Sciatica

Sciatica is a nerve pain usually caused by irritation and inflammation of one of the 5 roots of the sciatic nerve within the lumbar spine. Patients may or may not also have back pain depending on circumstances. Pain is referred down the nerve into the leg, usually travelling down the back of the thigh to the outside or back of the calf and into the foot. The pain is often very severe and feels like an electric shock with sudden stabs or shooting pains and often numbness or pins and needles.

Sciatica should be one of the easiest to treat spinal problems provide it is treated in a timely and progressive fashion. In general the scheme could be

time  0 – 6 weeks. Pain killers and Physical therapy unless the pain is very severe then inject early

6-12 weeks.  Targetted (transforaminal) Steroid injections

3  – 6 months – Treat the cause:

  • contained protrusion  – percuatneous decompression
  • slipped disc or extrusions  – day case transforminal endoscopic discectmy – if suitable. If not-
  • Microdiscectomy (surgery: usually performed around 6 months).

Most cases would be treated successfully by this progressive scheme and ew would be allowed to become chronic.

Causes:

In younger (up to late 50s) patients, the main cause is slipped or protruded disc. In older spines, restriction of the exit canal of the nerve due to loss of disc height and enlargement (arthritic change) of the facet joint or slippage of adjacent vertebrae (listhesis) may also play a part.

Contained versus Non-contained Disc protrusion:

it is helpful to understand the different degrees of disc nucleus problems which can occur, since these determine the available treatments.

Non-Contained protrusion (sliped disc)

Where the disc annulus tears completely (through and through) a volume of disc nucleus can protrude all the way into the vertebral canal and may become detached and migrate up or down from its level of origin (this is called a sequestered fragment). This is called unconfined protrusion or extrusion.  Extruded slipped discs are usually treated by surgical removal of the nucleus fragment.  This is the standard Micro- or key hole – discectomy.  However there is an even less invasive alternative in the form of endoscopic discectomy which is performed as a day case  through a skin stab incision (see below).

MRI Scan showing a large prolapsed disc fragment

MRI Scan showing a large prolapsed disc fragment

 

Contained disc protrusions (Bulging Discs)

These differ in that the annulus tears from the inside but is not fully torn and the nucleus remains contained within it.  This causes the disc to bulge (visible on MRi scanning) and importantly, the interior of the disc remains pressurised which may contribute to disc-generated back pain. The bulge and associated inflammation in the vertebral canal frequently cause sciatica (ie the leg pain) as well.  In many cases, open surgery to reduce a bulging disc is not preferred and these can be difficult to treat with conventional microdiscectomy but are ideal for minimally invasive decompression techniques such as endosocpic discectomy, coblation nucleoplasty or the recently introduced “mini-microdiscectomy” by Disc-Fx (see below)

A disc protrusion of this sort can be treated but is not favoured for surgery because of the central position and the fact the annulus is intact.

MRI  of a large central, contained protrusion.      A disc protrusion of this sort can be treated but is not favoured for surgery because of the central position and the fact the annulus is intact.

The Role of Inflammation:

While physical irritation of the nerve by “slipped” disc nucleus is one mechanism, probably more important in the generation of pain is the effect of inflammation which occurs around a nerve root as a result of adjacent disc damage. Protrusion of disc material into the epidural space beside a nerve provokes a local inflammatory reaction. An inflamed nerve is an angry nerve and rapidly generates pain signals which are felt in the tissues (in this case the muscles and skin of the leg) which the nerve normally serves (referred pain). Relief of this local inflammation by targeted injection is therefore, in my view, one of the the most effective ways to rapidly reduce sciatic pain.

Acute inflammation is mainly mediated by local chemical messengers (such as (prostaglandins, bradykinins ). If inflammation persists, immune cells become involved and attempts at healing by fibrosis or scarring occur but do not always result in resolution of the problem. On the contrary, tethering of the nerve by persisting inflamed scarring (adhesion) contributes to impaired nerve function, mobility and pain.

Injection Treatments

Transforaminal Epidural Steroid Injection (TFESI):

The technical standard for this injection is described in the ISIS guidelines and I employ that technique.

A needle is placed under continuous X-ray guidance (fluoroscopy) to just above and behind the root of the painful nerve as it exits the spine through the exit foramen (window). An initial injection of x-ray contrast is given to show where the injection will go to allow accurate targeting. Then usually 2 mls (a teaspoon is 5mls) of steroid solution with 40-80mg of steroid are injected and typically travel mainly upwards along and around the nerve root to the level of the disc above. By this means, concentrated steroid solution can be deposited accurately to the source of the problem.

nerve sleeve inj

TFESI is routinely helpful in controlling acute sciatica and most patients are treated with one injection though it can be repeated. At the minimum the anti-inflammatory injection relieves pain while nature takes its course towards improvement which is to be expected in the early months (but not after).

Caudal Epidural Steroid Injection:

“Caudal” means tailward and this technique accesses the epidural space by passing a needle through the sacral hiatus. This method is used when a wide spread of injection is preferable, for example if there are symptoms on both sides or more than one level. To be fully effective X-ray guidance and injection of contrast (epidurogram) is required to ensure correct placement. Spinal block is a possible adverse event with this injection.

For many years the efficacy of this treatment has been debated.  For sure it is not a panacea for back pain but is still useful for appropriate cases, particularly acute sciatica or where there are symptoms on both sides.  Fluoroscopy guidance is required to ensure the injection doesn’t miss.

Treatment of Fibrosis and Adhesions

In more chronic cases of disc prolapse and sciatica, once adhesions have formed, simple TFESI may be less effective and so slightly different techniques are used. The intervertebral disc is at the front (ventral or belly side) of the epidural space and so that is where the problem starts and spreads backwards (literally towards the back). This becomes relevant if adhesions are forming and restricting a nerve root since it follows that treatment has to go to the front to release firm adhesions, rather than fluid inflammation. It is not adviseable to place sharp needles to the front of the nerve exit canal because that is where the blood vessels lie. So a blunt needle technique is used and, after contrast localisation an injection of Hyalase (which breaks up adhesions) then steroid are given. The blunt needle has to pass the nerve root en route (so to speak) and this is often a bit painful, but not damaging.

A variety of techniques can be used

“Racz” catheter. named after the designer Gabor Racz, a clinician from Texas, this soft tipped semi-steerable catheter can be positioned into or adjacent to areas of the epidural space which are obstructed by adhesions and injection of hyalase and steroid given directly to the affected area.

Epiduroscopy. This is described above. With this instrument is possible to directly visualise and steer a catheter to affected areas and use the catheter to blunt dissect (tease apart) adhesions and release nerve roots prior to injections of hyalse and steroid. It is reserved for particularly difficult, often post (after) surgical cases.

Discectomies and Disc Decompression

Minimally Invasive/Endosocipc Discectomy

The Max More Transforaminal endoscopic Discectomy – Day Case Discectomy

As with other types of surgery, techniques for removal of disc fragments by closed or percutaneous methods using endoscopes and cameras to reach and visualise internal structures.  At KIMS, Dr Hammond and neurosurgical colleagues combine skills to use the “Max More” Transforaminal Endoscopic Discectomy system and are amongst the first in the country to be able to offer this treatment.  The development has been supported clinically by an expert clinician from Munich, Dr Michael Hess.

This is slide from a presentation on Endoscpic discectomy by my clooeagie dr Michael Hess showing he instrument in place at L4/5 , the appearance of disc down the scope and the fragment removed

This is slide from a presentation on Endoscpic discectomy by my colleague Dr Michael Hess showing the instrument in place at L4/5 , the appearance of disc down the scope and the fragment removed.

This technique allows a full discectomy to be performed as a day case under sedation.  The benefits for patiets are faster recovery and reduced posibility of complications.  This technique is suitable for selected cases where the disc fragment causing sciatica is placed to one side and has not migrated to far up or down, which a common situation.  None-the- less, large fragments of disc can be removed from L5/S1 as shown below.

this acute protrusion was removed endoscopically fro  young mother as a day case procedure by endoscopic discectomy

this acute protrusion was removed endoscopically fro young mother as a day case procedure by endoscopic discectomy

Judgement has to be exercised at L5/S1 where access may be restricted particularly in males due to the high and narrow pelvic brim. I am currently working with imaging specialists from GE to adapt their live fluoroscopy image guidance software (track vision) to overcome this problem.

3D reconstruction of patient fluoroscopy with trajectory planing arrows for advanced image-guided endoscopic discectomy

3D reconstruction of patient fluoroscopy with trajectory planing arrows for advanced image-guided endoscopic discectomy

Recovery post procedure: you will be sore at the operation site for 1-2 days. You will be advised to take 1 week off work/commuting/driving but can readily work from home. We will provide a light corset to remind you not to bend or strain the back. At the end of this time you may return to light duties but will be advised not to lift or strain. Full activities and physical therapy are restored at 4 weeks, really just giving time for things to heal up nicely.

Percutaneous Decompressions

1. 

Mini-microdiscectomy by Disc FX (Elliquence, NY)

This is a very new, innovative and potentially very powerful minimally invasive system with considerable scope for the treatment of more significant disc derangements causing both back pain and sciatica.  I had the privilege to be the first user of this technology in the UK.  Reported outcomes and safety are very good but clearly, experience is limited and so enthusiasm has to be tempered with appropriate caution at this time.  For example, certain authors report less good results from certain forms of focal disc protrusion in sciatica. Thus far my experience extends to around 40 cases but has been very positive.

This miniature system (3mm diameter introducer) allows the possibility of combining the major modalities of treatment: physical removal by small forceps (ronguers), RF tissue ablation (coblation) and annular heat denervation (the same principle as using heat to selctively remove the nerve from the facet joint) along with endoscopic visualisation in a day case procedure.

Access is gained through a small skin incision and once placed inside the disc, a small pair of forceps is used to physically remove disc nucleus (just as surgeons may do through an open approach), then the steerable RF catheter is used to further remove nucleus tissue by coblation to reduce the possibility of reprolapse, finally the same catheter is used with a different setting to heat seal and denervate the back of the disc annulus from the inside.  The procedure can be controlled and viewed endoscopically.

This is suitable for larger, contained slipped discs (ie not protruding through a fully torn annulus), including those causing sciatica, discogenic back pain and related syndromes. I have treated multiple levels and also disc with a protrusion well out to one side (far lateral).  The images bellow show a central contained protrusion before and after DISC FX treatment.

A disc protrusion of this sort can be treated but is not favoured for surgery because of the central position and the fact the annulus is intact.  Itreated tis by DiscFX
A disc protrusion of this sort can be treated but is not favoured for surgery because of the central position and the fact the annulus is intact. Itreated tis by DiscFX
This is the same disc as above after Disc FX mini-micro-discectomy showing restoration of the disc contour.
This is the same disc as above after Disc FX mini-micro-discectomy showing restoration of the disc contour.
Recovery post procedure: recovery is between coblation and full endoscopic discectomy.  You should expect some pain at the operation site for 1-2 days.  You need to respect the back for a bit to allow the hole which has been made in the disc annulus to heal and to avoid straining the disc till it has.  Usually you will be advised to take a full 1 week off work/commuting/driving but can readily work from home.  Sitting pressures the disc so you will be asked not to sit for too long at a time without change or lying down. We will provide a light corset to remind you not to bend or strain the back. At the end of this time you may return to light duties but will be advised not to lift or strain. Full activities and physical therapy are restored at 4 weeks, really just giving time for things to heal up nicely.

2. by coblation “Nucleoplasty”:

The coblation (cold ablation) catheter (Arthrocare) is simple to use and very safe. It uses electrical radiofrequency energy to vaporise tissue with which it is physically in contact and so provides a very targeted means of removing tissue.  Surgeons in numerous disciplines have been using this technology for years and I have used it in the spine over at least 6 years.  By using this in the disc nucleus, one can reduce a small volume of the nucleus material, rapidly reducing pressure and also inducing a variety of anti-inflammatory changes.

Coblation is an effectivefor reducing small slipped discs and has been used worldwide for this indication.  The coblation instrument is only slightly larger diameter than a standard blood test needle so this is a truly minimally invasive treatment once again used as a day case with light sedation.

Recovery post procedure: coblation is not particularly painful but there may be discomfort at the operation site for 1-2 days.  You need to respect the back for a bit to allow the small hole which has been made in the disc annulus to heal and to avoid straining the disc till it has.  Usually you will be advised to take 1 week off work/commuting/driving but can readily work from home.  This is usually more than enough time off.  We will provide a light corset to remind you not to bend or strain the back. At the end of this time you may return to light duties but will be advised not to lift or strain. Full activities and physical therapy are restored at 4 weeks, really just giving time for things to heal up nicely.

In passing, there is an adapted instrument for the same treatment in the neck, studied and reported on by Prof Cesaroni, Rome from whom I learned the technique and I have treated a few thoracic sliped discs with this technique, though that is a relatively rare situation.