Startle responses after different stimulus modalities differ in stroke.

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Medicine

Background:

• Auditory startle reaction (ASR) and somatosensory startle reflex (SSS) are involuntary responses originating in the brainstem.
• Changes in ASR are documented in stroke patients, but SSS pathways and plasticity in stroke remain less understood.

Purpose of the Study:

• To investigate the central pathways of SSS.
• To examine plasticity changes in SSS circuits across different stroke stages and locations.
• To compare SSS changes with those of ASR in stroke patients.

Main Methods:

• Prospective study of 39 stroke patients and 23 healthy controls.
• ASR and SSS recorded from orbicularis oculi, sternocleidomastoid, biceps brachii (BB), and abductor policis brevis (APB) muscles.
• Surface electromyography used for data acquisition.

Main Results:

• ASR probability was similar between stroke patients and controls overall.
• ASR probability increased in BB and APB muscles on the symptomatic side in stroke patients, particularly with pontine lesions.
• No significant differences in SSS latencies or presence rates were observed between stroke subgroups and healthy subjects.

Conclusions:

• ASR is facilitated in the arm and hand muscles on the symptomatic side of stroke patients.
• SSS did not exhibit significant changes related to stroke, suggesting differential effects on these startle pathways.