ZSFG Pearls: Abx associated encephalopathy and PAN

From neuro report and intern report at ZSFG, we have some juicy pearls coming your way…

Top Pearlzzzz:

  • From Arturo, neurologist extraordinaire: If the patient is older (>70), it is a normal variant for them to have lost/diminished ankle reflexes. It’s not just our (amazing) exam technique
  • Visual hallucinations are generally not from a primary psychiatric etiology. Consider delirium causes with a special emphasis on primary neurologic ones
  • See a patient picking at their bed sheet? Consider this to be “Lint picking behavior” or CARPHOLOGIA which tends to be strongly associated with delirium


We also discussed antibiotic-associated encephalopathy (AAE) in the form of a case of an older man receiving Cefepime for sepsis of likely urinary etiology who developed confusion and carphologia on HD3. The delirium work-up did not show an obvious cause, and the MRI was nL.  His sx’s were attributed to AAE and improved once Cefepime was stopped. A recent review in Neurology (see below) discussed three clinical phenotypes of AAE to know:

  • 1) Encephalopathy commonly accompanied by seizures or myoclonus arising within days after antibiotic administration
    • Causative agents: Cephalosporins and penicillin–>mechanistically it’s thought that the B-lactam ring interferes with GABA
  • 2) Encephalopathy characterized by psychosis arising within days of antibiotic administration
    • Causative agents: Fluroquinolones, macrolides, and procaine penicillin
  • 3) Encephalopathy accompanied by cerebellar signs and MRI abnormalities emerging weeks after initiation of antibiotics
    • Causative agent: Metronidazole



From Intern report today and the fascinating discussion on Vasculitis. Let’s make sure we pass on that amazing diagram of vessel size and corresponding entities:

vasculitis outline.jpg

A bit more about Polyarteritis Nodosa, specifically

  • Def’n: ANCA- negative, necrotizing vasculitis involving medium- sized arteries
  • Pathogenesis: immune complex deposition within the intima of medium- sized arterial vasculature; ~1/3 cases are associated with HBV but most are idiopathic
  • EPI: Rare, affecting fewer than 30 people per million
  • Clinical Presentation:
    • Systemic symptoms (fatigue, arthralgias, weight loss, or fever)
    • Multisystem involvement
      • Neurologic symptoms (peripheral neuropathy, mononeuritis multiplex)
      • Skin involvement (nodules, purpura, ulcerations or livedo reticularis, digital ischemia)
      • Renal involvement (but not associated with glomerulonephritis!)
      • GI: mesenteric ischemia (post-prandial abdominal pain)
      • Notably spares the pulmonary vascular bed
  • DX: Biopsy of nerve, skin, or muscle will show necrotizing arterial inflammation. ***Avoid the kidneys and liver for biopsy given the risk of hemorrhage or vascular rupture***


  • Visceral angiography will show microaneurysms in the renal, mesenteric or hepatic vasculature
  • Labs are supportive but not diagnostic
    • Elevated inflammatory markers
    • Usually ANCA negative (presence MPO or PR3 favors another dx)
    • Normal complements
    • low C4 suggests cryoglobulinemic vasculitis
    • low C3 and C4 suggests SLE
      • Treatment:
        • Glucocorticoids alone +/- cyclophosphamide or azathioprine
        • ACE inhibitors
        • Poor prognosis for patients with untreated PAN
        • 5-year survival rate of 13%; death is often a consequence of renal failure, MI, or stroke
        • With appropriate therapy, 5-year survival rate ~ 80%


      Reference: Bhattacharyya et al. Antibiotic-associated encephalopathy. Neurology. 2016 Mar 8;86(10):963-71. doi: 10.1212/WNL.0000000000002455. Epub 2016 Feb 17. PMID: 26888997

      Evernote: https://www.evernote.com/shard/s354/sh/4aa7e350-dd2c-4752-bc1e-a2085d7f4508/fb5c2e85bb02c1bd6149016ccf684866


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