Hypertrophy of the Spinalis Cervicis Muscle in Cervical Dystonia.

[BACKGROUND] Botulinum neurotoxin A (BoNT) is the first line treatment for cervical dystonia (CD) and treatment outcome significantly depends on the correct identification of the muscles involved.

[PHENOMENOLOGY SHOWN] In a case with insufficient response to BoNT treatment further work up with magnetic resonance imaging (MRI) of the neck revealed a hypertrophic spinalis cervicis muscle, that is not commonly involved in CD.

[EDUCATIONAL VALUE] This highlights the use of MRI for muscle selection in treatment refractory CD cases.