Pseudoulnar palsy with concurrent wrist drop: case report

Pseudoulnar palsy, characterized by weakness in the fourth and fifth digits, is a condition typically attributed to infarction of the medial aspect of the precentral gyrus's "hand knob." This anatomical site is located in the primary motor cortex of the brain, in the posterior lobe of the frontal cortex. This report presents a novel case of pseudoulnar nerve palsy in conjunction with wrist drop stemming from an infarction of the hand knob gyrus.

A 78-year-old female with hypertension and hyperlipidemia experienced sudden right wrist weakness and impaired mobility in her fourth and fifth digits. Clinical examinations, including neuroimaging, supported the diagnosis of an infarction in the medial precentral gyrus. Brain MRI confirmed the diagnosis of an acute infarction in the medial precentral gyrus. The patient was treated with enoxaparin, aspirin, and dexamethasone, and was discharged after symptom improvement.

Unlike the classical presentations, this case highlights the co-occurrence of ulnar and radial deficits following a unique infarction pattern. The distinct presentation of right pseudoulnar palsy with wrist drop was caused by an infarction at the level of the medial aspect of the hand knob.

This case underscores the importance of considering the central causes of peripheral-like deficits, especially in older individuals with vascular risk factors, emphasizing the significance of early intervention in mitigating potential long-term consequences. This report contributes to the evolving understanding of central neurological presentations, and serves as a reminder of the need for a comprehensive diagnostic approach.