Faculty Bibliography

BACKGROUND: Friedreich ataxia is a progressive neurodegenerative disorder affecting afferent cerebellar pathways and other neuronal systems, including afferent visual pathways. A systematic clinical outcome measure for examination of visual dysfunction in Friedreich ataxia has not been identified. We sought to identify a simple, reliable method for assessing clinical and subclinical visual dysfunction in patients with Friedreich ataxia. METHODS: Contrast letter acuity was measured binocularly in Friedreich ataxia patients and age-matched visually asymptomatic volunteers (control group) using the Low-contrast Sloan Letter Charts at three different low-contrast levels (5.0%, 1.25%, and 0.6%). Binocular high-contrast visual acuity (100% level) was also determined for each participant. RESULTS: Despite equal median binocular high-contrast visual acuities between the two groups, patients with Friedreich ataxia had significantly lower (worse) Low-contrast Sloan Letter Chart scores compared with controls, particularly at the lowest contrast levels (1.25% and 0.6%). Ambulation status significantly predicted Low-contrast Sloan Letter Charts scores in linear regression models accounting for patient age, suggesting a potential complementary role for Low-contrast Sloan Letter Chart testing in the assessment of disease status as well as visual function in Friedreich ataxia. CONCLUSIONS: This study demonstrates that Low-contrast Sloan Letter Chart testing may provide a useful clinical outcome measure for Friedreich ataxia and other neuro-ophthalmologic disorders.

Idiopathic intracranial hypertension (IIH), also known as pseudotumor cerebri, can be a serious vision-threatening disease. Visual acuity, visual fields, and ocular fundus appearance should be followed closely in all patients with IIH. Obese patients with IIH should be encouraged to lose weight. Medications that might cause or exacerbate IIH should be identified and discontinued if possible. Mild headaches can be treated with nonsteroidal anti-inflammatory drugs (NSAIDs) or migraine prophylactic agents. Some patients may not require additional treatment if they are otherwise asymptomatic and have no evidence of vision loss. Symptomatic patients (significant headache, visual complaints, tinnitus) or patients with visual field or acuity loss should be treated initially with acetazolamide. Furosemide may be a useful second-line agent. If vision loss is progressive despite maximal medical therapy or severe at the time of diagnosis, surgical intervention may be required. Optic nerve sheath fenestration is effective and safe, and may be repeated if initially unsuccessful. Lumboperitoneal shunting is also an option, especially if symptoms of headache are prominent and refractory to medical therapy, but it has significant complication and failure rates. Bariatric surgery can be an effective treatment for IIH in severely obese patients, but is not a useful acute intervention. Special issues must be considered when treating IIH in children or pregnant women.

The discovery of the genetic cause of Friedreich ataxia has significantly affected our understanding of the disorder at both the clinical and basic science levels. Friedreich ataxia results from a deficiency of functional frataxin, a protein that appears to be involved in mitochondrial iron homeostasis. This leads to iron accumulation and mitochondrial abnormalities with consequent oxidant damage. The clinical spectrum of Friedreich ataxia has also expanded with the recognition of broader phenotypic features, including the absence of classical Friedreich ataxia features, later age at onset, and spasticity instead of ataxia. Although no proven therapy is yet available, antioxidants are a potential method for therapeutic intervention.

Friedreich's ataxia is a progressive neurodegenerative disorder of the afferent cerebellar pathways associated with mitochondrial dysfunction at the cellular level. We have used noninvasive continuous near infrared muscle spectroscopy (NIRS) to investigate the delivery and utilization of oxygen in response to exercise in this disorder. Patients performed an incremental treadmill walking protocol in which levels of muscle deoxygenation or oxygenation were continuously measured in the medial calf muscle. The kinetics of recovery from exercise-induced deoxygenation, called the half-time of recovery (t(1/2)) were determined. The t(1/2) was prolonged in patients with Friedreich's ataxia compared with controls, and the degree of prolongation correlated with the length of the shorter GAA repeat, a genetic measure that correlates with the age of onset of disease. The t(1/2) also correlated inversely with patient age and with the maximum treadmill speed attained. Several patients also displayed features consistent with inadequate oxygen utilization by muscle. These results suggest that NIRS may be an effective tool for monitoring the biochemical and functional features of Friedreich's ataxia in parallel.

PURPOSE: To examine vision-specific health-related quality of life in a cohort of patients with multiple sclerosis (MS) using the 25-Item National Eye Institute Visual Function Questionnaire (VFQ-25), and to identify content areas for a brief MS-specific vision questionnaire. DESIGN: Cross-sectional survey. METHODS: The VFQ-25 and a modified version of the Optic Neuritis Treatment Trial (ONTT) Patient Questionnaire were administered by in-person interview to 80 patients at the University of Pennsylvania MS Center. Binocular visual acuities were obtained following a standard protocol using retroilluminated Early Treatment Diabetic Retinopathy Study charts. RESULTS: Despite a median binocular visual acuity of 20/16 (20/12.5-20/250), VFQ-25 subscale scores in the MS cohort were significantly lower (worse) compared with those of a published reference group of eye disease-free patients (P =.0001-0.009, two-tailed t tests). Rank-correlations of VFQ-25 composite (overall) scores with visual acuity were modest, but significant (r(s) = 0.33, P =.003), supporting construct validity for VFQ-25 scores in MS populations. Seven additional aspects of self-reported visual dysfunction in MS were also identified. CONCLUSIONS: Patients with MS have a high degree of self-reported visual dysfunction that is not entirely captured by visual acuity. The VFQ-25 is an effective measure of self-reported visual loss in MS. A brief MS-specific vision questionnaire may provide additional useful information when administered concurrently with the VFQ-25 in future investigations of MS and other neuroophthalmologic disorders.

Patients with typical acute monosymptomatic demyelinating optic neuritis should receive gadolinium-enhanced magnetic resonance imaging (MRI) of the brain and orbits to determine if they are at high risk for the subsequent development of clinically definite multiple sclerosis (CDMS). The presence of >or=2 white matter lesions (>or=3 mm in diameter, at least 1 lesion periventricular or ovoid) indicates high risk for CDMS; the following treatment should be considered for such patients: 1. Intravenous methylprednisolone sodium succinate (1 gram IV/day for 3 days) followed by oral prednisone (1 mg/kg/day for 11 days) with 4-day taper (20 mg on day 1, 10 mg on days 2 and 4); 2. Interferon beta 1-a (Avonex 30microg intramuscularly [IM] weekly, or Rebif 22 microg subcutaneously [SQ] weekly). These two drugs have been shown to reduce the short-term risk of CDMS in high risk monosymptomatic patients. In monosymptomatic patients with <2 white matter lesions, and in patients for whom CDMS has been established, IV methylprednisolone treatment followed by oral prednisone should be considered on an individual basis. Treatment in these patients may hasten visual recovery, but does not affect long-term visual outcome. Oral prednisone alone, without prior treatment with IV methylprednisolone, may increase the risk for recurrent optic neuritis and should be avoided.

The development of new and more sensitive clinical outcome measures for research in multiple sclerosis (MS) has been fueled by the development of effective therapies. As such, active arm comparison studies that require more sensitive clinical outcome measures are now commonplace. The Kurtzke Expanded Disability Status Scale (EDSS), the most widely used measure of neurologic impairment in MS, is particularly designed for classifying patients with respect to disease severity but has been criticized for its noninterval scaling, emphasis on ambulation status, relatively reduced sensitivity in the mid and upper ranges of scores, and absence of adequate cognitive and visual components. In response to perceived difficulties with the EDSS, the National Multiple Sclerosis Society Clinical Outcomes Assessment Task Force has developed the Multiple Sclerosis Functional Composite (MSFC). The MSFC includes three components that yield objective and quantitative results: 1) the timed 25-ft walk, 2) the nine-hole peg test, and 3) the 3-second paced auditory serial addition test. This scale has the advantages of continuous scoring with a composite Z score, standardized protocols, and high degrees of reliability and validity. Candidate visual function outcome measures for the MSFC, including the low-contrast Sloan letter chart, are currently under investigation. In addition to measures of neurologic impairment, health-related quality of life (HRQOL) measures have gained increasing importance as clinical trial outcome measures. The MS Quality of Life Inventory, a disease-specific HRQOL measure, has been developed to capture self-reported neurologic dysfunction and the impact of MS upon activities of daily living. MS clinical trials of the future, particularly active-arm comparison studies, will require more sensitive clinical outcome measures such as the MSFC. Measures of visual function and HRQOL should also be incorporated to capture the broad scope of neurologic impairment and disability in MS populations.

This review presents highlights and updates from of the most significant clinical trials in neuro-ophthalmology to date, the Optic Neuritis Treatment Trial, the Controlled High-Risk Avonex Multiple Sclerosis Prevention Study, and the Ischemic Optic Neuropathy Decompression Trial. The quality of evidence for treatment efficacy from these trials and other recent investigations of giant cell arteritis and idiopathic intracranial hypertension is classified herein according to published criteria based on sample size and study design.

This review highlights recent additions to the literature regarding the diagnosis, evaluation, and management of idiopathic intracranial hypertension (pseudotumor cerebri). Unique features of pediatric pseudotumor cerebri are addressed as well.