Increased Startle Responses In Interstitial Cystitis: Evidence For Central Hyper-responsiveness To Visceral Related Threat

Main Category: Urology / Nephrology
Article Date: 25 Apr 2009 - 1:00 PDT

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UroToday.com - Increased symptoms of BPS/IC associated with life stress, as well as the presence of bladder and somatic hypersensitivity to painful stimuli have led to the hypothesis that central pain amplification may have an important role in the pathophysiology of the predominant symptoms. It is also hypothesized that heightened reactivity within the emotional arousal circuits may accompany the pain and visceral hypersensitivity.

Dr. Christian Twiss and associates investigated this interesting concept using the acoustic startle reflex (ASR) in an experimental model. ASR is a cross-species defensive response to sudden, intense stimuli characterized in mammals by fast, involuntary eyelid closure, and contraction of facial, neck and skeletal muscles. Its magnitude is highly influenced by the presence or absence of aversive states and is mediated via extended amygdale circuits. The authors from UCLA and Ohio State Universities measured ASRs of patients with BPS/IC and healthy controls to standard procedures for eliciting context and cued fear responses germane to visceral pain using the threat of electrical abdominal stimulation.

The working hypothesis was that patients would show greater responsiveness to contextual threat evidence by enhance ASRs immediately after placement of the stimulation electrodes over the bladder region, and that patients would show greater responsiveness to cued threat evidenced by enhanced ASRs when abdominal stimulation was anticipated or imminent relative to safe periods.

Patients did show significantly greater startle responses than controls during nonimminent threat conditions. Both groups showed similar robust startle potentiation during the imminent threat condition. Higher rates of anxiety and depression symptoms in the patient group did not account for the group differences in startle reflex magnitude. The authors conclude that patients with BPS/IC over-respond to ambiguous, potentially threatening situations but may have normal responses to known and predictable threats. This type of research for BPS is in its infancy, but may prove invaluable as it inevitably progresses and becomes ever more sophisticated.

Twiss C, Kilpatrick L, Craske M, Buffington CA, Ornitz E, Rodríguez LV, Mayer EA, Naliboff BD
J Urol. 2009 181(5):2127-2133
doi:10.1016/j.juro.2009.01.025

Written by UroToday.com Contributing Editor Philip M. Hanno, MD, MPH

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