venerdì 18 novembre 2005
Lymphoma invading neuroforamina with cord compression
Axial T2 image (Figure 1) reveals a mass extending through the right neural foramina with obliteration of the CSF space and displacement and narrowing of the cord.
An axial T1 post-contrast image (Figure 2) demonstrates enhancement of the mass as it enters the right neural foramina.
Sagittal T1 post-contrast image (Figure 3) depicts a large enhancing epidural mass causing significant narrowing of the spinal canal. Diffuse heterogeneous enhancement of the visualized vertebral bodies is consistent with bone marrow involvement by tumor.
Diagnosis: Lymphoma invading neuroforamina with cord compression
Acute spinal cord compression is a potentially devastating neurological emergency that requires both prompt diagnosis and intervention to prevent permanent impairment. The frequency of metastatic cord compression is increasing as cancer prevalence rises and new treatment modalities prolong patient survival. Approximately 5% of patients with terminal cancer develop epidural spinal cord compression. Metastases are 25 times more common than primary tumors as a causative etiology. Intramedullary spinal cord metastasis have frequency of 1/16 that for epidural metastasis and are best diagnosed by MRI. Of note, approximately 20% of patients with spinal cord compression have the associated new neurological deficits as their initial manifestation of disease.
Many types of tumor metastasize to the epidural space. Relative incidence of spinal cord compression by a particular type of tumor is determined by a combination of tumor prevalence in the population and its predilection for spinal involvement. In adults the most common tumors causing cord compression are prostate, breast, lung, NHL, multiple myeloma, renal, and colorectal cancer. In children the most common types are germ cell tumors, Hodgkin's, and sarcomas, especially Ewing's. Lymphoma may classically extend through the neuroforamina into epidural space to cause spinal cord compression.
Information from the neurological exam is critical for localization of the lesion and optimization of the MRI protocol. Whole spine imaging is generally undesirable as it is more time-consuming, expensive, and difficult for patients who are often in considerable pain. It further lowers resolution on exams that are often suboptimal secondary to severe patient pain and patient movement. Spinal sensory levels on neurological examination may be up to several segments below the anatomic level of cord compression. Evaluation of motor function and reflexes is very useful for lesion localization. Pain is ubiquitous in cancer patients, and while it may be initially localized, it is not specific to cord compression and is more often related to vertebral metastasis and pathologic fracture. Pain increases in intensity with worsening compression. Pain from cord compression often worsens with recumbency.
Once the site of interest is more precisely identified, sagittal T1 and T2 images and axial T2 images are required for the diagnosis. Axial T1 images through the lesion may then be obtained for further characterization of the anatomy and evaluation of hemorrhage. Spinal cord compression may be defined on imaging as the presence of a mass lesion abutting the cord with the complete loss of intervening CSF. This must be accompanied by deformation of the spinal cord, and/or the presence of signal changes within the cord. The findings are best visualized on T2-weighted images. In the case of neoplasm, intravenous contrast may be useful for further characterization. However, intravenous contrast is not necessary for the diagnosis of acute cord compression.