A 42-year-old previously healthy woman comes to the office due to worsening double vision and gait unsteadiness. She states she had cramping abdominal pain and diarrhea 2 weeks ago after an outdoor picnic, which spontaneously resolved after 3 days. The double vision began 4 days ago and is persistent and progressive. The patient has also been stumbling while walking due to incoordination. She has had no fever, headache, neck pain, photophobia, or bowel or bladder dysfunction. The patient does not use tobacco, alcohol, or illicit drugs. Vital signs are within normal limits. On physical examination, she is fully alert and oriented with normal memory, speech, and language comprehension. There is mild ptosis of the right eye with weakness of the medial and upward gaze. Left eye movements are normal. Bilateral lower-extremity weakness with loss of deep tendon reflexes is present. There is dysmetria on heel-to-shin testing on both sides. Bilateral upper-extremity muscle strength, reflexes, and coordination are normal. Sensation to touch and pinprick is normal throughout. The remainder of the examination shows no abnormalities. Which of the following is the most likely cause of this patient's current condition?

Question

A 42-year-old previously healthy woman comes to the office due to worsening double vision and gait unsteadiness.  She states she had cramping abdominal pain and diarrhea 2 weeks ago after an outdoor picnic, which spontaneously resolved after 3 days.  The double vision began 4 days ago and is persistent and progressive.  The patient has also been stumbling while walking due to incoordination.  She has had no fever, headache, neck pain, photophobia, or bowel or bladder dysfunction.  The patient does not use tobacco, alcohol, or illicit drugs.  Vital signs are within normal limits.  On physical examination, she is fully alert and oriented with normal memory, speech, and language comprehension.  There is mild ptosis of the right eye with weakness of the medial and upward gaze.  Left eye movements are normal.  Bilateral lower-extremity weakness with loss of deep tendon reflexes is present.  There is dysmetria on heel-to-shin testing on both sides.  Bilateral upper-extremity muscle strength, reflexes, and coordination are normal.  Sensation to touch and pinprick is normal throughout.  The remainder of the examination shows no abnormalities.  Which of the following is the most likely cause of this patient's current condition?

Quizplus · Accepted Answer

This patient has ophthalmoplegia, lower-extremity weakness, ataxia, and areflexia that developed after a gastrointestinal illness. This presentation should raise suspicion for the Miller Fisher syndrome (MFS), a variant of Guillain-Barré syndrome (GBS). GBS represents a group of immune-mediated polyneuropathies that are thought to be caused by molecular mimicry. An antecedent event (eg, Campylobacter jejuni infection) provokes an immune response that cross-reacts with the myelin sheath or the components of peripheral nerves. Antibodies directed at GQ1b, a ganglioside found in peripheral nerves, are thought to contribute to the rapid-onset ophthalmoplegia (possibly due to the high levels of GQ1b in CN III, IV, and VI). Anti-GQ1b antibodies are highly sensitive for MFS (but may be present in other GBS variants with predominant ophthalmoplegia). Other characteristic symptoms of MFS include cerebellar-like ataxia (eg, dysmetria) and areflexia. Extremity weakness may occur, although unlike classic GBS, paralysis is less common. The diagnosis is supported by cerebrospinal fluid analysis demonstrating albuminocytologic dissociation (ie, elevated protein, normal white blood cell count). Management options include plasmapheresis and intravenous immunoglobulin. (Choice A) Ingestion of botulinum toxin causes gastrointestinal illness (eg, abdominal pain, diarrhea) followed by cranial neuropathies and weakness. However, botulism is associated with a symmetric descending weakness (as opposed to the lower-extremity weakness in this patient), and even though ophthalmoplegia may occur, facial weakness, dysphagia, and dysarthria are typical. (Choice B) Thiamine deficiency can cause Wernicke encephalopathy, which also presents with ophthalmoplegia and ataxia; however, it typically also causes altered mental status and nystagmus. In addition, it usually occurs in patients with chronic malnutrition (eg, alcohol abuse). (Choice D) West Nile virus is a neuroinvasive virus that can cause asymmetric flaccid paralysis and cranial nerve palsies; however, it typically manifests with fevers, myalgias, and encephalitis or meningitis. This afebrile patient has normal mentation, and her history of a gastrointestinal illness is more consistent with MFS. (Choice E) Vertebrobasilar artery occlusion (ie, brainstem stroke) may present with cerebellar signs and cranial nerve involvement; however, it typically results in unilateral findings. Furthermore, stroke typically presents with maximal symptoms at the time of initial onset, as opposed to this patient's gradually progressive symptoms. Educational objective: Miller Fisher syndrome (MFS) is a variant of Guillain-Barré syndrome, a group of immune-mediated polyneuropathies that are caused by molecular mimicry. MFS is characterized by ophthalmoplegia, ataxia, and areflexia; strength is often preserved. It is highly associated with anti-GQ1b antibody.

A 42-Year-Old Previously Healthy Woman Comes to the Office Due