Usefulness of (18)f-fluorodeoxyglucose positron emission tomography/computed tomography in management of cervical dystonia

Abstract

Objective: To evaluate the usefulness of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in the management of cervical dystonia (CD) with botulinum toxin type A (BoNT-A) injection.

Method: Thirty two subjects with CD were included. A BoNT-A injection was provided either by clinically targeting method (group 1) or by (18)F-FDG PET/CT-assisted, clinically targeting method (group 2). In group 2, selection of target muscles and dosage of BoNT-A were determined according to the increased (18)F-FDG uptake, in addition to physical examination and functional anatomy. The outcomes of BoNT-A injection was compared between the two groups, in terms of the number of subjects who had reinjection before and after 6 months, the number of reinjections, the interval of reinjections, the duration to the minimal Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS), the number of adverse events, the reduction rate of TWSTRS at 1-3 months and 3-6 months after injection, and the probability of reinjection-free living.

Results: The number of subjects who had reinjection within 6 months was significantly lower in group 2 than in group 1 (10 in group 1 vs. 3 in group 2). The reduction rate of TWSTRS after 3-6 months (37.8±15.7% of group 1 vs. 63.3±28.0% of group 2) and the probability of reinjection-free living were significantly higher in group 2 than in group 1.

Conclusion: These findings suggest that (18)F-FDG PET/CT study could be useful in management of CD in terms of the identification of dystonic muscles if there is an increase in the (18)F-FDG uptake in the cervical muscle of the images.

Keywords: 18F-Fluorodeoxyglucose; Botulinum toxin; Cervical dystonia; Positron emission tomography.

Fig. 1

The picture showing the clinically targeting group or ¹⁸F-FDG PET/CT-assisted, clinically targeting group in chronologic order.

Fig. 2

The ¹⁸F-FDG PET/CT images of 2 independent subjects with left torticollis. 1. A 20-year-old man with cervical dystonia whose main symptom was left torticollis (A-D). The ¹⁸F-FDG uptake is increased at the anterior and posterior neck muscles on the left side at the level of the C2 vertebral body. The hot uptake of ¹⁸F-FDG was seen in the left LC/Lc (black arrow head), left SPC (thick black arrow) and left SSC (thin black arrow) (B-D). 2. A 38-year-old man with cervical dystonia whose main symptom was left torticollis (E-H). The ¹⁸F-FDG uptake is increased at the anterior and posterior neck muscles at the levels of foramen magnum (FM; E), C2 vertebral body (F) and C3 vertebral body (G). The hot uptake of ¹⁸F-FDG was seen in the right OCS (thick white arrow), left LC (black arrow head) and left SPC (thick black arrow) (E). Increased ¹⁸F-FDG uptake was also seen in the right SCM (white arrow head), left LC (black arrow head), left SPC (thick black arrow) and left RCPM (thin black arrow) (F). The hot uptake of ¹⁸F-FDG was showed in the right SCM (white arrow head), right uTz (thin white arrow), left LC (black arrow head) and left SPC (thick black arrow) (G). LC: Longus capitis, Lc: Longus colli, SPC: Splenius capitis, SSC: Semispinalis capitis, OCS: Obliquus capitis superior, SCM: Sternocleidomastoid, RCPM: Rectus capitis posterior major, uTz: Upper trapezius.

Fig. 3

The Kaplan-Meier plot showing the probability of reinjection-free living after BoNT-A injection in clinically targeting group (group 1) and the ¹⁸F-FDG PET/CT-assisted, clinically targeting group (group 2). The probability of reinjection-free living is 0.8 in group 2, while the rate is 0.19 in group 1 when the duration of follow up is one year (365 days). The duration of follow-up for group 1 was 144 days (95% confidence interval: 134.2-153.8) when the reinjection-free living rate had come to 50%.