The following is a summary of “Distinguishing Distinct Neural Systems for Proximal vs Distal Upper Extremity Motor Control After Acute Stroke,” published in the July 2023 issue of Neurology by Lin et al.

Traditional stroke motor deficits don’t reflect the unique organization of healthy central nervous system circuits governing proximal and distal motor control. Researchers hypothesized & identified distinct clinical syndromes after acute stroke & individuals with these syndromes have unique neuroanatomical injury patterns.

They assessed proximal and distal motor impairment (Fugl-Meyer score) & strength (Shoulder Abduction Finger Extension score) in patients within 7 days of acute stroke. Partial correlation analysis examined the relationship between proximal & distal motor scores. The modified Rankin scale (mRS), Box and Blocks Test (BBT), and Barthel Index (BI) were analyzed for proximal & distal motor deficits. Voxel-based lesion-symptom mapping identified motor deficit-linked injury regions.

The results showed that 141 consecutive stroke patients (49% F) were examined 4.0 ±1.6 days after their stroke. Following acute stroke, distinct proximal and distal upper extremity motor components were distinguishable (P= 0.002). Approximately 23% of acute stroke patients displayed more proximal injury than distal injury, suggesting relatively preserved distal motor control. Those with maintained distal motor control had better outcomes at 1 week & 90 days post-stroke, even after accounting for the total extent of deficit (BBT: P= 0.51, P< 0.001; BI: P= 0.41, P< 0.001; mRS: P= 0.38, P < 0.001). Proximal motor deficits linked to subcortical injury, distal deficits to precentral gyrus injury, matching CNS circuitry.

They concluded acute stroke selectively damages upper extremity motor systems, causing dissociable deficits and functional consequences, leading to poststroke hemiparesis.

Source: n.neurology.org/content/101/4/e347