Magnetic resonance imaging of microneurovascular free muscle flaps in facial reanimation.

The purpose of this study was to describe the survival and volume of microneurovascular muscle flaps at different times after two-stage facial reanimation procedure by using magnetic resonance imaging (MRI) and to compare the functional outcome with MRI findings. Fifteen patients with a mean age of 36 years (range 7-63 years) operated on between 1988 and 1999 were available for this study. The muscles used for functional reconstruction were the latissimus dorsi (eight patients), gracilis (six patients) and serratus anterior (one patient). Hospital charts were reviewed and the clinical outcome of facial reanimation was graded on a scale from 1 to 6 according to House. The mean postoperative follow-up time was 7 years (range 3-14 years). Clinical grading and 1.5 T unit MRI of patients were performed concomitantly. The MR images were evaluated semi-quantitatively so that the muscle structure of the free flaps was graded on a scale from 1 to 4. The free flap area of each slice was defined and the volume of the free flap was calculated. Data were analysed statistically. The long-term functional outcome of the facial reanimation was regarded as good in 10 patients, which means they had only mild or moderate dysfunction of facial movements. In MR images, six free flaps displayed normal muscle structure, another six had a fatty appearance and two displayed severe muscle atrophy; in one patient the muscle tissue could not be identified. The volume of the free flap clearly declined in the course of the follow-up. A correlation was found between good functional outcome and normal muscle structure of the free flap in MRI, p = 0.020. The longer the follow-up time after muscle transplantation the poorer the functional result. A similar correlation was found between abnormal muscle structure in MRI and a long follow-up time. Magnetic resonance imaging can be used to assess the muscle structure of free microneurovascular flaps. Normal findings in MRI seem to correlate with a good clinical outcome in facial reanimation. A good functional result correlates with a shorter follow-up time and normal muscle structure in MRI.