Journal of neurosurgery
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Journal of neurosurgery · Aug 1983
Electrophrenic respiration following anastomosis of phrenic with branchial nerve in the cat.
Patients with high spinal cord injuries may be totally dependent on artificial ventilation. Prolonged use of mechanical devices requires intensive care, which restricts the mobility of these patients. Electrophrenic respiration has been used with success to overcome this difficulty. ⋯ Lack of rhythmic bursts of electrical activity in the anastomosed phrenic nerve and electromyographic activity in the ipsilateral hemidiaphragm confirmed that the anastomosed phrenic nerve remained disconnected from the respiratory motoneurons. Abundance of collagen matrix in the electron micrographs of the anastomosed phrenic nerve indicated that degeneration of the axons of phrenic motoneurons had occurred and the brachial nerve had grown into the phrenic nerve stump. These results indicate that electrophrenic respiration may be possible in patients with spinal cord injuries at the C-3 to C-5 vertebral levels if the phrenic nerve is kept viable by anastomosing it to a branch of the brachial nerve.
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Allen's weight-drop method for producing experimental spinal cord injuries was improved by placing a curved stainless steel plate anterior to the spinal cord to provide a smooth, hard surface for the receipt of posterior cord impact. In addition, an electronic circuit was used to ensure that cord injury was produced by a single impact, thereby enhancing the reproducibility of the injury mechanism. Using a spinal cord injury model with these modifications, the author found that the recovery of hindlimb function and the histopathological appearance of the injured cord 6 weeks after upper lumbar injury were closely related to injury magnitude. The curve of functional recovery versus injury magnitude has a sharp transition centered at 10 gm X 15 cm, and indicates that an injury of 10 gm X 20 cm produces a "threshold" lesion suitable for the future evaluation of spinal cord treatment methods.