Diagnostic Complications in the Left-Handed Patient with a Frontotemporal Syndrome and Positive pTau217 Testing

Abstract Objective Diagnosis of Frontotemporal Dementias (FTDs) ostensibly relies on congruence between presenting symptomology and disease syndrome. However, documentation of atypical lateralization and resulting syndromal divergence in left-handed patients (Perry et al., 2010; Miller et al., 2015) can complicate this task. The current paper contributes to the literature by presenting such a case, with additional discussion of diagnostic considerations stemming from increased reliance on pTau217 testing. Method The patient, a 55-year-old, left-handed, Caucasian male, initially presented to his primary care physician due to memory concerns, with gradual worsening over one-and-a-half years. Imaging made available after neuropsychological evaluation revealed moderate volume loss of the frontal lobes, with right-sided predominance and FLAIR/T2 hyperintensities in the periventricular and subcortical white matter. Subsequent pTau217 testing was elevated. Results Overall intellectual functioning measured in the borderline range. Borderline and impaired performances were noted on certain measures of verbal comprehension and language functioning, math computation, visuoconstruction, and executive functioning. Initial learning was also impaired, while retention was adequate. Informal neurobehavioral exam revealed bilateral hand tremors, orofacial dystonia, hypomimia, impaired motor sequencing, ideomotor praxis errors, finger agnosia, and left arm dysmetria. Conclusion The given patient’s language difficulties, coupled with imaging results and noted behavioral changes, are consistent with aforementioned work highlighting atypical lateralization in left-handed patients. Competing diagnoses provided by the neuropsychologist and neurologist, based on syndrome (FTD) and pathophysiology (AD), respectively, raise larger nosological questions for clinicians. In considering the popular and historical understanding of amnestic predominance in AD, the authors cite this case in argument for a syndromal approach to diagnostics.