Primary Tumors of the Spinal Cord

Presentation

IESCTs have a nonspecific clinical presentation that includes axial back or neck pain, as well as radicular or myelopathic signs and symptoms. Associated pain is usually most intense in the evening and morning. The specific symptoms of IESCTs mainly depend on the level involved and have no specific anatomic distribution. A study performed by Slin’ko and Al-Qashqish, however, examined 360 patients with IESCTs over an 11-year period and classified tumor location on both the axial and the longitudinal axis. The investigators found that on the longitudinal axis, most IESCTs occurred within the thoracic spine, followed by the cervical and lumbar spine, respectively. On the axial axis, the investigators determined that most lesions occurred on the dorsolateral division, followed, respectively, by the ventrolateral, dorsal, and ventral divisions.

In the case of NSTs, radicular sensory signs are the first to follow pain. Patients have pain because NSTs characteristically arise in the dorsal sensory roots. Radiculopathy with motor deficits is not common, even during involvement of functional roots of the cervical or lumbar spine. However, myelopathic motor signs manifest once the tumor achieves a critical mass, thus resulting in spinal cord compression. The myelopathy has no distinctive symptoms and may include signs such as Brown-Séquard syndrome (ipsilateral hemiplegia with ipsilateral fine touch sensory deficit and contralateral pain and temperature sensory deficit, and upper motor neuron involvement such as upward plantar reflex, hyperreflexia, and clonus). Chronicling the time progression of symptoms is important because rapidly worsening signs and symptoms indicate the presence of a fast-growing, aggressive tumor such as a malignant NST (MNST). Similarly, the presentation of spinal meningiomas is nonspecific and includes signs and symptoms such as progressive lower extremity numbness and weakness. Furthermore, many spinal meningiomas are often asymptomatic as a result of their slow growth and are discovered only incidentally during an imaging study or at autopsy.

Diagnosis

The two most common types of IESCTs are NSTs and meningiomas. The diagnosis of IESCTs is best made using magnetic resonance imaging (MRI) because plain radiography, computed tomography (CT), and CT with myelography do not provide sufficient delineation of an intradural neoplasm. However, when MRI is contraindicated, CT with myelography is the imaging modality of choice.

Of primary importance is determining whether the neoplasm is intramedullary or extramedullary. Extramedullary neoplasms have the following characteristics on MRI: displacement and compression of the spinal cord, expansion of the thecal sac, and a menisci-like interface with the cerebrospinal fluid. Intramedullary neoplasms are characterized by expansion of the spinal cord.

Most IESCTs are isointense to the spinal cord on T1-weighted imaging and hyperintense on T2-weighted images. Furthermore, IESCTs typically enhance with contrast on T1-weighted imaging ( Fig. 22-1 ). NSTs produce unique “target lesions” on MRI that correspond to the pathologic anatomy of the lesion. Despite the optimal ability of MRI to delineate the anatomic interface between the spinal cord and the neoplasm, this modality cannot provide a definitive diagnosis; the differential diagnosis also includes meningiomas, extramedullary ependymomas, mixed cell gliomas, hemangiomas, and cavernous hemangiomas. Definitive diagnosis is usually not made until pathologic examination of the surgical specimen. Patients with a positively identified IESCT should undergo further MRI of the remaining neuraxis to search for additional lesions, particularly in the setting of neurofibromatosis.