Interactions between voluntary head control and neck proprioceptive reflexes in cervical dystonia

Area of Science:

• Neuroscience
• Biomechanics
• Motor Control

Background:

• Cervical dystonia involves impaired head position control.
• Sensorimotor processing and reflexive-voluntary interactions are implicated.

Purpose of the Study:

• Investigate sensorimotor processing and reflexive-voluntary interaction deficits in cervical dystonia.
• Determine the impact on head position control.

Main Methods:

• Compared 13 cervical dystonia patients and 23 controls during head-on-trunk, trunk-under-head, and whole-body rotations.
• Assessed resistance to horizontal neck deflections without active resistance.

Main Results:

• Patients displayed a pre-stimulus torque bias and increased torque during rotations, unlike controls.
• Torque fluctuations were larger in patients, correlating with abnormal findings.
• Resistance changes were symmetrical, irrespective of torticollis direction.

Conclusions:

• Cervical dystonia patients have impaired postural reactions to head-trunk rotations.
• The deficit is bilateral and linked to abnormal posture.
• Malfunctioning proprioceptive feedback may underlie cervical dystonia pathophysiology.