AD – Autosomal dominant, AR – Autosomal recessive, XR – X-linked recessive

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

and adductor laryngeal dystonia (for which it is probably effective) [30,31].

Exercise-induced

DYT20

194 Seminars in Dysphagia

DYT18

**Table 1.** The hereditary dystonias \*

\*Based on Albanese et al. [3] and Lohmann and Klein [19]

dysphagia and neck weakness [29, 33-38].

As it is not easy for patients with CD to notice dysphagia, this condition is very often under‐ diagnosed [6,29].

Oropharyngeal function is usually investigated with the aid of videofluoroscopy. Clinical and videofluoroscopic evaluations have also indicated a high incidence of swallowing disorders in patients with CD before any treatment such as BoNT injection or rhizotomy [7-9]. In one study, swallowing abnormalities during video fluoroscopic examination were observed in over 50 % of CD patients [7].

In general, videofluoroscopic studies of CD patients show delayed initiation of swallowing and pharyngeal residue [7,10]. CD patients with these signs appear to have "neurogenic dysphagia" [7,43]. In contrast, asymmetric pharyngeal transit of large liquid boluses is consistent with tonic or clonic posturing of the head (and pharynx). Although the postural and neurogenic signs presumably relate to the same underlying neurologic dysfunction and both types might be considered "neurogenic," the authors of some studies suggest that the postural signs were sufficiently selective and specific to warrant a separate classification [7]. Therefore, Riski et al. [7] considered the presence of pharyngeal asymmetry with large boluses to be a sign of "postural dysphagia." Of 43 patients, 16 showed only neurologic signs; three showed only postural signs; and three showed combined postural and neurologic signs. The findings of Riski et al. suggest that swallowing abnormalities in CD are primarily neurogenic but may be solely postural or combined neurogenic and postural in nature. In agreement with this conclusion that CD involves neurogenic dysphagia, similar clinical and electrophysiological findings were reported in patients with OMD and laryngeal dystonia but not CD and in others with CD. Therefore, dysphagia can occur without abnormal head or neck movements [6]. Electrophysiological abnormalities in dystonic muscles are frequent and are all compatible with neurogenic dysphagia [6].

Two-thirds of those who complained of dysphagia showed evidence of swallowing abnor‐ malities, and at least one swallowing abnormality was detected radiographically in half of those who did not complain. This lack of close agreement between subjective reports and videofluoroscopic results may reflect several factors. Firstly, videofluoroscopic examination of swallowing can show dysfunctions; however, as the protocol is standardized, it does not simulate all factors present during meals in the patient's home, e.g., the full range of textures and bolus sizes, the speed of bolus presentation and the presence of external distractions. Secondly, some patients' concerns with the discomfort or cosmetic disability associated with their CD may overshadow the relatively subtle abnormalities in oropharyngeal function. Thirdly, CD patients may have adapted to changes in swallowing function and therefore be asymptomatic [7].

Dysphagia and dysarthria (which account for 10.2 % to 37 % and 0.9 % of complaints, respec‐ tively) are the two most common adverse effects of BoNT treatment for OMD [37,42]. Clinical and videofluoroscopic evaluations have also indicated a high incidence of swallowing disorders in CD patients before any treatment such as BoNT injection or rhizotomy [7-9]. In a study by Comella et al., although new radiologic changes occurred in 50 % of CD patients following BoNT treatment, clinically only 33 % of these patients reported new dysphagia symptoms. The severity of new dysphagia symptoms correlated highly with the severity of new radiologic pharyngeal abnormalities. This suggests that rather than being routinely indicated, videofluoroscopic swallowing evaluations should be reserved mainly for patients with the severest clinical symptoms as an objective measure to assess the possibility of aspiration [8].
