Thread by @IngridHoeritza1

pubmed.ncbi.nlm.nih.gov/33177221/

Cauda equina syndrome is a surgical emergency caused by compression of the cauda equina nerve roots. It can cause long term bladder, bowel & sexual dysfunction. Emergency medics & surgeons look carefully for it.1/12

But most of the scans done looking for cauda equina syndrome are normal or non-explanatory- 81% mean over 18 studies in pubmed.ncbi.nlm.nih.gov/32059184/. So what’s wrong with all the other people?

24% had cauda equina syndrome. What about the other 76%? Did they all have underlying neurological conditions causing their symptoms? No, 14 had neurological conditions diagnosed during admission. On 24month follow up 4 extra people got a neurological diagnosis. Total: 11%

76 patients had root compression/displacement and 61 had negative scans. For many symptoms, signs, medical and social history there was a dose-response effect with higher relative risk in mixed, and higher values again in ‘scan-negative’ patients.

Patients without CES compression were more likely to be female, have symptoms of a panic attack, dissociation & their worst ever back pain at symptom onset. Positive signs of a functional neurological disorder were significantly higher RR 1.5-2.6

Patients across all groups were in severe pain and used similar amounts of medications.

How would this work? How might pain (nerve root or muscular spasm), medications and prior bladder problems cause cauda equina syndrome symptoms? We’ll focus on the bladder

The bladder-brain axis is pretty amazing. It relies on messages between the bladder, the sacral cord and the pontine micturition and higher centres. Normally these work together, reacting to bladder volume and whether it’s possible and socially appropriate to pass urine.

We know that overactivity of the urethral sphincter can cause painless urinary retention by dampening down the pontine micturiton centre (and we also know it’s reversible) pubmed.ncbi.nlm.nih.gov/19735259/. Pain, medications and prior bladder problems can do that too

And the brain effect? Our higher centres assess safety when deciding whether it’s time to pass urine- being in extreme pain and extremely frightened will make that harder. These are triggers for functional neurological disorders too pubmed.ncbi.nlm.nih.gov/21836030/

Anything useful for the surgeons? An MRI is key as you can’t rely on clinical signs such as saddle anaesthesia, post void residual >500mls or abnormal rectal exam to tell the difference. Loss or reduction in ankle jerks bilaterally might be helpful though (p<0.0001)

So what? Well maybe we should start telling everyone that most scans will be normal, but their symptoms are real. Let’s start looking for panic, meds & baseline bladder function. Let’s start looking for Hoover’s sign in anyone with leg weakness and look at bilateral ankle jerks

While we are on the subject of rectal exams for cauda equina syndrome- why are we still doing rectal exams? Someone’s already done a study that shows they aren’t accurate pubmed.ncbi.nlm.nih.gov/25811266/ and pubmed.ncbi.nlm.nih.gov/23113877 and they aren’t nice

We don’t have all the answers but we’ve listened carefully and thought about how they symptoms could come about. We hope to improve care and get others researching this important area.

Thank you very much to the amazing patients who helped with the study, the amazing #ABN and Patrick Berthoud Charitable Trust who funded my fellowship and my supervisors @jonstoneneuro and @AlanCarson15