Background: Isolated wrist drop is typically due to peripheral nerve injury, but rarely results from cortical infarction. Failure to promptly distinguish between central and peripheral causes can lead to missed diagnoses and delayed management, risking adverse outcomes.Case: A 74-year-old Filipino woman with a 10-year history of well-controlled hypertension and diabetes mellitus presented with a two-week history of progressive, isolated left distal upper-extremity weakness. She denied headache, dizziness, visual changes, trauma, dysarthria, or bowel and bladder dysfunction. Outpatient spine MRI demonstrated mild thoracic spondylosis with dextroscoliosis, vertebral hemangiomas, and multilevel lumbar disc protrusions, while cervical MRI showed spondylosis with disc desiccation and mild to moderate left foraminal narrowing. Neurologic examination revealed 4/5 strength in the left distal upper limb with intact sensation, reflexes, cranial nerve, and cerebellar function. Nerve conduction studies showed reduced recruitment without denervation. Brain MRI identified acute cortical infarcts involving the right precentral gyrus and adjacent frontal and parietal regions. Laboratory evaluation, carotid duplex ultrasonography, and 24-hour Holter monitoring were unremarkable. The patient was treated with dual antiplatelet therapy, as she was outside the thrombolysis window.Conclusions: This case underscores the importance of early diagnosis of cortical hand-knob stroke as a rare but significant cause of isolated distal upper-limb weakness. Prompt neuroimaging is essential to ensure correct diagnosis, initiate appropriate management, prevent secondary stroke, and optimize rehabilitation, especially in patients with vascular risk factors.
Kathleen Ann Pañares (Thu,) studied this question.