Application of real-time shear wave elastography in the assessment of torsional cervical dystonia

Background: This study aimed to investigate the value of real-time shear wave elastography (SWE) in the assessment of torsional cervical dystonia (TCD). Methods: Ninety healthy volunteers and 30 TCD patients were recruited, and elastography was performed at musculi sternocleidomastoideus (MSD) and musculi splenius capitis (MSC). Mean shear elastic modulus of right MSD and MSC in healthy controls and bilateral MSD and MSC in TCD patients was determined. The thickness of MSD and MSC of affected muscles was measured in TCD patients. Results: In TCD patients, the mean shear elastic modulus of affected MSD and MSC was significantly higher than that of corresponding normal muscles (P<0.01) and that of controls (P<0.01). The diagnostic threshold was 24.9 kPa for MSD and 25.07 kPa for MSC (for MSD and MSC, the area under ROC was 0.979 and 0.979, with a sensitivity of 90% and 91.3%, and a specificity of 95.6% and 96.7%, respectively). The elastic modulus of neither affected nor normal MSD and MSC was significantly related to age and body mass index (P>0.05). The shear elastic modulus of affected MSD and MSC was positively related to the peak electromyography (r=0.83-0.73, P<0.01). The thickness of affected MSD and MSC was significantly thicker than that of corresponding normal muscles in TCD patients (P<0.01). Conclusions: Real-time SWE can identify the difference in shear elastic modulus of MSD and MSC between the affected and normal side in TCD patients, indicating important diagnostic value in the assessment of muscular status for these patients.