Case Six - Diagnosis

Patient Chart

History

TW is a 59-year-old male who presents to the ED complaining of extreme weakness in his lower extremities that has gotten progressively worse over the past 48 hours and is now involving his upper extremities as well. He states that he has no significant medical history, but did have what he thought was the flu last week. His sensorium is largely intact. Physical examination reveals a slightly overweight middle-aged male who appears to be anxious. Respiratory rate 26 and shallow, temperature 98.7o F, SpO2 (on room air) 96%.

Which of the following is the most appropriate diagnostic test to perform at this time?