Although the term torticollis has been applied to a wide variety of conditions concerned with abnormal postures of the neck, spasmodic torticollis is a specific entity of unknown etiology resulting in a failure of regulation of head position. It is characterized by varying degrees of a sustained (tonic) abnormal posture of the neck, and there may be superimposed intermittent (spasmodic) contractions of the neck muscles, although the spasmodic movements may be the dominant factor. The abnormal position of the head may represent rotation, tilting, or extension of the neck. If . the shoulders or trunk are involved, the disease should more properly be labeled dystonia. The condition may begin at any adult age, with a peak incidence between the ages of 30 and 40. The first manifestation may be a feeling of tightness of the neck muscles, and the patient may develop a tic-like movement in hopes of obtaining comfort. Symptoms may progress either rapidly or gradually, but usually a plateau is reached within a few years. There may be spontaneous remission, but only rarely if the problem lasts more than 6 months. Occasionally, the patient may have some facial or mouth grimacing along with the neck movements, especially with the spasmodic form. The amount of disability varies widely. Some patients are very distressed with modest symptoms that may cause cosmetic or psychological difficulties. Others may be disabled from severe fixed postural abnormality that prevents the patient from looking straight ahead or from walking, working, or driving. A peculiar characteristic of the clinical picture is the ability that many patients can correct the abnormal position of their neck by such maneuvers as placing the hand on the cheek, the occiput, the side of the chin, or the lip. Only a gentle touch is required, and the patient's own hand is often more effective than that of another. Some patients may have relief of the abnormal posture by forcing the head back against a chair or wall. It appears that a disproportionate number of spasmodic torticollis patients have significant psychopathology. Many patients are perfectionistic and compulsive or tend to be tense or anxious. So many patients have these characteristics, either primarily or secondary to the distraction of their head turning, that torticollis was once considered to be psychogenic. However, the majority of patients are emotionally stable, and the clinical picture is so consistent that the evidence for an organic disorder is convincing. One must be cautioned, however, that the group of patients with psychopathology may be dissatisfied with the result of any treatment, or may respond adversely to any surgical manipulation. The pathophysiology of spasmodic torticollis is unknown. It is not known whether it represents a basal ganglia disease, a vestibular disorder, a variant of dystonia, a counterpart of nystagmus, a neuromuscular disease, or even a nervous tic. Some patients have a history of encephalitis, but most have no common identifiable etiologic factor. Those few patients who have been studied at autopsy have either demonstrated no abnormality or have had other unrelated significant neurological disease. Numerous treatments of spasmodic torticollis have been attempted, none of which has been entirely successful. A variety of medications has been advocated, each briefly, as well as a number of manipulations and ministrations. Consequently, the patient who does not respond to minor tranquilizers or muscle relaxants may be referred to the neurosurgeon. The primary indications for surgery are:
I. The condition is sufficiently disabling.
With this in mind, a progressive program has evolved. It begins with a thorough neuropsychiatric evaluation to uncover any underlying psychiatric etiologies and to identify those patients for whom invasive procedures are contraindicated. Combined with the neuropsychiatric evaluation can be a program of relaxation training. Since many patients patients are tense, either as the etiology or because of their torticollis, relaxation techniques may be helpful.
As a supplement to relaxation, biofeedback may provide considerable symptomatic relief. If the patient's primary complaint is muscle tightness, electromyographic biofeedback with the electrodes over the cervical muscles may be most helpful. On the other hand, if the patient's main complaint is abnormal head posture, visual biofeedback may be employed. A cross is taped to a mirror and the patient stands before it to practice lining up the brows and nose with the cross. Transcutaneous stimulation of the neck area may supplement the conservative program significantly.
A number of patients may be improved by dorsal cord stimulation. Those patients who appear to be good candidates after undergoing the noninvasive part of the program may be tested with percutaneously inserted cervical dorsal column stimulating electrodes. The electrodes may be inserted into the subarachnoid space laterally at the CI-C2 level, with a monopolar electrode threaded down to the C4-C5 level for a 7- to 10-day trial of stimulation. Approximately two-thirds of torticollis patients tested have improvement in their symptoms with dorsal cord stimulation. Interestingly, most patients respond best to higher frequencies, usually between 1100 and 1500 Hz. Those patients who have significant relief and tolerate the stimulation may have a permanent dorsal column stimulator electrode implanted. Surgical implantation of an epidural electrode in the midline at the CI-C2 level is recommended; it is sutured in place, so that it cannot become dislodged with remaining neck movement. Patients who qualify for invasive procedures but do not respond to dorsal cord stimulation may be offered selective rhizotomy and spinal accessory nerve section.
In 1923, McKenzie and Cushing introduced anterior and posterior rhizotomy of C1-C3 with eleventh nerve section. In 1930, Dandy modified the procedure by sectioning only the ventral roots and sectioning the spinal accessory nerves peripherally. The procedure eventually became standardized to include interruption of the anterior roots of C I-C3 and both spinal accessory nerves intradurally. It is important to include the motor root of Cl, which may consist of only a few very fine fibers far above the foramen magnum. The C4 anterior root may be divided on the more involved side. Because the disease is bilateral and invariably involves the cervical muscles as well, it is generally necessary to section both the anterior roots and the spinal accessory nerves, and it is always necessary to section them bilaterally. Selective denervation of the sternocleidomastoid muscle should be reserved for mild cases. Intradural section of the spinal accessory nerve results in incomplete denervation of the sternocleidomastoid muscle in 50 percent of patients, A few fibers that innervate that muscle appear to be part of the tenth nerve intradurally and join the eleventh nerve in the jugular foramen, so they may be missed if the nerve is sectioned intradurally. Consequently, it is recommended that electromyographic evaluation of the sternocleidomastoid muscle be done within several days of surgery and, if there is any remaining innervation, that the spinal accessory nerve be sectioned peripherally. Alternatively, patients who require good shoulder strength, such as heavy laborers, may have minimal postoperative shoulder weakness by omitting the intradural section of the spinal accessory nerve and interrupting the branch of that nerve to the sternocleidomastoid muscle within the muscle after the branch to the trapezius has been given off. Overall, one can expect 16 percent of patients to benefit from peripheral spinal accessory nerve section alone. Selective anterior rhizotomy along with spinal accessory nerve section will yield satisfactory results in 65 percent to 80 percent of patients. Patients who initially have satisfactory results can be expected to maintain their improvement. Anterior root section is not without significant complication. There may be up to an 8 percent mortality rate and up to a 32 percent incidence of dysphagia, presumably because of the interruption of the blood supply to the brain stem through the fine radicular arteries accompanying the anterior roots.
Consequently, surgery for torticollis has recently been modified by Bertrand. Instead of a laminectomy with intradural section of the nerve roots, dissection is carried through fascial planes to expose and section the posterior primary rami throughout all cervical levels. Denervation is selective, in that preoperative spontaneous electromyographic activity is used to identify involuntary movement, and only the involved side or the involved segments are denervated. Results are comparable to those of intradural section, but the brain stem complications are avoided.
As with other movement disorders, spasmodic torticollis at first seemed ideal for stereotactic treatment. It may be simulated in unanesthetized cats by stimulation of the globus pallidus or pallidothalamic system, which produces horizontal turning of the whole body or the head to the opposite side. Ipsiversive turning can be elicited by stimulation of the putamen, Head rotation or tilting may be induced by low-frequency stimulation of the ipsilateral interstitial nucleus of Cajal or its projections to the Voi nucleus of the thalamus. These observations led to the theoretical consideration that the torticollis may be due to damage to one putamen, and uninhibited normal activity of the remaining pallidum may cause head turning to the opposite side, so that a lesion in that pallidum might correct the imbalance. A similar mechanism concerning head tilting was theorized for the interstitio-thalamic system. Consequently, a lesion in the interstitio-thalamic fibers was recommended to correct the tilted posture of the head and a lesion in the pallidofugal fibers or Forel' s field to combat turning movements. Various authors have had varying results with stereotactic procedures. In general, one-third of patients are reported to have excellent results, and another third, good results. Curiously, the effect of the surgery is not immediately apparent and may take 3 to 6 months to manifest itself. Also, it is not always clear how many of the patients in the series may have dystonia musculorum deformans with truncal involvement rather than pure spasmodic torticollis alone, which could account for the results. The results have not been encouraging enough for this to become a widely accepted indication for stereotactic surgery. Myotomy is still occasionally used for the management of spasmodic torticollis. The dominant sternocleidomastoid muscles must be sectioned, Individual deep cervical muscles may be investigated electromyographically, and those muscles under spasm sectioned or resected. Such surgery is extensive, and it may be mutilating and accompanied by significant blood loss. In addition the results do not appear to be superior to less traumatic procedure.