Monochorea of the Upper Limb in a Patient with Spinocerebellar Ataxia Type 12

Field: Medicine (Health Sciences)

Autosomal dominant cerebellar ataxias are classified according to genetic subtype and collectively known as SCAs. Movement disorders including tremor, dystonia, parkinsonism, chorea, myoclonus, paroxysmal nonkinesigenic dyskinesia, stiff person-like syndrome, akathisia, myokymia, stuttering, tics, restless leg syndrome, spasmodic-like dysphonia, laryngeal stridor, and palatal tremor have been reported in some of the SCAs.1 They may be present at the disease onset or during the overall disease course and sometimes they may be present even before the development of ataxia.1 A 69-year-old male patient, presented with asymmetric onset tremulousness of his upper limbs for the last 15 years. There was progressive gait ataxia, head tremors, and involuntary, random, non-rhythmic, and flowing movements of his left upper limb for the last 3 years. There was clumsiness and frequent dropping of objects more with left hand due to these involuntary random and flinging movements and they were aggravated on walking and subsided during sleep. His past medical history was unremarkable. He had a family history of tremors of upper limbs and head tremor in his mother, eldest sister, and maternal aunt (Fig. 1i). His general and systemic examinations were normal. Extra-ocular examination showed square wave jerks. On motor examination tone and power were normal, deep tendon reflexes were brisk and bilateral plantars were extensor. His sensory examination was normal. He had head tremor and left upper limb chorea which was more severe when he extended his arm in an outstretched position. During walking the chorea was more severe. He also had mild ataxia and intention tremors in the upper limbs (See Video 1). His magnetic resonance imaging of the brain showed diffuse atrophy including the cerebellum (Fig. 1ii). Given his clinical presentation and strong positive family history, spinocerebellar ataxia (SCA) panel was ordered, and he was found to be positive for SCA12 (PPP2R2B gene) with 49 CAG repeats. Our patient had monochorea in the left upper limb which has been rarely reported in SCA12 patients. Huntington's Disease-like presentation in SCA 12 was earlier reported in an Italian family, where the index patient had choreo-athetoid movements along with ataxic and parkinsonian features within other family members.2 Choudhury et al., reported 21 cases of genetically diagnosed patients of SCA12 and found that tremor was the most common initial non-ataxic manifestation and none of their patients had chorea.3 Huntington's chorea-like presentation is more common in SCA17.4 Apart from SCA17, chorea is also reported in SCA2, SCA1, SCA3, SCA27, DRPLA, and SCA48.1, 4, 5 In SCA 27 chorea can be the sole manifestations, whereas in DRPLA a combination of chorea, myoclonus and dystonia is seen.1 SCA12 is mostly prevalent in specific ethnic groups “Agrawal communities” and our patient also belonged to this community.3 Although tremors are not specific to a given SCA, SCA12 is the only SCA in which action tremor is the presenting and most common sign. Also, very asymmetric postural and action tremor can occur in these patients.3 Our case illustrates that “Chorea” can be one of the clinical manifestations of SCA12 which is of utmost importance in a country like India since it is the second most common type of SCA.3 (1) Conception and design of the study; (2) Acquisition and analysis of data; (3) Drafting a significant portion of the manuscript and figures. SB: 1, 2, 3 CR: 1, 2, 3 SP: 1, 2, 3 The authors confirm that the approval of an institutional review board was not required for this work. We also confirm that the patient has given written informed consent for the publication of his video. We confirm that we have read the Journal's position on issues involved in the ethical publication and affirm that this work is consistent with those guidelines. No specific funding was received for this work. The authors declare that there are no conflicts of interest relevant to this work. The authors declare that there are no additional disclosures to report.