Insights from an old-timey classic

(Nerve root journal club 1)

Jul 21, 2022

Thanks for reading the 54th edition of my newsletter. This newsletter tracks my research as I write a book about sciatica, and another one (out last week) about cauda equina syndrome.

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Hi everyone,

As you might know, Cauda Equina Syndrome: The MSK Clinician’s Guide went on sale last week. The first copies are starting to arrive now… it’s all very exciting.

What do people think? From one reader: “This is extremely high value information… the type of stuff that separates expert clinicians from the others!” And from another: “This is a must have for MSK clinicians.”

To get your copy, just click the button below. The book will make your practice better, and your support would be much appreciated :)

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Okay, enough of all that. This week I thought I would start a little experiment of a ‘nerve root journal club’. I’m calling it a journal club because I hope that as things go on, readers can join in in the comments, on twitter or maybe even on Zoom or something. We’ll see.

But to start, of course, it’s just me. I chose a very readable old-timey paper on CES, with lots of lovely case descriptions that you don’t tend to see in today’s hyper-standardised papers.

Here’s a link to the pdf.

This paper is a pretty early one in the CES literature. 1959. It’s only the fifth English-language paper on pubmed with ‘cauda equina syndrome’ in the title.

Number of publications mentioning “cauda equina syndrome” over time

The paper is a summary of 13 case studies from a London hospital. The patients have quaint occupations like ‘cinema projectionist’, ‘tulip exporter’ and ‘lathe turner’. One patient, a ‘tool-setter’, ‘had sustained an initial severe jolt to the spine during the battle of Alamein, when he was thrown out of a dugout after a direct hit by a shell’.

The author, a neurosurgeon named R H Shephard, starts by telling us that in all 13 cases “the involvement of the cauda equina at and below the level of the disk compression was incomplete”. This is one of those obvious-when-you-know-it things that helps to explain why the presentation of CES can be so variable. When disc herniations splurge out, they’re not going to press on all the roots of the cauda equina evenly and equally.

In fact, Shephard says that in some cases there was “a marked asymmetry of impairment of function as between the two sides”. So again, there’s no reason for a cauda equina compression to be uniform and in fact it’s often asymmetrical. For example, a loss of saddle sensation can be one-sided or radicular pain can be unilateral.

Shephard’s description of the symptoms of CES are pretty close to how we describe them today. He says that

Bladder symptoms are ‘difficult micturition or retention of urine; failure of appreciation of the filling of the viscus or loss of urethral sensation; and in some cases, stress incontinence’. I’m not totally sure what he means by stress incontinence here; is it his way of saying overflow incontinence?
Bowel symptoms are ‘constipation, and, in most cases, lack of appreciation of rectal distension and loss of anal sensation’. Yep.
And there’s also ‘loss of sexual power’. A very evocative phrase which he does not elaborate upon.

Shephard doesn’t include loss of saddle sensation as a symptom of its own. He just thinks of it as part of a loss of sensation in general, which would include the legs.

In general I was quite surprised by how similarly the symptoms are described. I thought maybe back in 1959 there would have been more unknowns or omissions.

Another thing that struck me as unexpected was that Shephard also identified what we now call ‘grumbling CES’. Two of the 13 patients had slow-onset symptoms caused by ‘only a diffuse backward bulge of the disc’.

The remaining group of patients had a more rapid onset, although most had on/off spinal pain for a long time (an average of six years) prior to developing CES. Interestingly, most of them had one injury or strain in the run up to their onset of CES, but then another injury or strain that actually caused the CES. Think ‘I put my back out last week… it’s been bad since… then yesterday I did something and I really buggered it’.

To me, all this is a reminder that, much as we like to think of a disc herniation as all-or-nothing, they are in fact often ongoing events (as I wrote here).

There are implications for safety-netting and vigilance here. I might be wrong but I think there is a perception out there that CES comes out of nowhere. Of course it does, in a sense, but for most of the people included in this study it really came out of a background of years of on/off back and leg pain.

It’s also worth noting that none of Shephard’s patients had any sort of trauma. All the injuries/strains were all “apparently trivial”: twisting, bending etc.

Next, Shephard has a stab at estimating the time it took for CES symptoms to become ‘established’.

In five cases, it took 12 hours or less.
In another five, it took 7 days or less.
And in one case, it took more than a week.

(This excluded the two ‘grumbling’ cases)

The fact that time to onset is fairly variable is important. You sometimes hear a bit of fatalism when it comes to CES. ‘If you’re in MSK, by the time you see it it’s too late. And by the time they get to an MRI, it’s definitely too late’. Maybe so for those whose CES becomes complete in a matter of hours. But clearly some people have CES that develops over days or even a week or more.

Shephard also records the time to onset of radicular symptoms:

It took a few minutes in six cases
A few hours in two cases
And a few days in three cases.

So, all pretty quickly. But another reminder that radicular pain can have a delayed onset after a back strain, for whatever reason (I wrote about this here). This is relevant to the debate about safety netting because some people say CES safety netting is excessive for people with back pain but no leg pain. In our CES book we argue in favour of safety-netting people with acute back pain because any acute back pain is liable to become a case of radicular pain.

I will not detail all the cases that Shephard describes, as you can read the paper for yourself. They all have interesting points to them. But it is quite sad to read them and think of the people behind the case. Such as ‘case 5’, the 33-year-old cinema projectionist, whose 11 months of back pain turned suddenly into bilateral sciatica when he took a jolt on his motorcycle.

“During the next 12 hours the pain became very severe indeed… the next day, retention of urine had developed. He was referred to his own doctor, who relieved the urinary retention by catheter. Constipation developed with the urinary retention and complete numbness in the saddle area. [...] At operation I removed a disk extrusion measuring 2 by 1 by 1cm. After operation the return of bladder function was slow, and on discharge from hospital six weeks later manual compression was still needed [...] He had been rendered impotent by the disc extrusion and [3 years after his operation] remained so”.

Shephard closes by claiming that CES is “not so rare as is generally supposed” (I agree!). He then warns against performing manipulations “if there is any evidence to suggest a central disk prolapse”. As he points out, “relatively trivial trauma” like twisting and bending can be the final straw in triggering CES, and so it follows that manipulation can be too (and in fact was, for one of his 13 patients). I think this perspective is a reasonable one: it’s not a ‘chiro causes CES’ scare story, but a recognition that sometimes something bad is about to happen, and you don’t want to be the one to trigger it.

Okay, so there’s my thoughts on this interesting paper. I couldn’t find much information on the author online, but I’m grateful that Mr Shephard took the time to observe his patients and write down what he saw.

What do you think? Please leave your thoughts in the comments, or reply by email.

Tom’s Nerve Root Newsletter

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