A 64-year-old man presented to the emergency department with diplopia, vertigo, unstable gait, and dysarthria. He reported to have had headaches during the preceding 3 weeks. Apart from a type II diabetes mellitus, which was reasonably controlled by metformin (HbA1c 6.4%), his medical history was unremarkable. Upon physical examination, the patient had a slurred speech, slight right-sided brachiofacial hemiparesis, and partial oculomotor paresis on the left, but no nuchal rigidity. Body temperature was 38.1 C.
On the day of admission, a cranial CT was performed and showed a small hypodensity in the left thalamic region, compatible with focal ischemia. Subsequent lumbar puncture and CSF analysis revealed a mixed pleocytosis (700 cells/muL), elevated protein and lactate (3.5 mmol/L), and slightly reduced glucose (53 mg/dL). No microorganisms were detected in the Gram stain of the CSF. Latex agglutination tests for cell wall polysaccharides of typical bacteria causing meningitis (S. pneumoniae, N. meningitidis, group B streptococci, H. influenzae) were all negative. Empiric therapy for meningitis was started with a combination of ceftriaxone, ampicillin/sulbactam, and aciclovir. The initial and repeated CSF cultures taken on days 4 and 10 after hospitalization remained sterile, and PCR for 16S bacterial rRNA genes as well as specific PCRs for Tropheryma whipplei, Mycobacterium tuberculosis, non-tuberculous mycobacteria, and the herpes viruses HSV and VZV were all negative. No evidence for infection with Borrelia burgdorferi, Treponema pallidum, FSME, or HIV was found by serology.
NMR imaging on day 3 revealed infarction in the left thalamus, based on diffusion-weighted imaging and hyperintensity in the FLAIR sequence (Figure 1A), as well as an enlargement of the sellar region consistent with an adenoma of the pituitary gland. Despite an initial clinical response to the treatment with antibiotics and corticosteroids, which was accompanied by a drop of the CSF cell count to 280/muL on day 3, the patient continued to have fever. As he deteriorated clinically and the pleocytosis of the CSF persisted, the antibiotic regimen was changed to a combination of ampicillin, levofloxacin, and doxcycline because anamnestic exposure to sheep and excretions of wild birds during cleaning of nesting boxes suggested the possibility of a zoonotic pathogen. However, serological tests for antibodies to Coxiella burnetii, Rickettsia spp., Brucella spp., Mycoplasma pneumoniae, Leptospira spp., and Francisella tularensis were all negative; Toxoplasma gondii- and Chlamydia-specific antibodies were detected at low titers, consistent with past infections. Analysis of the CSF for cryptococcal antigen was repeatedly negative.
On day 8, NMR imaging was repeated and suggested vasculitis of the basilar artery with a small infarction of the brain stem. The cCT scan obtained on day 10 revealed sinusitis sphenoidalis and an increase in the space-occupying sellar process was observed, leading us to consider a fungal infection (Figure 1B). Therefore, additional treatment with the antimycotic agent voriconazole was initiated (200 mg every 12 h). On day 12 after initial hospitalization, the patient was transferred to the neurosurgical department of the university hospital to obtain a tissue biopsy and histology of the sellar process. Within 2 h after transfer, the patient deteriorated dramatically, developed a respiratory arrest and absent pupillary reflexes. Emergency cCT showed a massive subarachnoidal hemorrhage (Figure 2A), caused by active bleeding from a fusiform aneurysm of the basilar artery tip as revealed by digital subtraction angiography (Figure 2B). Bleeding could be stopped by insertion of a flow diverting stent (Figures 2C,D). However, the patient did not improve clinically during the following days but was comatose without reaction to nociceptive stimuli yet with intact corneal reflexes. The EEG showed a burst-suppression pattern. On day 17, large demarcated infarction areas were seen by NMR in the mesencephalon, the cerebellum, and brain areas supplied by the A. cerebri anterior and posterior (Figure 2E). Given the poor prognosis at this stage, a decision was made to limit therapy after consultation with the family of the patient. The patient died on day 18 after admission.
Although cultures of repeated CSF samples did not yield growth of bacteria or fungi, the development of a presumptive mycotic aneurysm of the basilar artery despite broad and high-dose antibiotic therapy, along with the radiologic suspicion for a possible infectious process in the sellar region, prompted us to re-consider a fungal infection in this patient. Therefore, remaining CSF samples from days 4, 10, and 13 after admission were analyzed for the presence of Aspergillus galactomannan antigen using the Platelia  assay (Bio-Rad, Marnes la Coquette, France) (Table 1). The index values were positive in all three samples (4.2, 10.2, and 1.4, respectively, cutoff 0.5); serum was only tested for Aspergillus galactomannan on day 13 and was negative. CSF samples taken at day 4 and day 10 were weakly positive for fungal 5S-28S rRNA spacer DNA using PCR amplification and identified as derived from A. fumigatus by sequencing (Table 1).
Brain autopsy revealed generalized brain edema with uncal/transtentorial as well as tonsillar/cerebellar herniation. At the sites of herniation, there were foci of necrosis and hemorrhage including the midbrain and pons region. There was prominent subarachnoid hemorrhage within the basal cisterns and intraventricular extension of the hemorrhage. In addition, widespread hypoxic-ischemic damage in supra as well as infratentorial areas was observed. The cause of death was a rupture of an aneurysm of the basilar artery (Figures 3A-C). Microscopic analysis of the aneurysmatic vessel wall revealed inflammation and foci of hyphal structures with septae and dichotomous ramifications, which were best visualized by Grocott histochemical staining (Figures 3D-F), arguing for a mycotic aneurysm due to a hyphomycetal infection. The sellar region showed a pituitary adenoma with immunohistochemical expression of adrenocorticotrophic hormone (ACTH) in terms of a corticotroph adenoma (Figures 3G,H) with invasiveness concerning the adjacent bone and dura. There was also invasion of hyphae into the dura surrounding the sphenoid sinus (Figure 3I). Furthermore, one of the autopsy samples (taken from the right thalamus) was culture-positive for A. fumigatus (Table 1). Thus, invasion and destruction of adjacent tissue by the pituitary adenoma may have facilitated the intracranial invasion of A. fumigatus and subsequent vasotropic infection of the basilar artery.