SELECTIVE PERIPHERAL DENERVATION FOR THE TREATMENT OF CERVICAL DYSTONIA. AN UPDATE
CARLOS A ARCE, M.D.
Since the introduction of Selective Peripheral Denervation in the 1980’s by Dr. Claude Bertrand, more than 2000 patients with cervical dystonia have been treated successfully all over the world with significant improvement of their dystonic movements and quality of life. This is the only operation presently done that was created to treat only patients with cervical dystonia. It is also an operation in which the brain and the spinal cord are not touched and, as such, is the safest surgical procedure available to treat patients with cervical dystonia. The principle of the operation is based on the fact that in most of the cases of cervical dystonia the head of the patient turns, tilts, or moves only in one direction and therefore only a limited group of neck muscles are acting in an abnormal way; the ones that turn or pull the head in that direction. Once the abnormal muscles are determined by performing an EMG of the neck muscles and a complete examination, including a study of a videotape, a selective denervation (sectioning of the nerves going only to those muscles) is done outside the spine and close to the abnormal muscles, preserving the normal muscles and allowing the patient to remain with a good range of movement in most of the cases, depending on the extent of the denervation needed.
Selective Peripheral Denervation helps the four most common types of cervical dystonia: the rotational-type in which the head turns, the lateral-type in which the head tilts to one side, the retro-rotational-type in which the head turns and goes backwards, and the retrocollis-type in which the head goes backwards; however, Selective Peripheral Denervation will not help patients with anterocollis in which the head goes forward, patients with traumatic dystonia, and patients with segmental or generalized dystonia. This procedure is also not a treatment for head tremor, which can affect patients with cervical dystonia. In these patients, Selective Peripheral Denervation will help the dystonia but the tremor will continue.
Over the last ten years we have used a different approach (called the lateral muscle-splitting approach) than the one used initially by Dr. Bertrand, and this has allowed for a faster post-operative recovery and a shorter hospital stay, due to decreased post-operative pain, with the patients staying in the hospital for a day and requiring small doses of pain medication, and with many patients requiring no pain medication at all. The results when we compared the two approaches are equal, with an overall percentage of significant improvement achieved in 80 % of the patients.
In order to have a quantitative method to evaluate the results in our last one hundred patients, we have been measuring the angle of turning, tilting, and extension pre-operatively and comparing them with post-operative measurements. In all of the patients that we have treated there have been no patients who have a rotation or tilt of less than 45 degrees, with most of them having a rotation of at least 55 degrees. To tabulate the results we consider a result excellent when the patient has a remaining rotation or tilt of 0 to 10 degrees, a result is considered good when it is between 11 and 30 degrees, and poor when higher than 30 degrees. In order to evaluate for the extension of the head we measured the distance between the chin and the chest and considered it an excellent result if there was a decrease in extension of an inch or more after the denervation. As the goal of any surgical treatment for cervical dystonia is to improve the degree of abnormal movement, we feel doing this gives a more accurate evaluation of the success of the treatment for cervical dystonia than asking the patient or the physician for a subjective evaluation. In our last 100 patients, including the four types of dystonia previously described, the results have been excellent in 84%, good in 15%, and poor in 1%.
Selective Peripheral Denervation continues to be a good surgical option for patients with cervical dystonia and should be considered if other forms of treatment do not achieve a significant improvement of the dystonic movement. It can be considered at any time after having had the dystonia for a year and a half, and there is no need to wait until the patient becomes resistant to botulinum toxin. On the contrary, it should be considered before developing a resistance to botulinum toxin because in some cases small doses of botulinum toxin can be used after the denervation to complement this treatment, especially if the shoulder muscles are involved. It is also better to consider Selective Peripheral Denervation before developing an abnormal posture of the spine which can occur after a few years from the constant turning or tilting.
In conclusion, Selective Peripheral Denervation continues to be an excellent option in the treatment of patients with the four types of cervical dystonia described (rotational, lateral, retro-rotational, and retrocollis) and offers them an excellent rate of success and improvement in their quality of life.
My mom and I wanted to thank you for hosting such a great symposium this year. This was our third year and we are looking forward to next years. E. Mathews