gms | German Medical Science

Objective: So far, a method was lacking to quantify the atrophy of facial muscles after lesion of the facial nerve and muscle recovery after nerve repair. Therefore, we examined whether muscle volume measurement by segmenting the 3 Tesla MRI is suitable for this purpose.

Materials and methods: In a 3 Tesla MRI (Tim Trio, Siemens, Erlangen) using a 12-channel head coil, isometric high-resolution T1-weighted MRI data (voxel size of 1 mm x 1 mm x 1 mm) of the head of patients with unilateral peripheral facial palsy were acquired. Subsequently, single facial muscles (eg orbicularis oris muscle) and muscle (eg zygomaticus major et minor, nasalis and levator labii superior muscles) and segmented muscle volume were determined. As a control, both the muscles of the non-injured contralateral sides and the temporalis muscle than is not innervated from the fazialis nerv were segments.

Results: Patients with denervation showed a progressive atrophy of the muscle innervated by the facial nerve. Neither the temporalis muscle nor the muscles of the healthy contra lateral side showed relevant changes. Only after reinnervation, e.g. after a hypoglossal-facial-jump nerve anastomosis this loss of muscle mass stopped.

Conclusions: The technique introduces the possibility to determine the muscle mass of individual facial muscles and muscle groups selectively on both sides and compared over time. Thus we have for the first time an objective quantitative marker for both of severe of atrophy as well as for the post-interventional success of the recovery of individual facial muscles.