Same or Opposite? Association of Head-movement Weakness With Limb Paresis in Stroke

Objectives: The precise innervation of the sternocleidomastoids is uncertain. Of clinical interest is whether a unilateral hemispheric lesion leads to an ispilateral or contralateral sternocleidomastoid weakness. Methods: Sternocleidomastoid strength was assessed in 124 consecutive acute stroke patients during yaw, pitch, and roll head movements. This was correlated with limb paresis and neuroimaging findings. Results: The incidence and the degree of sternocleidomastoid paresis were low (16.9%). In all cases, head rotation weakness away from the affected hemisphere was observed. Lateral tilt and vertical head rotations were unaffected. No weakness was detected in lesions that did not cause manifest limb paresis. Conclusions: Our data point to an ipsihemispheric sternocleidomastoid control. Sternocleidomastoid paresis in stroke is expected only with concomitant limb paresis and is always less severe. Head tilt is not affected probably due to sparing of ancillary neck-muscle function.