Mollaret's meningitis, also known as idiopathic recurrent meningitis, refers to a rare condition characterised by recurrent attacks of sudden aseptic meningitis with complete recovery followed by unpredictable recurrences 6. Presence of typical monocytes in CSF samples are helpful in diagnosis.
Mollaret’s meningitis refers only to idiopathic cases of recurrent aseptic meningitis. Some studies related HSV-2 as a possible cause and thus creating some terminology controversy. This article follows a logical thinking that knowing an aetiological agent you do not have an idiopathic condition anymore, and so these cases should be referred to as recurrent viral meningitis 6.
Presentation is usually with fever, myalgia and arthralgia and signs and symptoms of meningism, including neck-stiffness, nausea and vomiting, photophobia, although these are variable 1,2.
The condition by definition is idiopathic. See the discussion on terminology above.
The increased cellularity of CSF is largely due to monocytes which have characteristic appearance and the tendency to aggregate into small groups 2. The cells are described as having "bean-shaped bilobed nuclei as well as multiple deep nuclear clefts depicting the so-called “footprint” appearance" 2. It was these cells that were initially described by Mollaret in 1944 2.
As is the case with other viral meningitis the role of imaging is limited. It is reasonable to obtain an MRI when patients are asymptomatic to ensure that no other abnormality is present which may be causing a recurrent chemical meningitis (e.g. intracranial epidermoid cyst 4 or neurenteric cyst 5) which have been reported as causing clinical presentation indistinguishable from HSV-2 and from Mollaret's meningitis.
Treatment and prognosis
Although each attack is self limited, given the strong association with HSV-2 therapy and prophylaxis with acyclovir or valacyclovir has been proposed 2.
Recurrent aseptic meningitis should raise the suspicion for:
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- 2. Chan TY, Parwani AV, Levi AW et-al. Mollaret's meningitis: cytopathologic analysis of fourteen cases. Diagn. Cytopathol. 2003;28 (5): 227-31. doi:10.1002/dc.10261 - Pubmed citation
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- 5. Weiss MA, Gebarski SS, McKeever PE. Foramen magnum neurenteric cyst causing mollaret meningitis: MR findings. AJNR Am J Neuroradiol. 1997;17 (2): 386-8. Pubmed citation
- 6. Pearce JM. Mollaret's meningitis. Eur. Neurol. 2008;60 (6): 316-7. doi:10.1159/000159930 - Pubmed citation