[Spinal cord stimulation therapy at an early stage for unresponsive patients with hypoxic encephalopathy]

Recently, spinal cord stimulation (SCS) has been used for the treatment of patients in prolonged coma. However, the results of SCS in unresponsive patients with hypoxic encephalopathy at the chronic stage have not been satisfactory. Considering these circumstances, we began SCS from one month after the onset of hypoxic encephalopathy and evaluated its effect. Twelve patients (5 males and 7 females) with hypoxic encephalopathy, ranging in age from 7 to 72 years, were treated with SCS. The causes of hypoxia were acute cardiac failure in 4, automobile exhaust gas poisoning in 2, and asthma, pneumothorax, anaphylaxis, asphyxia, drowning and hypotension during aortic surgery in one patient each. One month after the onset, an electrode for electrical stimulation was implanted in the epidural space at the C2-C4 level under general anesthesia. The spinal cord was stimulated for 8 hours each day, starting on the day after implantation, and was continued for 3 months. Magnetic resonance imaging (MRI), cerebral blood flow (CBF) measurement using xenon-computed tomography (Xe-CT), and measurement of auditory evoked potential (AEP) and somatosensory evoked potential (SEP) were carried out 3 weeks after the onset for presurgical evaluation. Among the 12 patients, 7 (58%) showed clinical improvement, beginning within two weeks after starting stimulation. They were able to communicate with others and to express their emotion. However, disturbance of writing, picture drawing and calculation were not improved by stimulation. From presurgical evaluation, cases in which SCS therapy was effective had the following features: 1) No hemorrhagic infarction in the basal ganglia was demonstrable by MRI. 2) Mean hemispheric CBF measured by the Xe-CT method exceeded 25 ml/100 g per min. 3) The mean increase in hemispheric CBF 20 min after acetazolamide administration exceeded 5 ml/100 g per min. 4) An N20 peak was evident on the median nerve SEP, SCS appears to be an effective supplementary for unresponsive patients with hypoxic encephalopathy at the subacute stage, in addition to rehabilitation and drug therapy.