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Question Date: 10/02/2024

Question: A 35-year-old female presents to the emergency department with leg weakness. She has had several days of nausea, abdominal pain, and constipation before her arrival at the emergency room (ER). She was dragging her feet while walking and even had a fall. Her husband mentioned she had visual hallucinations and confusion during this same time. While in the ER, she is tachycardic with labile blood pressures. She is somnolent but arousable and disoriented. Her neurological examination reveals intact cranial nerves, normal strength in the arms, decreased strength throughout the legs, and absent patellar reflexes with preserved ankle jerk reflexes. She has normal sensation in all her extremities. Which of the following tests would be most helpful in making the diagnosis?

Options:

Lumbar puncture for cytoalbuminological dissociation
Electromyography (EMG) and nerve conductionstudy (NCS)
Urine porphobilinogen and -aminolevulinic acid
Stool test for botulinum toxin

Correct Answer: Urine porphobilinogen and -aminolevulinic acid

Explaination: This patient presents with typical features seen in acute porphyria. Porphyria is marked by autonomic dysfunction (constipation, abdominal pain, nausea, tachycardia, labile blood pressures, and orthostasis). Later in the course patients can develop an acute motor neuropathy that looks like Guillain-Barr syndrome (GBS). They may also develop encephalopathy, hallucinations, or even seizures. Urine porphobilinogen and -aminolevulinic acid are increased in most types of porphyria. Lumbar puncture for cytoalbuminological dissociation would rule out GBS, which is less likely because of her encephalopathic state and hallucinations. Although EMG/NCS would be helpful for determining pure motor involvement, it would not give a specific diagnosis. This patients history is not typical for botulism because of the significant cognitive symptoms