9.1.3 Headache attributed to intracranial fungal or other parasitic infection

Description:
Headache of variable duration caused by intracranial fungal or other parasitic infection. It is usually observed in a context of congenital or acquired immunosuppression. In most cases it resolves once the infection has been eradicated, but rarely it becomes persistent.

Diagnostic criteria:
A. Any headache fulfilling criterion C
B. Intracranial fungal or other parasitic infection has been diagnosed
C. Evidence of causation demonstrated by at least two of the following:

    1. headache has developed in temporal relation to the onset of the intracranial fungal or other parasitic infection
    2. headache has significantly worsened in parallel with worsening of the intracranial fungal or other parasitic infection
    3. headache has significantly improved in parallel with improvement in the intracranial fungal or other parasitic infection
    4. headache develops progressively1, and is either or both of the following:

      a) holocranial
      b) located in the nuchal area and associated with neck stiffness

D. Not better accounted for by another ICHD-3 diagnosis.

Note:
1. The clinical symptoms tend to evolve over weeks, in parallel with the level of immunosuppression.

Comments:
9.1.3 Headache attributed to intracranial fungal or other parasitic infection should be suspected whenever headache is associated with fever, progressively altered mental state (including impaired vigilance) and/or multiple focal neurological deficits of increasing severity, and neuroimaging shows enhancement of the leptomeninges and/or diffuse brain oedema.

Early diagnosis is best made by CT or MRI. Besides CSF culture and CSF PCR investigations, other tests on CSF and blood are available. These include direct detection of the pathogen (cytological detection, microscopic visualization, culture and identification of fungal elements in the biological materials under observation) and tests for indirect detection of the pathogen (identification of an antigen or another element of the capsule). In the case of aspergillosis, the galattomannan antigen can be detected in biological fluids (serum, bronchoalveolar washing liquid or CSF). In other systemic fungal infections, serum 1,3-β-D-glucan may be diagnostically helpful. The India ink test enables staining of the capsule of cryptococcus.

It is noteworthy that fungal and parasitic infections of the meninges or encephalon are almost exclusively observed in immunodepressed patients or old people. More specifically, the following groups are to be considered at risk:

1) people with significant neutropaenia (<500 neutrophils/mm3) detected in close temporal relation to the infection;

2) people who have undergone allogenic graft of stem cells;

3) people undergoing chronic steroid therapy (prednisone 0.3 mg/kg/day or equivalent for more than three weeks);

4) people with ongoing or recent (within the previous 90 days) treatment with immunosuppressor drugs (cyclosporine, TNF blockers, monoclonal antibodies, analogues of nucleosides);

5) people with severe hereditary immunodeficiency.

A persistent post-infectious subform of 9.1.3 Headache attributed to intracranial fungal or other parasitic infection is not well supported by evidence; it appears only in the Appendix as A9.1.3.3 Persistent headache attributed to past intracranial fungal or other parasitic infection.