Chief Complaint: 19-year-old man with a broken back. History:
John Doe, a 19-year-old college student, was rock climbing when she fell 30 feet to the ground. Paramedics arriving at the scene found him lying in the supine position, unable to move any extremities and complaining of neck pain. He was awake, alert, and oriented to his current location, the date and day of the week, and the details of his fall. His responses to questioning were appropriate. He complained that he could not feel his arms and legs. His pupils were equal and reactive to light. He showed no other signs of injury except for several scrapes on his arms. His vital signs revealed a blood pressure of 110 / 72, heart rate of 82 beats per minute, respirations of 18 per minute. The paramedics applied a cervical collar, placed him on a back board, immobilized his head, and transported him to the trauma center by helicopter.
Upon examination at the hospital, Doe had minimal biceps brachii stretch reflexes, but no triceps or wrist extensor reflexes. All other muscle stretch reflexes in the upper and lower extremities were absent. His perception of sensory stimuli ended bilaterally at an imaginary line drawn across his chest about 3 inches above the nipples (i. e. everything below felt numb). He had some sensation in his arms, but could not localize touch or describe texture with any consistency there. He was able to raise her shoulders and tighten his biceps brachii slightly in each arm, but could not raise either arm against gravity. His lower extremities were flaccid, despite attempts to move them. Vital signs were taken again at the hospital and were as follows: blood pressure=94 / 55; heart rate=64; respiratory rate=24 (with shallow breathing). His oral temperature was 102.2 degrees F. His color was dusky and his skin was warm and dry to the touch.
X-rays taken upon arrival revealed a fractured vertebra at a particular location. A chest X-ray showed a decreased lung expansion upon inhalation. Blood tests were normal, with the exception of a respiratory acidosis (blood pH = 7.25). The neurosurgeons immobilized her neck by inserting tongs into the skull above the ears to hold her neck in a position so that no further injury could occur. Joe was transferred to intensive care and her condition was stabilized.
A physical examination four days later revealed normal vital signs and no change in his arm strength or sensation, but also marked spasms and exaggerated stretch reflexes of the lower extremities. He also had urinary incontinence which required the placement of a Foley catheter connected to a urine collection bag.
Questions:
Why did Doe's heart rate and blood pressure fall in this time of emergency (i. e. at a time when you'd expect just the opposite homeostatic responses)?
Upon admission to the hospital, Doe's breathing was rapid and shallow. Can you explain why?
Why did Doe lose some sensation in his arms and all sensation from the upper trunk down?
Why did Doe have dry skin and a fever upon admission to the hospital?
Based upon the physical exam findings, which vertebral bone do you think was fractured? Give reasons for your answer.
What is the normal pH of the blood? Why was Doe's blood pH below normal?
What is the primary muscle of respiration? What nerve innervates this muscle?
Which spinal nerves contribute neurons to the nerve you named in question #7?
By four days after the injury, some of Doe's signs and symptoms had changed. Doe's arm muscles were still flaccid, yet his leg muscles had become spastic and exhibited exaggerated stretch reflexes. Use your knowledge of motor neural pathways to explain these findings.
Why did Doe suffer from urinary incontinence?