Information "gating" in pelvic pain patients

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Gating of sensory information differs in patients with interstitial cystitis/painful bladder syndrome

Written by Philip M. Hanno, MD
Tuesday, 07 September 2010

BERKELEY, CA (UroToday.com) - Do IC/BPS Patients Process Sensory Information Abnormally?

Altered sensory processing, including increased pain sensitivity and decreased habituation to non-noxious sensation has been suggested in some studies in patients with IC/BPS. Lisa Ann Kilpatrick and coworkers from Los Angeles sought to carry this observation further to determine whether sensory processing deficiency of the central nervous system manifested by an inability to adequately filter incoming visceral afferent information may be central to the disorder.

As measured in humans by the eye blink reflex, the acoustic startle response is a rapid defensive response to a sudden intense stimulus that is mediated by brainstem structures and modulated by higher brain structures. Acoustic startle response amplitude can be decreased by a weak nonstartling stimulus (prepulse) presented 30-300 milliseconds before the startle-eliciting stimulus. This phenomenon is referred to as PPI or prepulse inhibition. It is considered a neurophysiologic measure of the early pre-attentive stages of information processing and an operational measure of sensorimotor gating.

The researchers recruited 14 female patients with IC/BPS and 17 female controls. PPI was assessed at 60 and 120 millisecond prepulse-to-startle stimulus intervals. They looked at the relationships between prepulse inhibition, neuroticism and acute stress ratings.

In this, the first study to evaluate sensorimotor gating in patients diagnosed with IC/BPS, the data presented is interpreted to show that patients as a group have a significant deficit in PPI vs. controls, suggesting decreased ability to adequately filter incoming information and perform appropriate sensorimotor gating. The greatest PPI decrease (impaired sensorimotor gating) was reported in those whom increased stress was reported during the study procedures. Patients reported significantly greater stress after the procedure than controls. On the other hand, increased neuroticism was associated with a greater PPI, and thus had a moderating effect on the lowered PPI.

The authors conclude that this preliminary study suggests that IC/BPS is associated with deficits in early stage information processing and specifically with inefficient gating of incoming sensory information. Previous studies have shown that vigilance can increase PPI, perhaps explaining the mitigating effect of neuroticism/trait anxiety.

Kilpatrick LA, Ornitz E, Ibrahimovic H, Hubbard CS, Rodríguez LV, Mayer EA, Naliboff BD

J Urol. 2010 Sep;184(3):958-63
10.1016/j.juro.2010.04.083

PubMed Abstract
PMID: 20643444