IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, VOL. 55, NO. 1, JANUARY 2008 181 Percutaneous Biphasic Electrical Stimulation for Treatment of Obstructive Sleep Apnea Syndrome Lianggang Hu, Xiaomei Xu, Yongsheng Gong*, Xiaofang Fan, Liangxing Wang, Jianhua Zhang,and Yanjun Zeng Abstract—In this paper, we study the effect of stimulation of the genioglossus with percutaneous biphasic electrical pulses on pa- tients with the obstructive sleep apnea syndrome (OSAS). The ex- periment was conducted in 22 patients clinically diagnosed with OSAS. The patients were monitored with polysomnography (PSG) in the trial. When the sleep apnea was detected, the genioglossus was stimulated with percutaneous biphasic electrical pulses that were automatically regulated by a microcontroller to achieve the optimal effect. The percutaneous biphasic electrical stimulation caused contraction of the genioglossus, forward movement of the tongue, and relieving of the glossopharyngeal airway obstruction. The SaO , apnea time, hypoxemia time, and change of respiratory disturbance index (RDI) were compared in patients with treatment and without treatment. With percutaneous biphasic electrical stim- ulation of the genioglossus, the OSAS patients showed apnea time decreased , RDI decreased , and SaO increased . No tissue injury or major discomfort was noticed during the trial. The stimulation of genioglossus with per- cutaneous biphasic electrical current pulse is an effective method for treating OSAS. Index Terms—Genioglossus, obstructive sleep apnea syndrome (OSAS), percutaneous biphasic electrical stimulation, sleep medicine. I. INTRODUCTION O BSTRUCTIVE SLEEP APNEA SYNDROME (OSAS) is a common disease, which is characterized by breathing abnormalities that vary from reduction to complete cessation of airflow. Almost one third of the population had clinical symp- toms of OSAS [1]. The occurrence of OSAS was 7.5% based on a research on the middle-aged males living in Indian urban cities [2]. The prevalence increases markedly among the elderly (be- tween 60 and 70 years old) [3]. Importantly, OSAS can be asso- ciated with hypoxemia and sleep fragmentation that lead to right ventricular failure and cognitive dysfunction. OSAS is caused by an occlusion of the upper airway. The upper airway can be obstructed by excess tissue, large tonsils, and a large tongue and Manuscript received July 31, 2005; revised March 24, 2007. This work was supported by the Zhejiang Medical Research Foundation under Grant 2002A063 and the Wenzhou Science and Technology Program under Grant Y2004A080. Asterisk indicates corresponding author. L. Hu, X. Xu, X. Fan, and L. Wang are with the Institute of Cor Pulmonale, Wenzhou Medical College, Wenzhou, Zhejiang 325027, China. *Y. Gong is with the Institute of Cor Pulmonale, Wenzhou Medical College, West Xueyuan Road, Wenzhou, Zhejiang 325027, China (e-mail: fxb@wzmc. net). J. Zhang is with the Department of Automatic Control and Systems Engi- neering, The University of Sheffield, Sheffield S1 3JD, U.K. Y. Zeng is with the Biomedical Engineering Center, Beijing University of Technology, Beijing 100022, China. Digital Object Identifier 10.1109/TBME.2007.897836 by the airway muscles relaxing and collapsing during sleep [7], [8]. The severity is related to the respiratory disturbance index (RDI; the total number of occurrences of apneas and hypop- neas per hour) [9]. The treatment is complicated and the re- sults are not always satisfactory. The most common and suc- cessful treatment of OSAS is continuous positive airway pres- sure (CPAP) ventilation. However, 10%–50% patients treated with CPAP found the treatment intolerably uncomfortable and discontinue its use within a short period of time. Persistent sleep apnea is frequent in patients treated with CPAP [4]. The most common surgery for sleep apnea is uvulopalatopharyngoplasty (UPPP), which intends to enlarge the airway by removing the uvula, the tonsils, and the adenoids, as well as part of the soft palate or roof of the mouth. The overall efficacy is only 40.7% [5], [6]. The genioglossus plays an important role in maintaining the upper airway patent. The genioglossus forms the anterior wall of the oropharynx. Its functional abnormality could result in collapse and closure of the upper airway. It was found that the collapsibility of the upper airway in OSAS patients was higher than that of normal healthy persons. The noradrenergic neuron could selectively increase the activity of the genioglossus. The monoaminergic neuron could decrease the dilating force of the upper airway when the noradrenergic neuron was inhibited during sleep [10]. The negative pressure in the pharyngolaryn- geal area was able to modulate the activity of the genioglossus in fully awake OSAS patients. The length-force curve of the genioglossus in OSAS patients was stretched longer than that in the normal subjects [12]. It was found that the response of the genioglossus to negative airway pressure in OSA patients is not impaired compared with age-matched groups of normal controls and appear to have higher than normal basal ge- nioglossus muscle activity during wakefulness to compensate for the anatomic compromise of the airway [13]. The increased activity of the genioglossus could improve remarkably the stability of the upper airway [14]. However, the responsiveness of the muscle decreased during sleep [11]. In electromyography (EMG) spectral analysis of the genioglossus muscle obtained during submaximal contractions, the time to recovery of the initial maximal force was significantly greater in the OSAS group [15]. All these studies suggest that stimulation of the genioglossus may play a role in treating OSAS patients. Stimulation of the genioglossus directly or indirectly has been studied in animal models and in patients with OSAS [16]. The results were promising. The RDI remarkably decreased and noc- turnal blood oxygen saturation and sleeping architecture im- proved. In order to study the structure change caused by stimu- lation of the genioglossus, tracheotomized rats were stimulated 0018-9294/$25.00 © 2007 IEEE