Ultrasonographic Evaluation of Functioning Free Muscle Transfer: Comparison between Spinal Accessory and Intercostal Nerve Reinnervation

ABSTRACT

This study focuses on the application of ultrasonography as a means of measuring the cross-sectional area (CSA) of the transferred muscle and evaluating its force recovery following functioning free muscle transfer. The objective of the study was to compare the CSA of a transferred muscle that is either reinnervated by the spinal accessory nerve (SAN) or the intercostal nerve (ICN), and to evaluate the difference in their force recovery. Ten patients with complete avulsion of the brachial plexus who underwent a double free muscle technique for restoring prehensile function were evaluated. All patients were followed up for at least 1.5 years after the operation. The CSAs of 20 transferred gracilis muscles in 10 patients, reinnervated either by SAN or ICN, were measured by ultrasonography. The CSA was measured at relaxation and at maximal isometric contraction. The force recovery of each muscle was expressed as the contraction rate (CR), calculated by dividing the CSA of the muscle in maximum isometric contraction by the CSA of the muscle in relaxation. The mean CSA of the transferred muscles reinnervated by the SAN was 2.98 ± 0.723 cm² in relaxation and 3.95 ± 1.296 cm² in maximum isometric contraction; thereby a CR of 1.32 ± 0.174 was obtained. The mean CSA of the transferred muscles reinnervated by the ICN was 2.32 ± 0.520 cm² and 2.69 ± 0.566 cm² in relaxation and maximal isometric contraction, respectively; thus a CR of 1.16 ± 0.068 was obtained. Results showed that the CR was significantly higher among the transferred muscles reinnervated by the SAN than those by the ICN. This study demonstrated that muscles that are reinnervated by the SAN resulted in stronger recovery than those reinnervated by the ICN, and that ultrasonography has the capacity to evaluate force recovery of each muscle by measuring the CSA during the two phases of muscle activity.

KEYWORDS

Ultrasonography - functioning free muscle transfer - donor nerve - spinal accessory nerve - intercostal nerve

REFERENCES

• 1 Salmi A, Tukiainen E, Markku H, Sirpa A S. A prospective study of changes in muscle dimensions following free-muscle transfer measure by ultrasound and CT scanning.  Plast Reconstr Surg. 1996;  97 1443-1450
• 2 Kuno S, Fukunaga T. Measurement of muscle fibre displacement during contraction by real-time ultrasonography in humans.  Eur J Appl Physiol. 1995;  70 45-48
• 3 Hodges P W, Pengel L HM, Herbert R D, Gandevia S C. Measurement of muscle contraction with ultrasound imaging.  Muscle Nerve. 2003;  27 682-692
• 4 Doi K, Muramatsu K, Hattori Y et al.. Restoration of prehension with the double free muscle technique following complete avulsion of brachial plexus: indication and long-term results.  J Bone Joint Surg Am. 2000;  82 652-666
• 5 Doi K, Hattori Y, Tan S H, Dhawan V. Basic science behind functioning free muscle transplantation.  Clin Plast Surg. 2002;  29 483-495
• 6 Manktelow R T, McKee N H. Free muscle transplantation to provide active finger flexion.  J Hand Surg Am. 1978;  3 416-426
• 7 Hattori Y, Doi K, Fuchigami Y, Abe Y, Kawai S. Experimental study on donor nerves for brachial plexus injury: comparison between the spinal accessory nerve and the intercostal nerve.  Plast Reconstr Surg. 1997;  100 900-905
• 8 Hattori Y, Doi K, Ohi R, Fukushima S, Baliarsing A S. Clinical application of intraoperative measurement of choline acetyltransferase activity during functioning free muscle transfer.  J Hand Surg Am. 2001;  26 645-648
• 9 Hattori Y, Doi K, Dhawan V, Ikeda K, Kaneko K, Ohi R. Choline acetyltransferase activity and evoked spinal cord potentials for diagnosis of brachial plexus injury.  J Bone Joint Surg Br. 2004;  86 70-73