ANORECTAL FUNCTION IN FLUCTUATING (ON-OFF) PARKINSONS-DISEASE - EVALUATION BY COMBINED ANORECTAL MANOMETRY AND ELECTROMYOGRAPHY

Anorectal dysfunction and constipation are well recognized in Parkinso n's disease and may reflect the direct involvement of the gastrointest inal tract by the primary Parkinson's disease process. We hypothesized , therefore, that anorectal function would alter in parallel with fluc tuations in motor function related to on- and off-periods in Parkinson 's disease, and employed combined anorectal manometry and electromyogr aphy to investigate anorectal function during both on- and off-periods in patients with Parkinson's disease, Manometric recordings revealed a deterioration in voluntary sphincter squeeze during off-periods (squ eeze index, on versus off, mean +/- SEM: 46.4 +/- 11.1 versus 29.6 +/- 7.9 mm Hg, p < 0.05); correspondingly, simultaneous electromyographic (EMG) recordings showed poor recruitment of external anal sphincter a nd puborectalis muscles during off-periods. A hypercontractile (''para doxical'') rectosphincteric reflex response occurred during both on- a nd off-periods, and was associated with an increase in EMG activity in the external sphincter and/or the puborectalis muscle. These changes in manometric and EMG parameters paralleled changes in overall motor f unction. These findings provide further support for the involvement of the pelvic floor musculature in the Parkinson's disease process and a lso provide EMG correlates for some of the manometric abnormalities de scribed in Parkinson's disease.