Nozu Tsukasa, Kudaira Miwako, Kitamori Shigeru, Uehara Akira
Department of Comprehensive Medicine, Hokkaido University Hospital, Kita 14, Nishi 5, Sapporo, 060-8648, Japan.
J Gastroenterol. 2006 Mar;41(3):217-22. doi: 10.1007/s00535-005-1748-z.
A reduced rectal perceptual threshold has been reported in patients with irritable bowel syndrome (IBS), but this phenomenon may be induced by a comorbid psychological state. We evaluated the rectal pain threshold at baseline and after conditioning (repetitive rectal painful distention: RRD) in patients with IBS or functional abdominal pain syndrome (FAPS), which is an abdominal pain disorder, and in healthy controls, and determined whether rectal hypersensitivity is a reliable marker for IBS.
The rectal sensory threshold was assessed by a barostat. First, a ramp distention of 40 ml/min was induced, and the threshold of pain and the maximum tolerable pressure (mmHg) were measured. Next, RRD (phasic distentions of 60-s duration separated by 30-s intervals) was given with a tracking method until the subjects had complained of pain six times. Finally, ramp distention was induced again, and the same parameters were measured. The normal value was defined by calculating the 95% confidence intervals of controls.
Five or six of the seven IBS patients showed a reduced rectal pain threshold or maximum tolerable pressure, respectively, at baseline. In all patients with IBS, both thresholds were reduced after RRD load, but they were reduced in none of the patients with FAPS. RRD significantly reduced both thresholds in the IBS group (P < 0.05), but it had no effect in the control or FAPS groups.
Rectal hypersensitivity induced by RRD may be a reliable marker for IBS. Conditioning-induced visceral hypersensitivity may play a pathophysiologic role in IBS.
已有报道称肠易激综合征（IBS）患者的直肠感知阈值降低，但这种现象可能由共病的心理状态诱发。我们评估了IBS患者、功能性腹痛综合征（FAPS，一种腹痛疾病）患者以及健康对照者在基线时和条件反射后（重复性直肠疼痛扩张：RRD）的直肠疼痛阈值，并确定直肠超敏反应是否为IBS的可靠标志物。
通过恒压器评估直肠感觉阈值。首先，以40 ml/min的速度进行斜坡扩张，测量疼痛阈值和最大耐受压力（mmHg）。接下来，采用跟踪方法给予RRD（持续60秒的阶段性扩张，间隔30秒），直到受试者抱怨疼痛6次。最后，再次进行斜坡扩张，测量相同参数。通过计算对照者的95%置信区间来定义正常值。
7例IBS患者中有5例或6例在基线时分别表现出直肠疼痛阈值降低或最大耐受压力降低。所有IBS患者在RRD负荷后两个阈值均降低，但FAPS患者中无一例降低。RRD显著降低了IBS组的两个阈值（P < 0.05），但对对照组或FAPS组无影响。
RRD诱导的直肠超敏反应可能是IBS的可靠标志物。条件反射诱导的内脏超敏反应可能在IBS的病理生理过程中起作用。
