MRCP2-3229
A 42-year-old woman arrives at the Emergency Department in the early hours of the morning with a 2-week history of progressive weakness in her arms and legs, preceded by a tingling sensation in her hands and feet. She describes the weakness as ‘slowly taking over me’. Over the last day, she has also noticed weakness in her face and difficulty making facial expressions. She reports experiencing shortness of breath, slurred speech, and difficulty swallowing food. She recently returned from a 3-month trip to South America and Africa, during which she had several episodes of diarrhea. The last episode occurred about 5 weeks ago, and she noticed blood in her stool. She has no significant medical history and is not taking any regular medications.
During the examination, she displays bilateral lower motor neuron VII nerve weakness and dysarthria. Her neck is weak, but there are no other significant cranial nerve signs. She has reduced power, particularly distally, with decreased ankle and knee jerks bilaterally. Plantar responses are absent. Sensory examination reveals decreased soft touch and pinprick sensation in her hands and feet.
What is the most appropriate initial management step?