Paravertebral muscle metastases as imaged by magnetic resonance venography- A brief report

Paraspinal muscle metastasis as initially suggested by an electromyographic pattern of isolated posterior primary ramus denervation and subsequently c onfirmed by magnetic resonance imaging has been reported. However, despite widespread systemic tumor dissemination, metastases to other skeletal muscl e occurs infrequently. Uniquely, the paraspinal muscles are drained by the paravertebral plexus of veins. Valveless and at very low pressures, they co mmunicate directly by collaterals with the portal system. Valsalva maneuver s with sudden increases of pressure within the intra-abdominal and intratho racic cavities can force venous blood from the systemic circulation into th e paravertebral plexus of veins. These same venous surges potentially carry tumor emboli to the vertebrae and/or from the vertebral medulla to the adj acent paravertebral muscle by the venous communicators. The inherent increa sed vascularity of metastatic tumor relative to the surrounding paraspinal muscle as demonstrated by magnetic venous angiography for the first time no w permits earlier confirmation and biopsy of the electromyographic-suspecte d metastatic lesion. In this reported instance of a magnetic resonance imag ing-recognized primary lung metastasis confirmed by magnetic resonance veno graphy, there is the future promise of identifying earlier and smaller lesi ons by this technique.