Effect of transcranial direct current stimulation on swallowing apraxia and cortical excitability in stroke patients

<b>Background:</b> Swallowing apraxia is characterized by impaired volitional swallowing but relatively preserved reflexive swallowing. Few studies are available on the effectiveness of behavioral therapy and management of the condition. <b>Objective:</b> This study aimed to investigate the effect of transcranial direct current stimulation (tDCS) on swallowing apraxia and cortical activation in stroke patients. <b>Methods:</b> The study included three inpatients (age 48–70 years; 1 male, 2 females; duration of stroke, 35–55 d) with post-stroke swallowing apraxia and six age-matched healthy subjects (age 45–65 years; 3 males, 3 females). Treatments were divided into two phases: Phase A and Phase B. During Phase A, the inpatients received three weeks of sham tDCS and conventional treatments. During Phase B, these patients received three weeks of anodal tDCS over the bilateral primary sensorimotor cortex (S₁M₁) of swallowing and conventional treatments. Swallowing apraxia assessments were measured in three inpatients before Phase A, before Phase B, and after Phase B. The electroencephalography (EEG) nonlinear index of approximate entropy (ApEn) was calculated for three patients and six healthy subjects. <b>Results:</b> After tDCS, scores of swallowing apraxia assessments increased, and ApEn indices increased in both stimulated and non-stimulated areas. <b>Conclusions:</b> Anodal tDCS might provide a useful means for recovering swallowing apraxia, and the recovery could be related to increased excitability of the swallowing cortex. Further investigations should explore the relationship between lesion size and/or lesion site and the prognosis of swallowing apraxia. <b>Clinical trial registry:</b>http://www.chictr.org Registration Number: ChiCTR-TRC-14004955

<b>背景：</b> 吞咽失用症（swallowing apraxia）以随意吞咽功能受损而反射性吞咽功能相对保留为特征。目前针对该病症的行为疗法有效性及临床管理的相关研究较为匮乏。
<b>目的：</b> 本研究旨在探讨经颅直流电刺激（transcranial direct current stimulation, tDCS）对脑卒中患者吞咽失用症及皮层激活的影响。
<b>方法：</b> 本研究纳入3例卒中后吞咽失用症住院患者（年龄48~70岁；男1例，女2例；卒中病程35~55天）以及6名年龄匹配的健康受试者（年龄45~65岁；男3例，女3例）。实验分为A、B两个阶段：A阶段中，住院患者接受为期3周的假经颅直流电刺激联合常规治疗；B阶段中，上述患者接受为期3周的双侧吞咽初级感觉运动皮层（primary sensorimotor cortex, S₁M₁）阳极经颅直流电刺激联合常规治疗。分别在A阶段开始前、B阶段开始前及B阶段结束后，对3例住院患者进行吞咽失用症评估。同时为3例患者及6名健康受试者计算脑电图（electroencephalography, EEG）的非线性指标——近似熵（approximate entropy, ApEn）。
<b>结果：</b> 经颅直流电刺激干预后，患者的吞咽失用症评估评分升高，且刺激区与非刺激区的近似熵指数均有所上升。
<b>结论：</b> 阳极经颅直流电刺激或可为卒中后吞咽失用症的康复提供有效手段，其康复效应可能与吞咽皮层的兴奋性增强有关。未来需进一步探究病灶大小、病灶部位与吞咽失用症预后之间的关联。
<b>临床试验注册：</b>http://www.chictr.org 注册编号：ChiCTR-TRC-14004955