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Selection Peripheral Denervation

Spasmodic Torticollis is a condition that has been known to exist for many centuries.  It is said that Rabelais was the first to use the term torticollis in the 16th century.  Although not a life-threatening condition, it is a condition that significantly affects the quality of life and physicians have been trying to help patients with torticollis for hundred of years.  In 1646 Isaac Minius performed the first surgical treatment for spasmodic torticollis when he divided the sternocleidomastoid muscle to help a patient with this condition.  Since then, many surgical procedures have been performed for torticollis.  These surgical
procedures can be divided into two groups:  Intracranial (performed in the brain itself) or Extracranial (done outside the brain).  The Extracranial procedures can be divided in two:  Intraspinal (requiring opening the spine) or Extraspinal (done outside the spine).  Because torticollis does not affect the life span of a patient and it is not a life- threatening condition, procedures done outside the brain or spine have been most frequently used over the centuries.  In the early 1980’s Dr. Claude Bertrand developed a new extraspinal procedure called Selective Peripheral Denervation.  He based the procedure on the fact that in torticollis only a small group of muscles in the neck are involved and the activity in these muscles is going to determine the direction of the movement.  He introduced the use of the EMG (a test in which electrodes are placed in the neck muscles to study the presence of abnormal activity) to determine the muscles responsible and then developed the procedure to denervate or section the nerves going only to these abnormal muscles.  Since its introduction, Selective Peripheral Denervation, or the Bertrand Procedure, has improved the quality of life of many patients with torticollis and, thanks to Dr. Bertrand’s’ work and contributions, more than a thousand patients have been treated in the United States, Canada, Europe and Japan.  The procedure has proved to be safe and effective, helping many of these patients significantly.  I would like to share with you my experience in treating over four hundred patients with this procedure.

WHICH PATIENTS ARE CANDIDATES FOR THIS PROCEDURE?

Torticollis is an unusual condition that affects patients in different ways. The muscles affected, the direction of movement, and the parts of the body affected can be different from patient to patient.  As such, every patient with torticollis is unique and needs to be treated on an individual basis.  To be considered for surgery, patients must have had torticollis for at least a year/year and a half, because there is an initial progression of the condition and in order to consider surgery the condition must have stabilized and reached a plateau.  Due to the different types of head movement and the different muscles involved, not every type of movement is helped.  The types of movements that are helped the most are the rotational (in which the head turns), laterocollis (in which the head tilts towards one shoulder), retrocollis (in which the head goes backward, and retro-rotation (in which the head turns and goes backwards).  Patients with mixed or complex movements can be helped, but the degree of success is going to depend on the muscles involved.  One movement that cannot be helped by selective denervation is anterocollis (in which the head goes down).

FACTORS THAT WOULD AFFECT THE SUCCESS OF SELECTIVE DENERVATION

-  One of the most important factors that affects the success of selective denervation is the development of an abnormal permanent posture of the spine.  Because in torticollis the head and neck are kept in an abnormal posture for long periods of time, this can lead to a fixed deformity of the spine.  The stress in the joints from the constant turning or tilting leads to arthritis in the joints between the vertebras in the side where the head is turning or tilting. 

This, combined with the atrophy of underused muscles, such as the ones that turn the head in the opposite direction, leads to fibrosis and stiffness of these joints and the development of a fixed, abnormal posture of the spine and loss of range of movement.  Once this develops, the success of any treatment would be decreased.  Patients need to be aware that this can happen and be vigilant to the development of this problem.  In some patients the spine deformity can develop rather quickly, within a year or two, and in others it may take years.  The severity of the torticollis, the degree of arthritis that the patient already had prior to the onset of torticollis, the age of onset and the reponse to medical treatments would influence how rapidly the patient develops a spine problem.  For example, a patient in whom the torticollis starts in his 50’s or 60’s has a higher chance of developing a spine problem than a person in his 20’s.  The spine problem can develop rather fast if the torticollis is severe and the patient keeps the head constantly turned.  If a patient has a severe torticollis with the head constantly turned or tilted because of the strong muscle contractions and Botulinum toxin does not help significantly, the patient should consider other alternatives, including surgery.  In cases like these, it may take only a few months for the patient to develop a severe spine problem.  In patients with less severe forms of torticollis who initially have good range of movement in spite of the torticollis, a progressive loss of range of movement, failure to respond to treatments that were helping, such as Botulinum toxin, and increased pain are signs that a spine problem may be developing.  One of the most important signs is the new onset of pain in a patient who had been free of pain when receiving Botulinum toxin.  Daily exercises of moving the neck in different directions, especially the opposite direction of the torticollis, helps to prevent or delay this problem. If surgical treatment is considered and the patient wants to obtain the maximum benefit from the surgery, this needs to be done before a spine problem develops.  Although surgery is usually considered a last resort form of treatment, it is important that patients with torticollis are aware of this potential problem and do not wait until it has developed.  We have seen a number of patients who would have been good candidates for the surgery, but because of the significant scoliosis and abnormal spine posture they had developed the surgery could not be performed.
-  The presence of dystonia in other parts of the body (segmental dystonia) would affect the success of selective denervation and in these cases it should be considered on an individual basis and after a thorough evaluation.  The presence of oromandibular dystonia does not affect the results of selective denervation.  However, in patients with segmental dystonia involving the arms or the trunk, the results of selective denervation are limited.  Selective denervation can be performed in these cases, but only to decrease the number of muscles involved and to help other treatments.
-  Many patients like to wait until they become resistant to botulinum toxin before considering surgical treatment.  Although this would seem to be a reasonable approach, there are some potential problems that need to be considered before opting for this.  One is that for some patients by the time they become resistant to botulinum toxin they have also developed an abnormal spine posture.  The other is that in some patients there is involvement of muscles that cannot be treated with denervation, such as the trapezius muscle.  These patients would obtain a better and more lasting benefit if surgery was combined with post-operative botulinum toxin treatments.  However, if they are resistant to Botulinum toxin this is not an option. 

 

EVALUATION

The evaluation of patients for selective denervation consists of three or four steps: 

Clinical examination, EMG evaluation, study of the videotape, and, in some cases, performance of an exam under anesthesia.  Because we are relying on an EMG to determine the muscles involved, and Botulinum toxin could affect the

readings of the EMG, we recommend the patient be off Botulinum toxin for at least four months prior to the evaluation.  The patients who need the exam under anesthesia are patients in whom we are concerned that they have developed an abnormal spine posture and /or have significant restriction of movement.  Under anesthesia, the muscles are relaxed so the patient has no torticollis and the head should be in a normal position.  If, under anesthesia, the patient remains with the head in an abnormal position, turned or tilted, it means that he or she has developed an abnormal posture of the spine.  If this has happened, the patient is not a good candidate for denervation or if surgery is performed the success will be limited and the patient will remain with the abnormal posture and/or restriction of movement.  We recommend that patients interested in having selective denervation in our institution send us a short videotape showing us the torticollis at its worst and the range of movement in the opposite direction of the torticollis.  In this way we can review the videotape and tell the patient before coming if we feel she/he is a reasonable candidate and if an exam under anesthesia will be needed so they can plan accordingly.

 

SURGICAL PROCEDURE AND HOSPITALIZATION

The operation is performed in one or two stages depending on the type of movement and number of muscles involved.  In the great majority of cases only one stage is needed.  Patients who need two stages are those who have involvement of muscles on both sides in the back of the neck, so one side is done in the initial procedure and the other side in a second procedure.  The operation takes five to six hours.  The operation is done with the patient in the sitting position.  There are usually two incisions, one in the side of the neck going back to denervate the sternocleidomastoid muscle (sectioning of one nerve), and another in the back of the neck to denervate the right or left posterior neck muscles (sectioning of at least five nerves).   The total number of muscles denervated in the usual case is about seven or eight.  The nerves are clipped, then divided and the distal portion of the nerve is avulsed so no re-growth of the nerve occurs.  Because the nerves are clipped, divided and avulsed they will not grow back, re-sprout, or re-attach.  In patients in whom the activity in a muscle previously denervated returns it is not because the nerve that was cut has grown again, but it is because there are nerves going to this muscle that are still present.  It is important to understand that the operation consists in finding small nerves in between the muscles and that the anatomy is not exactly the same from one person to another, so it is possible that a denervation can be incomplete, and lead to a recurrence.  However, in my experience the recurrences are usually related to activity in deeper muscles that we did not know were active or became active over time, or muscles such as the levator or trapezius that could not be denervated.  After the procedure the patient goes to the recovery room and then to a regular room.  The development of our new muscle-splitting approach to perform the denervation has allowed for a rapid post- operative recovery and patients stay in the hospital only overnight and are discharged the following day.  The new muscle splitting approach is less painful and has allowed a rapid recovery.  Patients are ambulating and having a normal diet the day after surgery and then they are discharged.  Patients need to return six days later for suture removal and wound check.

 

POST-OPERATIVE  THERAPY

During the first week or two until the wound heals, it is better to avoid strenuous neck movements or exercises, as this would increase the pain.  The main exercise immediately post-operatively is to try to maintain a normal posture of the head and neck.  Exercises turning the head in the opposite direction of the torticollis should be done in a progressive fashion.  Many patients with torticollis have lost the ability to know when their head is straight.  It is important to try to regain the sense of midline and they need the help of family members to remind them, or should look in a mirror to exercise maintaining a normal posture.  Some patients still have a degree of turning or tilting immediately post-operatively, but this usually improves in the following months.  Once the initial post-operative pain has decreased then more active exercises turning the head in the opposite direction of the abnormal movement and relaxing the shoulders is recommended.  Strong neck manipulation, strong deep massages and excessive amounts of neck exercises are to be avoided.

 

RESULTS

The success of the operation in patients who are good candidates with normal spine and range of movement is between 70-80% percent in the different series of patients treated in the United States, Canada, Europe and Japan.  In my own personal series of over 400 hundred patients, the success rate is about 80% in such patients.  In the last 50 patients in whom the lateral muscle splitting approach has been performed, the same success applies.  No mortality or significant morbidity has occurred.  In patients with involvement of muscles in both sides of the back of the neck, if both sides are done in one stage, swallowing difficulties may develop in some of them.  This problem usually resolves after several months.  In order to avoid this, we recommend that the denervation in these cases be performed in stages and when this is done the swallowing problems do not occur.  Other side effects include numbness in the back of the head from the denervation.  In the great majority of patients this has not been a problem and they become used to the feeling and lose the awareness of the numbness.  The etiology of pain in torticollis varies.  Some patients can have a mild degree of turning and severe pain and others a severe turning or tilting and no pain.  Selective denervation helps the pain in about 60-70% of patients.  If the pain is coming from the muscle contractions and not from arthritis or spine problems, the success in helping the pain is more significant.  Another reason for pain in torticollis is the presence of herniated discs or bone spurs.  If this were to be the source of pain, our advice is, usually, to perform the denervation before a fusion procedure is done in the neck.  Tremor is a different condition than torticollis, and selective denervation is not a surgical procedure performed to help tremor. If the patient has a head tremor associated with torticollis, the head tremor would persist in spite of the denervation helping the torticollis.  In a group of patients, a recurrence of torticollis will occur.  We do not have concrete data on the percentage of patients in whom this occurs.  I have followed patients for almost sixteen years with good success; however, there have been patients who have let me know of recurrences occurring six, seven, ten years later.  Most of the time the recurrences have not been as severe as the initial condition.  The reasons for this are unclear; however, further denervation is possible, depending on the muscle or muscles responsible for the recurrence.  Another reason not to wait to have the denervation until the patient has resistance to Botulinum toxin is that there is a possibility of recurrence, and if this happens the patient can be treated with Botulinum toxin, usually with good response, as the number of muscles involved is usually small.

 

SUMMARY

Selective denervation is a safe and effective procedure for patients with spasmodic torticollis.  No other procedure is available that has the low morbidity and success demonstrated in so many patients as selective denervation.  The goal of selective denervation is to improve the position of the head and improve the quality of life for patients with torticollis.  If the patient can obtain over a 70% improvement and this lasts from several years to a lifetime, the goal of the treatment has been accomplished.  Hopefully, our understanding of this condition will increase in the following years.  Our goal at the present time is to try and make selective denervation even easier for the patient and, hopefully, with further technical improvements, this can be achieved.  Other forms of treatment, such as deep brain stimulation, are being proposed; however, before we can compare the results of deep brain stimulation to selective denervation further experience and long term follow-up is needed, especially to justify the increase in risk and long-term care of a stimulator.  For patients with torticollis who have the types responsive to selective denervation, this is a good option of treatment.  The decision of what treatment to have is a personal decision by patients with torticollis and should be based on the extent of their condition and effects on their quality of life.  For example, if the patient is responding well to a normal dose of botulinum toxin and has a good range of movement they may not need other treatment.  If, on the other hand, they are developing restriction of movement and botulinum toxin, exercises, and physical therapy are helping only partially, or not helping, then they may consider other treatments.  The best time to consider selective denervation is before a spine problem develops and before the patient becomes completely resistant to botulinum toxin.  Constant awareness by the patients and their physicians that these two problems may develop will prevent them, and allow the patients to consider other forms of treatment, such as selective denervation, in a timely fashion.

Carlos A. Arce, M.D.
Department of Neurosurgery
580 W 8th St. Tower I. 8th Floor
Jacksonville, FL 32209
Phone:  (904) 244-3950