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The crossed adductor reflex in humans: an EMG study
Summary
This study investigated crossed adductor reflexes in patients with upper motor neuron lesions. Findings reveal short and long latency responses in contralateral adductors, indicating unique neural pathways.
Area of Science:
- Neuroscience
- Neurology
- Electromyography
Background:
- Upper motor neuron (UMN) lesions disrupt descending motor control.
- Understanding crossed reflexes is crucial for diagnosing neurological conditions.
- Femoral neuropathy can coexist with UMN lesions, potentially affecting reflex pathways.
Purpose of the Study:
- To characterize crossed adductor reflexes in patients with bilateral UMN lesions.
- To investigate the latency and amplitude of these reflexes.
- To explore the pathways mediating contralateral adductor responses.
Main Methods:
- Electromyography was used to record adductor reflexes.
- Ten patients with bilateral UMN lesions were studied.
- Stimulation involved tapping the adductor tendon, medial epicondyle, or patellar tendon.
Main Results:
- Short (18-27 ms) and long (60-67 ms) latency crossed adductor reflexes were observed.
- Patellar tendon reflex elicited short latency contralateral adductor responses.
- Absent ipsilateral adductor responses were noted during patellar tendon tapping.
Conclusions:
- Crossed adductor reflexes exhibit distinct short and long latency components in UMN lesions.
- Contralateral responses are mediated via an extraspinal mechanical pathway across the midline.
- These reflexes provide insights into motor pathway integrity following UMN damage.