Bilateral Presentation Research Articles

Lacrimal drainage anomalies in congenital rubella syndrome.

PurposeThe objective of this study was to ascertain the lacrimal drainage anomalies in a cohort of patients suffering from congenital rubella syndrome (CRS).MethodsThis was a retrospective case series performed in patients with CRS presenting with associated lacrimal drainage anomalies (LDA) over 6 years from 2011 to 2016. All the patients were confirmed as having CRS after clinical and laboratory testing. Data collected include demographics; associated lacrimal, ocular, and systemic anomalies; interventions performed for lacrimal anomalies; and their anatomical and functional outcomes.ResultsEighty five patients were diagnosed as having CRS during the study period, and of these 23 eyes of 12 patients with associated LDA were included in the study. The prevalence of LDA was 14% in CRS. The mean age at presentation was 15.5 weeks, and all except one had bilateral presentation. Seventeen eyes were diagnosed with simple congenital nasolacrimal duct obstruction (CNLDO) and the remaining six eyes had complex CNLDO with buried probes. Additional lacrimal anomalies noted in the six complex CNLDO cases included punctal agenesis (n=3), atonic sac (n=3), incomplete punctal canalization (n=2), and single canalicular wall hypoplasia (n=1). At a mean follow-up of 12.54 months, anatomical and functional success were noted in 91.3% (21/23 eyes).ConclusionSimple CNLDO was the most common of the LDA in CRS. Buried probe was universal among the cases with complex CNLDO. All CRS patients should be screened for lacrimal anomalies to initiate appropriate interventions for successful outcomes.

Absence of distracting information explains the redundant signals effect for a centrally presented categorization task

The redundant signals effect, a speed-up in response times with multiple targets compared to a single target in one display, is well-documented, with some evidence suggesting that it can occur even in conceptual processing when targets are presented bilaterally. The current study was designed to determine whether or not category-based redundant signals can speed up processing even without bilateral presentation. Toward that end, participants performed a go/no-go visual task in which they responded only to members of the target category (i.e., they responded only to numbers and did not respond to letters). Numbers and letters were presented along an imaginary vertical line in the center of the visual field. When the single signal trials contained a nontarget letter (Experiment 1), there was a significant redundant signals effect. The effect was not significant when the single-signal trials did not contain a nontarget letter (Experiments 2 and 3). The results indicate that, when targets are defined categorically and not presented bilaterally, the redundant signals effect may be an effect of reducing the presence of information that draws attention away from the target. This suggests that redundant signals may not speed up conceptual processing when interhemispheric presentation is not available.

Bilateral Bronchiectasis Presenting as Persistent Pneumonia in a 12 year Old Child

Bilateral Bronchiectasis Presenting as Persistent Pneumonia in a 12 year Old Child

Isolated Arthritis of the Temporomandibular Joint as the Initial Manifestation of Juvenile Idiopathic Arthritis.

To describe characteristics of patients with juvenile idiopathic arthritis (JIA) presenting with isolated arthritis of the temporomandibular joints (TMJ). Patients with JIA with isolated TMJ arthritis from 4 large tertiary pediatric rheumatology centers were included. Demographic and clinical data were analyzed using descriptive statistics. Fifty-five patients were identified (65% bilateral presentation). Six patients developed arthritis in other joints (median time 6 mos); 4 patients developed uveitis, all prior to arthritis. At last followup, 9% were still taking antirheumatic medications. JIA TMJ arthritis can occur in isolation, and is probably underdiagnosed. Care providers including dentists and orthodontists should be aware of this presentation.

Differences in onset between eyes in patients with Leber's hereditary optic neuropathy (LHON)

PurposeLeber's hereditary optic neuropathy (LHON) is an inherited mitochondrial disease characterized by a painless, subacute loss of central vision with over 95% of affected patients harbouring one of three mitochondrial DNA (mtDNA) classical point mutations (m.11778G>A, m.3460G>A and m.14484T>C). The purpose of this study was to compare the age of disease onset and time interval between affected eyes by mutation.MethodsAge of onset, unilateral versus bilateral presentation, interval between the first and second eye, and the mtDNA mutation were retrieved from two separate database registries consisting of 268 Italian and 71 U.S. patients.ResultsClinical data from 300 LHON patients with classical LHON mutations were evaluated (m.11778G>A, n = 216; m.3460G>A, n = 40; m.14484T>C, n = 44. Bilateral eye involvement was clinically documented in 99.4% of cases with 50.3% of all patients demonstrating sequential onset. In these latter cases the median inter‐eye delay was 12.8 weeks. Comparing the age of onset across mutation subtypes, the m.14484T>C mutation resulted in the lowest age at onset (19.2 ± 10.6 years) compared to m.11778G>A (25.8 ± 15.3 years) and m.3460G>A (20.9 ± 14.5 years) (p < 0.05). Interestingly, the m.14484T>C mutation exhibited more simultaneous than sequential onsets compared with the other two mutation subtypes (p < 0.001). Moreover, m.14484T>C showed a shorter and more reproducible interval between eyes (inter‐eye onset range = 1–44 weeks) versus m.11778G>A (range = 1–2016 weeks) and m.3460G>A (range = 2–816 weeks) for sequential presentations.ConclusionsThe m.14484T>C mutation, though least penetrant, manifested at an earlier age and resulted in a smaller inter‐eye delay interval range and higher incidence of simultaneous involvement compared to the other two classical mutations in LHON.

Lateralization of spatial rather than temporal attention underlies the left hemifield advantage in rapid serial visual presentation

In bilateral rapid serial visual presentation (RSVP), the second of two targets, T1 and T2, is better identified in the left visual field (LVF) than in the right visual field (RVF). This LVF advantage may reflect hemispheric asymmetry in temporal attention or/and in spatial orienting of attention. Participants performed two tasks: the “standard” bilateral RSVP task (Exp.1) and its unilateral variant (Exp.1 & 2). In the bilateral task, spatial location was uncertain, thus target identification involved stimulus-driven spatial orienting. In the unilateral task, the targets were presented block-wise in the LVF or RVF only, such that no spatial orienting was needed for target identification. Temporal attention was manipulated in both tasks by varying the T1-T2 lag. The results showed that the LVF advantage disappeared when involvement of stimulus-driven spatial orienting was eliminated, whereas the manipulation of temporal attention had no effect on the asymmetry. In conclusion, the results do not support the hypothesis of hemispheric asymmetry in temporal attention, and provide further evidence that the LVF advantage reflects right hemisphere predominance in stimulus-driven orienting of spatial attention. These conclusions fit evidence that temporal attention is implemented by bilateral parietal areas and spatial attention by the right-lateralized ventral frontoparietal network.

A TUBB6 mutation is associated with autosomal dominant non-progressive congenital facial palsy, bilateral ptosis and velopharyngeal dysfunction.

Congenital cranial dysinnervation disorders (CCDDs) comprise a heterogeneous spectrum of diseases characterized by congenital, non-progressive impairment of eye, eyelid and/or facial movements including Möbius syndrome, Duane retraction syndrome, congenital ptosis, and congenital fibrosis of the extraocular muscles. Over the last 20 years, several CCDDs have been identified as neurodevelopmental disorders that are caused by mutations of genes involved in brain and cranial nerve development, e.g. KIF21A and TUBB3 that each plays a pivotal role for microtubule function. In a five-generation pedigree, we identified a heterozygous mutation of TUBB6, a gene encoding a class V tubulin which has not been linked to a human hereditary disease so far. The missense mutation (p.Phe394Ser) affects an amino acid residue highly conserved in evolution, and co-segregates with a phenotype characterized by congenital non-progressive bilateral facial palsy and congenital velopharyngeal dysfunction presenting with varying degrees of hypomimia, rhinophonia, impaired gag reflex and bilateral ptosis. Expression of the mutated protein in yeast led to an impaired viability compared to wildtype cells when exposed to the microtubule-poison benomyl. Our findings enlarge the spectrum of tubulinopathies and emphasize that mutations of TUBB6 should be considered in patients with congenital non-progressive facial palsy. Further studies are needed to verify whether this phenotype is indeed part of the CCDD spectrum.

Clinical, epidemiological, and therapeutic profile of patients with a retinoblastoma diagnosis experience in the Costa Rica National Children's Hospital Oncology Unit from January 2009 to December 2015.

IntroductionRetinoblastoma represents only 3% of paediatric cancers, but it is the most prevalent intraocular tumour in this population. It develops in the retina as a primitive neuroectodermal tumour that affects development during gestation. The tumour presents in two different forms depending on whether or not it expresses a genetic modification. For patients diagnosed at preschool age, 75% are unilateral non-hereditary cases. While enucleation is the preferred treatment for advanced stages of the tumour, other modalities, such as systemic and intraocular chemotherapy, radiotherapy and local treatments with thermotherapy, cryotherapy, and brachytherapy can be used to try to preserve the eye. However, applying radiation therapy treatments increases the risk of secondary tumours.ObjectiveTo analyse the results obtained from patients with a retinoblastoma diagnosis at the Costa Rica National Children’s Hospital (HNN) Oncology Unit who received external beam radiation therapy and other therapeutic modalities during the period from January 2009 to December 2015.Materials and methodsData were extracted from the patient’s medical records and entered in a data collection instrument. We then analysed the results and formulated conclusions.ResultsA total of 36 patients were evaluated. This corresponded to 45 cases or the number of eyes affected by bilateral presentation of retinoblastoma. The documented incidence was 0.83 cases per 10,000 live births and the majority were female preschool-age children. Of these, 40% presented bilaterally and 13% were of hereditary origin. Up to 78% of these cases were diagnosed with advanced stage D and stage E. All patients who received conservative treatment progressed, requiring up to four lines of treatment. Eight patients, all in the most advanced stage, received external beam radiation due to the failure of other modalities. The main adverse effects observed were radiodermatitis, facial hypoplasia and conjunctivitis. Additionally, we report the emergence of a secondary neoplasm in two patients, one post-chemotherapy and the other post-radiotherapy.ConclusionsAdvanced-stage patients who initially received conservative treatments responded more poorly than those treated more aggressively with surgery alone or with surgery combined with another treatment modality. Treatment with radiation therapy was used in 22% of the cases (8 patients) and all patients treated with radiotherapy showed some adverse effects.

The Prevalence and Causes of Vision Loss in Indigenous and Non-Indigenous Australians: The National Eye Health Survey

To conduct a nationwide survey on the prevalence and causes of vision loss in Indigenous and non-Indigenous Australians. Nationwide, cross-sectional, population-based survey. Indigenous Australians aged 40 years or older and non-Indigenous Australians aged 50 years and older. Multistage random-cluster sampling was used to select 3098 non-Indigenous Australians and 1738 Indigenous Australians from 30 sites across 5 remoteness strata (response rate of 71.5%). Sociodemographic and health data were collected using an interviewer-administered questionnaire. Trained examiners conducted standardized eye examinations, including visual acuity, perimetry, slit-lamp examination, intraocular pressure, and fundus photography. The prevalence and main causes of bilateral presenting vision loss (visual acuity <6/12 in the better eye) were determined, and risk factors were identified. Prevalence and main causes of vision loss. The overall prevalence of vision loss in Australia was 6.6% (95% confidence interval [CI], 5.4-7.8). The prevalence of vision loss was 11.2% (95% CI, 9.5-13.1) in Indigenous Australians and 6.5% (95% CI, 5.3-7.9) in non-Indigenous Australians. Vision loss was 2.8 times more prevalent in Indigenous Australians than in non-Indigenous Australians after age and gender adjustment (17.7%, 95% CI, 14.5-21.0 vs. 6.4%, 95% CI, 5.2-7.6, P < 0.001). In non-Indigenous Australians, the leading causes of vision loss were uncorrected refractive error (61.3%), cataract (13.2%), and age-related macular degeneration (10.3%). In Indigenous Australians, the leading causes of vision loss were uncorrected refractive error (60.8%), cataract (20.1%), and diabetic retinopathy (5.2%). In non-Indigenous Australians, increasing age (odds ratio [OR], 1.72 per decade) and having not had an eye examination within the past year (OR, 1.61) were risk factors for vision loss. Risk factors in Indigenous Australians included older age (OR, 1.61 per decade), remoteness (OR, 2.02), gender (OR, 0.60 for men), and diabetes in combination with never having had an eye examination (OR, 14.47). Vision loss is more prevalent in Indigenous Australians than in non-Indigenous Australians, highlighting that improvements in eye healthcare in Indigenous communities are required. The leading causes of vision loss were uncorrected refractive error and cataract, which are readily treatable. Other countries with Indigenous communities may benefit from conducting similar surveys of Indigenous and non-Indigenous populations.

Abstract 259: A case series of vitreoretinal lymphoma in New York City with exposure to Chernobyl nuclear disaster decades earlier

Abstract Background: Vitreoretinal lymphoma (VRL) is an unusual presentation of primary central nervous system lymphoma and a subcategory of intraocular lymphoma (IOL). The etiology and epidemiology of this rare malignancy is unknown. Methods: We diagnosed 10 subjects with VRL in our clinical practices in New York City (NYC) during 2010-2013. Upon systematic collection of demographic and exposure history, 6 patients reported residence in regions proximal to the Chernobyl nuclear disaster (4 Ukraine, 1 Poland, 1 Moldova). We studied clinical variables including presentation, diagnostic parameters, therapies and survival of this case series. To provide context, we examined population-based incidence data from the Surveillance, Epidemiology and End Results (SEER) program to determine age-adjusted incidence rates of IOL (there is no unique code for VRL) per 100,000 person-years in the United States (US) during 1992-2013. New York State (NYS) rates are not reported to SEER and were examined separately using NYS Cancer Registry (NYSCR). Incidence trends using 10-year intervals (1992-2002 and 2003-2013) were also analyzed. Results: All six subjects (5 females) were diagnosed with diffuse large B-cell lymphoma with bilateral presentation. Diagnosis in all cases was made by immunohistochemical analysis on tumor specimen obtained by vitreous fine needle aspiration, vitreous biopsy or stereotactic brain biopsy. Median age at diagnosis was 76 years (range, 62-84 years). Median interval from Chernobyl accident (1986) to diagnosis was 26 years (range, 24-27 years). We identified no other common exposure or environmental risk factor. There were 68 cases of primary IOL during 1992-2013 in the 13 SEER areas. IOL rates per 100,000 person-years for both sexes were highest among Asian/Pacific Islanders (0.010 for males and 0.014 for females) followed by whites (0.009 for males and 0.008 for females) and (based on small numbers) by blacks. Analysis of incidence trends showed an increase in rates among Asian/Pacific Islander females from 0.005 in 1992-2002 to 0.018 in 2003-2013 and among males from 0.006 to 0.013. Rates among whites increased for both genders. Analysis of NYSCR data revealed 44 cases of primary IOL. IOL rates per 100,000 person-years for both genders were highest among whites (0.010 for males and 0.012 for females) followed by Asian/Pacific Islanders (0.007 for males and females). Analysis of trends revealed increase in rates for both genders and racial groups. Conclusions: Our analyses highlight the rarity of VRL and reveal an increase in incidence, particularly among Asian/Pacific Islanders where IOL rates tripled within two decades. Based on incidence rates, 8 cases of IOL (with a subset being VRL) are expected in 4 years in NYS. Our observation of 10 cases of VRL in 4 years in our practices in NYC is unanticipated. The sole common environmental factor we identified was residence in regions proximal to the Chernobyl nuclear disaster. Citation Format: Sanford Kempin, Paul Finger, Robert Gale, John Rescigno, Jeffrey Rubin, Walter Choi, Rebecca Fisher, Alexander Aizman, Ilona Genis, Roxana Moslehi* (Corresponding Author). A case series of vitreoretinal lymphoma in New York City with exposure to Chernobyl nuclear disaster decades earlier [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 259. doi:10.1158/1538-7445.AM2017-259

Effects of somatostatin/octreotide treatment in neonates with congenital chylothorax.

The influence of somatostatin/octreotide treatment on outcomes of neonates with congenital chylothorax remains controversial. We retrospectively reviewed our experience with somatostatin/octreotide therapy in neonates with this very rare disease.Fourteen neonates with congenital chylothorax who were treated with somatostatin (3.5–7 μg/kg/h, before 2016) or octreotide (1–6 μg/kg/h, after January 2016), along with traditional management between 2013 and 2016, were retrospectively reviewed in this observational study. Their daily volumes of pleural drainage and parameters of respiratory support were recorded, and the potential side effects of somatostatin/octreotide were screened.Four patients (28.6%) had a unilateral presentation of pleural effusion, whereas 10 patients (71.4%) had a bilateral presentation. Twelve patients (85.7%) survived until discharge without later recurrence or death, whereas 2 patients (14.3%) died within the first 3 days after birth. Somatostatin/octreotide treatment was maintained for a median period of 6 days (range 1–16 days). The chest tube was removed after a median duration of 14 days (range 2–51 days), and no patient needed pleurodesis or thoracic duct ligation surgery. The average daily drain output within 3 days post-treatment (median 62 mL, range 10–651 mL) was significantly lower than that before treatment (median 133 mL, range 70–620 mL) (P = .002). The need for ventilation support was reduced in most patients (85.7%) after the initiation of somatostatin/octreotide therapy. No serious side effects were identified.Somatostatin/octreotide treatment reduced pleural drainage and respiratory support without significant side effects. Further randomized controlled studies with more patients are necessary to ascertain the benefits of somatostatin/octreotide in neonates with congenital chylothorax.

A Case of Bilateral Opercular Stroke Presenting as Foix-Chavany-Marie syndrome: a 6-Month Follow-Up, Supplemented with a Physical Examination Video

A Case of Bilateral Opercular Stroke Presenting as Foix-Chavany-Marie syndrome: a 6-Month Follow-Up, Supplemented with a Physical Examination Video

Variation in the Course and Termination of the Cephalic Vein in the Deltopectoral Triangle

Summary The knowledge of cephalic vein variation would aid proper identification and prevent error in surgical emergencies. The path, distribution, and termination of the cephalic vein in relation to the deltopectoral triangle were studied in twenty formalin-embalmed cadavers. Results show the bilateral presentation of the cephalic vein in all the shoulders examined. Thirty-seven (37) cases presented with a superficial and lateral course of the cephalic vein in the deltopectoral groove, while the rest three cases presented a deep course. Of these 37 cases with the superficial course, two cases ascended anteriorly and above the clavicle and drained into the external jugular vein in the neck. Another case presented a cephalic vein that ascended anteriorly and then above the clavicle and drained into an unnamed vein in the neck. In one case, the cephalic vein ascended superficially in the deltopectoral groove and laterally in the deltopectoral triangle. In one bilateral pattern, the cephalic vein in the deltopectoral triangle drained into the axillary vein. In all the three cases where the cephalic vein ascended deep within the deltopectoral groove, they terminated deep in the deltopectoral triangle. In one of these, the cephalic vein received a tributary that originated from a venous network beneath the deltoid muscle and then drained into athe xillary vein, deep in the deltopectoral triangle. In the other two cases, the cephalic vein gave a tributary to the axillary vein and continued deep and medially in the deltopectoral triangle, passed below the clavicle and drained into the subclavian vein. The knowledge of these variations of the cephalic vein is essential to clinicians and surgeons for venous access during emergencies and surgery.

A paediatric case of bilateral mandibular condyle fracture presenting with bloody otorrhoea following trauma

A 7-year-old boy presented to the emergency department with bilateral bloody otorrhoea after falling from his scooter. Skull base fracture was suspected. CT showed no evidence of skull base fracture...

Rare Bilateral Variation of the Extensor Carpi Radialis Longus Muscle

ObjectiveThe extensor carpi radialis longus (ECRL) is a superficial extensor muscle with a single muscle belly and tendon. In humans, the ECRL is found on the lateral forearm and serves to extend and abduct the hand at the wrist. While anatomical variations of the musculature of the extensor forearm are uncommon, it is essential for physicians working in this area of the body to be aware of possible variations.MethodsDissections of 68 upper limbs from 34 cadavers were performed and the musculature and neurovasculature of the lateral forearm was assessed.ResultsOne cadaver displayed an accessory muscle belly bilaterally with a long slender tendon arising from the ECRL muscle and inserting distally near the wrist. Both the accessory muscle on the right upper limb and left upper limb inserted on the abductor pollicis brevis muscle.ConclusionThis is a rare instance of a bilateral presentation of an accessory ECRL muscle, also known as the extensor carpi radialis accessorius (ECRA). Due to its infrequency, awareness of this accessory muscle and tendon may help physicians avoid improper muscle recognition when visualizing the area. As it is likely that the ECRA only weakly assists with the extension function of the ECRL, when present it may be used as an attractive autograft option for reconstructive surgery with minimal adverse effects.

Syphilitic Bilateral Coronary Artery Ostial Stenosis Presenting as Acute Coronary Syndrome

Syphilis is an infectious disease which occurs through a series of frequently overlapping stages. It can impair the cardiovascular and neurological systems. In approximately 30% of non-treated patients, syphilis develops its tertiary form. We report a case of a 41-year male patient admitted due to acute coronary syndrome presented as unstable angina. Coronary angiography showed a 100% ostial lesion of left main coronary artery and 90% occlusion of the right coronary artery ostium. Subsequent Computed Tomography Angiography (CTA) scan showed prominent thickening of the aortic wall. The Venereal Disease Research Laboratory (VDRL) test was titrated to 1/16. The patient was referred for coronary artery bypass graft (CABG). Key words: Syphilis, Acute Coronary Syndrome, unstable angina, Coronary Angiography, Left Main Coronary Artery, Right Coronary Artery, Coronary ostial stenosis, Computed Tomography Angiography.

Computed Tomographyand Magnetic Resonance Image-Based Analysis of the Anatomical Variations of the Sylvian Fissure and Characteristics of the Middle Cerebral Artery

The aim of this cross sectional anatomical study is to determine the distribution of the defined anatomical variations of the Sylvian fissure (SF) in a normal population and to analyze its bilateral superposable presentation. Furthermore, we examined the course of the middle cerebral artery (MCA) and the division of the MCA branches in relation to the SF types.A total of 300 cranial CT scans - 100 CT angiography datasets and 86 MRIs of patients without intracranial pathologies - were reviewed. The SF was categorized in five types based on Yasargils description and our previous publication. The length, diameter and branches of the MCA were measured and compared to the SF types. SPSS 23.0 for Windows® was used for statistical analysis.We analyzed data of 300 patients (171 male, 129 female; mean age 51.6years). Symmetric and mirror-imaged coherence of the SF was found in 266 patients (88.7%, χ2(8)=3.04, p=0.932). The distribution of the SF types showed significant differences in patients younger than 60 years compared to older patients. A bifurcation was observed in 72.0%. A trifurcation was observed in 12.0% and a false bifurcation in 16.0% of patients. There was no significant difference of the measured diameters or length of the M1 segments according to the SF types.In this CT and MRI based anatomical study we could show that a twisted and narrow SF occurred more frequently in patients younger than 60 years of age. The SF has a high congruence intra-individually. The anatomical condition might influence the size and configuration of the proximal MCA, which in turn might influence the surgeon’s choice of the approach to the SF. Preoperative evaluation on the basis of the presented data, may help to decide for an appropriate approach to the SF.

Dissociated roles of the parietal and frontal cortices in the scope and control of attention during visual working memory

Mounting evidence suggests that multiple mechanisms underlie working memory capacity. Using transcranial direct current stimulation (tDCS), the current study aimed to provide causal evidence for the neural dissociation of two mechanisms underlying visual working memory (WM) capacity, namely, the scope and control of attention. A change detection task with distractors was used, where a number of colored bars (i.e., two red bars, four red bars, or two red plus two blue bars) were presented on both sides (Experiment 1) or the center (Experiment 2) of the screen for 100ms, and participants were instructed to remember the red bars and to ignore the blue bars (in both Experiments), as well as to ignore the stimuli on the un-cued side (Experiment 1 only). In both experiments, participants finished three sessions of the task after 15min of 1.5mA anodal tDCS administered on the right prefrontal cortex (PFC), the right posterior parietal cortex (PPC), and the primary visual cortex (VC), respectively. The VC stimulation served as an active control condition. We found that compared to stimulation on the VC, stimulation on the right PPC specifically increased the visual WM capacity under the no-distractor condition (i.e., 4 red bars), whereas stimulation on the right PFC specifically increased the visual WM capacity under the distractor condition (i.e., 2 red bars plus 2 blue bars). These results suggest that the PPC and PFC are involved in the scope and control of attention, respectively. We further showed that compared to central presentation of the stimuli (Experiment 2), bilateral presentation of the stimuli (on both sides of the fixation in Experiment 1) led to an additional demand for attention control. Our results emphasize the dissociated roles of the frontal and parietal lobes in visual WM capacity, and provide a deeper understanding of the neural mechanisms of WM.

A right hemisphere advantage at early cortical stages of processing alphanumeric stimuli. Evidence from electrophysiology

This study investigates hemispheric asymmetry evoked by non-target alphanumeric stimuli in a bilateral rapid serial visual presentation (RSVP) task. Our indicators of asymmetry are shorter latencies and larger amplitudes of the right hemisphere (RH) P1 and N1 components of visual evoked potentials (VEPs). This VEP asymmetry might reflect either a RH advantage, possibly in early perceptual processing, or for familiar stimuli, or for directing attention, or might be a paradoxical reflection of left hemisphere specialization in letter processing. Experiment 1 showed that the VEP asymmetry decreased, though remained present, with unfamiliar stimuli (Tibetan letters), as compared to familiar stimuli (Latin letters and Arabic digits). Experiment 2 showed that while leftward and rightward attentional biases affected the relation between hemispheres contra- and ipsilateral to attended visual fields, the VEP asymmetry remained independent of attention. As the most parsimonious explanation, the primary cause of the VEP asymmetry seems to be a general predominance of the RH in early perceptual processing.

Sequential bilateral retrobulbar optic neuritis in a young female

Optic neuritis (ON) is the demyelinating inflammation of the optic nerve head usually associated with multiple sclerosis. It is usually associated with sudden onset loss of vision with dyschromatopsia and retro-orbital pain. Atypical features for a demyelinating ON include the absence of pain, severe visual loss, progression of visual loss, pain for more than 2 weeks, and lack of recovery after 3 weeks. Atypical features in fundus examination include marked swelling of the nerve with retinal exudates, peripapillary hemorrhages and bilateral presentation, which may occur either simultaneously or sequentially. Atypical ON requires careful consideration and differentiation from demyelinating ON and ischemic optic neuropathy since the treatment is different. We describe a patient who presented with recurrent, sequential episode of visual loss over 2 years, without evidence of any additional neurological deficits, sarcoidosis, or systemic autoimmune disease. A diagnosis of chronic relapsing inflammatory optic neuropathy was made, and she was given intravenous steroids for 3 days, which improved the vision from hand movement close to face to 5/60 in the right eye. She was given immunosuppressants for 3 months, and oral steroids were gradually tapered. Her present vision is the right eye is 6/6 with normal intraocular pressure and color vision.