery if the patient achieves seizure freedom. Unlike many other brain tumors, radiation therapy and chemotherapy are generally not used for DNETs due to their benign nature and good response to surgical intervention. These therapies are reserved only for very rare, atypical situations.
Prognosis and Follow-Up
Individuals diagnosed with DNET tumors generally have an excellent prognosis, particularly when the tumor is completely removed through surgery. After successful surgery, a high percentage of patients, often between 80-90%, achieve freedom from seizures or experience significant improvement in seizure control. This can lead to a substantial enhancement in their quality of life.
Long-term follow-up care is an important aspect of managing DNET tumors, even after surgical removal. This typically includes regular neurological check-ups to monitor for changes in symptoms or neurological function. Imaging studies, such as MRI scans, are also recommended periodically to monitor the surgical site and check for any signs of tumor recurrence, although recurrence is rare.
Initially, MRI follow-ups might be scheduled every 6-12 months, gradually transitioning to annual scans for several years. Even if a small portion of the tumor remains after surgery, it often remains quiescent, contributing to the generally positive outlook.