Background:
Tremor is an important phenotypic feature of dystonia. Using the new concept (Col-Cap) of classification we examined the frequency of tremor in cervical dystonia (CD) patients, their main subtypes and muscles injected.
Methods:
In this large study conducted at multiple movement disorder centres in Europe and India, between January and June 2019, we examined 293 patients with idiopathic CD who were all treated with botulinum toxin (BTX).
Results:
The dystonic head tremor (DHT+) was present in 57.6 % of CD patients and they had a significantly longer duration of symptoms than patients without head tremor (DHT–). In DHT+ patients torticaput was the most common subtype and the majority (63.3%) had one or two subtypes only. There was no significant difference between the number of unilateral injections for any of the muscles in the DHT+ and DHT– groups, while the number of patients receiving bilateral injections in splenius capitis (78 vs 25; p = 0.00001), sternocleidomastoid (31 vs 6; p = 0.0005), trapezius (28 vs 9; p = 0.01), and obliquus capitis inferior (15 vs 2; p = 0.008) were significantly more in the DHT+ group. The mean doses of all three types of BTX/A were not significantly different between the two groups.
Conclusions:
The frequency of head tremor was 57.6% in our CD patients and torticaput was the most common dystonic subtype associated with tremor. Simple forms of CD seemed more likely associated with head tremor, than complex forms of CD. Most of the DHT+ patients received bilateral injections. The use of ‘Col-Cap’ classification was helpful in the identification of muscles likely to be involved in tremor in CD patients.
The classification of abnormal posture and the assessment of the affected muscles in cervical dystonia (CD) have changed in recent years. To determine the frequency of injected muscles, we studied 306 patients with CD. The mean age was 55.5 ± 13.1 years (range 21-90), 67% were female. Splenius capitis was the most commonly injected muscle (83%), followed by sternocleidomastoid (79.1%), and trapezius muscles (58.5%). The three next most common were the levator scapulae, semispinalis capitis, and obliquus capitis inferior muscles. The study shows that the most commonly injected muscles have remained unchanged over the past few decades, although the concept has changed. However, several new muscles have been added that were previously never, or hardly ever, considered.
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