You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Improvement in pelvic pain with botulinum toxin type A - Single vs. repeat injections. The aim of this prospective study was to report the outcomes of pain and vaginal pressures of successive botulinum toxin type A injections for women with objective pelvic floor muscle overactivity and a two-year history of pelvic pain. Between 2005 and 2008, 37 women underwent injection of 100 IU of botulinum toxin type A into the puborectalis and pubococcygeous muscles with dysmenorrhoea, dyspareunia, dyschesia, and non-menstrual pelvic pain assessed using a visual analogue scale (VAS), and vaginal pressure measured by vaginal manometry, at 0, 4, 12 and 26 weeks from each injection. 26 women (70%) had one injection of botulinum toxin type A and 11 (30%) had 2 or more injections. The second injection was performed at the earliest at 26 weeks after the first, with subsequent injections having a median time to re-injection of 33.4 weeks (range 9.4-122.7 weeks). Single and repeated injections both demonstrated a statistically significant reduction in dyspareunia by VAS scores from 54 to 30 in the single injection group and from 51 to 23 in the multiple injection group (p = .001), non-menstrual pelvic pain VAS from 37 to 25 (p = .04), as well as vaginal pressures; 40 versus 34 cm H(2)O (p = .02). No statistically significant difference in dysmenorrhoea or dyschesia was observed for either group from their baseline scores. Multiple injections of botulinum toxin type A in women with pelvic floor muscle overactivity provide significant relief from dyspareunia and non-menstrual pelvic pain. The upper limit between re-injection is not yet determined, nor is the maximum number of treatments. Clinical outcomes for single and subsequent injection of botulinum toxin type A for recurrent pelvic pain are equivalent. Women who have had benefit from a single injection of botulinum toxin type A can be reassured that if symptoms reoccur, repeated injections can be expected to be equally efficacious.
{"Chemical": ["H(2)O"]}