Effective botulinum toxin treatment in different patterns of cervical dystonia: a retrospective SPECT and EMG study.

[BACKGROUND] The Col-Cap classification for cervical dystonia (CD) is proposed to optimize treatment strategy with botulinum toxin type A (BTX-A). Although this concept has been used for 15 years, the efficacy of BTX-A in various CD patterns remains unclear. The present study compared the efficacy of BTX-A aided by single-photon emission computed tomography (SPECT) and electromyography (EMG) in various CD patterns.

[METHODS] CD patients who underwent SPECT scan to detect dystonic muscles were included. Candidate muscles were firstly selected by clinical evaluation and abnormal radioactivity on SPECT imaging. All patients were injected under the guidance of EMG and only those candidate muscles with positive EMG were injected. The efficacy of BTX-A was measured by subjective clinical improvement rate and the reduction rate of Tsui score at four weeks after injection.

[RESULTS] The study enrolled 252 patients. The subjective improvement rates were 63.5 ± 20.6% in simple types and 59.9 ± 22.2% in complex types, showing no significant difference (p = 0.247). The reduction rates of Tsui score showed no difference between the simple type (52.4 ± 24.2%) and the complex type either (49.6 ± 23.6%, p = 0.556). There were no significant differences in clinical improvement rates within each group of simple subtypes, complex subtypes, or patients with different types of tremors (p > 0.05).

[CONCLUSION] Different CD patterns exhibited comparable efficacy of BTX-A due to appropriate selection of dystonic muscles aided by SPECT and EMG, indicating that by employing multifaceted approaches to identify dystonic muscles, favorable outcomes can be achieved even in complex cases.