Saturday 9 October 2010

MRCP revision battle 28.2: Syphillis

Syphilis is another of those conditions which is a common differential in MRCP questions.



Syphilis is caused by the spirochaete treponema pallidum.



There are 4 stages of syphilis:


1) Primary
  • painless genital ulcer
  • known as a chancre
  • highly infectious


2) Secondary
  • occurs 4-8 weeks after the chancre
  • rash, malaise, lymphadenopathy, temperature
  • condylomata lata


3) Tertiary syphilis
  • >2yrs after secondary
  • gummas (=granulomas) form in skin, mucosa and viscera


4) Quaternary syphilis
  • cardiovascular
    • aortic aneurysm
    • aortic regurgitation
  • neurosyphilis
    • cranial nerve palsies
    • general paralysis of the insane
    • tabes dorsalis
      • sensory ataxia
      • numb legs
      • lightening pains
      • upgoing plantars
      • argyll robertson pupil


Tests:
  • cardiolipin antibody = VDRL, RPR
    • not syphilis specific
    • insensitive in late syphillis
    • becomes negative after treatment
    • false +ives in pregnancy, SLE, TB, leprosy, malaria, HIV
  • treponeme-specific antibody = TPHA
    • remains positive after treatment
  • dark ground microscopy


Treatment:
  • IM penicillin or PO doxcycline



Random eponymous warning - Jarisch-Herxheimer reaction:
  • raised pulse, temp and vasodilation
  • occurs hours after 1st dose of antibiotics
  • due to release of endotoxin
Occurs in around 90% of patients with secondary syphilis.




Now on for a bit of third nerve palsy....