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

Myotomy and Selective Peripheral Denervation Based on 18F-FDG PET/CT in Intractable Cervical Dystonia: A Case Report

Cervical dystonia, characterized by the involuntary contraction of cervical muscles, is the most common form of adult dystonia. In a patient with intractable cervical dystonia, we carried out a myotomy of the left obliquus capitis inferior and selective peripheral denervation (SPD) of the posterior branches of the C3-C6 spinal nerves based on preoperative 18F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT). The patient was a 65-year-old, right-handed man with an unremarkable medical history. His head rotated involuntarily to the left. Medication and botulinum toxin injections were ineffective, and surgical treatment was considered. ¹⁸F-FDG PET/CT imaging revealed FDG uptake in the left obliquus capitis inferior, right sternocleidomastoideus, and left splenius capitis. Myotomy of the left obliquus capitis inferior and SPD of the posterior branches of the C3-C6 spinal nerves was performed under general anesthesia. During the 6-month follow-up, the patient's Toronto Western Spasmodic Torticollis Rating Scale score improved from 35 to 9. This case shows that preoperative ¹⁸F-FDG PET/CT is effective in identifying dystonic muscles and determining the surgical strategy for cervical dystonia.

Therapeutic Efficacy and Prediction of 18F-FDG PET/CT-Assisted Botulinum Toxin Therapy in Patients With Idiopathic Cervical Dystonia

PURPOSE

This study aimed to investigate the therapeutic efficacy of 18F-FDG PET/CT-assisted botulinum toxin (BTX) injection therapy and predictive PET findings in relation to a good response in patients with idiopathic cervical dystonia (ICD).

MATERIALS AND METHODS

A total of 78 patients was enrolled from November 2007 to July 2018. The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) score was determined at baseline and 4 weeks after BTX injection guided by electromyography and PET/CT. The number of hypermetabolic muscles, the highest SUVmax among hypermetabolic muscles, and the total SUVmax of hypermetabolic muscles were evaluated as pretreatment PET parameters. A good response was defined as a reduction rate ≥30% and a point decrease ≥15 of the TWSTRS total score.

RESULTS

Half of the subjects showed a good response. Good responders had significantly higher baseline TWSTRS scores than poor responders (total score, P < 0.001; severity, P < 0.001; disability, P < 0.001; pain, P = 0.026). Good responders also had significantly higher numbers of hypermetabolic muscles and BTX-injected hypermetabolic muscles (P < 0.001, both). In multivariable analysis, the baseline TWSTRS disability subscale score and the number of BTX-injected hypermetabolic muscles were significant predictors for good response (P = 0.001 and P = 0.028). The aforementioned 3 PET parameters were positively correlated with the baseline TWSTRS scores. In addition, PET/CT well detected dystonic deep cervical muscles.

CONCLUSIONS

FDG PET/CT-assisted BTX injection therapy showed good therapeutic efficacy in ICD patients. The numbers of hypermetabolic cervical muscles and BTX-injected hypermetabolic muscles may be helpful in predicting a good response.

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: β, -4.86 [95%CI -9.40 to -0.32; P = 0.036]; Tsui: β, -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: β, -6.33 [95%CI -10.17 to -2.49; P = 0.001]; Tsui: β, -1.42 [95%CI -2.48 to -0.37; P = 0.008]) and T3 (TWSTRS: β, -6.05 [95%CI -11.09 to -1.01; P = 0.019]; Tsui: β, -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.

A methodological approach for botulinum neurotoxin injections to the longus colli muscle in dystonic anterocollis: A case series of 4 patients and a literature review

We review the current approaches and their feasibility to treat dystonic anterocollis by injecting longus colli muscle (LCo) with botulinum neurotoxin (BoNT) as well as present our personal experiences in this field compared with the findings from previously published studies. First, we searched the PubMed database for the publications reporting patients who received LCo injections for anterocollis; we also thoroughly examined the references included in each of the found publications. Second, we present and analyze our own experiences in injecting LCo under EMG guidance in patients with dystonic anterocollis due to heredodegenerative disorders. We found 11 publications describing administration of LCo injections for the treatment of dystonic anterocollis in a total of 28 patients with primary dystonia aged between 21 and 80 years. The mean age of our patients was 44.8 years with the mean anterocollis duration being 15 months. OnabotulinumtoxinA in a dose of up to 35 U per LCo muscle was not associated with the development of transient dysphagia. The mean percentage of patient satisfaction was 36.3%, and the mean duration of the beneficial effect was 2.5 months. All patients agreed to receive a repeat injection. We provide a set of empirically based suggestions on the current use of BoNT injections to LCo for managing anterocollis in outpatient clinics, including pretreatment work-up, injection technique, and dose range.

The Effect of Computed Tomography-Guided Botulinum Toxin Injection on Cervical Dystonia, Confirmed by a 9-Month Follow-Up Using Positron Emission Tomography/Computed Tomography

Although accurate targeting of the causative muscles is of paramount importance in the treatment of focal dystonia, this is often challenging because of distortion of the affected anatomical structures and difficulty in proper positioning of injections. We report a case of idiopathic cervical dystonia that was treated by computed tomography-guided injection of botulinum toxin into multiple deep muscles. Based on clinical presentation of combined torticollis and retrocollis, and needle electromyography results, botulinum toxin was injected under electromyography guidance. This treatment resulted in no improvement. Subsequently, target muscles were identified using F-fludeoxyglucose fusion positron emission tomography/computed tomography. botulinum toxin was injected into the hypermetabolic muscles guided by computed tomography. This injection successfully relieved the symptoms, and nine months of follow-up using positron emission tomography/computed tomography confirmed that hypermetabolic muscles had been normalized. This case indicated that computed tomography guidance may facilitate accurate targeting of botulinum toxin injection. To the authors' knowledge, this is the first case reporting a positive effect of botulinum toxin on cervical dystonia symptoms that lasted 9 mos, confirmed by follow-up positron emission tomography/computed tomography.

[99mTc]MIBI SPECT/CT for Identifying Dystonic Muscles in Patients with Primary Cervical Dystonia

PURPOSE

This study aimed to evaluate the usefulness of [^99mTc]sestamibi ([^99mTc]MIBI) single photon emission computed tomography (SPECT)/X-ray computed tomography (CT) imaging for the identification of dystonic muscles in primary cervical dystonia (PCD) patients who underwent botulinum neurotoxin type A (BoNT-A) therapy.

PROCEDURES

Thirty-six patients with PCD and 10 healthy subjects (control group) who underwent [^99mTc]MIBI SPECT/CT were enrolled. The image characteristics of dystonic muscles and normal muscles were evaluated. Muscle/background ratio (MBR) of six representative muscles was calculated for dystonic muscles in PCD group and normal muscles in control group. In PCD patients, target muscles injected with BoNT-A were selected by clinical evaluations and the results of needle electromyography (EMG) were considered as the gold standard. The sensitivity, specificity, and diagnostic efficacy of SPECT/CT were obtained from the receiver operator characteristic (ROC) curve.

RESULTS

Twenty-four PCD patients were included in our study eventually, because three PCD patients whose follow-up were lost and 9 PCD patients whose maximum reduction of Tsui scale scores was < 80 % were ruled out. Normal muscles of healthy subjects showed mild symmetrical radioactivity distribution, while in PCD patients, [^99mTc]MIBI uptake in dystonic muscles abnormally increased. The mean MBRs of dystonic muscles were significantly higher than those of normal muscles. The sensitivity, specificity, and area under the curve (AUC) of SPECT/CT were 93.2 %, 88.5 %, and 0.908, respectively.

CONCLUSIONS

Our study indicated that [^99mTc]MIBI SPECT/CT may be a useful method for identifying dystonic muscles and a guide to BoNT-A therapy in PCD patients.

An ¹⁸F-FDG PET study of cervical muscle in parkinsonian anterocollis

The underlying etiology of parkinsonian anterocollis has been the subject of recent debate. The purpose of this study is to test the hypothesis that anterocollis in parkinsonian syndromes is associated with dystonia of the deep cervical flexors (longus colli and capitis). Eight patients with anterocollis, six in the setting of parkinsonism and two primary cervical dystonia control subjects with anterocollis underwent prospective structured clinical evaluations (interview, examination and rating scales), systematic electromyography of the cervical extensor musculature and (18)F-FDG PET/CT studies of cervical muscles to examine evidence of hypermetabolism or overactivity of deep cervical flexors. Subjects with parkinsonian anterocollis were found to have hypermetabolism of the extensor and sub-occipital muscles but not in the cervical flexors (superficial or deep). EMG abnormalities were observed in all evaluated patients, but only one patient was definitely myopathic. Meanwhile, both dystonia controls exhibited hypermetabolism of cervical flexors (including the longus colli). In conclusion, we were able to demonstrate hypermetabolism of superficial and deep cervical flexors with muscle (18)F-FDG PET/CT in dystonic anterocollis patients, but not in parkinsonian anterocollis patients. The hypermetabolic changes seen in parkinsonian anterocollis patients in posterior muscles may be compensatory. Alternative explanations for anterocollis include myopathy of the cervical extensors, or unbalanced rigidity of the cervical flexors, but this remains to be proven.

Threshold of Clinical Severity of Cervical Dystonia for Positive (18)F-FDG PET/CT

Objective

To examine whether the clinical severity of cervical dystonia (CD) significantly correlates with ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) findings as well as to determine the threshold of the clinical severity of CD for positive ¹⁸F-FDG PET/CT study findings.

Methods

Forty-seven subjects with torticollis as one of the symptoms of CD were included. The clinical severity of CD was evaluated with the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) at the time of ¹⁸F-FDG PET/CT. The correlation between the clinical severity of CD and the highest SUVmax was examined. The threshold of the clinical severity of CD necessary for positive ¹⁸F-FDG PET/CT findings was determined using receiver operating characteristics curve analysis.

Results

Thirty-three of the 47 subjects (70.21%) showed positive ¹⁸F-FDG PET/CT findings. The ipsilateral splenius capitis/cervicis, oblique capitis inferior, and longus colli/capitis were the rotators most frequently involved. The highest SUVmax of ¹⁸F-FDG PET/CT was significant correlated with the TWSTRS. Subjects with a total TWSTRS exceeding 39 showed positive ¹⁸F-FDG PET/CT findings, with those having a total TWSTRS ≤22 showing negative ¹⁸F-FDG PET/CT results. The cutoff value of the total TWSTRS for positive ¹⁸F-FDG PET/CT findings was set at 27.5 with 90.9% sensitivity and 64.3% specificity.

Conclusion

A significant correlation was evident between the clinical severity of CD and ¹⁸F-FDG PET/CT findings, providing a threshold of the clinical severity of CD for acquisition of positive ¹⁸F-FDG PET/CT findings.