Spinal Surgery

Introduction

In one sense spinal surgery is the ‘poor relation’ of neurosurgical activity. It is less dramatic than brain surgery and is perceived as being less complicated. While it is true that outcome from spinal pathology or the complications of surgery are rarely life threatening as they often are with brain surgery, nevertheless the consequences of getting things wrong in spinal surgery are just as serious or even more so. As a junior neurosurgeon I found spinal surgery the hardest discipline to learn and I now find it the hardest to teach. It is a field where techniques are changing constantly which makes it difficult both to keep up with the latest techniques and to evaluate them in comparison to established methods of treating patients. The fact that something is new does not necessarily make it better. The adage ‘if it is not broken, don’t fix it’ certainly applies.

Personal experience

I was fortunate to be trained by some first rate spinal surgeons. My late colleague from Bristol, Huw Griffith was a great innovator who pioneered minimally invasive spinal surgery and whose technique for lumbar microdiscectomy I still use today. Working with Brian Cummins (retired colleague from Bristol) exposed me to the management of complex spine problems and I learnt from him how to manage these in the context of an individual patient’s lifespan. With progressive disease, one has to take a long term view and support patients over many years. Richard Cowie (Manchester) is a first rate technical surgeon whose efficient approach matched my own. ‘Learn to do the simple things well’ was his regular advice. In a field like spinal surgery where there is no one technique that is better than another, one learns something from everyone, not least from my present colleagues, Ian Nelson, Steve Gill and Ciaran Bolger to name three with whom I operate from time to time.

The major part of my pain surgery practice (link) involves the management of benign persistent pain in patients whom spinal surgery has failed. This practice has influenced my approach to spinal surgery in two ways. Firstly I am very conservative, If there is a way to manage a problem that does not involve surgery then I have no doubt that this should be tried first. Secondly I am convinced that the optimum management of spinal problems should be multidisciplinary. The more complex a problem the more important it is to take a multidisciplinary team approach. This is very hard to do in an environment where everyone is so busy.

Present practice

Throughout my consultant practice (although much worse in the last three years) the management of routine spinal problems at Frenchay has been difficult as the department has never been well enough resourced to allow emergency work, regional tertiary referral work and GP referral work to take place side by side. The emergency and tertiary referral activity inevitably takes preference so my spinal practice has been biased towards this. I treat intrinsic spinal disease with my neurology colleagues (Ian Ormerod). I work with the spinal injuries unit in Salisbury (Tony Tromans) treating the complications of spinal cord injury. 30% of the operating generated by the pain surgery service is ‘conventional’ spinal surgery. Where I have identified problems that require spinal fusion I generally refer patients to my spinal orthopaedic colleagues (Ian Nelson, John Hutchinson).

The waiting time for urgent spinal surgery in my practice has been 16 weeks while routine cases wait a year. Recently funds to treat routine cases have only been made available through the government’s waiting list initiative.

We are now required to meet targets for waiting times to be reviewed in outpatients. The problem is that tertiary referral activity (90% of my outpatient activity) is not recognized and therefore not subject to targets. The political pressure is for GP referrals to be seen in preference to tertiary referrals, a situation that is not appropriate for a regional specialist service like ours. In order to cope with this demand, some time ago we set up a physiotherapist led assessment service for spinal referrals. This at least meant that patients were seen reasonably promptly and investigations organized. Unfortunately waiting times for imaging and subsequent waiting times for surgery are such that the delay for spinal assessment and surgery has become unacceptable. We are trying to rectify this – see http://www.bathspine.com/

Lumbar Microdiscectomy

One of the commonest spinal operations is Lumbar Microdiscectomy. The technique I employ was pioneered by Huw Griffith in the early 1980’s when he advocated ‘day case’ disc surgery for the first time. This was viewed almost as heresy at the time although is quite commonplace now. Personally I prefer patients to have at least one night’s in patient stay after this operation. The average post operative stay is 2 nights.

The operation is performed under general anaesthetic and with X Ray control. A small (2-4cm) midline skin incision is made at the appropriate level and the ligament between the spines of the vertebrae exposed. The key to Huw Griffith’s technique was the disconnection of as few muscle insertions to the adjacent bone as possible and the avoidance of the use of cutting diathermy (which produces postoperative pain!) Done carefully, this gives more than adequate exposure to the bones and ligaments superficial to the disc space. A microscope is essential at this stage as it provides the necessary illumination as well as magnification to proceed to removal of the ligament and if necessary some bone to expose the dura, the nerve root and the disc prolapse. I learnt from Sandy Strang (retired neurosurgeon from Manchester) the importance of approaching the nerve root from a lateral approach. This allows removal of the disc prolapse with minimal retraction of the nerve root. If there is an element of bony entrapment of the nerve root as well I then remove the part of the joint that is producing the compression. (my technique, learnt from Richard Cowie is to use microchisels for this). There is no agreement as to how much disc material within the disc space should be removed. My approach is to be as thorough as I can about removing loose material within the disc but I do not try to remove the whole disc. The balance is between the risk of reprolapse of disc if loose material is left behind and the risk of discitis (inflammation / infection of the disc space) and the very rare complication of major blood vessel damage from over zealous clearance of the disc space. Once the nerve root has been decompressed it is a straightforward process to close the wound, infusing local anaesthetic into the muscle to reduce post operative discomfort. I like patients to mobilize as soon as they have recovered from the anaesthetic. The routine is to get out of bed the same day as surgery, mobilize with the physiotherapists on the flat on day 1 post surgery, do stairs on day 2 and then go home either on day 2 or day 3 post surgery.

How rapidly patients can return to normal activities depends on a number of factors, not least what constitutes normal activities for an individual patient! In general I prefer patients to take at least a month out of their lives to recover from disc surgery. They can gradually increase their activities with the proviso that if things hurt, they rest. The worst possible thing to do is to work through discomfort that is inevitable in the early postoperative days and weeks. I specifically ask patients to avoid heavy lifting, twisting their backs and sitting in soft armchairs. The act of standing up from a sitting position in a soft armchair inevitably tenses the erector spinae muscles and disrupts the muscle insertions that were disconnected during surgery. After six weeks or so patients can gradually return to normal activities although it is three months from surgery before the back fully recovers and is as strong as it is going to be.

Results of lumbar microdiscectomy

Retrospective notes review of cases operated on since August 1998 has shown the following results:

Admission type

Emergency 36 (55%)

Urgent 20 (31%)

Routine 7 }

Waiting List Initiative 2 }(14%)

Total 65

Presentation

Sciatica 52 (80%)

Foot Drop 2 }

Cauda equine syndrome 11 }(20%)

Total 65

Operation

Primary 59

Redo 6 (9%)

Total 65

Complications

Dural tear 6

Postop CSF leak 1

Epidural haematoma 1

Nerve root injury 1

Total 9 (14%)

Postoperative Bed stay

Results

Good 36

Improved – Residual sciatica 2

Backpain 9

Unchanged 2

Worse 0

No data* 19

Total 65

*pending further notes review

These results reflect the nature of my practice. 86% of admissions are emergency or urgent. Of the 36 emergency admissions, 13 (36%) had acute neurological deficit and 23 intractable pain. The complication rate is high – 14% but includes the complication of preoperative dural tear which is generally underreported in the literature. In one patient the dura had been eroded by chronic compression and was not torn by the surgery. Despite evidence of nerve damage from this, the patient improved with surgery. Waiting a year for surgery was inappropriate in this case and the outcome might well have been better is the surgery had been performed opportunely.