Three weeks after an upper respiratory illness, a 25-year-old man develops weakness of his legs, which progresses over several days. On physical examination he has 4/5 strength in his arms but only 2/5 in the legs bilaterally. There is no sensory deficit, but knee and ankle reflexes cannot be elicited. During a 2-day observation period the weakness ascends, and he begins to notice increasing weakness of the hands. He notices mild tingling, but the sensory examination continues to be normal. The workup of this patient is most likely to show which of the following?
Three weeks after an upper respiratory illness, a 25-year-old man develops weakness of his legs, which progresses over several days. On physical examination he has 4/5 strength in his arms but only 2/5 in the legs bilaterally. There is no sensory deficit, but knee and ankle reflexes cannot be elicited. During a 2-day observation period the weakness ascends, and he begins to notice increasing weakness of the hands. He notices mild tingling, but the sensory examination continues to be normal. The workup of this patient is most likely to show which of the following?
💡 Explanation
**Core Concept**
The patient's presentation of ascending weakness with normal sensory examination is suggestive of an autoimmune disorder affecting the peripheral nervous system, specifically Guillain-Barré Syndrome (GBS).
**Why the Correct Answer is Right**
GBS is characterized by an autoimmune response to peripheral nerve antigens, leading to demyelination and axonal degeneration. The ascending weakness is due to the spread of the autoimmune response to more proximal nerve segments. The normal sensory examination is due to the involvement of sensory nerves being less prominent in GBS. The absence of reflexes suggests a lesion in the peripheral nerves or nerve roots, which is consistent with GBS.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the patient's presentation of ascending weakness with normal sensory examination.
**Option B:** This option is not consistent with the patient's normal sensory examination.
**Option C:** This option is not a common finding in GBS.
**Clinical Pearl / High-Yield Fact**
Guillain-Barré Syndrome is often preceded by a gastrointestinal or respiratory infection, and it is essential to consider this diagnosis in patients with ascending weakness and normal sensory examination.
**Correct Answer:** C. Elevated protein in the cerebrospinal fluid (CSF) with a normal cell count is a common finding in Guillain-Barré Syndrome.
✓ Correct Answer: A. Acellular spinal fluid with high protein
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