Pearls and Oy-sters: Stroke in the Wrong Hemisphere: Tractography Solves the Puzzle
In brief
Diffusion tractography uncovers uncrossed corticospinal tract in ipsilateral stroke case
In a young woman with a right-hemisphere infarct but right-side weakness, diffusion tensor imaging showed a likely non-decussating corticospinal pathway, explaining the paradoxical ipsilateral deficits. The finding highlights that advanced diffusion imaging can resolve mismatches between lesion location and clinical signs, though it cannot definitively prove absence of the normal crossing.
- Journal
- Neurology (Q1)
- Published
- 23 July 2026
- Study design
- Case series / case report
- Evidence level
- Level 4, Very Low (CEBM 4)
- Authors
- Marcus Tulius T Silva, Giseli Quintanilha, Fernanda Rueda Lopes, Cíntia Lopes da Cunha da Silveira
- PMID
- 42492031
- DOI
- 10.1212/WNL.0000000000218250
Why clinicians should know about it
- Picked for Anatomy (paper of the day, 24 July 2026): Tractography resolves atypical corticospinal anatomy
Abstract
A young woman presented with sudden-onset dysarthria and right-sided weakness and hypoesthesia. MRI revealed an acute infarct in the right hemisphere, the same side as the patient's clinical deficits. This unusual alignment between symptoms and lesion laterality raised important diagnostic challenges. Standard vascular and etiologic investigations were unrevealing, and initial treatment with intravenous thrombolysis led to partial recovery. The persistence of a paradox between lesion location and motor deficit prompted further evaluation with diffusion tensor imaging with tractography (DTI) that demonstrated imaging findings consistent with a nondecussating corticospinal tract at the level of the medullary pyramids, providing a plausible anatomical explanation for the paradoxical ipsilateral presentation. Although tractography cannot definitively establish the anatomical absence of pyramidal decussation, the structural configuration observed was strongly suggestive of an uncrossed corticospinal organization. This case underscores the importance of diagnostic flexibility when fundamental neuroanatomical rules appear violated and highlights the role of advanced diffusion imaging in resolving clinical-radiologic discordance.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.