What injury occurs as a result of spinal injury above C6?

• A. Intercostal Paralysis
• B. Loss of sensation in arms
• C. Diaphragmatic Spasm
• D. Diaphragmatic Paralysis

Answer: (D)

When a spinal injury occurs at a level above where the phrenic nerve originates, the diaphragm loses its main motor drive. The phrenic nerve comes from spinal nerves at C3 to C5, which control the diaphragm, the primary muscle of respiration. If the injury is above C6, those descending signals to the phrenic motor neurons are disrupted, so the diaphragm cannot contract. Without diaphragmatic movement, breathing becomes severely impaired, leading to diaphragmatic paralysis. The body may try to rely on intercostal and accessory muscles, but without a functioning diaphragm, ventilation at rest is profoundly compromised. Diaphragmatic spasm isn’t a typical consequence of this injury, and while intercostal function can be affected by high cervical injuries, the hallmark and most direct effect on respiration from an injury above C6 is loss of diaphragmatic contraction.