Increased startle responses in interstitial cystitis: evidence for central hyperresponsiveness to visceral related threat.
OBJECTIVE
Hypersensitivity to visceral stimuli in interstitial cystitis/painful bladder syndrome may result from enhanced responsiveness of affective circuits (including the amygdala complex) and associated central pain amplification. Potentiation of the eyeblink startle reflex under threat is mediated by output from the amygdala complex and, therefore, represents a noninvasive marker to study group differences in responsiveness in this brain circuit.


METHODS
Acoustic startle responses were examined in female patients with interstitial cystitis/painful bladder syndrome (13) and healthy controls (16) during context threat (application of muscle stimulation electrodes to the lower abdomen overlying the bladder), and cued conditions for safety (no stimulation possible), anticipation and imminent threat of aversive abdominal stimulation over the bladder.


RESULTS
Patients showed significantly greater startle responses during nonimminent threat conditions (baseline, safe and anticipation periods) while 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.


CONCLUSIONS
Compared to controls, female patients with interstitial cystitis/painful bladder syndrome showed increased activation of a defensive emotional circuit in the context of a threat of abdominal pain. This pattern is similar to that previously reported in patients with anxiety disorders as well as those with irritable bowel syndrome. Since these circuits have an important role in central pain amplification related to affective and cognitive processes, these results support the hypothesis that the observed abnormality may be involved in the enhanced perception of bladder signals associated with interstitial cystitis/painful bladder syndrome.
Twiss
Christian
C
Department of Urology, Center for Neurobiology of Stress, Los Angeles, California, USA.
Kilpatrick
Lisa
L
Craske
Michelle
M
Buffington
C A Tony
CA
Ornitz
Edward
E
Rodríguez
Larissa V
LV
Mayer
Emeran A
EA
Naliboff
Bruce D
BD
D000161:Acoustic Stimulation; D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D018856:Cystitis, Interstitial / Q000150:complications / Q000175:diagnosis* / Q000523:psychology; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D006801:Humans; D008875:Middle Aged; D010147:Pain Measurement; D017288:Pain Threshold; D010812:Physical Stimulation / Q000379:methods; D011336:Probability; D012016:Reference Values; D012020:Reflex, Abdominal; D013216:Reflex, Startle / Q000502:physiology*; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014781:Viscera