INCIDENCE OF CONTRALATERAL VERSUS IPSILATERAL NEUROLOGICAL SIGNS ASSOCIATED WITH LATERALIZED HANSEN TYPE-I DISC EXTRUSION

Asymmetrical neurological signs were noted in 50 dogs presenting with Hansen type I thoracolumbar disc extrusion. Thoracolumbar myelograms a nd surgical decompression were performed in all cases. Dogs were divid ed into two groups (acute and chronic) based on the duration of clinic al signs prior to presentation to the University of Georgia. Lateralis ing extradural cord compressive lesions were noted on all myelograms. In the acute group, 35 per cent of the dogs had asymmetrical neurologi cal signs contralateral to the myelographic and surgical lesion, while In the chronic group only 11 per cent had neurological signs contrala teral to the lesion. There was found to be no significant difference i n frequency of contralateral asymmetrical clinical signs between the t wo groups (Fischer's exact test; P = 0.095). The high frequency of con tralateral signs documents the importance of thoracolumbar myelography for accurate localisation of the disc material before decompressive s urgery.