Ketamine, an N-methyl-Daspartate receptor antagonist,  has been widely used in anesthesia, psychiatrics and veterinary medicine since 1960s. As for low prices, accessibility and addictive characteristics, it has become popular among young adults in many countries over the past decade. However,  it was strongly convinced to damage urologic system. Despite the crackdown on smugglers and subsequent decreasing Ketamine abuse, refractory symptoms of ketamine cystitis, including lower abdominal pain, urinary frequency, urgency and hematuria, are difficult to treat and may destroy renal function. Despite that the mechanism of ketamine cystitis is not fully elucidated so that there is no gold standard for treatment, promising results are raised with the intravesical use of botulinum toxin. It indeed relieved of suprapubic pain and localized myofascial pain. Aim of this study is to investigate pelvic musculature hypertonicity in ketamine-induced cystitis (KIC) by magnetic resonance imaging (MRI).

MRI examinations were performed in 14 female patients diagnosed with KIC between 2015 and 2016 at our institution. We recruited age-matched control group  who had also received pelvic MRI. Patients with pelvic trauma or surgery were excluded. Baseline characteristics, visual analogue scale of chronic pain and renal function were recorded and analyzed by reviewing medical chart retrospectively. Two experienced and blinded radiologist measured the parameters of MRI, including the H-line, M-line, pubococcygeal line, urethral distance to pubococcygeal line, puborectalis width and length, posterior puborectalis angle and urethral area. Mann-Whitney test was applied.

Baseline characteristics, such as weight, height, body mass index and parity, were similar in both groups. However, more proportion in KIC group suffered from chronic pain and psychiatric conditions. In terms of parameters of MRI, M-line significantly decreased in KIC group(1.28±0.38, P‹0.01) compared with control group (1.80±0.44). Pubococcygeal line noticeably reduced in KIC group (8.07±1.06) compared with control group (11.44±2.93, P‹0.01). H-line decreased in KIC group without significance. In addition, urethral area increased in KIC group (2.07±0.62, P‹0.05) compared with control group (1.54±0.63). There is no significance between two groups in puborectalis width, puborectalis length and posterior puborectalis angle.

M-line, representing the descent of the levator from the reference pubococcygeal line, significantly decreased in KIC group. It may imply pelvic floor stay in high tension status. H-line, the puborectal line, that is the anteroposterior pelvic dimension, would be observed in patients with pelvic floor relaxation and even accompanying organ prolapse. Despite that there's no significant difference between two groups in H-line, it decreased in KIC group. Taken together, MRI might suggest hypertonicity of pelvic musculature in patients with ketamine-induced cystitis. Besides, urethral area meaningfully increased in KIC group. As we known, investigation about urethral area in cystitis was limited. We speculate it may be result from long-term inflammation and may be compatible with morphology of ketamine-induced uropathy and lower urinary tract symptoms, such as urinary incontinence.

MRI suggest hypertonicity of pelvic musculature in patients with ketamine-induced cystitis. For those with severe pain and lower urinary tract symptoms of KIC, therapies aimed at pelvic floor relaxation might by helpful. Further application about MRI information should be investigated.

Radiographics. 2008 Jul-Aug;28(4):949-67. doi: 10.1148/rg.284075139.
Int Urogynecol J DOI 10.1007/s00192-015-2794-6
International Journal of Urology (2015) 22, 816--825 doi: 10.1111/iju.12841