A simple infrared-augmented digital photography technique for detection of pupillary abnormalities.

BACKGROUND: The purpose of the study was to describe a simple infrared photography technique to aid in the diagnosis and documentation of pupillary abnormalities. METHODS: An unmodified 12-megapixel "point and shoot" digital camera was used to obtain binocular still photos and videos under different light conditions with near-infrared illuminating frames. The near-infrared light of 850 nm allows the capture of clear pupil images in both dim and bright light conditions. It also allows easy visualization of the pupil despite pigmented irides by augmenting the contrast between the iris and the pupil. RESULTS: The photos and videos obtained illustrated a variety of pupillary abnormalities using the aforementioned technique. CONCLUSIONS: This infrared-augmented photography technique supplements medical education, and aids in the more rapid detection, diagnosis, and documentation of a wide spectrum of pupillary abnormalities. Its portability and ease of use with minimal training complements the education of trainees and facilitates the establishment of difficult diagnoses.

Pediatric optic neuritis: brain MRI abnormalities and risk of multiple sclerosis.

BACKGROUND: Optic neuritis is often the initial presentation of multiple sclerosis (MS). As established by the Optic Neuritis Treatment Trial, an abnormal baseline brain MRI is a strong predictor of MS after isolated optic neuritis in adults. However, the rate of conversion to MS after optic neuritis in children based upon brain MRI findings is unknown. METHODS: We reviewed the medical records of children (<18 years) presenting with optic neuritis between 1993 and 2004 at the Children's Hospital of Philadelphia. Children with a history of demyelinating disease or prior optic neuritis were excluded. Symptoms, ophthalmologic findings, MRI findings, and clinical outcomes were recorded. RESULTS: We identified 29 consecutive children with idiopathic optic neuritis. Eleven patients (38%) had white matter T2/FLAIR lesions in the brain (not including the optic nerves). Eighteen patients were followed for more than 24 months, and 3 of the 18 (17%) developed MS. All 3 patients had an abnormal brain MRI scan at their initial presentation of optic neuritis. None of the patients with a normal brain MRI scan at presentation developed MS over an average follow-up of 88.5 months. Patients with one or more white matter lesions on MRI were more likely to develop MS (3/7 vs 0/11, p = 0.04, Fisher exact test). CONCLUSIONS: Children with brain MRI abnormalities at the time of the diagnosis of optic neuritis have an increased risk of multiple sclerosis. Larger collaborative studies are needed to further define the prognosis for childhood optic neuritis.

Functional magnetic resonance imaging of the visual system.

Functional magnetic resonance imaging (fMRI), which is a technique useful for non-invasive mapping of brain function, is well suited for studying the visual system. This review highlights current clinical applications and research studies involving patients with visual deficits. Relevant reports regarding the investigation of the brain's role in visual processing and some newer fMRI techniques are also reviewed. Functional magnetic resonance imaging has been used for presurgical mapping of visual cortex in patients with brain lesions and for studying patients with amblyopia, optic neuritis, and residual vision in homonymous hemianopia. Retinotopic borders, motion processing, and visual attention have been the topics of several fMRI studies. These reports suggest that fMRI can be useful in clinical and research studies in patients with visual deficits.

Functional magnetic resonance imaging of eye dominance at 4 tesla.

We studied eye dominance in visual cortex and lateral geniculate nucleus (LGN) using functional magnetic resonance imaging (fMRI) at a very high magnetic field (4 tesla). Eight normal volunteers were studied with fMRI at 4 tesla during alternating monocular visual stimulation. The acquisition was repeated twice in 4 subjects to confirm reproducibility. In addition, magnetic resonance signal intensities during three conditions (right eye stimulation, left eye stimulation, and control condition) were compared to determine whether the observed area was truly or relatively monocular in 2 subjects. In both the individual and group analyses, the anterior striate cortex was consistently activated by the contralateral eye more than the ipsilateral eye. Additionally, we found evidence that there were areas in the bilateral LGN which were more active during the stimulation of the contralateral eye than during the stimulation of the ipsilateral eye. The activated areas were reproducible, and the mean ratio of the overlapping area was 0.71 for the repeated scans. The additional experiment revealed that the area in the anterior visual cortex could be divided into two parts, one truly monocular and the other relatively monocular. Our finding confirmed previous fMRI results at 1.5 tesla showing that eye dominance was observed in the contralateral anterior visual cortex. However, the eye dominance in the visual cortex was found not only in the most anterior area corresponding to the monocular temporal crescent but also in the more posterior area, presumably showing the greater sensitivity of the temporal visual field (nasal retina) as compared with the nasal visual field (temporal retina) in the peripheral visual field (peripheral retina). In addition, it is suggested that the nasotemporal asymmetry of the retina and the visual fields is represented in the LGN as well as in the visual cortex.

Visual activation in functional magnetic resonance imaging at very high field (4 Tesla).

OBJECTIVES: Functional magnetic resonance imaging (fMRI) at very high field strengths provides functional brain mapping with the enhanced signal to noise ratio and the larger blood oxygenation level-dependent (BOLD) effect. We report activated areas in the standard space detected by fMRI at 4 Tesla (T) during simple visual stimulation. MATERIALS AND METHODS: Twelve healthy young subjects were scanned using a 4 T scanner during binocular flashing visual stimulation. Functional images were realigned to the first scan and then spatially normalized. Individual and group data analyses were performed to identify areas of visual activation. RESULTS: Activation of the bilateral primary visual cortex (V1/V2) was observed along the entire calcarine fissure in all subjects. The activated area extended to the extrastriate cortex in all subjects. Activation of the bilateral lateral geniculate nucleus (LGN) was detected in all subjects. The group data showed activation of the bilateral primary visual cortex and the bilateral lateral geniculate nucleus. CONCLUSIONS: Robust activation of the vision-related areas was successfully obtained in all subjects using a 4 T magnetic resonance scanner. These results suggest that fMRI at very high field strengths may be effective in showing visual system physiology, and that it can be a promising method to assess visual function of human subjects.

Extensive intracranial xanthoma associated with type II hyperlipidemia.

Xanthomas are associated with a spectrum of medical conditions, most commonly disorders of lipid storage and lipid metabolism. They occur primarily in the subcutaneous tissues, especially along the Achilles tendon and the extensor tendons of the hands. Intracranial xanthomas are extremely rare. We present a case of an extensive xanthoma of the temporal bone in a patient with hyperlipidemia.