Long-term functional restoration of the paralyzed hemidiaphragm in the dog

Document Type

Journal Article

Publication Date



Experimental Neurology








Functional restoration of the paralyzed hemidiaphragm in dogs with high cervical hemisections was achieved by chronically activating the crossed phrenic phenomenon. This phenomenon, described as a latent crossed pathway activating the contralateral phrenic motoneurons, is initiated by various manipulations which stress the respiratory system. Classically, the crossed phenomenon has been chronically activated by the complete severance of the phrenic nerve contralateral to the hemisection with resultant paralysis of the previously functioning hemidiaphragm. Experiments were designed to restore function to the paralyzed hemidiaphragm while maintaining integrity of the unaffected side. Left hemisection of the cervical spinal cord rostral to the phrenic nucleus resulted in paralysis of the ipsilateral diaphragm as evidenced by palpation, visual inspection, and EMG monitoring. Selective sectioning of the right fifth, sixth, and seventh cervical contributions to the phrenic nerve in the neck activated the left previously paralyzed hemidiaphragm. Sectioning either C5 or both C5 and C7 resulted in weak, unsustained contractions of the left paralyzed hemidiaphragm. Sectioning the right C6 contribution, however, produced strong and sustained contractions of the left hemidiaphragm without significant decrease in functional activity in the right hemidiaphragm. Functional activity of the entire diaphragm was observed for as long as 16 months. These findings may have clinical implications for patients with a paralyzed hemidiaphragm due to a high cervical cord lesion. © 1981.