Collum-caput (COL-CAP) concept for conceptual anterocollis, anterocaput, and forward sagittal shift

Objectives: Anterocollis as a rare subtype of cervical dystonia is difficult to treat and thus less appreciated than other subtypes of cervical dystonia. This review aimed at summarising and discussing recent advances in the management of anterocollis.

Methods: Literature review.

Results: Pure anterocollis is a rare condition but 1-24% of the cases of complex cervical dystonia present with an anterocollis component. Applying the collum-caput concept, anterocollis may be subdivided into conceptual anterocollis, anterocaput, and forward sagittal shift, which is useful to direct selection of dystonic muscles for treatment. Additionally, identification of dystonic muscles in conceptual anterocollis, anterocaput, or forward sagittal shift is achieved by electromyography, computed tomography, magnetic resonance imaging, or FDG-positron emission tomography. Treatment of choice is botulinum toxin A. In case of treatment failure, more rarely affected muscles need to be identified and injected. Deep muscles, as are frequently involved in conceptual anterocollis, anterocaput, and forward sagittal shift, should be injected only under guidance of electromyography, endoscopy, or imaging. The more accurately affected muscles are identified, the better the outcome.

Conclusions: Anterocollis as a subtype of cervical dystonia, responds poorly to botulinum toxin but management of this condition can be improved by application of identifying and guiding technologies.