Pattern of premature degenerative changes of the cervical spine in patients with spasmodic torticollis and the impact on the outcome of selective peripheral denervation

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Abstract
OBJECTIVES To characterise the pattern of and risk factors for degenerative changes of the cervical spine in patients with spasmodic torticollis and to assess whether these changes affect outcome after selective peripheral denervation. METHODS Preoperative CT of the upper cervical spine of 34 patients with spasmodic torticollis referred for surgery were reviewed by two radiologists blinded to the clinical findings. Degenerative changes were assessed for each joint separately and rated as absent, minimal, moderate, or severe. Patients were clinically assessed before surgery and 3 months postoperatively by an independent examiner using standardised clinical rating scales. For comparison of means at test was carried out. To determine whether an association exists between the side of degenerative changes and type of spasmodic torticollis a χ2 test was used. Changes in severity, disability, and pain before and after surgery were calculated using a Wilcoxon matched pairs signed ranks test. RESULTS Fourteen out of 34 patients had moderate or severe degenerative changes. They were predominantly found at the C2/C3 and C3/C4 level and were significantly more likely to occur on the side of the main direction of the spasmodic torticollis (p=0.015). There was no significant difference in age, sex, duration of torticollis, overall severity, degree of disability, or pain between the group with either no or minimal changes and the group with moderate or severe changes. However, in the second group the duration of inadequate treatment was longer (10.1v 4.8 years; p=0.009), head mobility was more restricted (p=0.015), and head tremor was more severe (p=0.01). At 3 months postoperatively, patients with no or minimal degenerative changes showed a significant improvement in pain and severity whereas no difference was found in those with moderate or severe changes. CONCLUSIONS Patients with spasmodic torticollis have an increased risk of developing premature degenerative changes of the upper cervical spine that tend to be on the side towards which the head is turned or tilted and compromise outcome after surgery. Effective early treatment of spasmodic torticollis with botulinum toxin seems to have a protective effect. Patients with spasmodic torticollis and restricted head mobility who do not adequately respond to treatment should undergo imaging of the upper cervical spine. Patients with imaging evidence of moderate or severe degenerative changes seem to respond poorly to selective peripheral denervation.