Initial report on the limited value of hypoglossal nerve transfer to treat brachial plexus root avulsions

Object. Hypoglossal nerve (12th cranial nerve) transfer was performed to treat the sequelae of brachial plexus root avulsion in 12 adults and two infants, and the patients were followed to assess the effectiveness of the surgery.Methods. The 12th cranial nerve was transected at the base of the tongue, and a sural nerve graft was used to bridge the gap between the donor (12th) and recipient nerves: C-5 spinal, axillary, suprascapular, or musculocutaneous nerve. The mean graft length in adult patients was 15.75 ± 5.5 cm (± standard deviation, median 14.5 cm) and in the two infants the graft lengths were 7 and 8 cm, respectively. After a mean postoperative interval of 1138 ± 254 days, electromyographic examination of the target muscles showed tongue movement—related activity in all patients. Muscle force strength measured according to the Medical Research Council's guidelines, was Grade 3 or higher in 21% of patients. Contraction, however, could only be attained by tongue movements, and volitional control was not achieved.Conclusions. Although recovery of muscle strength was obtained by 12th cranial nerve transfer, the functional gain remained virtually nonexistent because central control was missing.