Diagnosis of cerebral venous thrombosis
Neuroradiologic imaging is required to make a diagnosis of cerebral venous thrombosis. CT or MRI is often used initially, but a targeted venographic study, such as magnetic resonance venography (MRV) or computed tomography venography (CTV) should be considered. Cerebral venography may be used in cases in which clinical suspicion is high despite normal CTV or MRV findings.
Laboratory evaluation of cerebral venous thrombosis
Prothrombotic conditions are present in 21%–34% of patients with cerebral venous thrombosis, most commonly protein C deficiency, protein S deficiency, presence of antiphospholipid and anticardiolipin antibodies, factor V Leiden, presence of prothrombin G20210A mutation, and hyperhomocysteinemia. Other predisposing factors include pregnancy, use of oral contraceptives, and systemic conditions including cancer, facial infections, inflammatory diseases, and hematologic diseases.
Treatment of cerebral venous thrombosis
Treatment of cerebral venous thrombosis is directed toward the underlying condition. Therapies include use of anticoagulants, fibrinolytic drugs, and treatments to lower intracranial pressure. Antiepileptic drugs are used for patients with seizures. Steroid medications are typically not used in CVT treatment unless required for management of underlying inflammatory disease. Patients with CVT may benefit from receiving care in a dedicated hospital stroke unit to ensure adequate treatment and to prevent complications.
Neuro-Ophthalmic Manifestations of Infectious Diseases
Myriad infectious diseases may result in neuro-ophthalmic manifestations. This text covers the most common infections that produce neuro-ophthalmic symptoms and occur in the United States.
Human Immunodeficiency Virus Infection
Neuro-ophthalmic disorders associated with human immunodeficiency virus (HIV) infection may result either from direct infection or from indirect causes such as secondary opportunistic infections, malignancy, microvasculopathy, or uveitis. The eye, afferent visual pathways, and ocular motor system can all be affected. BCSC Section 9, Intraocular Inflammation and Uveitis, discusses the following conditions in detail.
Human immunodeficiency virus
HIV infection causes acute and chronic CNS manifestations. Acute aseptic meningitis and meningoencephalitis affect 5%–10% of patients, soon after initial HIV infection. Headache, fever, and meningeal signs may accompany a mononucleosis-like syndrome. Occasionally, altered mental status, seizures, optic neuropathy, and cranial neuropathies occur, most commonly seventh nerve paresis.
HIV encephalopathy, also known as the AIDS dementia complex or, more recently, as HIVassociated neurocognitive disorder, begins with impaired memory and concentration, behavior
changes, and mental slowness. Abnormal pursuit and saccadic eye movements and saccadic intrusions (square-wave jerks) may be present. Late manifestations include profound dementia, behavior changes, psychosis, psychomotor impairment, weakness, visual neglect, visual hallucinations, seizures, and tremor. An optic neuropathy may develop. Ocular signs of HIV infection include cotton-wool spots, perivasculitis, and retinal hemorrhages. MRI scanning demonstrates cerebral atrophy and areas of white matter hyperintensity on T2-weighted images that correspond to areas of demyelination produced by the virus.
Central nervous system lymphoma
After Kaposi sarcoma, which is the most common AIDS-associated neoplasia of the eyelid or conjunctiva, high-grade B-cell non-Hodgkin lymphoma is the second most common malignancy in patients with AIDS and the most common neoplasm to affect the CNS. CNS lymphoma can cause diplopia from third, fourth, or sixth nerve involvement. Lymphomatous infiltration of the orbit and optic nerve may lead to disc swelling and loss of vision. The diagnosis is made by confirming the presence of neoplastic lymphomatous cells in the spinal fluid or through results of stereotactic brain or meningeal biopsy. Changes shown on MRI scan may resemble those of toxoplasmosis, but they are typically periventricular with subependymal spread. Treatment consists of a combination of radiotherapy and chemotherapy.
Cytomegalovirus
Cytomegalovirus (CMV) infection is most commonly encountered by the ophthalmologist once retinal lesions develop. CMV infection is a common opportunistic infection in HIV-infected patients and a major cause of vision loss. CMV retinitis is often the presenting manifestation of untreated advanced HIV infection and only occurs in patients with extremely low CD4+ T-lymphocyte cell counts. Within the CNS, CMV infection causes optic neuritis and brainstem encephalitis. Anterior optic nerve infection produces acute loss of vision with optic disc swelling; this condition usually occurs in patients with severe CMV retinitis. Other patients exhibit anterior optic neuropathy with minimal retinitis (Fig 14-18). Posterior optic neuropathy, which is rare, is characterized by slowly progressive loss of vision without disc edema. Brainstem involvement may cause ptosis, internuclear ophthalmoplegia, ocular cranial nerve palsies, horizontal and vertical gaze paresis, and nystagmus.
Figure 14-18 A, Fundus photograph showing disc appearance of a 42-year-old woman who presented 3 weeks after noticing inferior shadows OD. Visual acuity was 20/20, but visual field testing (B) demonstrated an inferior arcuate visual field defect. The patient’s medical history was remarkable for transfusion 18 months prior, with evidence of subsequent Pneumocystis jiroveci pneumonia. She was found to be HIV-seropositive, and a diagnosis of CMV optic neuritis was
made. (Courtesy of Steven A. Newman, MD.)
The diagnosis of CMV infection is made clinically, based on the characteristic ocular findings. Results of serologic tests and cultures may indicate elevations or be inconclusive. Polymerase chain reaction (PCR) diagnostic testing of cerebrospinal fluid may be an important molecular tool. See BCSC Section 12, Retina and Vitreous, for a complete discussion of CMV diagnosis and treatment.
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Holland GN. AIDS and ophthalmology: the first quarter century. Am J Ophthalmol. 2008;145(3):397–408.
Herpesvirus
Herpes simplex virus (human herpesvirus 1 and 2) and herpes varicella-zoster virus can cause acute outer retinal necrosis resulting in photophobia, ocular pain, floaters, and decreased visual acuity. Ophthalmic findings include panuveitis, vitritis, retinal arteritis, disc edema, and a necrotizing retinitis that initially spares the posterior pole.
CNS encephalitis is the most common neurologic manifestation of herpes infection (Fig 14-19). Radiculitis may occur, producing herpes zoster ophthalmicus and Ramsay Hunt syndrome. In general, neuro-ophthalmic findings are uncommon with herpesvirus infection.