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Grant T Liu

Publications and source records attributed to Grant T Liu.

At least 19 recordsLinked to original sources
PubMed2006

Validation and test characteristics of a 10-item neuro-ophthalmic supplement to the NEI-VFQ-25.

PURPOSE: To determine whether a 10-Item Neuro-Ophthalmic Supplement increases the capacity of the 25-Item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) to capture self-reported visual dysfunction in patients with neuro-ophthalmologic disorders. DESIGN: A cross-sectional survey to examine the characteristics of a 10-Item Neuro-Ophthalmic Supplement to the 25-Item NEI-VFQ-25 in a cohort of patients with neuro-ophthalmologic disorders. METHODS: The 10-Item Neuro-Ophthalmic Supplement was designed previously by our research group by survey and focus-group methods. In the present study, the NEI-VFQ-25 and 10-Item Supplement were administered concurrently to patients and disease-free control subjects. High-contrast visual acuities with patient usual distance correction were measured with the use of Early Treatment Diabetic Retinopathy Study (ETDRS) charts. RESULTS: Diagnoses for patients (n = 215) included optic neuritis, multiple sclerosis, idiopathic intracranial hypertension, ischemic optic neuropathy, stroke, ocular myasthenia gravis, ocular motor palsies, and thyroid eye disease. Scores for the 10-Item Supplement had a significant capacity to distinguish patients vs disease-free control subjects that was independent of the NEI-VFQ-25 composite score (odds ratio in favor of patient vs control status for 10-point worsening in Supplement scores: 2.7 [95% confidence interval [CI], 1.6, 4.6]; P < .001, logistic regression models that account for NEI-VFQ-25 composite score, age, and gender). Patients with visual dysfunction (binocular Snellen equivalents worse than 20/20) had significantly lower mean scores (9-21 points lower); these differences remained significant after accounting for age and gender (P >or= .001, linear regression). Supplement items and composite scores demonstrated appropriate degrees of internal consistency reliability. CONCLUSION: The 10-Item Neuro-Ophthalmic Supplement demonstrates a capacity to capture self-reported visual dysfunction beyond that of the NEI-VFQ-25 alone, which supports validity for this new scale. The use of the 10-Item Supplement in clinical trials and epidemiologic studies will examine its capacity to demonstrate treatment effects in longitudinal cohorts.

Adult↗
PubMed2006

Decreased cortical activation in response to a motion stimulus in anisometropic amblyopic eyes using functional magnetic resonance imaging.

PURPOSE: Motion perception abnormalities and extrastriate abnormalities have been suggested in amblyopia. Functional MRI (fMRI) and motion stimuli were used to study whether interocular differences in activation are detectable in motion-sensitive cortical areas in patients with anisometropic amblyopia. METHODS: We performed fMRI at 1.5 T 4 control subjects (20/20 OU), 1 with monocular suppression (20/25), and 2 with anisometropic amblyopia (20/60, 20/800). Monocular suppression was thought to be form fruste of amblyopia. The experimental stimulus consisted of expanding and contracting concentric rings, whereas the control condition consisted of stationary concentric rings. Activation was determined by contrasting the 2 conditions for each eye. RESULTS: Significant fMRI activation and comparable right and left eye activation was found in V3a and V5 in all control subjects (Average z-values in L vs R contrast 0.42, 0.43) and in the subject with monocular suppression (z = 0.19). The anisometropes exhibited decreased extrastriate activation in their amblyopic eyes compared with the fellow eyes (zs = 2.12, 2.76). CONCLUSIONS: Our data suggest motion-sensitive cortical structures may be less active when anisometropic amblyopic eyes are stimulated with moving rings. These results support the hypothesis that extrastriate cortex is affected in anisometropic amblyopia. Although suggestive of a magnocellular defect, the exact mechanism is unclear.

Adolescent↗
PubMed2006

Spatial and temporal characteristics of physiological noise in fMRI at 3T.

RATIONALE AND OBJECTIVES: Physiological noise in blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) has been shown to have characteristics similar to the BOLD signal itself, suggesting that it may have a vascular dependence. In this study, we evaluated the influence of physiological noise in fMRI as revealed by the differences in vasculature sensitivity of gradient-echo echo-planar imaging (GE-EPI) and spin-echo EPI (SE-EPI). MATERIALS AND METHODS: The contribution of physiological noise to the fMRI signal during activation of the visual cortex was assessed by comparing its temporal characteristics with respect to echo time (TE), using both GE-EPI and SE-EPI. The correlation of the noise in fMRI with apparent diffusion coefficient (ADC) and the number of components required to describe its variance, as determined by principal-component analysis (PCA), were also assessed. RESULTS: The SE-EPI data were less affected by a TE-dependence of noise, in contrast to the apparent physiological noise in GE-EPI. Voxel-wise analysis revealed that total apparent noise increased as ADC values increased, and the relationship was different for GE-EPI and SE-EPI. PCA revealed that while the number of components characterizing the noise in SE-EPI data increased in a TE-dependent manner, approaching that of white noise at long echo time, the number of components from GE-EPI data was TE-independent. CONCLUSIONS: The difference in sensitivities to physiological noise between SE-EPI and GE-EPI suggests that extravascular BOLD processes around draining veins contribute significantly to physiological noise in BOLD fMRI, and the suppression of this noise component may enhance SE-EPI BOLD sensitivity at higher fields.

Echo-Planar Imaging↗
PubMed2006

Occult thyroid eye disease in patients with unexplained ocular misalignment identified by standardized orbital echography.

PURPOSE: To describe the clinical presentation, orbital echography (OE) findings, and neuroimaging results of patients with chronic unexplained ocular misalignment, which includes patients with clinically occult thyroid eye disease (TED) that is identifiable through a characteristic OE appearance. DESIGN: Retrospective observational case series. METHODS: Seventy-eight patients with chronic ocular misalignment suspected of TED because of a history of systemic thyroid disease, proptosis, dysmotility, positive forced ductions, or eyelid retraction or lag were categorized as TED positive, negative, and indeterminate with the use of standardized OE. Demographic, clinical, OE, computed tomography, and magnetic resonance imaging information was collected. Analyses determined the prevalence of TED and differences between TED positive, negative, and indeterminate groups. RESULTS: Fifty-five percent of the findings were suspicious for and most consistent with TED (TED positive); 26% of the findings were TED negative, and 19% of the findings were TED indeterminate. Of 30 patients with newly diagnosed TED by OE, 70% had no lid retraction, and 20% had no other findings of TED. The inferior rectus followed by the superior rectus/levator complex, medial rectus, and lateral rectus muscles were the most frequently involved muscles. Neuroimaging that was performed in only 26 of 78 patients (33%) did not appear to yield additional diagnostic information. CONCLUSION: TED is a potential cause of chronic unexplained ocular misalignment in a substantial proportion of patients. These patients frequently present in an occult fashion without other clinical findings that are typical of TED. In these patients, a diagnosis of TED by OE can reduce further costly evaluation. OE appears to have significant clinical usefulness in the diagnosis of TED in patients with unexplained ocular misalignment.

Chronic Disease↗
PubMed2006

Pediatric horner syndrome: etiologies and roles of imaging and urine studies to detect neuroblastoma and other responsible mass lesions.

PURPOSE: To evaluate the frequency of etiologies of Horner syndrome in children and suggest an imaging and laboratory diagnostic protocol to evaluate for neuroblastoma and other lesions in a child presenting with Horner syndrome and no known cause. DESIGN: Retrospective chart and data review. METHODS: A retrospective review of all children seen at a large pediatric neuro-ophthalmology referral center with a diagnosis of Horner syndrome between 1993 and 2005 with particular attention to underlying etiologies and the results of imaging and urine catecholamine studies. RESULTS: Fifty-six children met criteria for Horner syndrome and further review. Twenty-eight children (50%) had no previously identified cause for Horner syndrome. Of these children, 24 (85.7%) had urine catecholamine metabolite studies, and all had negative results. Twenty (71.4%) had complete modern imaging of the brain, neck, and chest. Of the 18 children who had complete imaging and urine studies, responsible mass lesions were found in six (33%). Four had neuroblastoma, one had Ewing sarcoma, and the other had juvenile xanthogranuloma. Of all patients (diagnosis known and unknown), neoplasm was the etiology in 13 of 56 (23%) of patients. CONCLUSIONS: We confirm that Horner syndrome in a child of any age without a surgical history requires a complete examination to exclude a mass lesion. In such patients, we recommend brain, neck, and chest magnetic resonance imaging (MRI) with and without contrast as well as urinary catecholamine metabolite testing. However, imaging is more sensitive than urine testing in this setting.

Abdominal Neoplasms↗
PubMed2006

Optic gliomas of the anterior visual pathway.

PURPOSE OF REVIEW: To review advances in the diagnosis and management of optic-pathway gliomas made within the past 5 years. RECENT FINDINGS: Important papers regarding optic-pathway gliomas have been published recently in the following areas: neuroimaging, natural history and how the presence of neurofibromatosis type 1 affects it, unusual presentations, visual prognosis, and treatment with fractionated stereotactic radiotherapy. SUMMARY: The diagnosis and treatment of optic-pathway gliomas has been aided greatly by a greater understanding of the natural history of these tumors and their prognosis related to the presence of neurofibromatosis type 1. Advances in magnetic resonance imaging are helping to delineate tumor extent. Newer radiation techniques that spare surrounding tissues are being used to treat optic-pathway gliomas, but chemotherapy has become the first-line treatment modality.

Glioma↗
PubMed2005

Near-infrared spectroscopy of the visual cortex in unilateral optic neuritis.

PURPOSE: To examine the occipital-lobe activation of patients with optic neuritis using near-infrared spectroscopy. DESIGN: Experimental study. METHODS: NIRS was performed on five patients with acute unilateral optic neuritis during monocular visual stimulation. As controls, six normal subjects were also tested in the same manner. RESULTS: In the patients with optic neuritis, the changes in the hemoglobin concentrations (oxyhemoglobin, deoxyhemoglobin, and total hemoglobin) in the occipital lobe were found to be markedly reduced when the clinically affected eyes were stimulated compared with the fellow eyes. The response induced by the stimulation of the affected eye was decreased, even when the patient's visual acuity improved to 20/20 in the recovery phase. There was no difference in the concentration changes between the two eyes in the control subjects. CONCLUSIONS: NIRS may be useful in detecting visual dysfunction objectively and noninvasively in patients with visual disturbance, especially when used at the bedside.

Adolescent↗
PubMed2005

Long-term follow-up and prognosis of orbital apex syndrome resulting from nasopharyngeal rhabdomyosarcoma.

PURPOSE: Nasopharyngeal rhabdomyosarcoma may present with a variety of ophthalmic symptoms. Direct extension of the tumor into the orbital apex can lead to ophthalmoplegia and loss of vision. The prognosis for recovery of vision and ocular motility in patients with an orbital apex syndrome due to nasopharyngeal rhabdomyosarcoma is examined. DESIGN: Retrospective case series. METHODS: Six eyes from four patients with nasopharyngeal rhabdomyosarcoma who presented to the Children';s Hospital of Philadelphia with a clinical orbital apex syndrome were identified. Complete ophthalmic examination, including visual acuity and extraocular motility at the time of presentation, was reviewed. Tumor extension into the orbital apex was confirmed radiographically. Follow-up ophthalmic evaluations were reviewed for all patients with an average follow-up of 5.5 +/- 3.1 years (range 1 to 8 years). RESULTS: Six eyes of four patients had limited ocular ductions along with marked loss of vision at presentation. All patients were treated with chemotherapy and radiation, with reduction of tumor mass. Ocular motility recovered in all patients, occurring by an average of 2.2 +/- 1.8 months after initiation of therapy. Four of six eyes had little or no recovery of visual acuity detected at long-term follow-up. CONCLUSIONS: Patients with ocular motor deficits in orbital apex syndromes caused by extension of nasopharyngeal rhabdomyosarcoma have an excellent prognosis for recovery after treatment of the tumor. The long-term prognosis for visual recovery, however, is poor.

Child, Preschool↗
PubMed2005

Recognition of objects in non-canonical views: a functional MRI study.

BACKGROUND: The neural correlate of object recognition in non-canonical views is uncertain, but there is evidence for involvement of neural pathways, possibly separate from those used for object recognition in canonical views. METHODS: Boxcar functional MRI (fMRI) techniques were used to detect neural activity while eight normal subjects were instructed to identify digital photographs of objects in non-canonical and canonical orientations. RESULTS: The right angular gyrus, the left inferior temporal gyrus, and the right cerebellum showed significant fMRI activity during non-canonical as opposed to canonical viewing. CONCLUSIONS: Subjects recognizing objects in non-canonical orientations engage in a process separate from, or in addition to, the process used in recognizing objects in canonical orientations.

Adult↗
PubMed2004

Acute ocular motor mononeuropathies: prospective study of the roles of neuroimaging and clinical assessment.

The role for immediate neuroimaging in patients 50 years of age or older with acute isolated third, fourth, and sixth nerve palsies is controversial. We prospectively evaluated 66 patients, aged 50 years and older (median 67 years, range 50-85), with acute isolated ocular motor mononeuropathies. Our purpose was to evaluate both the role of neuroimaging and the role of clinical assessment in determining etiology. We found that clinical features, including time to maximal diplopic symptoms, were not predictive of etiology (median 2 days to maximal diplopic symptoms for both peripheral microvascular and other etiologies). The presence of any common vascular risk factor, including diabetes mellitus, hypertension, hypercholesterolemia, or coronary artery disease, was significantly associated with peripheral microvascular etiology in this cohort (p=0.0004, Fisher's exact test). Despite the high prevalence of peripheral microvascular ischemia as an etiology in this age group, other causes were identified by magnetic resonance imaging (MRI) or computed tomography (CT) scanning in 14% of patients. Diagnoses included brainstem and skull base neoplasms, brainstem infarcts, aneurysms, demyelinating disease, and pituitary apoplexy. Neuroimaging procedures may have a role in the initial evaluation of patients 50 years of age or older with acute ocular motor mononeuropathies.

Abducens Nerve Diseases↗
PubMed2004

Optic radiation involvement in optic pathway gliomas in neurofibromatosis.

PURPOSE: Optic pathway gliomas (pilocytic astrocytomas) in neurofibromatosis type 1 (NF-1) typically involve some combination of the optic nerves, chiasm, or optic tracts. Involvement of the optic radiations is rare. DESIGN: This paper describes seven patients with NF-1 with gliomas involving the pregeniculate optic pathway in addition to the optic radiations. METHODS: A retrospective database review was made of all patients with NF-1 and optic pathway gliomas seen by one of the authors (G.T.L.) at the Children's Hospital of Philadelphia from July 1993 to October 2001. Patients with involvement of pregeniculate optic pathway and the optic radiations were identified. From November 2001 to February 2003, patients were sought prospectively. Cases were also identified from the practice of another author (M.C.B.) at Arkansas Children's Hospital. RESULTS: Four patients from Children's Hospital of Philadelphia (three of 83 total NF-1/optic pathway gliomas from July 1993 to October 2001 and one prospectively) and three from Arkansas Children's Hospital were identified. Two had expanding mass lesions within the white matter of the temporal or parietal lobes, which were histopathologically demonstrated to be pilocytic astrocytomas. The other five had radiographic involvement of the optic radiations but did not undergo biopsy. In three of the cases the vision was 20/200 or worse in each eye. CONCLUSIONS: Optic pathway gliomas in NF-1 may rarely involve the optic radiations. Optic radiation involvement may signal a more aggressive optic pathway glioma in patients with neurofibromatosis-1.

Child, Preschool↗
PubMed2004

Acquired, isolated third nerve palsies in infants with cerebrovascular malformations.

PURPOSE: To report two infants with acquired, isolated third nerve palsies attributable to intracranial cerebrovascular malformations. DESIGN: Observational case report. METHODS: Two patients are described. Each was examined in a university-based pediatric ophthalmology and neuro-ophthalmology practice. RESULTS: An 8-month-old child presented with a pupil-involving partial left third nerve palsy because of a partially thrombosed fusiform aneurysm of the left internal carotid artery. A 3-month-old infant developed a right third nerve palsy from a giant arteriovenous fistula arising from an M2 branch of the right middle cerebral artery. CONCLUSION: Patients younger than 8 months and 3 months with acquired, isolated third nerve palsies resulting from intracranial cerebrovascular malformations could not be found in a MEDLINE search. In conclusion, at even this young age, acquired, isolated third nerve palsies may be the initial manifestation of an intracranial aneurysm or fistula. Magnetic resonance imaging (MRI) and MRI-angiography were adequate for detecting these processes.

Arteriovenous Fistula↗
PubMed2004

Alexia without agraphia following biopsy of a left thalamic tumor.

Alexia without agraphia is a rare disconnection syndrome characterized by the loss of reading ability with retention of writing and verbal comprehension. We report a patient who developed alexia without agraphia after undergoing a biopsy for a malignant glioma involving the left thalamus. A 15-year-old right-handed male presented with 3 days of severe headache, and vomiting, and 1 month of blurry vision in his right visual field. Magnetic resonance imaging of the brain disclosed a large exophytic mass originating in the left thalamus, with mass effect and hydrocephalus. The patient underwent biopsy of the left thalamic mass via a transcallosal approach. Postoperatively, the patient complained of inability to read or identify letters. Examination revealed alexia without agraphia. The syndrome of alexia without agraphia can be rarely caused after surgery. A transcallosal procedure through the splenium of the corpus callosum may disrupt the visual association fibers traveling from the right occipital cortex to the left angular gyrus. In our case the syndrome occurred because of a preexisting right homonymous hemianopia resulting from a left thalamic tumor.

Adolescent↗
PubMed2003

The role of unilateral temporal artery biopsy.

PURPOSE: To examine the role of unilateral temporal artery biopsy (TAB) in suspected giant cell arteritis (GCA). DESIGN: Retrospective interventional case series. PARTICIPANTS: We identified 181 subjects from pathology and diagnostic code databases at the University of Pennsylvania Medical Center who underwent TAB between January 1990 and January 2001. METHODS: The medical records for all subjects who underwent TAB were reviewed. Follow-up information was obtained by telephone or record review for those patients who had negative unilateral TAB. MAIN OUTCOME MEASURES: Follow-up information for patients with unilateral negative TAB was reviewed for potential adverse outcomes caused by missed or delayed diagnoses of GCA. Presenting signs and symptoms and laboratory values were recorded for all subjects. Comparisons of clinical profiles between subsets of subjects were performed using Fisher's exact test, significance level alpha = 0.01. RESULTS: Follow-up information was available for 88 (86%) of 102 subjects who had unilateral negative biopsy samples. One (1%) subjects of 88 had a subsequent positive contralateral TAB; no adverse outcomes occurred for this subject or for any other subjects with unilateral negative TAB. Compared with subjects who had unilateral positive or who underwent bilateral TAB (n = 74), those who had unilateral negative TAB (n = 88) had a significantly lower prevalence of jaw claudication (P = 0.007). Compared with subjects diagnosed with GCA (n = 39), those with unilateral negative TAB (n = 88) had significantly lower frequencies of jaw claudication (P = 0.001), "chalky white" optic disc edema (P = 0.002), and fever (P < 0.0001). Compared with subjects with positive TAB (n = 33), subjects with negative TAB (n = 148) had significantly lower prevalence of jaw claudication (P < 0.0001), "chalky white" disc edema (P = 0.0002), pale disc edema (P = 0.006), or any systemic symptom other than headache (P = 0.0002). ("Chalky white" denotes notably extreme disc pallor). The most common indications for biopsy in subjects with unilateral negative TAB were elevated erythrocyte sedimentation rate (ESR) (74%), headache (69%), visual complaints (58%), and ophthalmic signs (52%). Although ESR was a significant predictor of positive TAB overall (unilateral and bilateral TAB) in logistic regression models accounting simultaneously for subject age (P = 0.04), ESR did not significantly predict unilateral negative status in our patients (P = 0.13). CONCLUSIONS: In this cohort of patients, unilateral TAB was associated with an extremely low frequency (1%) of subsequent positive contralateral TAB and was not associated with adverse visual or neurologic outcomes for any subject. We conclude that in the hands of experienced physicians, a unilateral TAB is sufficient to exclude a diagnosis of GCA in populations for which clinical suspicion is low. Jaw claudication, pale optic disc edema, particularly "chalky white" disc edema, fever, or any systemic symptom other than headache should raise suspicion for a diagnosis of GCA.

Biopsy↗
PubMed2003

Pituitary apoplexy causing optic neuropathy and horner syndrome without ophthalmoplegia.

A 47-year-old woman presented with headache, acute monocular vision loss, and ipsilateral Horner syndrome. Apart from the optic neuropathy, all cranial nerve function was intact. Magnetic resonance imaging revealed an enlarged pituitary gland with compression of the orbital apex. The surgical specimen was consistent with pituitary apoplexy. The combination of headache, acute visual loss, and ipsilateral Horner syndrome without ophthalmoplegia, which may suggest carotid artery dissection, is evidently an unusual manifestation of pituitary apoplexy.

Anti-Inflammatory Agents↗
PubMed2003

Laser pointer visual field screening.

BACKGROUND: Sensitivity of confrontation visual field (CVF) screening is low unless defects are significant. We compared the sensitivity of laser pointer visual field screening (LVF) with conventional CVF for identifying eyes with abnormal automated perimetry. METHODS: Ninety consecutive patients presenting for HVF prospectively underwent a masked comparison of CVF and LVF testing (175 eyes) from April to May 2000. LVF was performed using a laser pointer target projected onto a tangent screen. Points were tested in random fashion on either side of the vertical and horizontal meridians, near central fixation, around the blind spot, and in each quadrant. Single and double simultaneous finger counting was used to test CVF. RESULTS: LVF demonstrated significantly greater sensitivity as compared with CVF (73% versus 31%, P = 0.001) in identifying field defects found on HVF. Specificities for LVF and CVF were 82% and 99%, respectively. The average testing times per eye were 0.5 minute for CVF, 1.5 minutes for LVF, and 8.0 minutes for HVF. CONCLUSIONS: In this cohort, laser visual field testing was significantly more sensitive than confrontation testing. It may represent an effective, time-efficient tool for visual field screening.

Cohort Studies↗