Objective: Describe a case of adult-onset stereotypy with abulia.

Background: Stereotypy is a non-goal directed but distractible behavior repeated continuously. While common in the pediatric population, adult onset stereotypy is rarer. We describe the utility of identifying this phenomenology to narrow the differential diagnosis of disparate neurologic disorders.

Method: Case report.

Results: A 75 y.o. man presented with a two-year history of involuntary movements in his arms, hands, and mouth, including rhythmic rubbing of his palms on his thighs, rubbing of his chest and abdomen when supine, and adventitious oral movements. He has a history of TBI, suffered in 2007, which resulted in short-term memory problems that remained stable post-injury. In 2010, he began exhibiting apathy, paucity of speech and anhedonia, but no abnormal movements. These behavioral changes have gradually worsened over time, with sharper decline since onset of involuntary movements in 2016. On mental status exam he displayed ideomotor apraxia, marked abulia with a paucity of spontaneous and prompted speech, inattention, and impaired Luria hand sequences. Motor exam revealed distractible and suppressible bilateral palmar thigh rubbing, stereotyped oral movements with lingual manipulation of dentures, and abdominal rubbing when supine, most consistent with stereotypy. MRI showed diffuse cortical atrophy, with a possible chronic infarct in the left anterior parietal lobe and periventricular microvascular changes. Neuropsychological testing revealed diffuse deficits spanning most cognitive domains; however, he was fully oriented and semantic knowledge was intact, making Alzheimer’s disease (AD) unlikely. His marked abulia, stereotypic movement disorder, and cognitive profile were deemed most consistent with frontotemporal dementia (FTD).

Conclusion: We present a patient with novel stereotypy, abulia, and progressive dementia which appears most consistent with an atypical FTD presentation. In a patient with a history of TBI, etiologic considerations regarding dementia syndromes can be challenging. In this case, stability of cognitive deficits for years post-TBI until onset of behavioral changes in 2010 are most suggestive of a co-occurring neurodegenerative process. Detailed history revealing a period of neurologic stability followed by a new presentation of abulia with subsequent sterotyped movement disorder helped narrow our differential to likely FTD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/adult-onset-stereotypy-an-atypical-presentation-of-frontotemporal-dementia/