Posttraumatic acquired aberrant neuronal connection between oculomotor and abducens nerves
Purpose. We identified three patients with acquired neural misdirection involving oculomotor and abducens nerves resulting in abnormal ocular muscle innervation. The injuries producing abnormal muscle movement were different in each case. We postulate that peripheral and central mechanisms are responsible for the aberrant neuronal reorganization with peripheral and central locations. Methods, We reviewed the records of three patients with acquired posttraumatic aberrant neuronal reorganization involving the oculomotor and abducens nerves. Results. Two patients had complete ophthalmoplegia except for adduction on attempted abduction. On attempted abduction there was no pupillary response and there was no adduction on attempted near fixation. One patient had an orbital injury while the second had a basal skull fracture. The third patient had bilateral ptosis and developed bilateral lid elevation on attempted abduction due to a midbrain hemorrhage. Conclusions. Since the neuroanatomic location of injury was different in each case, the resulting aberrant neuronal reorganization requires that different mechanisms are acting. Aberrant neuronal connections likely occurred at the following sites: 1) peripheral fibers of oculomotor and abducens nerves 2) abducens nerve nucleus and the ipsilateral medial longitudinal fasciculus 3) medial longitudinal fasciculus and central caudal nucleus in the third nerve nucleus complex. We suggest that both peripheral and central mechanisms can result in acquired abducens-oculomotor aberrant neuronal reorganization.