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BRITISH BROADCASTING CORPORATION
RADIO SCIENCE UNIT
CASE NOTES Programme No. 9 - Backs - Slipped Discs
RADIO 4
TUESDAY 27TH MAY 2008 2100-2130
PRESENTER: MARK PORTER
CONTRIBUTORS: STEVEN GILL
RODNEY LAING
DUNCAN MACKAY
JUDITH DUNNET
PRODUCER: ERIKA WRIGHT
NOT CHECKED AS BROADCAST
PORTER
Today's programme is all about slipped discs and I must declare a vested interest. I injured my back four months ago and remember thinking at the time that at least we wouldn't have to look far for a willing case study.
Little did I know. Rather than improve over the next six - eight weeks - as most slipped discs left to their own devices do - mine got progressively worse. By the 10th week I had lost feeling in the skin over my left shin and foot, and not all my muscles in my left leg were responding as they should. And then there was the pain - a searing ache that ran from my back to my foot. I couldn't stand up straight and was struggling to walk.
Suspecting a slipped disc I sought a second opinion from my GP, who referred me to Professor Steven Gill, a neurosurgeon at Frenchay Hospital in Bristol.
GILL
Mark, I've got a letter from your GP saying you've had an acute onset of sciatica or leg pain, what happened?
PORTER
Yeah almost 10 weeks and I was cleaning the car and I bent down to pick a half empty bucket up and I felt - I mean it was a nasty pain, I hit the deck and was ...
GILL
Was that the first time you've had problems?
PORTER
I've had you know aches and pains, I'm a very keen runner and I've had some - maybe a little bit of sciatica every so often. I ran the London Marathon a few years ago and had a bit of a problem after that but nothing that didn't - you know it lasted a couple of days.
GILL
So you picked this thing up and suddenly there was a shooting pain down the back of your leg?
PORTER
No, it felt like somebody had hit me in the back and ...
GILL
And what happened after that?
PORTER
Well I hit the deck for about five minutes and then I was fine. Then actually I had severe back pain for a couple of weeks but no pain in my leg. The back pain gradually got better and then I started to develop this pain going right down into my feet and pins and needles in my foot and that came on really and carried on getting worse for - well it probably peaked about a fortnight ago.
GILL
Describe the course of the pain - where did it go from?
PORTER
When I'm lying most of the time I'm pretty well pain free but the minute I try and stand up and walk at about 25 yards it hits me, in the back and the buttock a bit but the main thing is the outside of my leg and in my foot, it feels like my ankle's going to explode and I have great difficulty even lifting my foot.
GILL
And you were scuffing your foot ...
PORTER
Yeah in fact I've got a pair of shoes and I noticed that - I thought there was something wrong with the sole, I thought the sole was coming off and it was actually the way I was walking. I noticed I was catching the tip of my shoe. My whole leg doesn't feel quite right, so if you were to call my name and I was to turn around suddenly this leg gives way a bit, it feels like it's not trustworthy.
GILL
What about your right leg?
PORTER
Fine, I haven't had anything in that.
So what is a disc, and why do they go wrong? Rodney Laing from Addenbrookes Hospital in Cambridge is another consultant neurosurgeon with a special interest in the spine.
LAING
It's a joint that we find in the spine between adjacent vertical bodies. And it's a fantastic joint in the sense that it is immensely strong and also allows mobility in the spine. I mean you can imagine the spine is made up of blocks of bone and if these blocks of bone were all joined together then we would be rigid.
PORTER
You've got a model in front of you here of the lower back, looking at the discs, I mean they're quite fat aren't they, they're quite wide. What's the disc actually made up of?
LAING
The disc is a synthesis on either side of the bone, on the vertical body there is a layer of cartilage and joining the cartilage end plates is very strong fibrous tissue which is arranged in layers, concentric layers but also criss-crossed to produce a very, very strong but flexible structure.
PORTER
So that's the wall around - around the vertebrae but what's actually going on in the middle of the disc?
LAING
And then in the middle of the discs, certainly when we're young, is what we call the nucleus pulposus and this is a jelly like material, mostly fluid, and as you know fluids are incompressible. So it's a marvellous thing to put in the middle of your disc because you can't compress it and therefore it is the weight bearing structure within the disc. The fibrous structure around it contains the nucleus and holds it firmly in place.
PORTER
You hope. When we talk about slipped disc, the disc doesn't actually slip does it?
LAING
Well actually I often use that word "slip" because part of the disc material does slip from where it should be, between the vertical bodies, backwards into the spinal canal or slightly laterally to compress the nerve root as it leaves the spinal canal. And in either event a nerve can be compressed and cause pain in the leg, as I think you know.
PORTER
Yes all too well.
GILL
What I want you to do now is to get you to push this leg down into the bed.
PORTER
Okay, so extend it yeah?
GILL
Yeah. So it's giving way relatively easily on that side, it's not quite the same is it on the right?
PORTER
Back in Bristol Steven Gill has examined me and confirmed that all is not well with my left leg. And an MRI scan of my lower back reveals why.
GILL
There are five lumbar vertebrae and between them are the discs that you can see here. And if you look at the shade of the disc on the MRI scan it's a light grey, whereas as you come to the lower discs they've gone black. And what the MRI scan is is basically a scan looking at the water content of your body and there's less water in your discs at those two levels. And so they appear to be black. And if you look at the L45 disc, this one here, you can see that there is a crack in the capsule and you've got, what's called, an extruded fragment. So sometimes the whole disc can bulge because the capsule is weakened and bulges into the nerves. Well that's not happened in you, your disc has dehydrated and you've got a small protrusion, and this is the protrusion that's impinging on your nerve root. This disc has become dehydrated, lost its water content, and so instead of being like a shock absorber the impact that it's taking has caused the material to extrude through the capsule of the disc which is like a tough fibrous ring.
PORTER
So that colour change is a degenerative change that most people would have, that's wear and tear on the disc itself?
GILL
By the time you're 30 I think most people have probably got these sorts of appearances on the scan, losing some of the water content of some of the discs.
PORTER
But that makes it more prone to the injury that I have.
GILL
Yeah, so that happened, it's been there and it's been a problem for a while potentially...
PORTER
Because it's a pretty inconsequential action - picking up a bucket of water - so it just was the final straw.
GILL
Exactly.
LAING
What I always find amazing is that the amount of stress that's required in order to produce a prolapse can vary dramatically, either from a patient having a car accident at one extreme or somebody rolling over in bed at another. But the commonest way is if we're bending and twisting, particularly bending, twisting and lifting. Think about putting a suitcase into the back of your car, that would be the sort of classic example - you're bent forwards, you're twisting slightly, you're in a rush and bang something happens.
PORTER
And why is that disc giving way, what's happening to the outer wall to allow that central jelly liquid stuff to come out through it?
LAING
Well it's a very interesting question but there are a sequence of changes that occur within all the fibrous tissues within the body and essentially the collagen becomes weakened and as we get older our discs gradually change and these changes can sometimes lead to weakening of the disc and problems.
GILL
These are relatively normal changes and by the time you're 60 you'll have multiple levels, looking very similar, and you won't necessarily ....
PORTER
Something to look forward to.
GILL
Yeah. Because disc prolapses are actually rare, I mean a lot of people get backache but only about 5% of people with back problems have a disc prolapse. So you've been unlucky, particularly that it's impacted on your nerve root, you can see on the scan here.
PORTER
So this is looking down from on top.
GILL
Yeah. And so these are a series of slices through and a piece of the disc has come out here and here. Now although it's only a few millimetres the problem is that it's just caught you in the wrong place because the nerve, as it emerges from the bag that's containing all the nerves going down your spine and then goes out through the root canal to go down to your leg, as it's emerging it's just being caught between the bone and the disc. And you can see there it's absolutely flattened against the bone by this chunk of disc that's come out here. So what I would recommend is I think a microdiscectomy.
PORTER
Microdiscectomy involves opening the spine to remove part of the disc that's squeezing the nerve root. It's done via an operating microscope through a tiny incision in the back and takes around an hour and half.
It's now the standard treatment for the minority of slipped discs that require surgery because they are not getting better, or because they are causing worrying neurological symptoms. It's not only done by neurosurgeons - many orthopaedic surgeons do it too - but whatever their background, the surgeon must have a special interest in spinal work if you are to get the best result.
GILL
The pain relief should be very quick but the recovery may take longer because the nerve is like a telephone cable with thousands of tiny nervelets in it, if you like, that are going to supply multiple muscles and the skin. So if you crush that from the outside you may have actually disrupted some of those fibres permanently and other ones will be badly distorted and not function for several weeks. And in fact it may be several months before you get your full recovery, as good as it's going to be, and there's no guarantee that it will be completely full. Often the motor side, which is the important bit in some respects, does tend to recover more quickly than the sensory side so you could be left with some permanent altered sensation over your calf and the top of your foot.
PORTER
Lastly, in terms of the operation, it's a pretty successful procedure?
GILL
The statistics on it are that between 80 and 95% of people get a very good outcome from it.
PORTER
So all being well would I be out the next day?
GILL
Yeah. And what I would tend to do is to put some local anaesthetic in there immediately after surgery and then you get up and get going fairly quickly. And the quicker you get walking and going the better you're going to do. I think you're going to lie in the better end of the spectrum in terms of recovery. Your disc is overall when you look at the scan is not bulging into the canal, it's just that extruded fragment, so ...
PORTER
Perfect.
GILL
... all those things are pretty good.
PORTER
Great. So I'm booked in for Thursday at one.
And, for me, the big day couldn't come too soon. Forty eight hours later I was lying in the anaesthetic room, about to be put to sleep by consultant anaesthetist Dr Judith Dunnet. This is hopefully the only time you'll ever hear me slur my words on air!
DUNNET
When did you last have anything to eat or to drink?
PORTER
At half past seven I had some toast and I had a drink at 10 o'clock.
DUNNET
Okay. And any loose teeth, caps or crowns?
PORTER
Not loose but I have got a gold crown and a porcelain crown.
DUNNET
Right, anything artificial I'm afraid is a little bit at risk when you have an anaesthetic just because some people, when they wake up, the first thing they do is just bite their teeth together. Okay, just let your hand go nice and floppy, that's fine. Small scratch coming and a bit of pushing, sorry a bit unpleasant. Excellent, well done. Don't worry about the beeping.
GILL
What I've done is positioned Mark so he's on his tummy on blocks on the operating table so that the lumbar spine, where we're going to operate, is relatively flat, in fact slightly curved forward to ease my access. And now I need to check the levels, it's difficult to determine sometimes at exactly which level to go in. So I'm going to put in a needle and then we're going to get an x-ray and screen to make sure we're in the right spot.
These are Mark's scans and you can see right there a lump of disc that's come out, that's the bit I'm going to try and remove. Now it's difficult to know whether it's there - there's certainly a fragment that's being pushed out but there may be some going back inside the disc itself. So the key thing here is whether he'll be left with a hole in the disc or whether he's actually just pushed out a piece and that hole is more or less closed off. And that makes a bit of a difference to what he can do post-operatively.
There are certain landmarks you can use to define where the right level is, so if you look at the top of the hips or the pelvis that's pretty much in line with the fourth vertebra, so I've just put a needle in at about that level and I think that's - hopefully that's right, that'll soon be checked out with the x-ray.
Just confirmed with the x-ray that we're in the right spot now. I've made a small incision, it's about an inch long, and it's right between the spinous processes, the bits of bone you can feel if you feel down your back, little knobbly bits, right between the two of them, between the fourth and the fifth vertebra, so I've put a mid-line incision there and then what I need to do is to over that very small area move the muscle off the bone, it's actually attached to a ligament which I'll just separate off that and then I'll expose the gap between the laminae, which are the bridges of bone at the back of spine, and that's where I can then open a small ligament called the ligamentum flavin, the yellow ligament, and then I should be looking at the nerve and then I can trace back to where the disc has come out.
The space I've made is just big enough to fit my index finger, so I can now feel the gap between the vertebrae and I'm now going to put in - and I use an operating microscope to look down that space. I've just exposed this yellow ligament and I'm now going to open it to have a look at the nerve.
You can see the pink nerve just there on the screen and I can see down my microscope, which is not very clear, that it's been pushed back by the bulging disc, it's got some blood vessels over it, so veins which are distended and engorged because there's compression there. I'm just going to bi-polar those, seal those off, and then I'll open the disc and remove that. You've got to be very, very gentle indeed and it's just been moved a couple of millimetres and if you bruise it he'll feel that and you could cause damage quite easily so we've got to be very careful.
And you can see now that I've just opened that membrane that all the discs - that white fibrous material sitting underneath, it's like crab meat. See it all herniating out there, that lump, quite a big piece actually, surprising.
Okay what I'm doing now I've taken the disc bulk out and I'm just using [indistinct word], we're just shrinking the capsule down to make that hole much smaller because the fibres are all stretched out and you can see now that little pale blob there, that's the size of the hole now, which is really much, much smaller than it was.
But I do need to make sure - something you can get a piece of disc that's sort of migrated down into the root canal, so I need to just chase that to make sure there's nothing down there with a little hook. The root's free so now I'm just going to wash everything around the area and close up. I've put some local anaesthetic in at the end so it'll be much more comfortable for him in the immediate post-operative period, he can get up and about and the quicker he gets up and about the better.
PORTER
Steven Gill operating on my back - and I can't tell you how weird it was listening to that. But so far, so good. I awoke pain free, walked out the hospital the next morning and haven't needed so much as paracetamol since. I am not out the woods yet - there's a 1 in 20 chance the disc will give way again - and I need to take it easy for the next couple of months.
Now, if you mention the term slipped disc, most people automatically think of back trouble like mine, but that's not the only part of the spine that's affected - discs often cause trouble in the neck too. Rodney Laing has a particular interest in cervical disc problems.
LAING
The same thing can happen in the neck and the reason for that is that the neck has exactly the same structure - a series of bones, vertical bodies, separated by discs.
PORTER
But presumably they're not subject to the same sort of load as the ones in the lumbar part of the spine?
LAING
No they're not, I mean your head weighs seven or eight kilograms but is in constant movement and if you just look round at the people around you when they're talking you'll see their heads moving all the time. So there is a lot of movement, less weight but enough to cause problems. And of course the discs in the neck aren't as strong as the discs in our back.
PORTER
As Duncan Mackay, one of Rodney Laing's patients, discovered the hard way.
MACKAY
It started quite mundanely, I noticed I was getting some pins and needles in my lower right arm and that gradually progressed over a period of a couple of months to become much more painful, such that I was experiencing, almost like shooting pains down my right arm when I would be sitting doing my job at a desk or whatever. And I ended up having difficulty in sleeping, having difficulty when you wake up in the morning and there's a lot of pain and I have to say that looking forward day by day knowing that you'll be in that pain was not at all pleasant.
PORTER
You were getting the pain and the pins and needles in your arm but were you actually getting any symptoms in your neck?
MACKAY
Strangely enough no, a little bit of tightness perhaps across the shoulder but not really, it was more specifically in my arm.
PORTER
Well you eventually had an MRI and you went to see Mr Laing and the problem was revealed, what were you told was wrong?
MACKAY
First of all I have to say I was really quite pleased that we could attribute it and find out what was actually wrong, so the MRI scan for that was very good. And it was clear when we saw the pictures you could see the deformity and the disc had prolapsed out and was pressing on the nerve and that that was the root cause of the problem.
PORTER
So he suggested surgery. But you had more than one disc that was affected.
MACKAY
I did yes, I had two discs immediately next to each other that were prolapsed but I only had symptoms in my right arm at that point, so he could tell from the MRI scan that it was one particular disc that seemed to be giving me all the symptoms - that was the lower disc.
PORTER
And had you done anything to injure your neck?
MACKAY
I don't recall any specific incident at all.
LAING
Well it can happen in anybody really at any time and often patients describe waking up in the morning with the first suggestion that they've got a problem and often these problems start with neck pain, the patients have a lot of neck pain and the pain doesn't settle and then over the next two or three days they may develop neurological symptoms - pain in the arm, numbness, tingling, something like that. Or if it's a very large disc prolapse it can press on the spinal cord and that can cause other problems - numbness, tingling in the legs and difficulty walking.
PORTER
Of course one of the problems with the neck is that the spinal cord is sitting there, if it's damaged at neck level that's a much more sinister injury than damaging it further down, is that something that is in your mind as a neurosurgeon?
LAING
Well yes of course. I mean the big difference to remember is that there is a spinal cord coming down through the cervical spine - the neck - but in the lumbar spine the spinal cord has finished and in the - behind the lumbar discs we just have nerve roots. So that is why there is this big difference between the neck and the back in terms of the potential seriousness of a disc prolapse.
PORTER
So with a cervical spine we're actually looking at, if you like, the trunk is still there whereas we get down the lumbar spine it's already broken up into its branches.
LAING
That's a very nice analogy, exactly. And the trunk is responsible for the movement of all our limbs - for both arms and legs. And so clearly very important.
PORTER
And the management of a prolapsed disc in the neck is it watchful waiting for most people?
LAING
It's analogous to the management in the lumbar spine. We know the natural history's very favourable, we know certainly when we're talking about patients who present with arm pain that the vast majority of those patients will get better without any intervention.
PORTER
And it would be fair to talk about the arm pain being the sort of neck equivalent of sciatica basically?
LAING
Exactly. The arm pain due to pressure on a cervical nerve root is exactly the same as the leg pain - sciatica - due to pressure on a lumbar nerve root.
PORTER
So left to their own devices most people would get better?
LAING
Ninety five per cent of people can expect to get better.
PORTER
Unfortunately Duncan Mackay was not one of those lucky 95%. He needed surgery and, like me, staged a miraculous recovery. At least to start with…
MACKAY
I woke up the next morning and I felt great, I felt no pain whatsoever, I thought this is fantastic, everything's fixed and I was discharged and came home. Approximately a day later I was out visiting for friends for dinner and everything was great but I woke up that night with some severe pain in my left hand side which was the opposite arm from where I'd had the symptoms.
PORTER
So the disc that they'd left was now causing trouble just two days later?
MACKAY
Yeah. Unfortunately for me it meant a second operation. Again very straightforward procedure - it's amazing, I was quite nervous in the first procedure but much more relaxed about the second one because I knew what to expect and I knew that there wouldn't be any real problems at all.
PORTER
And in terms of looking after your neck since then do you have to do anything special?
MACKAY
I think for the first few weeks they recommended you know not to sit and read too much because that makes your neck go forwards and downwards. But other than that there's been no other specific physiotherapy or anything that I've had to have no.
PORTER
And you've remained symptom free?
MACKAY
Yes absolutely, it's fantastic.
LAING
We get involved surgically, either in a patient who has severe arm pain that hasn't settled and when we've done a scan and we can see clear evidence of a disc pressing on the nerve or in patients who have spinal cord compression because that's a group of patients who clearly one has to be much more proactive in terms of their management because if you leave the compression of the spinal cord for long periods then it may become irreversible.
PORTER
And the sort of operation that you're doing on these discs is similar to the microdiscectomy that I had on my back?
LAING
Very similar. Again if you think the key aim of the operation is to take the pressure off the neural structures - the spinal cord or the nerve root - and so if the disc is pressing on the spinal cord or nerve root then that's the structure that we wish to remove. But for many years there's been quite a controversy about what we do having removed the disc. Curiously in the lumbar spine most of us are agreed that we just remove the disc, whereas in the cervical spine for many years now there's been a controversy about whether having removed the disc we should replace it with something else.
PORTER
And that's because the movement in the neck is different in that there's more movement of the spine than neck?
LAING
Quite why there is that difference in management is one of those very interesting historical questions. But suffice it to say that most of my colleagues would think that the appropriate thing to do, having removed a disc from the neck, would be to replace it, either with a piece of bone taken from the patient's hip or with a piece of replacement which we call a cage which is often made of plastic or metal.
PORTER
But both of those techniques are effectively fusing the two vertebrae together, either side of the damaged - they're not replacing like with like are they?
LAING
And that has led to the latest development which is actually to place disc replacement, an artificial disc if you like, between the vertebral bodies and of course the idea of that is to try and restore normal anatomy and function. The rationale of that comes of course from hip replacements. Many years ago the only operation that my orthopaedic colleagues could do was to fuse a painful hip and then over the years technology advanced and the total hip replacement came in and that has been an absolutely fantastic advance for surgical technique. And people have thought about applying that same technology to the spine. It's a very interesting idea, the two joints are not analogous and it remains very controversial as to whether it is the appropriate action for the surgeon to take at the end of the operation.
PORTER
Because we're 20-30 years plus into hip replacement but presumably this type of cervical disc replacement's still relatively new?
LAING
It's relatively new, it's been around for at least 10 years now. I think the main thing that people need to remember is that between the leg and the pelvis, where the hip joint is, there is only one joint so if you fuse that joint then the patient has a stiff leg. If we move to the spine there are lots of joints between each of the adjacent vertical bodies. So if I fuse two of these bones together you're simply not going to notice the difference. In fact many patients, paradoxically, can move their heads more after they've had a disc removed and a fusion and that's simply because we've removed the pain that was causing the muscles around the neck to go into spasm and they paradoxically get more head movement after this. The main worry that I have about artificial discs is that they're expensive and if they're not adding a great deal to patients' outcomes and quality of life then we do risk spending a lot of money on what is a very exciting technology but with only a very limited gain in health outcomes and that's the debate that's going on at the moment.
PORTER
If I was sitting here as a patient wanting to know whether I should have my disc operated on or not and was to ask you about the likely outcome how would you explain that, what do you say to your patients?
LAING
Well I think traditionally there's been a lot of scepticism about the effectiveness of spinal surgery and also its dangers. There are people with always anecdotal stories of somebody who knows somebody else who went in for a simple operation on the spine, ended up in a wheelchair. Well those things can happen but they are vanishingly rare and usually can only happen in the even of somebody undergoing a very major spinal operation. The sorts of operations like the one you had Mark, involving a disc removal, are very safe.
PORTER
Neurosurgeon Rodney Laing.
Just to re-iterate: Most people with slipped discs - in their back or neck - will get better without surgery and they generally settle, or start to settle, within the first six weeks.
But if the pain, pins and needles, or weakness start to affect both legs - or you are having difficulty controlling your bowels or bladder - that suggest more worrying nerve compression and constitutes a medical emergency. Contact your doctor immediately.
And if your symptoms have not improved by six weeks then I would advocate asking your GP for referral to a specialist who can arrange an MRI scan to confirm what is going on and advise accordingly.
Just time to say thank you to Steven Gill and his team for their sterling work on my back. And to say that Case Notes returns for a new series later in July. Until then, goodbye.
Ends
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