Can peripheral neuropathy be ruled out in a patient with normal sensory test results, including pinprick, temperature, proprioception, and vibration, after taking one dose of levofloxacin (levofloxacin) 750mg, presenting with burning feet from the knee down bilaterally?

Fluoroquinolone-Induced Peripheral Neuropathy: Diagnosis and Assessment

Peripheral neuropathy cannot be ruled out in this patient despite normal sensory test results, as fluoroquinolone-induced neuropathy can present with burning sensations even when standard sensory tests are normal. 1

Clinical Presentation and Diagnosis

Levofloxacin can cause sensory or sensorimotor axonal polyneuropathy affecting small and/or large axons, resulting in paresthesias, hypoesthesias, dysesthesias, and weakness. These symptoms may occur soon after initiation of levofloxacin and can potentially be irreversible 1.

The patient's presentation is highly suggestive of fluoroquinolone-induced peripheral neuropathy:

• Bilateral burning sensation from knee down
• Temporal relationship with levofloxacin administration (symptoms after just one dose)
• Pattern consistent with sensory symptoms in a stocking distribution

Why Normal Sensory Tests Don't Rule Out Neuropathy

Several important considerations apply to this case:

1. Small fiber involvement: Fluoroquinolone-induced neuropathy often affects small fibers first, which may not be detected by standard sensory testing 2

2. Early presentation: The patient developed symptoms after just one dose, suggesting an acute reaction that may not yet show objective sensory deficits

3. Diagnostic limitations: Standard sensory testing (pinprick, temperature, proprioception, vibration) may be normal in early or mild cases of peripheral neuropathy 2

Assessment Algorithm

1. Classify severity based on symptoms:

   • Using the Total Neuropathy Score framework 2:
   • Sensory symptoms limited to feet/lower legs = Score 1-2
   • Normal sensory testing = Score 0 for objective measures
   • This suggests mild peripheral neuropathy

2. Evaluate for other causes:

   • Check for pre-existing risk factors:
     • Diabetes
     • Vitamin B12 deficiency
     • Renal dysfunction
     • Prior neuropathy

3. Management decisions:

   • Immediate discontinuation of levofloxacin 1
   • Consider alternative antibiotics if infection treatment is still needed
   • Monitor for progression of symptoms

Management Recommendations

• Discontinue levofloxacin immediately to prevent potential irreversible damage 1
• Document the adverse reaction in the patient's medical record
• Consider symptomatic treatment for neuropathic pain if needed
• Schedule follow-up within 1-2 weeks to reassess symptoms
• Consider electrophysiological studies if symptoms persist or worsen

Important Caveats

• Normal sensory testing does not exclude peripheral neuropathy, especially in early stages or with predominant small fiber involvement 2
• Fluoroquinolone-induced neuropathy can occur after a single dose and may be irreversible in some cases 1
• The FDA drug label explicitly states that levofloxacin should be discontinued immediately if the patient experiences symptoms of neuropathy including pain, burning, tingling, or numbness 1
• Burning sensations in a stocking distribution are classic for small fiber neuropathy, which may not be detected by standard sensory testing 2

Follow-up Recommendations

If symptoms persist after discontinuation of levofloxacin:

• Consider nerve conduction studies and electromyography
• Evaluate for other potential causes of neuropathy
• Consider referral to a neurologist if symptoms worsen or don't improve