Temporal analysis of regional anaesthesia-induced sensorimotor dysfunction: a model for understanding phantom limb

Area of Science:

• Neuroscience
• Anesthesiology
• Sensory-motor integration

Background:

• Regional anesthesia (RA) causes sensory deafferentation, leading to misperceptions of limb size-shape and posture.
• Patients under RA often report 'phantom limbs' in fixed, illusory positions, suggesting underlying stable postural patterns.
• The existence and nature of movement illusions following anesthesia require prospective investigation.

Purpose of the Study:

• To prospectively investigate and describe the phenomenology of kinesthetic (K) illusions induced by regional anesthesia.
• To analyze the temporal relationship between different types of sensory illusions and sensorimotor dysfunction during RA.

Main Methods:

• Prospective examination of body image alterations in 20 patients undergoing infraclavicular blocks.
• Multimodal sensory testing (pinprick, temperature, vibration, joint position sense) and motor function assessment every 5 minutes for 60 minutes.
• Patients described phantom limb sensations, including size-shape (S), posture (P), and kinesthetic (K) illusions.

Main Results:

• Kinesthetic illusions occurred significantly later (44 min) than size-shape (7 min) and posture (22 min) illusions.
• Onset of K illusions strongly correlated with proprioceptive impairment (arthrokinesia, pallesthesia) and loss of motor activity.
• Principal component analysis indicated size-shape and posture illusions were primarily linked to proprioceptive deficits.

Conclusions:

• This study provides the first temporal analysis of sensorimotor dysfunction and K illusion onset during RA.
• Results suggest that altered proprioception and motor function are key factors in the development of RA-induced kinesthetic illusions.
• Findings support the motor awareness theory regarding sensory-motor integration and perception during anesthesia.