Effects of tethering on regional spinal cord blood flow and sensory-evoked potentials in growing cats.

The spinal cords of 2-week-old kittens were tethered by fixing the end of the filum terminale to the lower sacrum, to study the effects of tethering and untethering on regional spinal cord blood flow (rSCBF), sensory-evoked potentials (SEPs) and clinical features. Progressive sensorimotor deficits and incontinence were observed in all the tethered cats. Cord tethering induced a reduction of rSCBF in the distal spinal cord close to the tethering (L3) by 32% of the normal flow 2 weeks after tethering and by 67% 10 weeks after tethering. Untethering of the cord resulted in an increase of rSCBF, restoring it to the normal level in the group untethered 2 weeks after tethering, but rSCBF did not increase in the group untethered 8 weeks after tethering. The changes in SEPs were observed whenever rSCBF was below 14 ml/100 g per minute. Suppression of the early components of SEPs was observed 2 weeks after tethering and the components were progressively altered in amplitude and latency during the experimental period. It is assumed that early untethering can improve the spinal cord blood flow as well as the function of the cord.