To the Editor:-Muckart et al. blamed tracheal intubation for the spinal cord injuries sustained by two patients with undiagnosed cervical fractures, who were given anesthesia and having surgery for other injuries. This conclusion is not tenable. Their frank report made it clear that no particular attention was given to the disposition of the head and body, so that it is possible that the period of intubation was the only time that reasonable alignment occurred. The fact is that Muckart et al. presented no evidence other than that the patients were paralyzed after surgery, The cause is unlikely to be simple-what caused the quadriparesis reported after awake intubation and positioning in a patient with a diseased but stable neck?The possible case of spinal cord damage after direct laryngoscopy that Muckart et al. cite is suspect because the intubation (which failed) may have been necessitated by neurologic deterioration rather than being the cause of it and was complicated by severe hypotension, acidosis, and hypoxemia. Direct laryngoscopy produces little movement below C3, not “maximal movement and extension of the entire cervical spine.”
When treating patients with actual or suspected cervical abnormality, we should concentrate on maintaining spinal cord blood flow (SCBF). SCBF autoregulation is believed to be unreliable in disease, so that hypotension can cause cord ischemia; severe hypotension has caused quadriplegia in normal patients. This means avoiding hypotension at all times and taking care with positioning. In some patients, the SCBF may be so unstable that even maintaining normotension, awake intubation, and positioning is insufficient to prevent quadriparesis. 
Muckart et al. did not tell us whether their patients became hypotensive. I should be surprised if they did not because both had serious injuries (multiple gun shot wounds and broken legs), and cord damage itself causes hypotension. If hypotension was closely related to intubation, this could constitute evidence in support of their belief that it caused the cord damage. However, it would also be possible that any hypotension at induction resulted from hypovolemia. My “most likely” explanation of the cord injury sustained by Muckart et al.'s patients is that their SCBF was at risk because of cervical trauma, and cord ischemia resulted from hypotension during surgery.
All patients with a history of neck trauma are at risk of the subsequent development of acute spinal cord injury, whether a fracture is present or not. Care should certainly be taken with intubation and positioning, but avoiding hypotension is probably even more important.
Ian Calder, F.R.C.A.
National Hospital for Neurology and Neurosurgery; Queen Square; London, United Kingdom
(Accepted for publication January 20, 1998.)