Supratentorial ischemic stroke: more than an upper motor neuron disorder
Annette A van Kuijk1, Jaco W Pasman, Henk T Hendricks
1Department of Rehabilitation Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands. a.v.kuijk@tolbrug.nl
Summary
Secondary functional changes in peripheral motor units of the paretic upper extremity (UE) after ischemic stroke were identified. Decreased compound muscle action potential (CMAP) amplitude in the abductor digiti minimi muscle correlates with absent motor recovery in acute stroke patients.
Area of Science:
- Neuroscience
- Neurology
- Electrophysiology
Background:
- Ischemic stroke can lead to significant motor deficits, particularly affecting the upper extremity (UE).
- Understanding secondary functional changes in peripheral motor units is crucial for assessing stroke recovery.
- Electrophysiological assessments provide objective measures of peripheral nerve and muscle function.
Purpose of the Study:
- To identify secondary functional changes in peripheral motor units of the paretic UE following ischemic stroke.
- To determine the temporal development of these changes within the initial weeks post-stroke.
- To correlate electrophysiological findings with motor recovery status.
Main Methods:
- An inception cohort of 27 acute ischemic supratentorial stroke patients with UE paralysis was studied.
- Comparison was made with 10 healthy control subjects.
- Electrical stimulation of the ulnar nerve and electromyographic recordings from the abductor digiti minimi muscle were performed to measure compound muscle action potential (CMAP) amplitude at 1 and 3 weeks post-stroke.
Main Results:
- Mean CMAP amplitude was significantly lower on the paretic side compared to the non-paretic side and controls.
- Over half of stroke patients exhibited decreased CMAP amplitude, sometimes as early as 4 days post-stroke, persisting in most cases.
- Decreased CMAP amplitude was consistently associated with the absence of motor recovery at the time of assessment.
Conclusions:
- Reduced CMAP amplitude in the abductor digiti minimi muscle is an early electrophysiological finding in acute ischemic stroke, independent of peripheral nerve conditions.
- This electrophysiological change is linked to the absence of upper motor neuron (UMN) recovery.
- These findings are critical for the accurate interpretation of electrophysiological data in stroke patients and understanding early recovery trajectories.
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