Abstract
The motor branches to the abductor and adductor muscles of the larynx were dissected unilaterally and Inserted separately into an infrahyoid muscle in six dogs. Sixty days later a strip of muscle nourished only by the nerve's vessels was transposed to replace submucosally extirpated intrinsic laryngeal muscles. After 36 months, three surviving dogs showed normal electrical activity in the transposed muscles but no effective motion of the affected cord.
Two dogs were treated similarly except that the entire cross section of the sternothyroid was transposed with vessels intact. At 12 months one of the dogs had essentially normal laryngeal function, which ceased upon section of the nerve. Six dogs had a cross section of the sternothyroid with vessels sutured into the larynx and concurrent insertion of motor branches into abductor and adductor regions of the muscle. At three years, one surviving dog had a normal range of motion on the experimental side and an excellent voice. Histologic sections showed predominantly normal fibers in the transposed muscle.
In another group, the sternohyoid was sectioned transversely and sutured to the muscular process of the arytenoid to function as the adductor muscles and received the adductor branch of the nerve. The sternothyroid was sectioned at midlength, the distal end of the proximal segment was turned craniad and sutured to replace the abductor muscle, and it received the abductor nerve. This procedure was abandoned since it embarrassed the blood supply of sternothyroideus, and was replaced with a procedure in which the sternothyroid muscle was sectioned free of the thyroid cartilage and moved dorsally substitute for the abductor muscle.
Correlation of visual and electromyographic observations strongly suggests that normal emg potentials may be recorded in reinnervated muscles with little or inappropriate mechanical function, as well as in those with normal function.
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