Selective hand motor cortex lesions masquerading as “Pseudoperipheral Nerve Palsy”

Abstract

Strategic cortical lesions involving the hand motor cortex (HMC) presenting acutely as distal upper limb pure motor weakness certainly do need to be differentiated on clinical grounds from “pseudoperipheral palsy.” This rare phenotype can imitate peripheral motor nerve deficits and should not be easily overlooked. The? isolated “central hand and finger weakness” presenting as an acute onset of varying combinations such as pseudomedian, pseudoradial, and/or pseudoulnar nerve palsy is intriguing to the novice. In literature, this phenotype has been reported solely to result from cortical cerebral infarction and documented to occur in <1% of all ischemic strokes. The apropos of six “unforgettable patients” here highlights the heterogeneous pathophysiologic etiologies and mechanisms that included not only the conventional stroke risk factors but also hyperhomocysteinemia, common carotid artery thrombosis due to hyperhomocysteinemia and severe iron-deficiency anemia, biopsy-proven giant cell arteritis (GCA), cerebral metastasis, and dilated cardiomyopathy-related left ventricular thrombosis. Physicians and neurologists alike, as clinicians, need to be familiar with the peculiarities and clinical presentations of central hand control network cortical lesions.

Keywords

• diffusion-weighted imaging
• hand motor cortex
• magnetic resonance imaging
• precentral hand knob area
• pseudomedian nerve palsy
• pseudoperipheral palsy
• pure motor weakness
• cerebral metastasis stroke
• stroke chameleon
• giant cell arteritis
• stroke masquerader
• hyperhomocysteinemia
• common carotid artery thrombosis
• iron-deficiency anemia