Visual loss due to cryptococcal meningitis in AIDS patients

Visual loss in HIV-associated cryptococcal meningitis: A case series and review of the mechanisms involved

Permanent visual loss is a devastating yet preventable complication of cryptococcal meningitis. Early and aggressive management of cerebrospinal fluid pressure in conjunction with antifungal therapy is required. Historically, the mechanisms of visual loss in cryptococcal meningitis have included optic neuritis and papilloedema. Hence, the basis of visual loss therapy has been steroid therapy and intracranial pressure lowering without clear guidelines. With the use of high-resolution magnetic resonance imaging of the optic nerve, an additional mechanism has emerged, namely an optic nerve sheath compartment syndrome (ONSCS) caused by severely elevated intracranial pressure and fungal loading in the peri-optic space. An improved understanding of these mechanisms and recognition of the important role played by raised intracranial pressure allows for more targeted treatment measures and better outcomes. In the present case series of 90 HIV co-infected patients with cryptococcal meningitis, we present the clinical and electrophysiological manifestations of Cryptococcus-induced visual loss and review the mechanisms involved.

Early clinical and subclinical visual evoked potential and Humphrey's visual field defects in cryptococcal meningitis

Cryptococcal induced visual loss is a devastating complication in survivors of cryptococcal meningitis (CM). Early detection is paramount in prevention and treatment. Subclinical optic nerve dysfunction in CM has not hitherto been investigated by electrophysiological means. We undertook a prospective study on 90 HIV sero-positive patients with culture confirmed CM. Seventy-four patients underwent visual evoked potential (VEP) testing and 47 patients underwent Humphrey's visual field (HVF) testing. Decreased best corrected visual acuity (BCVA) was detected in 46.5% of patients. VEP was abnormal in 51/74 (68.9%) right eyes and 50/74 (67.6%) left eyes. VEP P100 latency was the main abnormality with mean latency values of 118.9 (±16.5) ms and 119.8 (±15.7) ms for the right and left eyes respectively, mildly prolonged when compared to our laboratory references of 104 (±10) ms (p<0.001). Subclinical VEP abnormality was detected in 56.5% of normal eyes and constituted mostly latency abnormality. VEP amplitude was also significantly reduced in this cohort but minimally so in the visually unimpaired. HVF was abnormal in 36/47 (76.6%) right eyes and 32/45 (71.1%) left eyes. The predominant field defect was peripheral constriction with an enlarged blind spot suggesting the greater impact by raised intracranial pressure over that of optic neuritis. Whether this was due to papilloedema or a compartment syndrome is open to further investigation. Subclinical HVF abnormalities were minimal and therefore a poor screening test for early optic nerve dysfunction. However, early optic nerve dysfunction can be detected by testing of VEP P100 latency, which may precede the onset of visual loss in CM.

Monolateral visual loss due to cryptococcal meningitis

A case of retrobulbar monolateral optic neuritis due to disseminated Cryptococcosis in a 32-year-old man with a new diagnosis of AIDS is described in the era of combination antiretroviral therapy (cART). The patient presented a monolateral rapid visual loss on day 7 of a liposomal amphotericin B treatment. Neuroradiological imaging showed the presence of retrobulbar neuritis. After starting ART and intravenous metilprednisolone 1 g daily for 3 days, we assisted to a progressive improvement of visual acuity. At 3 months of follow-up, complete clinical resolution was obtained. In this case, in the presence of effective antiretroviral and antifungal treatment, a short course of metilprednisolone was a safe therapy.

Bilateral blindness after starting highly active antiretroviral treatment in a patient with HIV infection and cryptococcal meningitis

A 26-year-old HIV-seropositive Caucasian man with cryptococcal meningitis developed permanent bilateral blindness shortly after starting highly active antiretroviral treatment. The blindness may have been a consequence of an immune reactivation inflammatory syndrome caused by this treatment.

Opportunistic infections of the CNS in patients with AIDS: diagnosis and management

The CNS is the second most commonly affected organ in patients with AIDS. Many opportunistic infections may involve the brain, but the four most frequent conditions are toxoplasmosis, progressive multifocal leukoencephalopathy (PML), cryptococcosis and cytomegalovirus infection. Although the incidence of these infections among patients with AIDS has decreased in the past years as a consequence of the introduction of highly active antiretroviral therapy (HAART), they remain a major cause of morbidity and mortality in this patient group. This article summarises the clinical manifestations, diagnostic procedures and management strategies for these four conditions. The clinical manifestations are nonspecific and depend on the type and location of the lesions. In clinical practice, the diagnosis of these entities is made with noninvasive methods. Imaging studies, especially magnetic resonance imaging, are very useful for the diagnosis of toxoplasmic encephalitis and PML, although their usefulness for the diagnosis of cryptococcal meningitis and cytomegalovirus infections is lower. The presence of multiple ring-enhancing lesions with surrounding oedema and mass effect is characteristic of toxoplasmosis. The response to antitoxoplasmic therapy, which is usually observed within the first 2 weeks, is also used for diagnostic purposes. Molecular methods applied to the CSF are essential for the diagnosis of PML and cytomegalovirus infections. In addition, the quantification of viral DNA of both JC virus (the causative agent of PML) and cytomegalovirus has prognostic implications and may serve to evaluate the response to therapy. Cryptococcosis may be easily diagnosed by CSF stains and cultures, as well as by the detection of the cryptococcal capsular polysaccharide antigen in the blood and, especially, the CSF. Effective treatments are available for toxoplasmosis and cryptococcosis, although adverse effects are common and some patients may not respond to therapy. In contrast, there is no specific treatment for PML, and the efficacy of anticytomegalovirus therapy is poor and the toxicity significant. HAART has improved the outcome of patients with AIDS who have infections of the CNS, and the initiation of this therapy is mandatory for all patients with such infections, particularly in those conditions for which effective therapy is not available. Lifelong secondary prophylaxis with agents for the opportunistic infections was necessary before the HAART era because the risk of recurrence was very high if only induction therapy was administered. However, today, the discontinuation of secondary prophylaxis in patients treated with HAART who have stably reached a certain immune reconstitution is possible.