Peled Migraine Surgery Blog

Information and knowledge about migraine relief surgery.

TO DECOMPRESS OR TRANSECT IS THE QUESTION

TO DECOMPRESS OR TRANSECT THAT IS THE QUESTION

There continue to be questions raised both in my office as well as online about the difference between neurectomy/implantation (transection of the nerve and implanting it in the local muscle) and decompression.  Along with these questions come many misconceptions about the advantages and disadvantages to each.  This post hopes to address some of those issues.

To decompress a nerve means simply to remove some form of external compression that is putting excess pressure on that structure.  As has been mentioned previously, compression can be a result of scar tissue, tight muscles, abnormal blood vessel anatomy, connective tissue, etc.  Decompression also means that the nerve is left intact and that hopefully, once the effects of the operation (e.g. swelling) and the effects of the compression wear off, the nerve will function well again.  There are advantages to decompression.  The most obvious advantage is that the nerve is preserved so hopefully sensation to that area will also be preserved.  Secondly, since the nerve is not cut, the chances of a post-operative neuroma are theoretically low.  There also disadvantages to this approach.  First, the surgeon and/or patient make a judgement call that the nerve will recover if simply decompressed, but this doesn’t always occur.  I believe that this is the primary reason some people who have decompression ultimately require neurectomy and implantation Second, just because the chances of a neuroma are low it doesn’t mean that they are zero - you can still get a neuroma-in-continuity, especially if there is a lot of manipulation required to adequately decompress a nerve.  Third, if the compression has been severe and long-standing, the nerve may take many months to fully recover.  Fourth, if recovery does occur, there is no guarantee that sensation to the relevant area will be “normal”.  It may always feel a little bit off.

The biggest misconception with a neurectomy is that it is like pulling the plug out of a wall outlet.  However, the injured nerve is not ripped out of the spinal cord.  A better analogy is that the injured portion of the nerve is identified and the area just upstream where the nerve appears healthier is where the nerve is transected.  This maneuver is just like cutting the central portion of a power cord to a lamp where the wires have frayed.  The downstream part of the nerve (e.g. that which goes to the skin) is now irrelevant just like the part of the cord that is still attached to the lamp.  There is no longer any electricity going though that part so the bulb will not turn on.  However, that upstream cut end is still a live wire as it is still connected to the wall outlet and therefore must be capped. In a human being the “capping” goal is achieved by implanting the upstream (proximal) nerve end (which is still getting nerve impulses from the spinal cord) into the local muscle.  There are advantages and disadvantages to this approach.  One advantage is that you may see immediate improvement in symptoms although not always.  Sometimes, people continue to experience pain in that nerve even though when they touch their skin they are numb.  This situation exists because the nerve that used to go to that area of skin is getting impulses from the spinal cord and brain albeit ending within the muscle and so your brain thinks that part of the skin hurts even though when you touch it, it is numb.  Eventually in most cases, the nerve end in the muscle calms down and the pain improves.  Another potential advantage is less dissection because the downstream area of the nerve doesn’t need to be dissected once transected as it is now irrelevant. There are potential disadvantages as well such as persistent nerve pain if the implanted nerve doesn’t calm down, a neuroma if the nerve comes out of the muscle and the obvious numbness in that nerve distribution. Another misconception is that neurectomy is a guaranteed, home-run result which is not true for those reasons mentioned above.  There are clearly other nuances that exist which is why discussing these issues with your peripheral nerve surgeon is so important.  Just as each patient is unique, each person will have different tolerances for different post-operative outcomes so a good discussion is useful both for the patient and the surgeon.

 

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WHY DO NERVES TAKE SO LONG TO RECOVER?

WHY DO NERVES TAKE SO LONG TO RECOVER

I hear this question quite often from just about every patient I see, whether for chronic headaches or tarsal tunnel syndrome.  The answers have to do with the technical aspects of the surgical procedure, the physiology of peripheral nerves as well as the wound healing process itself.    As you can imagine, a compressed nerve is usually compressed on all sides because it is a three dimensional structure.  Therefore when decompressing a nerve, it has to be manipulated such that the superficial, deep, medial, lateral, cranial and caudal aspects of the nerve can be examined and released if necessary. In addition, there are often multiple compression points (the GON has up to 6 that have been described and often others that are noted intra-operatively).  Moreover, there are times when there is intra-neural scarring (scarring within the nerve, not just around it) which also requires removal.  Hence, there is a fair bit of manipulation usually required (albeit with microneurosurgical techniques) during any decompression and or neurolysis procedure.

As part of the normal wound healing process, there is swelling.  The more neural manipulation required during the operation, the more swelling of the nerve you’re likely to have post-operatively.  I tell my patients to think of nerves as electrical wires, pure and simple.  All they do is conduct electrical signals back and forth, but it is the brain the interprets these signals as ‘hot’, ‘cold’, ‘painful’, ‘ticklish’ etc.  Therefore nerve swelling after an operation is similar to pouring water into the drywall in your house near the electrical wires – doing so will cause the lights to flicker on and off until the water dries up because the fluid is interfering with efficient electrical conductivity.  In the same way, swelling of the nerve can result in all sorts of “unusual firing” of the nerve and is one reason many patients may experience weird, sometimes painful sensations post-op.  However, if the nerves are going to recover, within a few weeks or months when the swelling has subsided, this “unusual firing” abates and the nerves “calm down”.  Just like with cutaneous scars (which also swell as part of the healing process) the time for swelling to decrease is usually longer than a few days or weeks.

Another reason why nerves may take a while to recover has to do with the severity and duration of compression.  I’m sure everyone has fallen asleep on their arm(s) at some point in their lives.  Sometimes, when you wake up, your hand is just a little numb and it takes about 10 seconds of shaking your hand to restore normal sensation.  Other times, however, when you wake up the entire arm seems paralyzed, weak and numb!  In these cases, aside from some transient agita, it takes several minutes of shaking the arm out for function and sensation to return fully.  Phew!  The difference between these two situations is that in the latter, the compression of the nerves to the arm has been present for longer and may have been more severe as compared with the former.  Therefore, it takes longer for sensation (and function) to return.  Now take that phenomenon and stretch the timeline out months and often years (sometimes decades) - that is how long many peoples’ nerves have been compressed.  Therefore, it can take weeks or months for function to return to “normal”.  Also, since the blood flow to the nerves in the latter scenario has been compromised for a longer period of time, they become more engorged with blood after flow is restored and then that extra blood takes time to return to its baseline levels.  It is for this reason that you often experience that sensation of tingling and pain after you remove pressure from the arm and as blood flow resumes. The same thing happens when blood flow is restored after decompression - (more intra-neural blood flow usually combined with more surgical manipulation).  Finally, we don’t immobilize our heads after surgery because doing so would stiffen all the joints and increase the likelihood that the nerve will become re-entrapped in scar. As a result, the nerves will glide right away after we manipulate them and also likely contributes to the lengthy recovery process. The take home message is that as patients and physicians, we have to be patient in assessing whether or not decompression has been successful as the final results may not be apparent for many months (as noted by many here).  After all, the same would true of a facelift or breast augmentation.

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Three Reasons Why Nerves Become Compressed

nerves-3115722_1280

nerves 3115722 1280

Patients are often asking me why nerves become compressed and what causes the compression. Many different structures can cause nerve compression and there are any number of biologic processes that can also result in nerve pressure on a nerve. However, after distilling it down to its basic essence, there are, in my humble opinion, three reasons why nerves can become compressed and I will list those below.   The key thing to remember is that all peripheral nerves travel some distance going from the spinal cord to the structure(s) they innervate.  Along the course of their travels, they pass along many other structures and through many little spaces.  The most common example is the carpal tunnel.  Most people have heard the term ‘carpal tunnel syndrome’ and this clinical entity occurs when the median nerve experiences undue pressure as it passes through a normal anatomic canal known as the carpal tunnel in going from the wrist to the hand. 

Using the carpal tunnel example, the first basic thing that can cause pressure on a nerve is if the nerve swells within a fixed space.  The carpal tunnel is bounded, by bone and ligaments and like the skull, will not expand.  Hence when the median nerve is swollen passing through that fixed space, there is pressure on that nerve that didn’t exist when the nerve was not swollen. As the wrist flexes back and forth, that nerve is asked to glide back and forth as well and because it no longer glides as easily, there can be trauma to that nerve that may further exacerbate the damage caused directly by the pressure. 

Nerve Surgery Before

Nerve Surgery After

Another basic factor that can cause nerve compression is if the nerve is passing through a fixed space, but that space becomes narrowed.  A prime example of this phenomenon would be arthritis.  Recall that any ’itis is an inflammation of something.  Mastitis is inflammation of the breast, colitis an inflammation of the colon and so forth.  Arthritis is an inflammation of the joints and the wrist joint is one prime example.  Therefore if a normal sized median nerve is trying to pass through an inflamed wrist joint, there is less room to allow passage and once again the nerve becomes compressed.  Similarly as in the above example, as the wrist moves back and forth, the nerve is unable to glide as easily and the same pathologic processes noted above likely occur.

The final basic factor that can result in nerve compression is a combination of swelling of the nerve and narrowing of the space through which it is trying to pass. In this case, the nerve is often very compressed.  Putting these three basic principles into play, one can also see that there are many structures that can cause these problems.  For example, in the case of the greater occipital nerve, it often passes through a narrow fascial window comprised of the insertion of the trapezius muscle at the base of the skull. At around this level, the GON also passes in close proximity to the occipital artery.  If the artery is enlarged (e.g. aneurysmal secondary to trauma) the space through which the nerve passes is by definition narrowed.  Moreover, the beating of that larger blood vessel against the GON may be one reason why many people report a “pounding” headache.  Alternatively, the supraorbital nerve is theoretically supposed to pass from the back/top of the eye socket to the forehead through a notch in the frontal (i.e. forehead bone) known as the supraorbital notch.  In some patients, however, that notch is actually a bony foramen - in other words the nerve is completely surrounded by bone.  Bone is therefore the culprit here and the treatment is to convert that foramen into a notch.  I have attached two pictures that illustrate this maneuver.  The take home message is that the causes of nerve compression are actually simple in their most basic form, but a thorough knowledge of peripheral nerve anatomy and experience in peripheral nerve surgery are key factors in putting these principles into action and in achieving a good outcome from surgical intervention.

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An Olympic Crash and Migraines

An Olympic Crash and Migraines

If you’ve been paying attention to the Winter Olympics in South Korea, you might have seen American luger Emily Sweeney crash on her fourth and final run at approximately 68 miles per hour.  It was clear that she was initially stunned, but happily was able to get up and walk away on her own.  Sometime later, she was being interviewed by a reporter from NBC and stated that she was ok adding that she was also very sore and stiff and was about to get an x-ray of her back.  Obviously, we all hope that Ms. Sweeney has no significant, permanent injuries and we all respect her courage and toughness in competing at a difficult sport at such a high level, especially when faced with the prospect of injury.  However, in watching her interview, I couldn’t help, but feel that there was some continued suffering in her affect and voice.

If you watch her actual crash, you can’t help but notice the impact of the speed and ice on her body as you see her hit her head and the contortions that follow.  Sadly, I see people who have had similar injuries from motor vehicle accidents, falls from horses and other types of sports who suffer from chronic headaches.  Many of these people have been diagnosed with “whiplash” which tends to be a basket diagnosis when someone has continued chronic pain, usually headaches, but whose workup including x-rays and MRIs don’t show any pathology and whose etiology remains unclear.  Unfortunately, at this point in time x-rays and MRIs (even magnetic resonance neurograms) are often not sensitive enough to pick up injuries in very tiny nerves that can cause significant pain.  In the case of neck injuries following which people experience chronic headaches, I believe that many of these symptoms are caused by traction (i.e. stretch) injuries of the various occipital nerves resulting in scar impingement around the nerves or actual tears within the nerves themselves.  These tears then heal with scar impacting nerve conduction and resulting in numbness, tingling and/or pain.  As a result, these patients end up seeing many different types of doctors who often prescribe many different types of drugs and give many types of injections in the hopes of treating this pain permanently. 

However, whenever there is a mechanical injury of a nerve, for example, compression secondary to scar tissue formation, a mechanical solution needs to be found.  For these patients, a simple nerve block (i.e. injection of local anesthetic) used in a diagnostic manner, will not only provide temporary relief, but allow the experienced peripheral nerve surgeon to discern which nerve or nerves may be involved in that particular person’s symptoms thereby pointing the way to a potential surgical solution which is often permanent.  Sadly, peripheral nerve pathology as a cause for many cases of whiplash or sports concussions with resulting headaches remains very unrecognized.  However, some physicians including some prominent neurologists are actually coming around to recognizing that structures outside of the brain and spinal cord can cause debilitating headaches.  Happily, they refer these patients to a trained peripheral nerve surgeon for appropriate diagnostic workup and ultimately treatment.  Hopefully Ms. Sweeney will not require surgical intervention of any kind, but if she were to experience chronic headaches with no other identifiable cause, I would hope that her trainers and doctors consider the possibility that a stretch injury to a peripheral nerve may be the underlying etiology which will save her and perhaps many others years of suffering.

To learn more about how migraine surgery can help with migraines caused by peripheral nerve damage from sports injuries or whiplash, visit www.peledmigrainesurgery.com today or call (415) 751-0583 to make an appointment.  Don't live with migraines if you don't have to. 

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Recent Comments
Ziv M. Peled, MD
Kathy. Thank you for your comment. Actually, the GON and TON are both accessed through the same midline incision since they are ... Read More
Monday, 19 February 2018 14:51
Ziv M. Peled, MD
With regards to the above reply, this first picture demonstrates the larger GON more cephalically and the TON more caudally. The ... Read More
Monday, 19 February 2018 17:58
Ziv
Kathy, I'm not sure the gist of your last question, but whether you're doing excision or decompression the nerves are accessed thr... Read More
Wednesday, 21 February 2018 17:04
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