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CHORDOMA CHORDOMA is a tumor that arises from cells that were originally involved in the formation of the Skull and Axial Skeleton (Spine) during the embryological development of the affected individual. This embryological entity is known as the "NOTOCHORD". CHORDOMAS are very rare primary bone tumors (comprising less than 1% of CNS tumors) that can occur at almost any point along the axis of the Spine from the Base of the Skull to the Sacrum and Coccyx (tailbone).The microscopic appearance of Chordoma cells, when examined by the Neuropathologist, is rather benign. Despite some efforts to classify them as "malignant" consequent to their location, invasive nature, and recurrence rate, these tumors do not metastasize. Nevertheless, Chordomas are considered to be very dangerous lesions. Approximately 1/3 of Chordomas are located along the Clivus (the centrally located bone that forms the Base of the Skull which is located immediately in front of the Brainstem and behind the nasopharynx (See Figures 1A & 1B). The Skull Base, the Vertebrae and the Sacrococcygeal area (the bottom of the Spine) are affected with equal frequency by Chordomas. Most Chordomas occur sporadically among the population; however, there are small groups of people who develop this tumor as a result of a mutation inherited as an autosomal dominant trait. For further information related to this unusual aspect, please refer to the U.S National Institutes of Health/National Cancer Institute website devoted to issue. ECCHORDOSIS PHYSALIPHORI is a term that refers to small, well-circumscribed, gelatinous masses that are adherent to the Brain Stem and are composed of notochordal remnants as well. While it is recognized that Ecchordosis physaliphori seldom progresses into Chordoma, there are some unusual circumstances where Ecchordosis physaliphori becomes sufficiently large to produce Brain Stem and Cranial Nerve compression and symptoms. Ecchordosis physaliphori is a reported finding in approximately 2% of autopsy examinations, but Chordomas are quite rare.
 Grossly, Chordomas are variable in size. They are soft, gelatinous, smooth, or lobulated and are gray-white in color on their outer surface (See Figure 2A.) Even though Chordomas usually are slow-growing tumors, they are locally aggressive with a tendency to infiltrate into adjacent tissues and organs. In spite of modern treatment, local recurrence of this tumor results in local destruction of vital neural structures which eventually is the cause of death. Metastases are most uncommon. SYMPTOMS Symptoms related to a Chordomas depend upon the location and size of the tumor. The most common presenting symptoms of an intracranial Chordoma are diplopia (double vision) and headache. One half of all patients with Clival region Chordomas develop Cranial Nerve palsies as result of direct involvement by the tumor of the 3rd, 4th, 5th and 6th Cranial Nerves.(See Figures 1 & 2 as examples of involvement of these Cranial Nerves.)DIAGNOSIS CT scan or MRI studies are the basic Neuroimaging studies that are used to evaluate Chordomas. MRI Scans are very helpful in demonstrating important anatomical information about the extent of the tumor and its relationship to vital adjacent structures. CT Scans are particularly useful in identifying the extent of bone destruction of the Clivus. This tumor usually appears as a well demarcated locally destructive lesion. All of this information is imperative in planning the optimal surgical approach.
TREATMENT The natural history of any particular Chordoma and the effectiveness of the different kinds of therapy are not well defined consequent to the rare incidence and slow-growing nature of Chordomas.Medical Therapy There are no current medical therapies available although some research protocols are in clinical trial. One such study is evaluating the effectiveness of "Gleevec" (imatinib mesylate) which has been shown to have some anti-tumor activity in Chordomas. To date, chemotherapy has not been effective for Chordomas.Surgery The extent of surgical removal of Chordomas depends on the size and location of the tumor. As a rule, complete resection of a Chordoma with wide removal of its "margins" is the treatment of choice. Unfortunately radical excision of a Clivus Chordoma with "clean margins" is not feasible without producing severe, if not catastrophic, neurological deficits since the Chordoma usually involves vital Cranial Nerves and Cerebral Vessels.Smaller tumors with less extensive local invasion may be more amenable to "radical resection" without producing major deficits. This type of extensive resection is associated with a longer disease-free interval. Radiation Therapy In most cases, however, subtotal excision is the only option (usually due to location and proximity to vital and sensitive anatomical structures.) The addition of Radiation Therapy can lengthen the time to the tumor's inevitable recurrence. In Skull Base Chordoma cases where Radiation Therapy is utilized without surgical removal, only 50% can expect 10-year local control.The use of Proton Beam Radiation Therapy in the treatment of Chordoma has been of particular interest for many years. Unfortunately, this too, has been shown to have significant risk to vision. Stereotactic Radiosurgery is an alternative form of Radiation Therapy that is more available than Proton Beam and may be the most effective of any of these different radiation modalities in the treatment of Chordomas.
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All content ©2024 by Neurosurgical Consultants, P.A. Author, Martin L. Lazar, MD, FACS All Rights Reserved. See Usage Notices. |