Efficacy of single-photon emission computed tomography aided botulinum toxin injection in cervical dystonia: A double-blind, randomized study

Background: Although single-photon emission computed tomography (SPECT/CT) could help to predetermine dystonic muscles in patients with cervical dystonia (CD), its efficacy in aiding botulinum toxin injection is undetermined. This randomized, double-blinded study aimed to assess the efficacy of SPECT/CT aided botulinum toxin injection in CD. Methods: Patients were randomized into study group (candidate muscles selected by SPECT/CT and clinical evaluation) or control group (clinical evaluation). Follow-ups were done at two weeks (T1), one (T2), three (T3) and six months (T4). The primary outcomes included symptom improvement assessed using Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and Tsui score at T2. Results: A total of 122 patients were enrolled and 108 patients accomplished the study. For primary outcomes, the study group had significantly better symptom improvement at T2 (TWSTRS: beta,-4.86 [95%CI-9.40 to-0.32; P = 0.036]; Tsui: beta,-1.65 [95%CI-2.77 to-0.54; P = 0.004]). For secondary outcomes, the study group also showed better outcomes at T1 (TWSTRS: beta,-6.33 [95%CI-10.17 to-2.49; P = 0.001]; Tsui: beta,-1.42 [95%CI-2.48 to-0.37; P = 0.008]) and T3 (TWSTRS: beta,-6.05 [95%CI-11.09 to-1.01; P = 0.019]; Tsui: beta,-1.24 [95% CI-2.40 to-0.08; P = 0.037]). The interval of re-injection was significantly longer in the study group than the control group (159.1 +/- 28.6 versus 141.8 +/- 51.0 days, P = 0.032). Conclusions: SPECT/CT could improve the efficacy of botulinum toxin in CD. It could become a useful tool to aid botulinum toxin injection.