**3. Phenomenology and clinical features of cranio-cervical dystonias**

#### **3.1. Blepharospasm**

the incidence increases to 72 % on electrophysiological evaluation of oropharyngeal swallow‐ ing and after selective rhizotomy [8,9]. Similarly, dysphagia in patients with spasmodic dysphonia has been reported before and after treatment of this condition [13-15]. Because of the anatomical distribution of the affected muscles, OMD and co-existing oral-buccal-lingual (OBL) dyskinesias are associated with abnormal perioral, oral and lingual movements that can interfere with tasks such as chewing, swallowing and speaking, leading to social embarrass‐ ment and even eating disorders and weight loss. Eating dysfunction has been reported in 15.6 % of OMD cases [16]. Pharyngeal OMD often affects the pharyngeal constrictor muscles and can occur with spasmodic dysphonia. Choking and difficulty in swallowing are common complaints. After treatment of spasmodic dysphonia, there may be an unexpected improve‐ ment in pharyngeal dystonia. Treatment for pharyngeal constriction muscle dysfunction is

Although new radiologic changes were observed in 50 % of CD patients following BoNT-A treatment, clinically only 33 % of the patients reported new dysphagia symptoms. The severity of the new dysphagia symptoms correlated strongly with the severity of new radiologic

In this chapter the role of dysphagia as a clinical symptom of cranio-cervical dystonia is discussed and the occurrence of dysphagia as a common adverse effect of treatment for

If defining dystonia is difficult and controversial, classifying the various forms of dystonias is a much more complex task, primarily because the term dystonia can mean not only a disease but also a symptom that can be part of many disorders with a wide range of causes. In an attempt to clarify the term, three "surnames" for dystonia were proposed: "symptom", "movement" and "disorder". A patient may complain of dystonia if, for example, he has a twisted neck. The patient has a dystonia symptom (dystoniaSx). On examination, the signs of dystonia may be confirmed. This patient then has a dystonia movement (dystoniaMov). Finally, dystonia as a disorder (dystoniaDx) requires a clinicopathologic understanding of the etiology of the disease, i.e., whether it is genetic, late-onset, post-traumatic, or has other etiologies [18]. These new definitions led to the replacement of the 1998 dystonia classification [3] by a new one in 2013. The dystonias are now subdivided according to whether they are the result of pathological changes or structural damage, have acquired causes or are hereditary. If there is no clearly defined etiology, the dystonia can be classified as idiopathic familial or idiopathic

Recent years have seen significant progress being made in our understanding of the genetics of dystonias as new loci and genes have been identified. For generalized dystonias, the genetic mechanisms are better understood, while for focal dystonias, the genes and genetic suscepti‐ bility to the disorder are not yet well identified. Hereditary dystonias (dystoniaDx) are clinically and genetically heterogeneous. The known genetic forms include all monogenic inheritance

nearly always associated with dysphagia [17].

pharyngeal abnormalities [8].

**2. Classification of dystonias**

dystonias is described.

190 Seminars in Dysphagia

sporadic [3].

Blepharospasm (BSP) is a form of focal dystonia characterized clinically by involuntary periocular spasms resulting in forceful eye closure [20,21,22]. BSP is characterized by tonic, phasic or combined involuntary tonic-phasic contractions of the orbicularis oculi muscles, producing repeated and frequent blinking and persistent forceful closure of the eyelids with various degrees of functional blindness. The characteristic features of BSP include sensory tricks that patients use to relieve their symptoms (geste antagoniste) and a high frequency of ocular symptoms starting before or at the onset of the spasm [20,21,22]. BSP may be associated with inhibition of the levator palpebrae muscle (apraxia of eyelid opening) or involuntary movements in the lower face or jaw muscles [20,21,22]. Apraxia of eyelid opening may in turn be associated with other neurological conditions, such as progressive supranuclear palsy and corticobasal degeneration [21,22].

#### **3.2. Oromandibular dystonia**

OMD refers to involuntary spasms of masticatory, lingual, and pharyngeal muscles that result in jaw closing (JC), jaw opening (JO), jaw deviation (JD), or a combination of these abnormal movements [22,23]. When OMD is associated with blepharospasm, the combination is referred to as "cranial dystonia" or, less appropriately, as "Meige's syndrome" [24]. Because of the anatomical distribution of the affected muscles, OMD and co-existing OBL dyskinesias are associated with abnormal perioral, oral and lingual movements that can interfere with chewing, swallowing and speaking, leading to social embarrassment [25] and even eating disorders and weight loss [26]. Examination may reveal a variety of antagonistic maneuvers, or sensory tricks, including touching the lips or chin, chewing gum, or biting on a toothpick [21]. Even using these sensory tricks, patients often feel socially embarrassed by the spasms, which give them a disfigured appearance [22].

#### **3.3. Lingual dystonia**

Dystonic involvement of the tongue is a well-recognized feature of tardive dystonia as well as OMD, both primary and secondary, although primary focal lingual dystonia (PFLD) has only rarely been described. PFLD presents as an action dystonia during speech or in paroxysmal episodic lingual dystonic spasms [27]. A rare disorder, it can be severe enough to affect speech, swallowing and breathing. Tardive lingual dystonia secondary to dopamine-receptorblocking drugs may manifest as a relatively isolated problem. Although severe tongue protrusion, particularly during eating, is characteristic of neuroacanthocytosis, it can also be seen in other rare forms of symptomatic dystonias such as pantothenate kinase-associated neurodegeneration and Lesch–Nyhan syndrome [21].

#### **3.4. Laryngeal dystonia**

Laryngeal dystonia (spasmodic dysphonia) is a neurological voice disorder with low preva‐ lence. It is characterized by involuntary adductor (toward the midline) or abductor (away from the midline) vocal fold spasms during phonation that cause phonatory breaks [20,22]. Some patients also present with a mixed type of this disorder. Onset of laryngeal dystonia frequently occurs late in life and presents in mild to severely disabling forms that lead to long-lasting impaired verbal communication. Adductor spasmodic dysphonia (SD) is undoubtedly the most common form [22]. Both forms rarely occur in the same individual. Around one-third of SD sufferers also present with voice tremor, which makes the pitch and loudness of the voice waver at 5 Hz during vowels and is most apparent when the sound "/a/" (as in "all") is produced for at least 5 s [28].

#### **3.5. Cervical dystonia**

CD is characterized by involuntary posturing of the head as a result of involuntary spasms, jerks, or tremors (or a combination of all three) and is often associated with neck pain. Clinical classification is based on the position of the head and type of movement. The most common form is rotational torticollis (>50 %). Other relatively frequent forms include laterocollis and retrocollis, while anterocollis and complex forms of CD (in which there is no predominant component) are less common. Patients frequently present with a combination of abnormal patterns, even when it is possible to identify a predominant component [29]. A number of sensory tricks, including touching the contralateral side of the face as well as ipsilateral to the direction of head rotation, can produce a temporary improvement in involuntary neck movements. As with other forms of focal dystonia, the symptoms of CD are exacerbated by stress and improved by relaxation [20,29].



seen in other rare forms of symptomatic dystonias such as pantothenate kinase-associated

Laryngeal dystonia (spasmodic dysphonia) is a neurological voice disorder with low preva‐ lence. It is characterized by involuntary adductor (toward the midline) or abductor (away from the midline) vocal fold spasms during phonation that cause phonatory breaks [20,22]. Some patients also present with a mixed type of this disorder. Onset of laryngeal dystonia frequently occurs late in life and presents in mild to severely disabling forms that lead to long-lasting impaired verbal communication. Adductor spasmodic dysphonia (SD) is undoubtedly the most common form [22]. Both forms rarely occur in the same individual. Around one-third of SD sufferers also present with voice tremor, which makes the pitch and loudness of the voice waver at 5 Hz during vowels and is most apparent when the sound "/a/" (as in "all") is

CD is characterized by involuntary posturing of the head as a result of involuntary spasms, jerks, or tremors (or a combination of all three) and is often associated with neck pain. Clinical classification is based on the position of the head and type of movement. The most common form is rotational torticollis (>50 %). Other relatively frequent forms include laterocollis and retrocollis, while anterocollis and complex forms of CD (in which there is no predominant component) are less common. Patients frequently present with a combination of abnormal patterns, even when it is possible to identify a predominant component [29]. A number of sensory tricks, including touching the contralateral side of the face as well as ipsilateral to the direction of head rotation, can produce a temporary improvement in involuntary neck movements. As with other forms of focal dystonia, the symptoms of CD are exacerbated by

**Clinical category Designation Clinical characteristics Locus Gene Inheritance pattern**

generalized dystonia 9q *TOR1-A or DYT1* AD

idiopathic dystonia - *-* AR

1p *-* AD

DYT6 Mixed dystonia 8p *THAP1* or DYT6 AD

neurodegeneration and Lesch–Nyhan syndrome [21].

**3.4. Laryngeal dystonia**

192 Seminars in Dysphagia

produced for at least 5 s [28].

stress and improved by relaxation [20,29].

DYT2

DYT13

DYT1 Early-onset primary

Autosomal recessive

Early-onset primary segmental craniocervical

dystonia

**3.5. Cervical dystonia**

Isolated dystonias Persistent dystonias Childhood- or adolescent-onset dystonias

