OnabotulinumtoxinA in the Walking Patient: Trading Urgency for Catheterization
A man with multiple sclerosis who has never catheterized is being offered a treatment proven to control his incontinence but shown, in the same trials, to sometimes cause the very dependency he has spent years avoiding.
Ben T., a 52-year-old man who has coached Little League for eleven straight springs and has no plans to give it up now, was diagnosed with relapsing-remitting multiple sclerosis fourteen years ago and still walks the field most practices, cane in one hand and a bucket of balls in the other. Urgency incontinence has become the thing that actually limits him more than his legs do: he has had two episodes at practice in the past month, timed badly enough that he now maps every dugout and parking lot for the nearest bathroom before a single pitch is thrown, a habit he mentioned with the specific embarrassment of a man used to being the one in charge on that field. He has failed adequate trials of both oxybutynin and mirabegron, the first stopped after eight weeks for intolerable dry mouth and constipation, the second carried a full twelve weeks at an adequate dose before being judged simply not controlling him well enough, and he has never performed intermittent catheterization in his life.
His urodynamic study confirmed detrusor overactivity with contractions to 55 cm H2O and a functional capacity of only 180mL, findings consistent with the severity that has failed two oral mechanisms already. The pooled pivotal trials of onabotulinumtoxinA in neurogenic detrusor overactivity, Ginsberg et al.'s and its companion study, showed real, durable reductions in incontinence episodes at both the 200- and 300-unit doses — but a later long-term extension of that same population tracked new catheterization dependence across repeat cycles and found it newly initiated in roughly 30% of the patients who were not already catheterizing, at the 200-unit dose on the first cycle, rising toward 43% at 300 units. Two hundred units is what the drug is actually labeled for in adults, and the label says it should not be exceeded; the 300-unit arm exists in the trials, not in practice, and its own numbers explain why. The stratification that matters for Ben runs the other way from the one he would choose: among patients not catheterizing at baseline, the label reports that those with multiple sclerosis were more likely to require catheterization after injection than those with spinal cord injury. He is a multiple sclerosis patient who has never catheterized, which puts him on the unfavorable side of the only split the label bothers to draw — and the outcome it predicts is the one he named unprompted as worse than the incontinence itself.
Neuro-urology clinic, after two failed oral trials
OnabotulinumtoxinA is the right next step. The pooled pivotal trials showed real, durable reductions in incontinence episodes at exactly his severity, and he's failed two different oral mechanisms already — there isn't a third pharmacologic class left to try that's likely to do better.
The retention risk is real, but it's a minority outcome, and most patients who develop it are managed successfully once it's identified.
"A minority outcome, managed successfully" undersells what Ben told us directly — that starting to catheterize is the one outcome he'd consider worse than the leaking.
The trial reports catheterization initiation as a safety endpoint, a number in a table; for him it's an identity question. I'm not against the drug, but I think the decision needs to be his, made with that specific risk stated as plainly as the efficacy number is, not folded into a general safety disclosure.
I'd add one practical piece, though it's narrower than it sounds. The two doses studied were 200 and 300 units, and 200 is the one that became the labeled dose — the extra hundred bought no meaningful incontinence advantage and roughly thirteen more points of catheterization risk. So there isn't really a dose lever in this decision. There's a labeled dose, and there's an arm of a trial.
Which is why I'd resist framing 200 units as the cautious choice. We aren't being careful by giving 200, we're giving the only dose he can be given. The lever that does exist is the one the pharmacologist is describing — what he's told before he consents — and the multiple sclerosis subgroup makes that conversation more urgent, not less.
Agreed: onabotulinumtoxinA 200 units, with the catheterization-initiation risk discussed with Ben directly and explicitly, not folded into a general consent conversation, and close post-injection monitoring for retention.
Not agreed, carried forward rather than resolved: what to do if his 6-week follow-up shows incomplete response. Two hundred units is the labeled dose for adult neurogenic detrusor overactivity and the label states plainly that it should not be exceeded, so no one proposed going above it — the disagreement is over what remains. The neuro-urologist would re-treat at the 12-week minimum interval rather than waiting out a longer response, pointing to the extension study's own finding that de novo catheterization fell from roughly 30% at the first treatment to under 4% at the second. The pharmacologist and rehabilitation physician would hold the interval and add a second oral agent instead, unwilling to spend another injection cycle on a dose already given once.