The effect of an alpha-2 agonist on bladder function and cord histology after spinal cord injury.

Spinal injury in cats is accompanied by urinary bladder and hind limb dysfunction. Ten cats subjected to spinal contusion at the ninth thoracic segment were treated with guanabenz (an alpha-2 agonist) intraperitoneally (0.65 mg./kg.) three hours after injury, and twice daily for eight weeks. An additional six spinal cats were untreated and served as controls. Urodynamic studies were performed on a weekly basis on all animals. Guanabenz modified the vesico-somatic reflex: detrusor-sphincter dyssynergia was either ablated or abolished. In contrast, the controls demonstrated detrusor-sphincter dyssynergia, high residual urine, and spasticity below the lesion. Histological evaluations of the spinal cords revealed that the six paraplegic animals (untreated) suffered marked cavitation of the cord and complete destruction of the grey matter. The five incomplete paraplegic animals (treated) showed minimal cavitation with some preservation of the grey matter. The five ambulators (treated) demonstrated some distortion of grey matter with preservation of white matter. Treatment with guanabenz post traumatic cord injury results in decreased cord cavitation. Detrusor-sphincter dyssynergia is diminished and hind limb function is improved in treated animals.