Which viral studies are performed in the diagnosis of Ramsay Hunt syndrome?

Updated: Jul 16, 2018
  • Author: Sombat Muengtaweepongsa, MD, MSc; Chief Editor: Niranjan N Singh, MBBS, MD, DM, FAHS, FAANEM  more...
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Answer

Viral studies include the following:

  • VZV isolation in conventional cell culture is considered the definite diagnostic test. However, growing VZV in cell culture can be difficult and is usually too slow to be clinically helpful.

  • The sensitivity of conventional cell culture is 30-40%, with a specificity of 100%.

  • Other tests, including Tzanck test, electron microscopy, and polymerase chain reaction (PCR) are generally more rapid and sensitive. The sensitivity of conventional PCR technique is estimated to be 60%.

  • VZV has been detected by PCR in the tear fluid of patients with Bell palsy (prevalence, 25-35%).

  • VZV antigen detection by direct immunofluorescence assay (DFA) is also possible, with sensitivity of 90% and specificity close to 99%. [15]

  • Antibody determinations on paired sera may be helpful in establishing the diagnosis by comparing titers at time of presentation and a few weeks later.

  • VZV DNA in cerebrospinal fluid (CSF) may help to predict degree of nerve damage, however, it is not correlated with clinical outcomes. [16]


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