Dysfunction of the medullary cardiovascular center may cause acute spinal cord swelling

Acute brain swelling is well known to be acute vasodilatation of cerebral vessels and sometimes results from brain injury. One of the causes of acute brain swelling may be disturbance of central control mechanisms of cerebral vessels. However, the presence of acute spinal cord swelling is little noticed. We present here a possibility that acute spinal cord swelling may be occur following the dysfunction of the cardiovascular center of the medulla. In urethane-anesthetized, paralyzed and artificially ventilated rats, the neurons in the rostral ventrolateral pressor area (VLPA), origin of the sympathetic nerve activities in the brain stem, were chemically stimulated by microinjection of L-glutamate and the spinal cord blood flow (SCBF) was determined using labeled microspheres. The SCBFs of cervical, thoracic, and lumbar cord decreased significantly from 27 +/- 3 (mean +/- S.E.M.) to 20 +/- 2 (p < 0.01), from 22 +/- 1 to 17 +/- 2 (p < 0.05), and from 41 +/- 5 to 26 +/- 3 (p < 0.05) ml.min-1.(100 g)-1, respectively (n = 12). The spinal cord vascular resistances (SCVRs) of cervical, thoracic, and lumbar cord increased significantly from 3.7 +/- 0.4 to 5.0 +/- 0.6 (p < 0.05), from 4.2 +/- 0.2 to 5.9 +/- 0.7 (p < 0.05), and from 2.5 +/- 0.2 to 3.8 +/- 0.4 (p < 0.05) mmHg per [ml.min-1.(100 g)-1], respectively (n = 12). These results suggest that the neurons within the VLPA may play a role in the control of spinal cord circulation. There is a possibility that the dysfunction of the VLPA may cause acute spinal cord swelling.