Aphasia Leading to the Diagnosis of Myotonic Dystrophy Type 1: A Case Report
Bibliographic record
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystem autosomal dominant disorder primarily characterized by myotonia and distal muscle weakness. Central nervous system (CNS) involvement, including cognitive, executive, and emotional dysfunctions, is increasingly being recognized; however, language impairment as an initial presentation is rare. A 50-year-old right-handed woman with a six-month history of progressive word-finding difficulty, vague speech, and social withdrawal was referred for evaluation. Neurological examination revealed distal muscle atrophy (grip strength: 5 kg right, 8 kg left) without overt dysarthria or dysphagia, and intact reflexes and coordination. Neuropsychological testing revealed fluent spontaneous speech with anomia, semantic paraphasia, impaired comprehension of longer sentences, and surface dyslexia/agraphia (Mini-Mental State Examination-Japanese: 22/30, Frontal Assessment Battery: 8/18, Raven's Colored Progressive Matrices: 28/36, Montreal Cognitive Assessment-Japanese: 21/30). Brain magnetic resonance imaging revealed left-sided frontotemporal and limbic atrophy, and 99mTc-ethyl cysteinate dimer single-photon emission computed tomography showed a corresponding left-dominant hypoperfusion. Amyloid positron emission tomography (PET) scan results were negative. Two weeks later, percussion and grip myotonia emerged. Genetic analysis revealed a cytosine-thymine-guanine repeat expansion (~1500 repeats) in the myotonic protein kinase 1 gene, confirming the diagnosis of DM1. The patient's semantic‐variant primary progressive aphasia-like profile (impaired semantic processing with preserved fluency) and frontotemporal imaging findings were consistent with rare CNS phenotypes reported in DM1. Previous studies have described frontotemporal atrophy, hypoperfusion, and cognitive/emotional changes in DM1. Negative amyloid PET excluded Alzheimer-related primary progressive aphasia. The subsequent detection of myotonia and a positive family history were key to diagnosis. We conclude that this case expands the clinical spectrum of DM1 to include progressive aphasia as an initial manifestation. Clinicians should maintain a high suspicion of neuromuscular disorders and actively pursue targeted genetic testing when atypical aphasia symptoms are accompanied by distal muscle atrophy.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.004 | 0.002 |
| Meta-epidemiology (broad) | 0.002 | 0.003 |
| Bibliometrics | 0.006 | 0.003 |
| Science and technology studies | 0.005 | 0.003 |
| Scholarly communication | 0.003 | 0.003 |
| Open science | 0.003 | 0.003 |
| Research integrity | 0.008 | 0.005 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".