Mollaret meningitis

Radiopaedia • CC-by-nc-sa 3.0 • de

Mollaret meningitis, also known as idiopathic recurrent meningitis, refers to a rare condition characterized by recurrent attacks of sudden aseptic meningitis with complete recovery followed by unpredictable recurrences . Presence of typical monocytes in CSF samples are helpful in diagnosis.

Terminology

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 etiological agent you do not have an idiopathic condition anymore, and so these cases should be referred to as recurrent viral meningitis .

Clinical presentation

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 .

Pathology

Etiology

The condition by definition is idiopathic. See the discussion on terminology above.

Microscopic appearance

The increased cellularity of CSF is largely due to monocytes which have characteristic appearance and the tendency to aggregate into small groups . The cells are described as having "bean-shaped bilobed nuclei as well as multiple deep nuclear clefts depicting the so-called “footprint” appearance" . It was these cells that were initially described by Mollaret in 1944 .

Radiographic features

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  or neurenteric cyst ) 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 .

History and etymology

The French neurologist and epidemiologist Pierre Mollaret (1898-1987) first reported a series of patients with "recurrent benign endothelioleukocytic aseptic meningitis" in 1944 . He is also known for describing the anatomical connections of the Guillain-Mollaret triangle.

Differential diagnosis

Recurrent aseptic meningitis should also raise the suspicion for: