In Myotonic Dystrophy Type 1 Head Repositioning Errors Suggest Impaired Cervical Proprioception

Area of Science:

• Neurology
• Human Physiology
• Biomedical Engineering

Background:

• Myotonic dystrophy type 1 (DM1) is a genetic disorder causing muscle weakness and increased fall risk.
• Proprioceptive and vestibular deficits contribute to falls in DM1 patients.
• Alterations in neck muscle spindles are suspected to impair cervical proprioception.

Purpose of the Study:

• To investigate cervical proprioception deficits in DM1 patients.
• To test the hypothesis of impaired head position sense due to neck spindle abnormalities in DM1.
• To correlate head repositioning errors with clinical and balance measures in DM1.

Main Methods:

• Observational cross-sectional study comparing 16 DM1 patients with 16 controls.
• Head-to-target repositioning test with blindfolded participants.
• Optoelectronic system measured joint position error (JPE) in multiple planes; dynamic posturography assessed static balance.

Main Results:

• DM1 patients and controls showed similar accuracy in intended sagittal and horizontal head repositioning.
• DM1 patients exhibited significant unintended lateral head bending (frontal JPE) during rotation, unlike controls.
• No correlation was found between JPEs and posturography or clinical balance scales.

Conclusions:

• Lateral head bending during rotation suggests latent neck proprioception impairment in DM1.
• This impairment may contribute to the multifactorial fall risk in DM1.
• Cervical proprioception assessment could be valuable in DM1 management.