Complete Binocular Blindness as the First Manifestation of HIV-Related Cryptococcal Meningitis

A 58-year-old man presented with acute visual disturbance. He had been treated for hypertension for 2 years. He was divorced 30 years ago and was living alone. He had suffered from intermittent headache for 2 months and had taken benzodiazepines and analgesics under the diagnosis of somatoform disorder at a local clinic. Brain MRI with gadolinium enhancement performed at that time produced normal findings. He had a 5-day history of diplopia and a 3-day history of blurred vision that progressed to blindness during the preceding 24 hours. On admission his blood pressure was 130/70 mmHg, pulse rate was 82/min, respiratory rate was 20/min, and body temperature was 36.3℃. On neurologic examination the patient was alert and exhibited no meningeal signs. Both of his pupils were slightly dilated and reactive to light. Only light perception was possible in both eyes, but no other neurological abnormality was noted. Lumbar puncture showed the opening pressure of 160 mm H₂O with clear cerebrospinal (CSF) fluid. CSF evaluation showed 30 red blood cells/mm³, 80 white blood cells/mm³, 80% lymphocytes, 41 mg/dl glucose, and 114 mg/dl protein. His body temperature increased to 38.8℃ 1 day after admission, but CBC revealed no leukocytosis. Brain MRI showed no meningeal enhancement, parenchymal lesion, or intracranial vascular abnormality supplying the optic nerve, optic chiasm, or optic tract. He exhibited intermittent confusion on the third day after admission. The results of fundoscopic examinations were unremarkable, and visual evoked potential showed no wave formation on bilateral pathways (Fig. 1). An India ink smear of the CSF demonstrated encapsulated yeast, and Cryptococcus neoformans was cultured (Fig. 2). We started intravenous amphotericin B treatment. He was found to be seropositive for HIV with a high antibody titer (53.87 S/CO). CD4 cells comprised 10% of the total T lymphocytes. He was treated with both antiretroviraland antifungal agents, and his visual acuity had improved upon discharge.

Figure 1
No wave formation on visual evoked potential for half-field stimulation suggested conduction defects on bilateral pathways.

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Figure 2
India ink staining showing round, thin-walled encapsulated yeast.

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Neuro-ophthalmic lesions are present in 6% of patients with HIV infection during the course of the disease, with most of them being are attributable to cryptococcal meningitis.3 Cryptococcus neoformans, the cause of cryptococcal meningitis, is the fourth most common source of life-threatening infection in AIDS patients after infections of cytomegalovirus, Pneumocystis carinii, and Mycobacterium avium intracellulare.1 It is present in pigeon droppings and infects by inhalation of contaminated soil. Cryptococcal meningitis is fatal in HIV-infected patients if not treated, and hence early diagnosis is very important. The signs and symptoms of cryptococcal meningitis include headache (80~92% of cases), meningeal signs (50~80%), nausea/vomiting (40~80%), fever (36~67%), and visual disturbances (33~47%).1 Our patient presented with acute blindness without other definite clinical symptoms at the time of admission.

Possible mechanisms for binocular blindness due to cryptococcal meningitis include direct fungal infiltration of the optic nerve, optic chiasm, or optic tracts, adhesive arachnoiditis, cerebral vasculitis, and intracranial hypertension.4 It has been suggested that rapid-onset visual loss is caused by infiltration of the optic nerve or optic chiasm, while slow-onset visual loss is due to increased CSF pressure.4 A CSF opening pressure exceeding 200 mmH2O and papilledema reflect intracranial hypertension, but our patient showed a normal CSF opening pressure and unremarkable fundoscopic examination findings. Moreover, his visual symptoms developed very early in the course of the disease. Thus, the sudden visual loss might have been due to retrobulbar fungal infiltration.

Whereas the prevalence of cryptococcosis is decreasing because of the widespread availability of antiretroviral therapy, cryptococcal meningitis is still a fatal complication of HIV infection. Thus, both early diagnosis of cryptococcal meningitis and detection of the underlying causes are important. In our opinion, unexpected sudden binocular blindness should be considered as a possible initial manifestation of cryptococcal meningitis related to HIV infection.