Jaw‐Opening Oromandibular Dystonia Associated With Spinocerebellar Ataxia Type 2

SCA2 is an autosomal‐dominant neurodegenerative disease caused by expansion of CAG repeats in the ATX2 gene on chromosome 12.1 As with other polyglutamine expansion diseases, SCA2 is characterized by anticipation, with earlier onset in more recent generation, associated mostly with paternal transmission and larger expansion. Besides progressive cerebellar ataxia, SCA2 is characterized by slow saccadic movements and decreased/absent tendon reflexes. Cognitive decline, extrapyramidal or pyramidal signs, and myoclonus may occur.2

We describe an Italian patient with genetically confirmed SCA2, showing jaw‐opening oromandibular dystonia. The patient is a 26‐year‐old man, followed‐up in our clinic since age 18 for progressive limb and gait ataxia, dysarthria, mild dysphagia, and slow saccadic eye movements. The patient's father and paternal grandmother were also affected by ataxia and received genetic diagnosis of SCA2. CAG triplet repeats were 38 and 22 in the father and 39 and 22 in the grandmother. The father had onset at 38 years and the grandmother at 47. The progression was slow. Genetic testing of the ATX2 gene confirmed the diagnosis of SCA2 in the proband. CAG triplet repeats were 50 and 22, showing a larger expansion, compared to the father. The disease progression was faster, with loss of independent walking after 5 years of disease duration. He also developed a rapidly progressive cognitive decline since age 24 and anarthria at 25. At 26, he developed recurrent episodic dystonic movements restricted to the oromandibular region, characterized by extreme and sustained jaw‐opening spasm, tongue dyskinesias within the mouth, and elevation of soft palate, with duration of approximately 30 to 60 seconds (Video). The most severe episodes were associated with dyspnea and cyanosis. No particular trigger events or sensory tricks were associated. He had never been exposed to neuroleptics, and his history was negative for oromandibular‐facial trauma or dental procedures. Neurological examination showed severe ataxia with inability to walk, cognitive impairment, anarthria, saccade slowing, brisk knee jerks, and Babinski signs. Brain MRI showed severe cerebellar and brainstem atrophy with hot cross bun sign (cruciform hyperintensity of the pons on T2‐weighted images) as well as mild supratentorial atrophy. In the first 5 months after onset of dystonia, the episodes were rather sporadic, with good response to clonazepam. After, frequency and duration of the episodes of jaw‐opening dystonia increased and a severe dysphagia to both solids and liquids developed, requiring a percutaneous endoscopic gastrostomy. After the procedure, the patient was transferred to the intensive care unit because of a respiratory failure. At last evaluation, the patient state was that of a decreased level of consciousness with a permanent tracheostomy and gastrostomy. The parents refused botulin toxin or other treatments.

Among features accompanying ataxia, dystonia is present in approximately 14% of SCA2 patients and is usually associated with larger expanded repeats.3 Only few studies have reported on the localization of dystonia in SCA2, with several cases of cervical dystonia4 and few cases of writer's cramp and foot dystonia.5 Oromandibular dystonia, which has been previously described in other SCAs as SCA1,6 SCA8,7 and SCA36,8 may be a serious complication, leading to, or worsening, chewing and swallowing difficulties. On the other hand, dysphagia may be present in approximately 41% of SCA2 patients, especially in the late stage of the disease,9 or in cases with infantile onset.10

Author Roles

(1) Research Project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript: A. Writing of the First Draft, B. Review and Critique.

A.A.: 1A, 1B, 1C, 3A

S.P.: 1A, 1B, 1C, 3A

F.S.: 3B

G.D.M.: 1A, 3B

A.F.: 1A, 1B, 1C, 3B

Disclosures

Funding Sources and Conflicts of Interest: The authors report no sources of funding and conflicts of interest.

Financial Disclosures for previous 12 months: A.F. has received grant funding from POR CREME 2007‐2013. G.D.M. has received grant funding from the Italian Ministry of Education, University, and Research (PRIN 2010–2011 20108WT59Y_007).

Supporting information

Video. Oromandibular dystonia in the SCA2 patient, characterized by extreme jaw opening with elevation of soft palate and tongue dyskinesias. The episode concluded with a quick adduction of palatopharyngeal archs and repetitive chewing‐like movements.