Surgical trauma to the lateral semicircular canal with preservation of hearing.

Surgical trauma to the lateral semicircular canal (LSC) is a rare complication which does not always result in cochlear damage. The authors present six such cases, discuss the histopathological findings of one case, and review 12 previous reports. Transient cochlear depression with normalization of function within 6 weeks of trauma occurred in most instances. Vestibular symptoms were pronounced and, although compensation was not delayed, positional dizziness and instability usually persisted for several months and occasionally for a year or more. Histopathological findings (two specimens) were significant for obliterative scarring of the LSC at the site of injury and for the structural integrity of the labyrinth and cochlea. The mechanism of cochlear protection in these cases remains obscure; however, clean injuries away from the ampullary end of the canal occurring in patients without preexisting inner ear disease appear to have a better prognosis. Intraoperative closure of the defect, postoperative bed rest, and antibiotics are the basic elements of management.