Objective: We present a rare case of Ataxia-telangiectasia (AT) characterized by intermittent action-induced dystonic opisthotonus causing frequent vomiting after meals intake [figure1].

Background: AT is a multisystem autosomal recessive disorder caused by biallelic ATM kinase deficiency. Clinical features include early-onset ataxia, oculomotor apraxia, and immunodeficiency. Dystonia can be part of the clinical presentation in AT, but its genotype-phenotype relationship remains unclear. We present a patient presenting with cognitive impairment combined with intermittent action-induced dystonic opisthotonus, where the final diagnosis was AT.

Method: A detailed clinical history and examination were performed and whole exome sequencing with repeat expansional disorder genetic assays were done.

Results: A 14-year-old boy, born to healthy, non-consanguineous parents [figure2B], presented with global developmental delays from around one year of age, along with progressive gait disturbances, slurred speech and intellectual disability. By five years of age, he experienced frequent infections such as otitis media, pneumonia, and cellulitis. At 14, he developed intermittent, patterned dystonic contractions of the left upper limb during activities such as eating and writing, accompanied by a hyperextended posture that led to vomiting after meals [figure1B, 1C]. Neurological examination revealed mild dysarthria, oculomotor apraxia, ocular telangiectasia [figure1A], hypotonia, reduced deep tendon reflexes and action-induced dystonic opisthotonus. Brain MRI showed cerebellar atrophy [figure2A], and blood tests revealed decreased serum IgG/ IgA levels with elevated AFP. Genetic testing identified a truncating ATM variant (c.67C>T/ p.Arg723Ter, c.3755_3757del/ p.Tyr1252_val3056del) [figure2C]. Surface EMG confirmed generalized dystonia with cervico-brachial-truncal involvement, with burst durations of approximately 1.2 seconds [figure3]. Treatment with Trihexyphenidyl and baclofen improved the dystonic episodes.

Conclusion: Dystonia can be part of the clinical spectrum in AT and may obscure the presence of ataxia. Action-induced dystonic opisthotonus is a severe neurological complication in AT. Early recognition and timely management are crucial to improving the patient’s quality of life.

Figure 1

Figure 2

Figure 3

« Back to 2025 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/action-induced-dystonic-opisthotonus-as-an-atypical-presentation-in-ataxia-telangiectasia/