Clival chordoma is a rare cancerous tumor that develops at the base of the skull, in the clivus. This slow-growing malignancy originates from remnants of the notochord, an embryonic structure involved in spine formation. While the notochord usually disappears early in fetal development, some cells can persist in the skull base or spine. Clival chordomas are sarcomas, accounting for a small percentage of primary bone tumors. Their location in the skull base poses challenges for diagnosis and treatment due to proximity to delicate neurological structures.
Causes and Symptoms of Clival Chordoma
The exact cause of clival chordomas is not fully understood; most cases appear sporadically. These tumors are linked to persistent notochordal cells that undergo DNA changes, becoming cancerous. Genetic factors are being researched, but specific environmental triggers have not been identified.
Symptoms of a clival chordoma arise from the tumor’s growth and the pressure it exerts on nearby nerves, the brainstem, and other structures. A common early symptom is double vision, occurring when the tumor compresses cranial nerves responsible for eye movement. Patients may also experience facial numbness or pain due to pressure on cranial nerves.
Difficulty swallowing or changes in voice can develop if the tumor affects cranial nerves involved in these functions. Headaches, often persistent and severe, are another frequent symptom, resulting from the tumor’s mass effect on the brainstem. Balance problems or unsteadiness can also occur as the brainstem is affected.
If the tumor extends forward, it can lead to nasal symptoms like congestion, obstruction, or bleeding. Hearing loss or ringing in the ears may also arise depending on the tumor’s impact on auditory pathways. Since these symptoms can be general, diagnosis often occurs after the tumor has grown to a noticeable size.
The Diagnostic Process
Diagnosing a clival chordoma begins with a thorough medical history and a neurological examination. During this initial assessment, a healthcare provider checks for issues with balance, coordination, vision, facial sensation, and other nerve functions. These findings help guide further investigation to identify the underlying cause of symptoms.
Imaging studies are a subsequent step in diagnosis. Magnetic Resonance Imaging (MRI) is the most effective tool for visualizing clival chordomas, providing detailed images of the tumor and its relationship to surrounding soft tissues like the brainstem, nerves, and blood vessels. MRI scans show the tumor’s signal characteristics, which helps distinguish it from other lesions.
A Computed Tomography (CT) scan is also performed to complement MRI findings, offering a detailed view of bone involvement and any destruction the tumor has caused in the clivus. CT scans are useful for assessing calcification within the tumor and the extent of bone erosion. While imaging can strongly suggest a chordoma, a definitive diagnosis requires a biopsy. This involves taking a tissue sample from the tumor, which a pathologist examines to confirm specific chordoma cells. Often, this biopsy is performed during planned surgical removal.
Treatment Approaches
The primary treatment objective for a clival chordoma is the greatest safe surgical removal of the tumor. The choice of surgical technique depends on the tumor’s size, location, and its relationship to surrounding structures. A common minimally invasive method is the endoscopic endonasal approach, where surgeons access the tumor through the nose and nasal sinuses. This approach avoids external incisions and provides a direct path to many clival chordomas, often resulting in a high rate of tumor removal and fewer complications.
For larger or more complex tumors that extend beyond the reach of the endonasal approach, a traditional open craniotomy might be necessary. This involves temporarily removing a section of the skull to gain direct access to the tumor. Regardless of the technique, the goal is to remove as much of the tumor as possible without causing harm to nearby brain structures or cranial nerves.
Following surgery, radiation therapy is usually recommended to target any remaining tumor cells. Chordomas are resistant to conventional radiation, making precise, high-dose delivery important. Proton beam therapy is a preferred form of radiation for chordomas due to its unique physical properties. Protons deliver their energy at a specific depth, minimizing radiation exposure to healthy tissues and structures beyond the tumor. This precision helps reduce potential side effects while maximizing the dose delivered to the tumor bed.
Chemotherapy is not a primary treatment for clival chordomas because these tumors do not respond well to standard agents. However, in rare cases of tumor recurrence or spread, targeted therapies or participation in clinical trials exploring new agents may be considered. These newer treatments aim to target specific molecular pathways involved in chordoma growth.
Recovery and Long-Term Management
The recovery period following treatment for a clival chordoma varies based on the extent of surgery and radiation therapy. Patients may experience temporary side effects from surgery, such as nasal congestion or swelling, or headaches and fatigue from a craniotomy. Radiation therapy can also cause fatigue, skin irritation in the treatment area, or temporary hair loss, though proton beam therapy aims to minimize these effects due to its precision.
Clival chordomas have a tendency to recur, even many years after what initially appears to be successful treatment. This makes long-term surveillance an essential part of managing the disease. Recurrence rates can be high.
A lifelong surveillance plan is implemented, involving regular follow-up appointments with a multidisciplinary team of specialists. Periodic Magnetic Resonance Imaging (MRI) scans are performed to monitor for any signs of tumor regrowth. The frequency of these scans may decrease over time but continues indefinitely due to the potential for late recurrence.
Receiving care at a major medical center with a team experienced in treating skull base tumors and chordomas is beneficial. Such centers often have specialized neurosurgeons, radiation oncologists, neuroradiologists, and other professionals who collaborate to provide comprehensive and individualized care. This coordinated approach helps optimize outcomes and ensures ongoing monitoring for this challenging and persistent disease.