A 31-year-old man comes to the office for follow-up. Four weeks ago, the patient was diagnosed with sinusitis-associated frontal lobe abscess. Culture of the purulent material obtained by stereotactic needle aspiration grew multiple bacteria, including several species of Streptococcus and Bacteroides. He is receiving ceftriaxone and metronidazole therapy and his prior symptoms of headache and fever have resolved. The patient began experiencing numbness and a burning sensation in his toes several days ago that has progressed to involve the proximal feet. He also reports similar symptoms in his fingertips but has had no muscle weakness or back pain. He has no other chronic medical conditions and does not use tobacco, alcohol, or illicit drugs. Vital signs are within normal limits. Physical examination shows loss of pain, touch, and vibration sensations in the feet and bilateral fingers. Deep tendon reflexes and motor strength are normal. Blood cell counts and serum chemistry studies are within normal limits. Which of the following is the most appropriate next step in management of this patient's current symptoms?

Question

A 31-year-old man comes to the office for follow-up.  Four weeks ago, the patient was diagnosed with sinusitis-associated frontal lobe abscess.  Culture of the purulent material obtained by stereotactic needle aspiration grew multiple bacteria, including several species of Streptococcus and Bacteroides.  He is receiving ceftriaxone and metronidazole therapy and his prior symptoms of headache and fever have resolved.  The patient began experiencing numbness and a burning sensation in his toes several days ago that has progressed to involve the proximal feet.  He also reports similar symptoms in his fingertips but has had no muscle weakness or back pain.  He has no other chronic medical conditions and does not use tobacco, alcohol, or illicit drugs.  Vital signs are within normal limits.  Physical examination shows loss of pain, touch, and vibration sensations in the feet and bilateral fingers.  Deep tendon reflexes and motor strength are normal.  Blood cell counts and serum chemistry studies are within normal limits.  Which of the following is the most appropriate next step in management of this patient's current symptoms?

Quizplus · Accepted Answer

11ec25c8_d5c0_9de8_bc81_89f44cd33552_MD0003_00 This patient has developed rapidly progressive sensory loss in a distal, symmetric, stocking-glove distribution, which is characteristic of a length-dependent axonal polyneuropathy. Although chronic polyneuropathy is often due to systemic disease (eg, diabetes mellitus, HIV infection), acute polyneuropathy (as seen in this patient) is more likely related to toxins or medications. In this patient, the most likely cause is metronidazole, which can cause toxic polyneuropathy with longer-term use; 50% of patients will develop polyneuropathy within 2 months of use. Other medications commonly implicated include dapsone, fluoroquinolones, amiodarone, and digoxin. In contrast to patients with chronic polyneuropathy, those with acute toxic polyneuropathy are more likely to have significant pain (burning) accompanying the sensory loss. Sensory loss (eg, pain, light touch, vibration) typically begins in the toes and fingers and progresses proximally in a stocking-glove distribution, often over a period of 2-3 weeks. Reflexes may become hypoactive, usually affecting the ankle (ie, most distal) reflexes first. Motor function is typically spared. Cessation of the offending medication is often the first step in management. (Choice B) Although multiple myeloma can cause peripheral neuropathy, it is unlikely in this young patient with normal laboratory studies. (Choice C) Spinal MRI can identify cord compression, which can cause diverse neurologic deficits, including sensory loss. However, cord compression typically affects all dermatomes and myotomes below the level of the lesion. In contrast, stocking-glove pattern deficits are more typical of a length-dependent polyneuropathy. (Choice D) Lumbar puncture can help diagnose Guillain-Barré syndrome, which can present with rapidly progressive, symmetric, ascending neurologic deficits. However, although sensory symptoms may be present, it is primarily a motor polyneuropathy that presents with muscle weakness and diminished or absent deep tendon reflexes. Educational objective: Progressive sensory loss in a distal, symmetric, stocking-glove distribution is characteristic of a length-dependent axonal polyneuropathy. If it occurs acutely, it is likely to be related to a toxin or medication such as metronidazole.

A 31-Year-Old Man Comes to the Office for Follow-Up