Dynamic Aphasia as a Variant of Frontotemporal Dementia.

We describe two individuals with progressive verbal difficulty who exhibited impairment of propositional language, with relatively well-preserved auditory comprehension, naming, and repetition-a profile that is consistent with dynamic aphasia. By providing a brief review of pertinent literature and the results from our neurologic, speech and language, neuropsychological, and neuroimaging testing, this report sheds light on the infrequently reported dynamic aphasia in the context of frontotemporal dementia. Our patients' insights into their verbal difficulty tend to support the notion that dynamic aphasia results from interference at the stage where thoughts are converted into verbal messages-that is, the thought-verbal interface.

A Case of Atypical Alzheimer's Disease With Clinical Manifestation That Straddled the Boundary Between Primary Progressive Aphasia and Posterior Cortical Atrophy.

INTRODUCTION: In the context of Alzheimer's disease phenotypes, patients may present with symptoms and signs that do not exclusively fit into one of the existing phenotypic categories, which often delays timely diagnosis and initiation of services to optimize patient awareness and coping. CASE REPORT: A 74-year-old woman presented with the complaint of progressive word-finding difficulty, raising our suspicion for primary progressive aphasia. Clinical evaluations, however, also revealed emerging cortical visual deficits consistent with posterior cortical atrophy. During evaluation 1 year later, Gerstmann syndrome was evident. Her in vivo neuroimaging was positive for beta-amyloid and tau biomarkers of Alzheimer's disease pathology. CONCLUSION: In addition to contributing to the literature on the heterogeneity of the clinical manifestations of Alzheimer's disease, this report highlights that a breakdown in the visual-lexical interface can account for anomia in posterior cortical atrophy at least in some cases. Other relevant clinical insights pertinent to this case are discussed.

Dynamic aphasia with emerging agrammatism, anomia, and aberrant frontal behaviors in a case of atypical parkinsonism.

A 57-year-old man presented with dynamic aphasia with evolving agrammatism and anomia. Additionally, he exhibited emerging atypical parkinsonism and features of behavioral variant frontotemporal dementia. Insights pertinent to this complex clinical presentation are discussed.

Seeking neurophysiological manifestations of speech production: An ERP study.

The aim of this study was to examine the neurophysiological correlates of speech production by elucidating pertinent ERP components. Such examination can pave way for investigations on typical and atypical speech neuromotor control. Participants completed a speech task by saying a specific word (speaking condition) or withholding the verbal response (non-speaking condition) based on the color of a frame placed around a fixation cross that were displayed on a computer screen. They also completed a simple hand motor task by pressing a button with the right or left index finger based on the color of a frame. The hand motor task was administered to verify that neural activity specific to motor preparation was detectable. Two ERP components emerged from the multichannel principal component analysis (PCA) as distinguishing between the speaking and no speaking conditions: a posterior negative component, and a left lateralized positive component. The morphology of the posterior negative component, as well as the correlation between its magnitude and mean response time suggest that this component is closely associated with speech motor control. The left-lateralized component was interpreted as reflecting a process possibly mediated by the speech dominant left hemisphere.

Late-onset Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like Episodes Presenting With Auditory Agnosia.

INTRODUCTION: Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a multisystemic mitochondrial disorder that usually presents in childhood. Patients can have a wide array of neurological symptoms when presenting with stroke-like episodes, and imaging characteristics during the episodes can overlap with different neurological disorders. CASE REPORT: A 61-year-old woman presented with communication difficulties consistent with auditory agnosia and was found to have bitemporal abnormalities on imaging that first raised the concern for herpes simplex virus encephalitis. Further work-up, in conjunction with the patient's past medical and family history, suggested a mitochondrial disorder. Mitochondrial full genome analysis revealed m.3243A>G variant in the MT-TL1 gene, with 6% heteroplasmy in blood leading to a diagnosis of MELAS. CONCLUSIONS: MELAS is a disorder with clinical variability. Neuroimaging studies during stroke-like episodes in MELAS can provide significant clues to the underlying disorder. Although patients typically present in childhood, the first stroke-like episode can occur later in life in some patients, potentially related to a lower heteroplasmy level.