Acute onset of cerebellar ataxia in a spinocerebellar ataxia type 10 patient after use of steroids

Abstract

Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant disorder caused by an expansion of a pentanucleotide (ATTCT) repeat in intron 9 of the ATXN10 gene on chromosome 22q13.31,2. SCA10 gene encodes a 475 KD protein of largely undetermined function. The pathogenic number of ATTCT repeat units ranges from 800 to 4,500 repeats. SCA10 represents a rare form of SCA, described only in Latin America1,2. While clinical manifestations of families described in Brazil are those of a predominantly “pure” cerebellar syndrome, it is often accompanied by epilepsy and occasionally peripheral neuropathy in the Mexican ones1,2. Here, we presented the case of a patient with genetically confirmed SCA10, who developed sudden onset of cerebellar ataxia after a course of corticosteroid therapy. A 34-year-old previously asymptomatic Brazilian woman suddenly developed gait ataxia and dysarthria two weeks after a pulse therapy with methylprednisolone for the treatment of idiopathic thrombocytopenic purpura. The patient was admitted with a clinical picture of body petechiae, gingival bleeding, and hematochezia, which started four days earlier. She had a platelet count of 1,000, which improved with the use of corticosteroids. Neurological assessment revealed gait ataxia, dysarthria, and ocular dysmetria. The Scale for the Assessment and Rating of Ataxia (SARA) was 7.5. Brain magnetic resonance imaging (MRI) showed moderate cerebellar atrophy. Family history was positive for SCA10, including previously reported relatives (aunt and two cousins), whose symptoms were initially manifested during pregnancy3. Interestingly, this same family has also reported the occurrence of cerebellar symptoms triggered by ingestion of small amounts of alcohol, which was previously also published by the authors4. SCA10 is the second most common autosomal dominant cerebellar ataxia in Brazil (after SCA type 3) and in Mexico (after SCA 2). To our knowledge, there is no report of acute cerebellar ataxia development after steroid therapy in patients with SCAs. Based on the case reported here and on family history of onset of symptoms during pregnancy and on postpartum period3, the authors hypothesized that hormonal factors may have a role in the emergence of SCA10 clinical symptoms and signs in previously asymptomatic patients in this family. The mechanisms by which hormones act on cerebellar function and its afferent and efferent connections remain unknown. Previously established genetic variables could be responsible for a lower threshold for manifestation of SCA10 in the course of steroid therapy, and additional studies are necessary to confirm this finding. On the other hand, it is widely known that stress seems to cause acute neuronal death or dysfunction5. Therefore, another possibility is that factors related to stress, involved in acute medical situations, such as pregnancy and postpartum period, could have a pivotal role in the development of acute symptoms of cerebellar ataxia in patients with asymptomatic cerebellar atrophy due to SCA10.