Duplicated posterior belly of digastric muscle and absence of omohyoid muscle: a case report and review of literature
Omohyoid muscle transfer to the denervated posterior cricoarytenoid muscle (PCA) was performed in three monkeys. The transposed omohyoid muscle was reinnervated by the phrenic nerve by performing nerve anastomosis prior to muscle transfer. The muscles were sutured over the denervated ipsilateral PCA muscle to allow for neurotization of the denervated PCA muscle in such a way as to reproduce the directional vector of PCA contraction, eg, to mimic the directional pull of the PCA muscle. The muscle flaps were found to be long enough to reach the contralateral PCA muscle, confirming that the technique might be used ultimately for bilateral simultaneous PCA reinnervation. Each animal achieved reinnervation. The superiorly based omohyoid muscle flap was found to more closely emulate the size and orientation of the underlying PCA muscle. Electromyography, videolaryngoscopy, and histologic examination were used to confirm the results. The procedure has the potential for PCA muscle replacement in long-standing cases of paralysis with PCA denervation atrophy as well as for reinnervating a denervated PCA muscle.