Parkinson's Symptoms/Torticollis

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Torticollis
Asymmetric spasm of the neck muscles

The following references are relevant:-

Bronstein and Rudge (1986)  Vestibular involvement in spasmodic torticollis

Jahanshah (2000)  Factors that ameliorate or aggravate spasmodic torticollis 

Thompson et al (2011) Convergent mechanisms in etiologically-diverse dystonias