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Biomedical subjects

Laura J Balcer

Publications and source records attributed to Laura J Balcer.

At least 19 recordsLinked to original sources
PubMed2026

Dose-dependent white matter changes associated with repetitive head impacts in former American football players.

Repetitive head impacts sustained during American football have been associated with neuropathological changes such as white matter shear injuries. However, the impact of specific factors, such as age of first exposure and cumulative head impact burden, on white matter integrity remains unclear. This study investigated in vivo white matter microstructural changes using diffusion tensor imaging and tract-based spatial statistics in 165 male former American football players (mean age 57.3 years, range 45-74) and 52 unexposed asymptomatic male controls (mean age 59.4 years, range 45-74) in the DIAGNOSE CTE Research Project. Compared to controls, former football players exhibited significantly higher fractional anisotropy (FA) in 1.97% of the white matter skeleton (1552 voxels; Cohen's d = 0.587) and higher tissue-corrected FA (FAt) in 1.48% of the white matter skeleton (1004 voxels; Cohen's d = 0.616). No significant differences were observed for mean diffusivity, axial diffusivity, radial diffusivity, or free water between football players and controls. Among football players, there were no significant differences in the white matter microstructure between players diagnosed with traumatic encephalopathy syndrome and those without the diagnosis. Lower FA was significantly associated with older age (P < 0.00001) and an earlier age of first exposure to tackle football (P < 0.01), while lower FAt was associated with greater cumulative head impact burden, specifically higher linear acceleration (P < 0.04) and rotational force (P < 0.02). This study highlights the influential role of exposure factors on white matter microstructure in former American football players, as well as the utility of diffusion tensor imaging to aid in characterizing the long-term effects of repetitive head impacts in contact sport athletes.

American football↗
PubMed2026

Regional ventricular enlargement as an in vivo biomarker of cumulative biomechanical neurodegeneration in former American football players.

INTRODUCTION: Repetitive head impacts (RHIs) have been linked to later life neurodegeneration, yet the in vivo structural correlates of cumulative biomechanical loading remain unclear. We examined whether regional ventricular morphology in former American football players reflects exposure burden and traumatic encephalopathy syndrome (TES) classification. METHODS: Participants included 170 male former football players and 54 age-matched asymptomatic male controls from the Diagnostics, Imaging, and Genetics Network for the Objective Study and Evaluation of Chronic Traumatic Encephalopathy Research Project. Subject-specific manual segmentation quantified lateral ventricle, inferior horn, third ventricle, and fourth ventricle volumes. Group and exposure associations were tested using generalized least squares models. RESULTS: Former players showed larger left inferior lateral ventricle volume than controls, with the largest effects among professional players. Greater cumulative linear and rotational acceleration exposure was associated with enlargement across lateral ventricular and inferior horn regions. DISCUSSION: Regional ventricular enlargement may represent an in vivo marker of cumulative biomechanical loading after RHI exposure.

Humans↗
PubMed2006

Fear sensitivity and the psychological profile of patients with psychogenic nonepileptic seizures.

Psychogenic nonepileptic seizures (PNES) remain a poorly understood phenomenon for both patients and their physicians. Recent work has begun to focus on the possible psychological underpinnings of this diagnosis, but few studies have focused on specific emotional pathologies. This study sought to investigate the impact of a specific emotional measure: self-reported fear sensitivity. Three patient groups (patients with PNES, patients with epilepsy, and healthy volunteers) were administered the Modified Fear Survey Schedule, along with other neuropsychological batteries. As expected, the PNES and epilepsy cohorts demonstrated elevated levels of depression, anxiety, and comorbid psychiatric conditions. The PNES group independently exhibited a statistically significant higher level of fear sensitivity compared with both patients with epilepsy and healthy volunteers. This fear-specific trait was independent of other comorbid psychological factors or psychiatric conditions. These results suggest that patients with PNES exhibit disproportionately elevated fear sensitivity on self-report measures when compared with patients with epilepsy. This finding may reflect an elevated internal "setpoint" for appraising the intensity of emotional settings.

Adult↗
PubMed2006

Relation of visual function to retinal nerve fiber layer thickness in multiple sclerosis.

PURPOSE: To examine the relation of visual function to retinal nerve fiber layer (RNFL) thickness as a structural biomarker for axonal loss in multiple sclerosis (MS), and to compare RNFL thickness among MS eyes with a history of acute optic neuritis (MS ON eyes), MS eyes without an optic neuritis history (MS non-ON eyes), and disease-free control eyes. DESIGN: Cross-sectional study. PARTICIPANTS: Patients with MS (n = 90; 180 eyes) and disease-free controls (n = 36; 72 eyes). METHODS: Retinal never fiber layer thickness was measured using optical coherence tomography (OCT; fast RNFL thickness software protocol). Vision testing was performed for each eye and binocularly before OCT scanning using measures previously shown to capture dysfunction in MS patients: (1) low-contrast letter acuity (Sloan charts, 2.5% and 1.25% contrast levels at 2 m) and (2) contrast sensitivity (Pelli-Robson chart at 1 m). Visual acuity (retroilluminated Early Treatment Diabetic Retinopathy charts at 3.2 m) was also measured, and protocol refractions were performed. MAIN OUTCOME MEASURES: Retinal nerve fiber layer thickness measured by OCT, and visual function test results. RESULTS: Although median Snellen acuity equivalents were better than 20/20 in both groups, RNFL thickness was reduced significantly among eyes of MS patients (92 mum) versus controls (105 mum) (P<0.001) and particularly was reduced in MS ON eyes (85 mum; P<0.001; accounting for age and adjusting for within-patient intereye correlations). Lower visual function scores were associated with reduced average overall RNFL thickness in MS eyes; for every 1-line decrease in low-contrast letter acuity or contrast sensitivity score, the mean RNFL thickness decreased by 4 mum. CONCLUSIONS: Scores for low-contrast letter acuity and contrast sensitivity correlate well with RNFL thickness as a structural biomarker, supporting validity for these visual function tests as secondary clinical outcome measures for MS trials. These results also suggest a role for ocular imaging techniques such as OCT in trials that examine neuroprotective and other disease-modifying therapies. Although eyes with a history of acute optic neuritis demonstrate the greatest reductions in RNFL thickness, MS non-ON eyes have less RNFL thickness than controls, suggesting the occurrence of chronic axonal loss separate from acute attacks in MS patients.

Acute Disease↗
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↗
PubMed2005

Performance measures in Friedreich ataxia: potential utility as clinical outcome tools.

Although several neuroprotective agents have been proposed as potential therapies in Friedreich ataxia (FA), clinical trials of their efficacy are limited by a lack of sensitive outcome measures. We assessed whether performance measures (nine-hole peg test, the timed 25-foot walk, and low-contrast letter acuity) provide valid measures of disease status in FA. Scores for each measure correlated significantly with neurologic disability and disease duration. Rank correlations between scores for performance measures were moderate in magnitude, suggesting that the each test captures separate yet related dimensions of neurological function in FA. Linear regression models demonstrated that scores from the nine-hole peg test and the timed 25-foot walk (after reciprocal transformation) were predicted by age and triplet repeat length in patients with FA. In addition, comparison of the temporal courses of change for each performance measure demonstrated that scores from the timed 25-foot walk change early in the course of FA, nine-hole peg test scores change slowly over the full course of the disorder, and low-contrast letter acuity scores change in the later stages of the disease. Thus, a composite scale derived from these performance measures may provide the best overall measure for assessing disease progression throughout the illness.

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

Endocrine and metabolic deficiency.

Endocrine and metabolic disorders that cause neuro-ophthalmologic manifestations are frequently encountered by ophthalmologists in clinical practice. This review focuses on three of the most common entities for which neuro-ophthalmologic signs and symptoms are a prominent feature. These entities include pituitary disorders (adenoma, apoplexy, and hypophysitis), thyroid-associated ophthalmopathy, and neuro-ophthalmologic complications of diabetes mellitus, such as ischemic ocular motor mononeuropathies and diabetic papillopathy.

Endocrine System Diseases↗
PubMed2003

Lack of effect of polymorphisms in dopamine metabolism related genes on imaging of TRODAT-1 in striatum of asymptomatic volunteers and patients with Parkinson's disease.

SPECT scanning using (99)Tc-TRODAT-1, a ligand that binds to dopamine transporters, may be useful for detection of early Parkinson's disease (PD), diagnosis of presymptomatic individuals, and monitoring disease progression. Understanding whether genetic factors contribute to inter-individual variability is crucial for interpreting imaging results in the context of disease pathophysiology. We tested whether polymorphisms in the genes for catechol-O-methyltransferase (COMT), monoamine-oxidase B (MAO-B), and the dopamine transporter (DAT) influence dopamine uptake parameters in the striatum in vivo in asymptomatic volunteers and patients with PD as measured with (99)Tc-TRODAT-1. (99)Tc-TRODAT-1 binding declined with age in both asymptomatic volunteers and PD patients, and depended on disease duration in PD patients. We found no significant association between COMT, MAO-B, and DAT polymorphisms and results of (99)Tc-TRODAT-1 testing in asymptomatic volunteers or patients with PD. In PD patients, the age of disease onset and speed of progression did not differ based on these polymorphisms. These results demonstrate that these specific genetic variations do not alter the fidelity of (99)Tc-TRODAT-1 as a measure of dopaminergic function in asymptomatic volunteer individuals or patients with PD.

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↗
PubMed2002

Friedreich ataxia: effects of genetic understanding on clinical evaluation and therapy.

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.

Animals↗
PubMed2002

Near infrared muscle spectroscopy in patients with Friedreich's ataxia.

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.

Adolescent↗