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[Isolated inferior rectus muscle paresis from midbrain infarction]
K Negoro1, F Sasabe, M Morimatsu
1Department of Neurology, Yamaguchi University School of Medicine.
Rinsho Shinkeigaku = Clinical Neurology
|April 1, 1993
Summary
Sudden double vision in an elderly woman was linked to a stroke in the midbrain affecting eye movement. Prompt diagnosis of focal ischemic midbrain lesions is crucial for isolated oculomotor nerve issues.
Area of Science:
- Neurology
- Neuro-ophthalmology
- Neuroimaging
Background:
- Oculomotor nerve (cranial nerve III) palsy can arise from various causes, including vascular events.
- Isolated partial oculomotor nerve paresis, particularly without other neurological deficits, can present a diagnostic challenge.
Observation:
- A 74-year-old woman with hypertension and dilated cardiomyopathy experienced sudden onset of diplopia (double vision).
- Clinical examination revealed isolated left inferior rectus muscle paresis, with no other neurological abnormalities.
- Magnetic resonance imaging (MRI) demonstrated increased signal intensity in the right ventral midbrain on T2-weighted and proton density-weighted images.
Findings:
- The MRI findings were consistent with an infarction (stroke) involving the fascicular oculomotor fibers in the midbrain.
- This focal ischemic midbrain lesion was identified as the cause of the isolated partial oculomotor nerve paresis.
- The patient experienced complete resolution of diplopia and normal ocular motility after 3 months.
Implications:
- Focal ischemic midbrain lesions should be considered in the differential diagnosis of isolated partial oculomotor nerve paresis.
- This case highlights the importance of neuroimaging in identifying the etiology of specific cranial nerve palsies.
- Early recognition and management of midbrain strokes can lead to favorable outcomes in neuro-ophthalmological presentations.