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Ascending Weakness 01

Topic: Adult

Created on Saturday, October 25 2008 by jdmiles

Last modified on Saturday, October 25 2008.

A 19 year-old, previously healthy sunflower grower presents with a 2 day history of worsening ascending weakness, which began shortly after he started complaining of severe abdominal pain.
On exam, he is disoriented. The cranial nerves appear intact. He has diffuse, symmetric weakness. Sensation appears intact. Reflexes are normal for his strength.
The abdomen is tender to palpation.
Nerve conduction studies show low motor amplitudes and normal conduction velocities, with normal F responses. Needle EMG is normal.
Lumbar puncture is unremarkable.
Of the following choices, which of the following studies is most likely to be diagnostic?

A) GQ1B antibody assay

B) GM1 antibody assay

C) Abdominal ultrasound

D) Urine porphobilinogen and delta-amino-levulinic acid

E) MRI of the cervical spinal cord

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This question was created on October 25, 2008 by jdmiles.
This question was last modified on October 25, 2008.

ANSWERS AND EXPLANATIONS

A) GQ1B antibody assay

This answer is incorrect.

Presence of GQ1B antibodies is associated with Miller-Fisher syndrome, which this patient does not have. (See References)


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B) GM1 antibody assay

This answer is incorrect.

The patient's history and exam are suggestive of acute intermittent porphyria. Assessment of urine porphobilinogen and delta-amino-levulinic acid may be diagnostic. The presentation is similar to Guillain-Barre syndrome (GBS), but the normal CSF, present reflexes, and Nerve conduction study results all argue against GBS. In GBS, F waves are often absent or delayed, and a pattern of demyelination (rather than axonal loss) may be seen.
GM1 antibody is associated with several disease states, including multifocal motor neuropathy, and GBS. However, it is not likely to aid in the diagnosis of acute intermittent porphyria. (See References)


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C) abdominal ultrasound

This answer is incorrect.


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D) urine porphobilinogen and delta-amino-levulinic acid

This answer is correct.

The patient's history and exam are suggestive of acute intermittent porphyria. Specific features suggestive of porphyria are the altered mental state, weakness, and abdominal pain. Assessment of urine porphobilinogen and delta-amino-levulinic acid may be diagnostic. The presentation is similar to Guillain-Barre syndrome (GBS), but the normal CSF, present reflexes, and Nerve conduction study results all argue against GBS. In GBS, F waves are often absent or delayed, and a pattern of demyelination (rather than axonal loss) may be seen. While abdominal pain is often seen in GBS, the altered mental status should suggest porphyria. (See References)


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E) MRI of the cervical spinal cord

This answer is incorrect.


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References:

1. Rowland, L.P. (Ed) (2000). Merritt's Neurology, 10th Edition. Lippincott Williams & Wilkins, Philadelphia. (ISBN:0683304747)	Advertising:
2. Allan H. Ropper, Robert H. Brown. . New York : McGraw-Hill Medical Pub. Division, 2005. (ISBN:007141620X)	Advertising:
3. Sadiq, S.A., Thomas, F.P., Kilidireas, K., Protopsaltis, S., Hays, A.P., Lee, K.W., Romas, S.N., Kumar, N., van den Berg, L., and Santoro, M. (1990). "The spectrum of neurologic disease associated with anti-GM1 antibodies." Neurology, 40(7) 1067-72. (PMID:2162499)


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adult
Ascending Weakness 01
Question ID: 102508152
Question written by J. Douglas Miles, (C) 2006-2009, all rights reserved.
Created: 10/25/2008
Modified: 10/25/2008
Estimated Permutations: 8400