A 79-year-old man with a past history of diabetes mellitus and tuberculosis presented with decreased visual acuity on the right side and was diagnosed with retrobulbar optic neuritis. Medical treatment with a steroid (prednisolone 40 mg/day) was initiated and continued for 2 months but provided no symptom relief and subsequently resulted in a recurrence of tuberculosis. The steroid was discontinued, antituberculosis therapy was initiated. As the patient's cognitive function began to decline 2 weeks later, cerebrospinal fluid (CSF) examination and MRI were performed. A CSF examination showed an elevated cell count and the protein level (cell count: 139/dL, glucose: 72 mg/dL, protein: 101 mg/dL) and was positive for the Aspergillus antigen. Fluid attenuated inversion recovery (FLAIR) imaging revealed an isointense lesion in the right side of the sphenoid sinus and a high-intensity lesion spreading at the bottom of the bilateral frontal lobes (Fig. 1A, B). Based on these findings, a diagnosis of fungal meningoencephalitis due to intracranial extension of Aspergillus sinusitis was made.
Antifungal therapy with amphotericin B was started, but it was subsequently changed to micafungin because of an adverse effect on renal function. Follow-up CSF examination and MRI performed 26 days after starting of antifungal therapy showed decreased CSF cell counts (cell count: 6/dL, glucose: 71 mg/dL, protein: 130 mg/dL), some shrinkage of the sphenoid sinus lesion, and a de novo right ICA aneurysm projecting anteriorly into the sphenoid sinus at the C3 portion (Fig. 1C). It was noted that bilateral anterior cerebral arteries (ACAs) distal to the anterior communicating artery (AcoA) were pooly visualized, suggesting the presence of arterial stenosis caused by frontal base meningoencephalitis. Because a three-dimensional computed tomography (3D-CT) angiogram taken 5 days later showed rapid growth of this fungal aneurysm (from 9 mm x 3 mm to 11 mm x 10 mm) (Fig. 1D), we planned an emergency operation to prevent the aneurysm rupturing, which might have resulted in fatal epistaxis. Pre-operative single photon emission computed tomogram (SPECT) showed presence of a hypoperfusion area in the anterior cerebral artery distribution (Fig. 1E).
Under endotracheal general anesthesia, a high-flow bypass from the external carotid artery to the M2 portion of the middle cerebral artery (MCA) was established on the right side using a radial artery graft following a superficial temporal artery (STA) - MCA assist bypass to the M4 portion distal to the anastomosis site of the high-flow bypass. Subsequently, the right ICA was trapped between its origin in the neck and the C2 portion of the ICA. A marked granulomatous change was seen in the dura mater in the frontal base. The right ophthalmic artery was involved in the trapping, as the patient's right visual acuity consisting of only light perception just before the operation. We believed that performing anterior clinoidectomy to expose the ophthalmic artery might further accelerate the intracranial invasion of Aspergillus species. Finally, we anastomosed the frontal branch of the STA to the cortical branch of the right ACA to increase perfusion in its territory.
The patient's postoperative course was uneventful. MRI taken 4 days after the operation showed patency of both the radial artery graft and the frontal branch of the right STA (Fig. 2A). There was no new cerebral infarction. The right ICA had been obliterated and the aneurysm was not visualized. Post-operative SPECT taken 2 weeks after the operation showed improved perfusion in the right anterior cerebral artery distribution (Fig. 2B). Antifungal treatment was continued with itraconazole until plasma concentrations of beta-D-glucan had decreased to within normal limits. Fifty-five days after the operation, the patient was transferred to a rehabilitation hospital because of persisting cognitive function impairment.