An imposed oscillating electrical field improves the recovery of function in neurologically complete paraplegic dogs

We show that an applied electric field in which the polarity is reversed ev ery 15 minutes can improve the outcome from severe, acute spinal cord injur y in dogs. This study utilized naturally injured, neurologically complete p araplegic dogs as a model for human spinal cord injury. The recovery of par aplegic dogs treated with oscillating electric field stimulation (OFS) (app roximately 500 to 600 mu V/mm; n = 20) was compared with that of sham-treat ed animals (n = 14). Active and sham stimulators were fabricated in West La fayette, Indiana. They were coded, randomized, sterilized, and packaged in Warsaw, Indiana, and returned to Purdue University for blinded surgical imp lantation. The stimulators were of a previously unpublished design and meet the requirements for phase I human clinical testing. All dogs were treated within 18 days of the onset of paraplegia. During the experimental applica tions, all received the highest standard of conventional management, includ ing surgical decompression, spinal stabilization (if required), and acute a dministration of methylprednisolone sodium succinate. A radiologic and neur ologic examination was performed on every dog entering the study, the latte r consisting of standard reflex testing, urologic tests, urodynamic testing , tests for deep and superficial pain appreciation, proprioceptive placing of the hind limbs, ambulation, and evoked potential testing. Dogs were eval uated before and after surgery and at 6 weeks and 6 months after surgery. A greater proportion of experimentally treated dogs than of sham-treated ani mals showed improvement in every category of functional evaluation at both the 6-week and B-month recheck, with no reverse trend. Statistical signific ance was not reached in comparisons of some individual categories of functi onal evaluation between sham-treated and OFS-treated dogs (ambulation, prop rioceptive placing); an early trend towards significance was shown in other s (deep pain), and significance was reached in evaluations of superficial p ain appreciation. An average of all individual scores for all categories of blinded behavioral evaluation (combined neurologic score) was used to comp are group outcomes. At the 6-month recheck period, the combined neurologic score of OFS-treated dogs was significantly better than that of control dog s (p = 0.047; Mann-Whitney, two-tailed).