**4. Treatment of craniocervical dystonias with BoNT**

While BoNT treatment remains the treatment of preference for most focal dystonias, pharma‐ cological and neurosurgical treatments are also important in the treatment algorithm. Treat‐ ment with BoNT in properly adjusted doses is known to be effective and safe for cranial and cervical dystonia, but not OMD. In recent years, long-term studies on the efficacy and safety of BoNT-A have been published, a new BoNT-A formulation has been marketed and new studies on BoNT-B have been carried out [30]. Systematic reviews and guidelines recommend that BoNT injections should be offered as a treatment option for CD (for which it has been proven to be effective) and can be offered for blepharospasm, focal upper extremity dystonia and adductor laryngeal dystonia (for which it is probably effective) [30,31].

The first study on the use of BoNT for CD was a single-blind study with 12 patients and used electromyography guidance and a total maximum BoNT-A dose of 200 U (then called Oculi‐ num®) (Smith-Kettlewell Institute, San Francisco, CA, USA). Improvements lasting 4 to 8 weeks were observed in 92 % of the patients, and 25 % reported transient neck weakness [32]. These early results were confirmed by a double-blind, placebo-controlled crossover study of 21 patients using 100 U of BoNT-A which showed an improvement based on investigator ratings and patient assessment of CD severity [33]. Since then some 80 studies have evaluated BoNT in CD. Table 2 shows the main results of some studies. Adverse events included dysphagia and neck weakness [29, 33-38].

While some forms of dystonia are relatively common, such as adult-onset CD, others are less frequent, and not all clinicians have enough clinical experience to guide their practice [39]. OMD is a type of focal dystonia that affects the lower facial, masticatory, labial and lingual musculature. When OMD occurs with blepharospasm, the term cranial dystonia is used. Meige's syndrome, a variant of OMD, is a combination of upper and lower facial motor dysfunction that includes blepharospasm and OMD [40]. Isolated OMD is relatively rare and represents only 5 % of all dystonias. However, cranial dystonias (OMD, blepharospasm and Meige's syndrome) are the second most frequent dystonias (22 %) [40, 41].

Dystonia is not a stereotyped disorder, and in OMD it has a highly variable presentation. Consequently, treatment must be individualized to accommodate the patients particular requirements and symptoms. OMD dystonia can be classified into the following types: JC, JO, JD, lingual, pharyngeal and mixed [41]. BoNT has become the therapy of choice for OMD, and its use in JO, JC, and JD OMD has been well documented. Although most of the reported literature on OMD consists of open studies, all these have reported improvement with BoNT. In general, JO dystonia is more difficult to treat than JC dystonia [41,42].


**Table 2.** Studies with botulinum toxin A (BOTOX®) for cervical dystonia
