Neuro-Ophthalmic Deficits after Head Trauma

Characteristics of ocular injuries associated with mortality in patients admitted with major trauma

BACKGROUND

Few ocular trauma studies have addressed mortality outcomes. We sought to determine characteristics of mortality-related ocular trauma admissions and compared them with non-fatal injuries.

METHODS

A retrospective study was conducted using de-identified data of patients admitted with major trauma from the National Trauma Data Bank (2008-2014). Patients with ocular injury were identified using ICD- 9CM codes. Demographics, intention and mechanism, types of ocular and head injuries, and injury severity were documented. Mortality was determined using post-admission disposition. Statistical analysis using student t-test, chi-square, and odds ratios (OR) calculations were performed with STATA-17 software. Significance was set at P < 0.05.

RESULTS

Of 316,485 patients admitted with ocular trauma, 12,233 (3.86%) were mortality related. Expired patients were older than survivors: mean (SD) of 50.1(25.5) vs. 41.5(22.8) years. White (OR = 1.32; P < 0.001), ≥ 65years old (OR = 2.25; P < 0.001), and male (OR = 1.05; P = 0.029) patients were most likely to expire than their counterparts. Common mechanisms of injury in survivors were falls (25.3%), motor vehicle traffic-occupant, MVTO (21.8%) and struck by/against (18.1%) and for fatal injuries, falls (29.7%), MVTO (21.9%) and firearms (11.5%). Traumatic brain injury (TBI) was documented in 88.2% of mortality-related admissions. Very severe injury severity scores (ISS > 24) (OR = 19.19; P < 0.001) and severe Glasgow Coma Score (GCS < 8) (OR = 19.22; P < 0.001) were most associated with mortality than survival. Firearms were most associated with very severe ISS (OR = 3.73; P < 0.001), severe GCS (OR = 4.68; P < 0.001) and mortality (OR = 5.21; P < 0.001) than other mechanisms. Patients with cut/pierce injuries had the greatest odds of survival (OR = 13.48; P < 0.001). Optic nerve/visual pathways injuries (3.1%) had the highest association with very severe ISS (OR = 2.51; P < 0.001), severe GCS (OR = 3.64; P < 0.001) and mortality (OR = 2.58; P < 0.001) than other ocular injuries. Black patients with very severe ISS (OR = 32.14; P < 0.001) and severe GCS (OR = 31.89; P < 0.001) were more likely to expire than other race/ethnicities with similar injury severity.

CONCLUSIONS

Mortality-related admissions were older, male, and mostly of White race than ocular trauma admissions of survivors. Firearms were the deadliest mechanism. TBI was commonly associated and patients with optic nerve/pathway injuries, very severe ISS and severe GCS had higher mortality rates. Characteristics and demographic variations identified in this study may be useful in developing focused measures aimed at preventing trauma-related deaths.

Optic nerve diseases and regeneration: How far are we from the promised land?

The retinal ganglion cells (RGCs) are the sole output neurons that connect information from the retina to the brain. Optic neuropathies such as glaucoma, trauma, inflammation, ischemia and hereditary optic neuropathy can cause RGC loss and axon damage, and lead to partial or total loss of vision, which is an irreversible process in mammals. The accurate diagnoses of optic neuropathies are crucial for timely treatments to prevent irrevocable RGCs loss. After severe ON damage in optic neuropathies, promoting RGC axon regeneration is vital for restoring vision. Clearance of neuronal debris, decreased intrinsic growth capacity, and the presence of inhibitory factors have been shown to contribute to the failure of post-traumatic CNS regeneration. Here, we review the current understanding of manifestations and treatments of various common optic neuropathies. We also summarise the current known mechanisms of RGC survival and axon regeneration in mammals, including specific intrinsic signalling pathways, key transcription factors, reprogramming genes, inflammation-related regeneration factors, stem cell therapy, and combination therapies. Significant differences in RGC subtypes in survival and regenerative capacity after injury have also been found. Finally, we highlight the developmental states and non-mammalian species that are capable of regenerating RGC axons after injury, and cellular state reprogramming for neural repair.

Review: Emerging Eye-Based Diagnostic Technologies for Traumatic Brain Injury

The study of ocular manifestations of neurodegenerative disorders, Oculomics, is a growing field of investigation for early diagnostics, enabling structural and chemical biomarkers to be monitored overtime to predict prognosis. Traumatic brain injury (TBI) triggers a cascade of events harmful to the brain, which can lead to neurodegeneration. TBI, termed the "silent epidemic" is becoming a leading cause of death and disability worldwide. There is currently no effective diagnostic tool for TBI, and yet, early-intervention is known to considerably shorten hospital stays, improve outcomes, fasten neurological recovery and lower mortality rates, highlighting the unmet need for techniques capable of rapid and accurate point-of-care diagnostics, implemented in the earliest stages. This review focuses on the latest advances in the main neuropathophysiological responses and the achievements and shortfalls of TBI diagnostic methods. Validated and emerging TBI-indicative biomarkers are outlined and linked to ocular neuro-disorders. Methods detecting structural and chemical ocular responses to TBI are categorised along with prospective chemical and physical sensing techniques. Particular attention is drawn to the potential of Raman spectroscopy as a non-invasive sensing of neurological molecular signatures in the ocular projections of the brain, laying the platform for the first tangible path towards alternative point-of-care diagnostic technologies for TBI.

Surgical approach for traumatic chiasmal syndrome and complete third nerve palsy following severe head trauma

Traumatic chiasmal syndrome and traumatic third nerve palsies are rare entities usually caused by severe, high-speed, closed-head road accidents that require a thorough diagnostic work-up and complex medical and surgical management. This report presents the case of a young adult who was involved in a motorcycle accident and sustained blunt frontal head trauma, resulting in optical chiasmal syndrome and complete unilateral third nerve palsy. Ophthalmological examination demonstrated a right complete ptosis, a downward and outward position of the right eye with a fixed and dilated pupil, and bitemporal hemianopsia. In addition, funduscopy revealed bilateral optical nerve atrophy. After stabilisation and during follow-up, strabismus surgery was performed with improvement of ocular alignment in the primary position. Subsequently, eyelid surgery was carried out with good amplification of the visual field, particularly on the left side. Although challenging, surgical intervention in these cases should be considered for both functional and cosmetic reasons.

Mild-to-Moderate Traumatic Brain Injury: A Review with Focus on the Visual System

Traumatic Brain Injury (TBI) is a major global public health problem. Neurological damage from TBI may be mild, moderate, or severe and occurs both immediately at the time of impact (primary injury) and continues to evolve afterwards (secondary injury). In mild (m)TBI, common symptoms are headaches, dizziness and fatigue. Visual impairment is especially prevalent. Insomnia, attentional deficits and memory problems often occur. Neuroimaging methods for the management of TBI include computed tomography and magnetic resonance imaging. The location and the extent of injuries determine the motor and/or sensory deficits that result. Parietal lobe damage can lead to deficits in sensorimotor function, memory, and attention span. The processing of visual information may be disrupted, with consequences such as poor hand-eye coordination and balance. TBI may cause lesions in the occipital or parietal lobe that leave the TBI patient with incomplete homonymous hemianopia. Overall, TBI can interfere with everyday life by compromising the ability to work, sleep, drive, read, communicate and perform numerous activities previously taken for granted. Treatment and rehabilitation options available to TBI sufferers are inadequate and there is a pressing need for new ways to help these patients to optimize their functioning and maintain productivity and participation in life activities, family and community.

Traumatic Brain Injury-Related Optic Nerve Damage

Vision disorders are associated with traumatic brain injury (TBI) in 20%-40% of clinical cases and involve a diverse set of potential symptoms that can present acutely or chronically. Due to its structure and position, the optic nerve is vulnerable to multiple forms of primary injury, which can result in traumatic optic neuropathy (TON). Multiple studies have shown that the optic tract may also be injured during TBI, though data regarding the temporospatial resolution of injury to the optic nerve are sparse. We evaluated the time course of optic nerve injury and visual impairments in our closed head impact acceleration mouse model of mild TBI (mTBI) designed to mimic repetitive injuries experienced in the context of sport. Our results show that inflammation and gliosis occur acutely in response to injury. Additionally, indications of optic nerve degeneration and functional loss of vision beginning at 1-month postinjury, and retinal ganglion cell loss at 7 months, revealed that the degeneration is continuous and permanent. Together, this study demonstrated that the optic nerve is vulnerable to damage during mTBI, which can cause TON and vision loss. These findings will be important for clinicians to consider to determine whether optic nerve is injured in the TBI patients with vision problems.

Raloxifene, a cannabinoid type-2 receptor inverse agonist, mitigates visual deficits and pathology and modulates microglia after ocular blast

Visual deficits after ocular blast injury (OBI) are common, but pharmacological approaches to improve long-term outcomes have not been identified. Blast forces frequently damage the retina and optic nerves, and work on experimental animals has shown the pro-inflammatory actions of microglia can further exacerbate such injuries. Cannabinoid type-2 receptor (CB2) inverse agonists specifically target activated microglia, biasing them away from the harmful pro-inflammatory M1 state toward the helpful reparative M2 state. We previously found that treating mice with CB2 inverse agonists after traumatic brain injury, produced by either focal cranial air blast or dorsal cranial impact, greatly attenuated the visual deficits and pathology that otherwise resulted. Here we examined the consequences of single and repeat OBI and the benefit provided by raloxifene, an FDA-approved estrogen receptor drug that possesses noteworthy CB2 inverse agonism. After single OBI, although the amplitudes of the A- and B-waves of the electroretinogram and pupil light response appeared to be normal, the mice showed hints of deficits in contrast sensitivity and visual acuity, a trend toward optic nerve axon loss, and significantly increased light aversion, which were reversed by 2 weeks of daily treatment with raloxifene. Mice subjected to repeat OBI (5 blasts spaced 1 min apart), exhibited more severe visual deficits, including decreases in contrast sensitivity, visual acuity, the amplitudes of the A- and B-waves of the electroretinogram, light aversion, and resting pupil diameter (i.e. hyperconstriction), accompanied by the loss of photoreceptor cells and optic nerve axons, nearly all of which were mitigated by raloxifene. Interestingly, optic nerve axon abundance was strongly correlated with contrast sensitivity and visual acuity across all groups of experimental mice in the repeat OBI study, suggesting optic nerve axon loss with rOBI and its attenuation with raloxifene are associated with the extent of these two deficits while photoreceptor abundance was highly correlated with A-wave amplitude and resting pupil size, suggesting a prominent role for photoreceptors in these two deficits. Quantitative PCR (qPCR) showed levels of M1-type microglial markers (e.g. iNOS, IL1β, TNFα, and CD32) in retina, optic nerve, and thalamus were increased 3 days after repeat OBI. With raloxifene treatment, the overall expression of M1 markers was more similar to that in sham mice. Raloxifene treatment was also associated with the elevation of IL10 transcripts in all three tissues compared to repeat OBI alone, but the results for the three other M2 microglial markers we examined were more varied. Taken together, the qPCR results suggest that raloxifene benefit for visual function and pathology was associated with a lessening of the pro-inflammatory actions of microglia. The benefit we find for raloxifene following OBI provides a strong basis for phase-2 efficacy testing in human clinical trials for treating ocular injury.

Spontaneous Recovery of Traumatic Unilateral Superior Oblique Palsy and Ocular Factors for Predicting Prognosis

Purpose

Methods

Results

Conclusions

Raloxifene Modulates Microglia and Rescues Visual Deficits and Pathology After Impact Traumatic Brain Injury

Mild traumatic brain injury (TBI) involves widespread axonal injury and activation of microglia, which initiates secondary processes that worsen the TBI outcome. The upregulation of cannabinoid type-2 receptors (CB2) when microglia become activated allows CB2-binding drugs to selectively target microglia. CB2 inverse agonists modulate activated microglia by shifting them away from the harmful pro-inflammatory M1 state toward the helpful reparative M2 state and thus can stem secondary injury cascades. We previously found that treatment with the CB2 inverse agonist SMM-189 after mild TBI in mice produced by focal cranial blast rescues visual deficits and the optic nerve axon loss that would otherwise result. We have further shown that raloxifene, which is Food and Drug Administration (FDA)-approved as an estrogen receptor modulator to treat osteoporosis, but also possesses CB2 inverse agonism, yields similar benefit in this TBI model through its modulation of microglia. As many different traumatic events produce TBI in humans, it is widely acknowledged that diverse animal models must be used in evaluating possible therapies. Here we examine the consequences of TBI created by blunt impact to the mouse head for visual function and associated pathologies and assess raloxifene benefit. We found that mice subjected to impact TBI exhibited decreases in contrast sensitivity and the B-wave of the electroretinogram, increases in light aversion and resting pupil diameter, and optic nerve axon loss, which were rescued by daily injection of raloxifene at 5 or 10 mg/ml for 2 weeks. Raloxifene treatment was associated with reduced M1 activation and/or enhanced M2 activation in retina, optic nerve, and optic tract after impact TBI. Our results suggest that the higher raloxifene dose, in particular, may be therapeutic for the optic nerve by enhancing the phagocytosis of axonal debris that would otherwise promote inflammation, thereby salvaging less damaged axons. Our current work, together with our prior studies, shows that microglial activation drives secondary injury processes after both impact and cranial blast TBI and raloxifene mitigates microglial activation and visual system injury in both cases. The results thus provide a strong basis for phase 2 human clinical trials evaluating raloxifene as a TBI therapy.

Visual Dysfunction after Repetitive Mild Traumatic Brain Injury in a Mouse Model and Ramifications on Behavioral Metrics

Mild traumatic brain injury (mTBI) is a major cause of morbidity and mortality with a poorly understood pathophysiology. Animal models have been increasingly utilized to better understand mTBI and recent research has identified visual deficits in these models that correspond to human literature. While visual impairment is being further characterized within TBI, the implications of impaired vision on behavioral tasks commonly utilized in animal models has not been well described thus far. Visual deficits may well confound behavioral tests that are believed to be isolated to cognitive functioning such as learning and memory. We utilized a mouse model of repetitive mTBI (rmTBI) to further characterize visual deficits using an optomotor task, electroretinogram, and visually evoked potential, and located likely areas of damage to the visual pathway. Mice were tested on multiple behavioral metrics, including a touchscreen conditional learning task to better identify the contribution of visual dysfunction to behavioral alterations. We found that rmTBI caused visual dysfunction resulting from damage distal to the retina that likely involves pathology within the optic nerve. Moreover, loss of vision led to poorer performance of rmTBI animals on classic behavioral tests such as the Morris water maze that would otherwise be attributed solely to learning and memory deficits. The touchscreen conditional learning task was able to differentiate rmTBI induced learning and memory dysfunction from visual impairment and is a valuable tool for elucidating subtle changes resulting from TBI.

Afferent Visual Manifestations of Traumatic Brain Injury

Traumatic brain injury (TBI) causes structural and functional damage to the central nervous system including the visual pathway. Defects in the afferent visual pathways affect visual function and in severe cases cause complete visual loss. Visual dysfunction is detectable by structural and functional ophthalmic examinations that are routine in the eye clinic, including examination of the pupillary light reflex and optical coherence tomography (OCT). Assessment of pupillary light reflex is a non-invasive assessment combining afferent and efferent visual function. While a assessment using a flashlight is relatively insensitive, automated pupillometry has 95% specificity and 78.1% sensitivity in detecting TBI-related visual and cerebral dysfunction with an area under the curve of 0.69-0.78. OCT may also serve as a noninvasive biomarker of TBI severity, demonstrating changes in the retinal ganglion cell layer and nerve fiber layer throughout the range of TBI severity even in the absence of visual symptoms. This review discusses the impact of TBI on visual structure and function.

Rebuilding Microbiome for Mitigating Traumatic Brain Injury: Importance of Restructuring the Gut-Microbiome-Brain Axis

Traumatic brain injury (TBI) is a damage to the brain from an external force that results in temporary or permanent impairment in brain functions. Unfortunately, not many treatment options are available to TBI patients. Therefore, knowledge of the complex interplay between gut microbiome (GM) and brain health may shed novel insights as it is a rapidly expanding field of research around the world. Recent studies show that GM plays important roles in shaping neurogenerative processes such as blood-brain-barrier (BBB), myelination, neurogenesis, and microglial maturation. In addition, GM is also known to modulate many aspects of neurological behavior and cognition; however, not much is known about the role of GM in brain injuries. Since GM has been shown to improve cellular and molecular functions via mitigating TBI-induced pathologies such as BBB permeability, neuroinflammation, astroglia activation, and mitochondrial dysfunction, herein we discuss how a dysbiotic gut environment, which in fact, contributes to central nervous system (CNS) disorders during brain injury and how to potentially ward off these harmful effects. We further opine that a better understanding of GM-brain (GMB) axis could help assist in designing better treatment and management strategies in future for the patients who are faced with limited options.

Vision therapy as part of neurorehabilitation after acquired brain injury - a clinical study in an outpatient setting

Introduction: Oculomotor (OM) functions may be affected by acquired brain injury (ABI). The ability to benefit from rehabilitation or to perform daily activities may be affected by OM dysfunctions and associated symptoms. The purpose of this study was to investigate the effects of vision therapy (VT) as part of neurorehabilitation after ABI.Materials and Methods: The study included two groups of outpatients (median 49.5-52.0 years, range 27-67) admitted to neurorehabilitation due to moderate to severe ABI. One group received VT while the other group served as controls to monitor the course of OM dysfunctions without VT.Results: The intervention group showed significant improvements in convergence (Z = 2.26, p = .02), vergence facility (Z = -2.16, p = .03) and vergence reserves (Z = -2.44, p < .01 and t = -4.47, DF = 15, p < .01) along with a significant reduction in vision-related symptoms (Z = 2.97, p < .01).Discussion: We conclude that OM issues were frequent and that targeted VT, as part of neurorehabilitation, can be an efficient treatment resulting in improved functions and reduced symptoms. Further study will be required to understand how improved functions link to performance and satisfaction with everyday activities.

CT Features of Posttraumatic Vision Loss

Clinical evaluation of patients with trauma is challenging, especially in the presence of neurologic injuries. Vision loss after trauma is a harmful and usually overlooked consequence that may be avoided with a prompt and accurate intervention. Head CT is commonly performed in patients with trauma. However, radiologists may be unfamiliar with the CT findings associated with injuries that may affect eyesight. Understanding the visual pathway anatomy and its critical landmarks is paramount for recognizing these findings. This article describes the use of head CT to evaluate the visual pathway to help avoid vision loss in patients with trauma. Injuries are presented in terms of those affecting the globe (rupture, hemorrhage, and lens trauma), optic nerve (direct and indirect traumatic optic neuropathy), orbit (orbital compression syndrome), and vasculature (traumatic carotid-cavernous sinus fistula and posterior cerebral artery injury or ischemia). Techniques for measuring the globe on CT to assess for injury are illustrated. Indications for screening CTA of the head and neck in patients with suspicion for blunt traumatic vascular injury are summarized. Emphasis is placed on the CT findings that warrant an emergency intervention to prevent traumatic visual impairment.

Visual problems associated with traumatic brain injury

Traumatic brain injury (TBI) and its associated concussion are major causes of disability and death. All ages can be affected but children, young adults and the elderly are particularly susceptible. A decline in mortality has resulted in many more individuals living with a disability caused by TBI including those affecting vision. This review describes: (1) the major clinical and pathological features of TBI; (2) the visual signs and symptoms associated with the disorder; and (3) discusses the assessment of quality of life and visual rehabilitation of the patient. Defects in primary vision such as visual acuity and visual fields, eye movement including vergence, saccadic and smooth pursuit movements, and in more complex aspects of vision involving visual perception, motion vision ('akinopsia'), and visuo-spatial function have all been reported in TBI. Eye movement dysfunction may be an early sign of TBI. Hence, TBI can result in a variety of visual problems, many patients exhibiting multiple visual defects in combination with a decline in overall health. Patients with chronic dysfunction following TBI may require occupational, vestibular, cognitive and other forms of physical therapy. Such patients may also benefit from visual rehabilitation, including reading-related oculomotor training and the prescribing of spectacles with a variety of tints and prism combinations.

Isolated Internuclear Ophthalmoplegia After Massive Supratentorial Epidural Hematoma: A Case Report and Review of the Literature

BACKGROUND

Isolated internuclear ophthalmoplegia (INO) after traumatic brain injury (TBI) is rare, with most reported patients having minor head injuries. We report a patient with INO after a massive supratentorial epidural hematoma. We review the literature published since 1966, to summarize the mechanisms of injury and clinical outcomes of INO after TBI.

CASE DESCRIPTION AND LITERATURE REVIEW

A 54-year-old woman had isolated INO 10 hours after emergent evacuation of a massive supratentorial epidural hematoma. The brainstem displacement caused by downward herniation led to a deficient blood supply. Magnetic resonance imaging showed an infarct at the right dorsal-medial pons. Her symptoms partially improved by 1.5 months postoperatively. A total of 27 patients, including ours, with INO after TBI have been reported over the past 50 years. Young male patients (mean age, 30.8 years; male, 67%) are more common, and INO tends to be bilateral (67%). Infarction, hemorrhage, and fiber injury are nearly equally responsible for causing INO (35%, 35%, and 30%, respectively). Most patients recover spontaneously; 65% gain full recovery at a median time of 3 months, and 91% have at least partial recovery at 4.5 months. The median time for full recovery after infarct, hemorrhage, and fiber injury is 12, 90, and 150 days, respectively.

CONCLUSIONS

INO should be in the differential diagnosis of patients with TBI with an adduction deficit, despite the rarity of the condition. Isolated INO is a relatively benign sequela of TBI, with all but 1 reported patient achieving at least partial recovery over 12 months.

Assessing subacute mild traumatic brain injury with a portable virtual reality balance device

PURPOSE

Balance impairment is a common sensorimotor symptom in mild traumatic brain injury (mTBI). We designed an affordable, portable virtual reality (VR)-based balance screening device (Virtual Environment TBI Screen [VETS]), which will be validated relative to the Neurocom Sensory Organization Test (SOT) to determine if it can replace commonly used postural assessments.

METHODS

This preliminary study examines healthy adults (n = 56) and adults with mTBI (n = 11). Participants performed six upright postural tasks on the VETS and the SOT. Analysis of variance was used to determine between-group differences. Pearson's correlations were used to establish construct validity. Known-groups approach was used to establish classification accuracy.

RESULTS

The mTBI cohort performed significantly worse than the healthy cohort on the new device (p = 0.001). The new device has 91.0% accuracy and an ROC curve with a significant area-under-the-curve (AUC = 0.865, p < 0.001). Conditions with dynamic visual stimulation were the most sensitive to health status. The SOT had an 84.8% accuracy and AUC =0.703 (p = 0.034).

CONCLUSIONS

The new VR-based device is a valid measure for detecting balance impairment following mTBI and can potentially replace more expensive and cumbersome equipment. Assessments that test visual-vestibular processing, such as VETS, increase sensitivity to mTBI-related balance deficits, which can be used to guide rehabilitation. Implications for rehabilitation Emerging technology using virtual reality can be economically integrated into the clinical setting for easy testing of postural control in neurologically impaired populations. Tailoring postural assessments to include tasks that rely on visual and vestibular integration will increase the accuracy of detecting balance impairment following mild traumatic brain injury.

The Craig Hospital Eye Evaluation Rating Scale (CHEERS)

BACKGROUND

Oculomotor deficits in smooth pursuit, saccades, vestibular-ocular reflex (VOR), vergence, and fixation are common problems seen after moderate to severe traumatic brain injury (TBI). No scale currently exists to rate all of these together. The Craig Hospital Eye Evaluation Rating Scale (CHEERS) was designed to systematically quantify frequency and severity of eye movement deficits in TBI.

OBJECTIVE

To assess the intra- and interrater reliability of a new rating scale for detecting the presence and degree of 5 oculomotor abnormalities after TBI.

DESIGN

A reliability study.

SETTING

This was an institution-based study at Craig Rehabilitation Hospital.

PARTICIPANTS

English-speaking patients between ages 18 and 65 years with a primary diagnosis of moderate to severe mechanical TBI and who were not blind in either eye were eligible.

METHODS

Between October 2013 and March 2014, a total of 11 TBI patients and 9 non-TBI controls were enrolled in the study. The median age was 30 years (range, 18-74 years) for subjects and 52 years (range, 28-63 years) for controls. All patients were male, and 8 of 9 controls were female. Eye movements (fixation, smooth pursuit, saccade, convergence, and vestibular-ocular reflex) were recorded for each on digital video. They were rated on 2 separate occasions by each of the 2 raters.

MAIN OUTCOME MEASUREMENTS

Inter- and intrarater reliability tests.

RESULTS

Median elapsed time between the first and second ratings was 7 days (range, 5-44 days). Intrarater agreement was very strong (Spearman ρ ≥ 0.900) for pursuit, saccades, and VOR for both raters, and strong (Spearman ρ ≥ 0.710) for vergence and fixation. The interrater agreement for detecting presence of any oculomotor abnormality was substantial (unweighted κ = 0.63). The interrater concordance on the full range of scale scoring was strongest on the VOR test (weighted κ = 0.98), was substantial for vergence, pursuit, saccades, and total score (weighted κ > 0.60), and was moderate for fixation. For TBI patients, every eye movement rated was found to be more abnormal than compared to those in the controls.

CONCLUSIONS

CHEERS is a reliable scale for assessing and quantifying oculomotor deficits commonly observed in moderate to severe TBI. Further studies to validate the scale's utility in outcome prediction, and its applicability to broader brain injury populations, are warranted.

LEVEL OF EVIDENCE

IV.

Sub-Chronic Neuropathological and Biochemical Changes in Mouse Visual System after Repetitive Mild Traumatic Brain Injury

Repetitive mild traumatic brain injury (r-mTBI) results in neuropathological and biochemical consequences in the human visual system. Using a recently developed mouse model of r-mTBI, with control mice receiving repetitive anesthesia alone (r-sham) we assessed the effects on the retina and optic nerve using histology, immunohistochemistry, proteomic and lipidomic analyses at 3 weeks post injury. Retina tissue was used to determine retinal ganglion cell (RGC) number, while optic nerve tissue was examined for cellularity, myelin content, protein and lipid changes. Increased cellularity and areas of demyelination were clearly detectable in optic nerves in r-mTBI, but not in r-sham. These changes were accompanied by a ~25% decrease in the total number of Brn3a-positive RGCs. Proteomic analysis of the optic nerves demonstrated various changes consistent with a negative effect of r-mTBI on major cellular processes like depolymerization of microtubules, disassembly of filaments and loss of neurons, manifested by decrease of several proteins, including neurofilaments (NEFH, NEFM, NEFL), tubulin (TUBB2A, TUBA4A), microtubule-associated proteins (MAP1A, MAP1B), collagen (COL6A1, COL6A3) and increased expression of other proteins, including heat shock proteins (HSP90B1, HSPB1), APOE and cathepsin D. Lipidomic analysis showed quantitative changes in a number of phospholipid species, including a significant increase in the total amount of lysophosphatidylcholine (LPC), including the molecular species 16:0, a known demyelinating agent. The overall amount of some ether phospholipids, like ether LPC, ether phosphatidylcholine and ether lysophosphatidylethanolamine were also increased, while the majority of individual molecular species of ester phospholipids, like phosphatidylcholine and phosphatidylethanolamine, were decreased. Results from the biochemical analysis correlate well with changes detected by histological and immunohistochemical methods and indicate the involvement of several important molecular pathways. This will allow future identification of therapeutic targets for improving the visual consequences of r-mTBI.

Metabolic, hereditary, traumatic, and neoplastic optic neuropathies

PURPOSE OF REVIEW

Toxic, nutritional, hereditary, traumatic, and neoplastic optic neuropathies result in significant disability due to visual dysfunction. Many of these conditions are treatable. Early diagnosis may allow for intervention to stabilize or improve vision and prevent unnecessary testing. These conditions have overlapping clinical features, and careful assessment of the visual system allows for accurate diagnosis and management.

RECENT FINDINGS

Newer treatment strategies are available for optic neuropathies previously thought untreatable, such as some hereditary optic neuropathies. Many conditions that previously were felt to represent distinct diseases can be linked by a common pattern of mitochondrial dysfunction.

SUMMARY

The optic nerve is susceptible to a wide variety of pathologic processes. The correct diagnosis depends on a thorough history and detailed evaluation of the visual system. Certain optic neuropathies selectively affect the papillomacular bundle, and particular attention to this location can considerably narrow the differential diagnosis and subsequent workup.