Stable reduction of upper cervical spinal cord area in cervical dystonia

While cervical dystonia (CD) is predominantly viewed as a disorder of brain-based motor network dysfunction, chronic dystonic head and neck posturing may affect the upper cervical spinal cord, a structure that has been largely overlooked, partly due to the lack of imaging protocols optimized for the craniovertebral junction.

To assess cross-sectional area (CA) and cord eccentricity (CE) of the upper cervical spinal cord at C1-C3 in patients with CD, compared with healthy controls (HC), and to examine their longitudinal stability over a period of 6.2 years.

37 patients with CD and 38 age- and sex-matched HC underwent 3T MRI with T1-weighted structural brain imaging covering the upper cervical spinal cord (C1-C3). CA and CE at C1-C3 were quantified using an automated ENIGMA-based spinal cord pipeline. Cross-sectional group differences were tested and longitudinal change was evaluated in 26 patients re-imaged after a mean follow-up of 6.2 years (Range: 2.1 - 11.9).

Compared with HC, patients with CD exhibited significantly reduced CA at C2 (Mdiff = 3.49 mm², p = .048) as well as at C3 (Mdiff = 4.07 mm², p = .048), while CA at C1 and CE measures at all levels did not differ. No longitudinal decline of CA was observed in CD patients over a period of 6.2 years (Range: 2.1 - 11.9).

CD is associated with stable reductions in upper CA at C2-C3 with no evidence of further decline over the observed follow-up period. These findings support the interpretation of a secondary structural adaptation related to chronic abnormal head-neck biomechanics, rather than a primary or progressive spinal cord pathology.