Spinal magnetic resonance imaging with reduced specific absorption rate in patients harbouring a spinal cord stimulation device - A single-centre prospective study analysing safety, tolerability and image quality
OBJECTIVE AND DESIGN This study was designed to test the hypothesis that initial TcPO2 helps predict clinical outcome in vascular patients treated with spinal cord stimulation. A randomized-controlled study with one year follow-up was made in 86 Fontaine stage IV patients with endstage peripheral arterial occlusive disease (PAOD) undergoing 21 day intravenous prostaglandin E1 (PGE1) therapy for nonhealing ulcers. MATERIALS AND METHODS All patients had arteriosclerosis, 13 also diabetes mellitus. Entry criteria included: non-reconstructible PAOD as proven by intra-arterial angiography or patient condition, ankle systolic pressure < 50 mmHg, severe rest pain despite analgetic medication, and presence of nonhealing foot ulcers or dry gangrene. One week after the start of PGE1 therapy, patients were randomized into receiving SCS plus PGE1 (n = 45 patients), or just PGE1 (n = 41 patients). Follow-up examinations were done at 1, 3, 6 and 12 months. BASELINE: There were no significant differences between both groups in the following: age, sex distribution, ischemic skin lesions, risk factors and several key group mean physiological values including ankle systolic pressure, ankle/brachial ratio (ABI) and foot TcPO2. The SCS group had more prior vascular leg surgeries (1.77 vs 1.58 per patient). RESULTS AT 12 MONTHS: There was significantly better total healing of foot ulcers in the SCS-group (69 vs 17%; p < 0.0001). Significantly more SCS-patients achieved an outcome of Fontaine stage II (claudication pain, no rest pain or lesions) (40 vs 10%, p = 0.0014). The frequency of minor and major amputations was not different, respectively 13 vs 15% and 16 vs 20%. The mean ABI at 12 months of the treated limb of the SCS-patients was not significantly greater. Foot TcPO2 increased significantly for the SCS-group (+213 vs -2%; p < 0.0001). Patients in either group whose TcPO2 rose to 26.0 +/- 8.6 mmHg on average were able to heal ulcers or toe amputation wounds. PGE1-patients had temporary TcPO2 elevations of about 33% on average but this was gone by six months. SCS-patients had steady increases in TcPO2, and maintained them at 12 months. Among the SCS-patients, those with baseline TcPO2 < = 10 mmHg had significantly less success at 12 months, this was not observed for the OMT-patients. The regional perfusion index increased significantly, 187 vs 0%; p < 0.001. CONCLUSIONS Spinal cord stimulation appears to provide a major benefit for lesion improvement in stage IV patients with non-reconstructible PAOD. Patients with an initial TcPO2 > 10 mmHg will respond better to the stimulation therapy. With pain relief and ulcer healing quality of life improved. Effects on limb salvage do not appear.