The efficacy of single-photon emission computed tomography in identifying dystonic muscles in cervical dystonia.

[INTRODUCTION] The key point for botulinum toxin type A injection in treating cervical dystonia is to accurately identify dystonic muscles. This study aimed to evaluate the efficacy of technetium-sestamibi single-photon emission computed tomography in identifying target muscles in cervical dystonia.

[METHODS] In the study group (n = 18), target muscles were selected according to clinical evaluation combined with technetium-sestamibi single-photon emission computed tomography, while in the control group (n = 18), target muscles were selected by clinical evaluation alone. All patients were followed-up at 2 weeks, 1, 3 and 6 months after botulinum toxin type A injection. The primary outcomes were the reduction rates in Toronto Western Spasmodic Torticollis Rating Scale and Tsui score at 1 month.

[RESULTS] Although the reduction rates in Toronto Western Spasmodic Torticollis Rating Scale and Tsui scores were not different between the two groups at 2 weeks and 1 month, the reduction rates in both scores were significantly higher in the study group at 3 and 6 months. The number of patients receiving re-injection within 6 months was significantly lower in the study group. Also, the re-injection interval was significantly longer in the study group. In the study group, more deep cervical muscles were injected, which concerns especially semispinalis capitis, longissimus capitis, and obliques capitis inferior muscles.

[CONCLUSION] technetium-sestamibi single-photon emission computed tomography is a useful method for screening target muscles in cervical dystonia. It helps clinicians draw a 'blueprint' for the distribution of dystonic muscles before botulinum toxin type A injection.