Photophobia Associated with Traumatic Brain Injury: A Systematic Review and Meta-analysis

Characterization of Mild Traumatic Brain Injury Cohort With Photophobia From the Defense and Veterans Eye Injury and Vision Registry

INTRODUCTION

Photophobia is a common visual symptom following mild traumatic brain injury (mTBI), which can adversely affect the military readiness and performance of service members (SMs). We employed the Defense and Veterans Eye Injury and Vision Registry (DVEIVR) to identify and describe a cohort of SMs diagnosed with photophobia post-mTBI. The objective of this study was to characterize comorbid conditions and symptoms in an mTBI cohort with photophobia, to assess their co-occurrence, to describe the persistence of photophobia, and to assess the effectiveness of utilization of currently available International Statistical Classification of Diseases and Related Health Problems (ICD) codes in reporting photophobia in this cohort.

MATERIALS AND METHODS

The DVEIVR database was searched to identify a cohort of SMs experiencing photophobia after mTBI. Photophobia and other potentially related conditions and symptoms, both coded and descriptive, which were abstracted directly from the medical records of SMs, were found within DVEIVR. The presence of the conditions and symptoms comorbid with photophobia was characterized on both patient and encounter levels. Analysis of co-occurrence of photophobia with these conditions or symptoms was performed on the encounter level using co-occur package in the statistical program R. Persistence of photophobia up to 1 year since the injury was assessed. The utilization of currently available ICD codes for photophobia was analyzed.

RESULTS

A total of 639 SMs exhibiting photophobia after mTBI were identified in DVEIVR. Headaches, including migraines, were the most frequently experienced comorbidity affecting 92% of the SMs in the cohort. The second most frequent complaint was dizziness and/or vertigo (53%) followed by nausea (42%), blurry vision (31%), and irritation and discomfort in the eye (17%). In all, 20% of encounters with photophobia had a complaint of headaches, followed by 8.3% of photophobia encounters co-occurring with dizziness and vertigo, 5.7%-with nausea, 4.5%-with blurred vision, and 2.1%-with subjective sensations in the eye. All comorbidities co-occurred with photophobia at probabilities higher than by chance alone. The percentage of mTBI SMs experiencing photophobia declined to 20% at 30 days after the injury, 17% at 3 months, 12% at 6 months, and 7% at 12  months post-injury, respectively. The use of currently available ICD codes for photophobia was very low-only 27.1% of the cohort had at least 1 ICD code recorded in their medical records.

CONCLUSIONS

The results of this study support the idea that there is a strong relationship between photophobia and headache after an mTBI. Additional research is warranted to better understand this relationship and its causes so that clinical management improves. The results of this study show a precipitous decline in the numbers of cases of photophobia after mTBI over the first 30 days and a longer-term persistence up to a year in a minority of cases, which is consistent with other research in this field. Various ICD codes, which are currently used to code for photophobia, along with other vision conditions, were not widely used to document photophobia symptoms. It is important to adopt a dedicated ICD code for photophobia to improve the surveillance, data collection, and analysis of this condition.

Trigeminal Sensitization in a Closed Head Model for Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is often accompanied by neurological and ocular symptoms that involve trigeminal nerve pathways. Laser-induced shock wave (LISW) was applied to the skull of male rats as a model for mTBI, while behavioral and neural recording methods were used to assess trigeminal function. The LISW caused greater eye wiping behavior to ocular instillation of hypertonic saline (Sham = 4.83 ± 0.65 wipes/5 min, LISW = 12.71 ± 1.89 wipes/5 min, p < 0.01) and a marked reduction in the time spent in bright light consistent with enhanced periocular and intraocular hypersensitivity, respectively (Sham = 16.3 ± 5.6 s, LISW = 115.5 ± 27.3 s, p < 0.01). To address the early neural mechanisms of mTBI, single trigeminal brainstem neurons, identified by activation to corneal or dural mechanical stimulation, were recorded in trigeminal subnucleus interpolaris/caudalis (Vi/Vc) and trigeminal subnucleus caudalis/upper cervical cord (Vc/C1) regions. The LISW caused marked sensitization to hypertonic saline and to exposure to bright light in neurons of both regions (p < 0.05). Laser speckle imaging revealed an increase in meningeal arterial blood flow to bright light after LISW (Sham = 4.7 ± 2.0 s, LISW = 469.0 ± 37.9 s, p < 0.001). Local inhibition of synaptic activity at Vi/Vc, but not at Vc/C1, by microinjection of CoCl2, prevented light-evoked increases in meningeal blood flow in LISW-treated rats. By contrast, topical meningeal application of phenylephrine significantly reduced light-evoked responses of Vi/Vc and Vc/C1 neurons. These data suggested that neurons in both regions became sensitized after LISW and were responsive to changes in meningeal blood flow. Neurons at the Vi/Vc transition and at Vc/C1, however, likely serve different roles in mediating the neurovascular and sensory aspects of mTBI.

Henle fiber layer thickening and deficits in objective retinal function in participants with a history of multiple traumatic brain injuries

Introduction

This study tested whether multiple traumatic brain injuries (TBIs) alter the structure of the Henle fiber layer (HFL) and degrade cell-specific function in the retinas of human participants.

Methods

A cohort of case participants with multiple TBIs and a cohort of pair-matched control participants were prospectively recruited. Directional optical coherence tomography and scanning laser polarimetry measured HFL thickness and phase retardation, respectively. Full-field flash electroretinography (fERG) assessed retinal function under light-adapted (LA) 3.0, LA 30 Hz, dark-adapted (DA) 0.01, DA 3.0, and DA 10 conditions. Retinal imaging and fERG outcomes were averaged between both eyes, and paired t-tests or Wilcoxon signed-rank tests analyzed inter-cohort differences.

Results

Global HFL thickness was significantly (p = 0.02) greater in cases (8.4 ± 0.9 pixels) than in controls (7.7 ± 1.1 pixels). There was no statistically significant difference (p = 0.91) between the cohorts for global HFL phase retardation. For fERG, LA 3.0 a-wave amplitude was significantly reduced (p = 0.02) in cases (23.5 ± 4.2 μV) compared to controls (29.0 ± 8.0 μV). There were no other statistically significant fERG outcomes between the cohorts.

Discussion

In summary, the HFL thickens after multiple TBIs, but phase retardation remains unaltered in the macula. Multiple TBIs may also impair retinal function, indicated by a reduction in a-wave amplitude. These results support the potential of the retina as a site to detect TBI-associated pathology.

Conservative Management of Acute Sports-Related Concussions: A Narrative Review

This review explores the application of the conservative management model for pain to sports-related concussions (SRCs), framing concussions as a distinct form of pain syndrome with a pathophysiological foundation in central sensitization. Drawing parallels with proven pain management models, we underscore the significance of a proactive approach to concussion management. Recognizing concussions as a pain syndrome allows for the tailoring of interventions in alignment with conservative principles. This review first covers the epidemiology and controversies surrounding prolonged concussion recovery and persistent post-concussion symptoms (PPCS). Next, the pathophysiology of concussions is presented within the central sensitization framework, emphasizing the need for early intervention to mitigate the neuroplastic changes that lead to heightened pain sensitivity. Five components of the central sensitization process specific to concussion injuries are highlighted as targets for conservative interventions in the acute period: peripheral sensitization, cerebral metabolic dysfunction, neuroinflammation, glymphatic system dysfunction, and pain catastrophizing. These proactive interventions are emphasized as pivotal in accelerating concussion recovery and reducing the risk of prolonged symptoms and PPCS, in line with the philosophy of conservative management.

TDP43 pathology in chronic traumatic encephalopathy retinas

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with repetitive head trauma. Brain pathology in CTE is characterized by neuronal loss, gliosis, and a distinctive pattern of neuronal accumulation of hyper-phosphorylated tau (p-tau) and phospho-TDP43 (p-TDP43). Visual anomalies have been reported by patients with CTE, but the ocular pathology underlying these symptoms is unknown. We evaluated retinal pathology in post-mortem eyes collected from 8 contact sport athletes with brain autopsy-confirmed stage IV CTE and compared their findings to retinas from 8 control patients without CTE and with no known history of head injury. Pupil-optic nerve cross sections were prepared and stained with hematoxylin and eosin (H&E), p-tau, p-TDP43, and total TDP43 by immunohistochemistry. No significant retinal degeneration was observed in CTE eyes compared to control eyes by H&E. Strong cytoplasmic p-TDP43 and total TDP43 staining was found in 6/8 CTE eyes in a subset of inner nuclear layer interneurons (INL) of the retina, while only 1/8 control eyes showed similar p-TDP43 pathology. The morphology and location of these inner nuclear layer interneurons were most compatible with retinal horizontal cells, although other retinal cell types present in INL could not be ruled out. No p-tau pathology was observed in CTE or control retinas. These findings identify novel retinal TDP43 pathology in CTE retinas and support further investigation into the role of p-TDP43 in producing visual deficits in patients with CTE.

Factors related to adverse long-term outcomes after mild traumatic brain injury in children: a scoping review

OBJECTIVE

To identify demographic, premorbid and injury-related factors, or biomarkers associated with long-term (≥3 months) adverse outcomes in children after mild traumatic brain injury (mTBI).

DESIGN

Scoping review of literature.

PATIENTS

Children and adolescents with mTBI.

RISK FACTORS

Any demographic, premorbid and injury-related factors, or biomarkers were included. We excluded genetic and treatment-related factors.

MAIN OUTCOME MEASURES

Postconcussion syndrome (PCS), recovery.

RESULTS

Seventy-three publications were included, reporting 12 long-term adverse outcomes, including PCS in 12 studies and recovery in 29 studies. Additional outcomes studied were symptom scores/severity (n=22), quality of life (n=9) and cognitive function (n=9). Forty-nine risk factors were identified across studies. Risk factors most often assessed were sex (n=28), followed by age (n=23), injury mechanism = (n=22) and prior mTBI (n=18). The influence of these and other risk factors on outcomes of mTBI were inconsistent across the reviewed literature.

CONCLUSIONS

The most researched risk factors are sex, age and mechanism of injury, but their effects have been estimated inconsistently and did not show a clear pattern. The most studied outcomes are recovery patterns and symptom severity. However, these may not be the most important outcomes for clinicians and patients. Future primary studies in this area should focus on patient-important outcomes. Population-based prospective studies are needed that address prespecified hypotheses on the relationship of risk factors with given outcomes to enable reliable prediction of long-term adverse outcomes for childhood mTBI.

Hypersensitivity to Noise and Light Over 1 Year After Mild Traumatic Brain Injury: A Longitudinal Study on Self-Reported Hypersensitivity and Its Influence on Long-Term Anxiety, Depression, and Quality of Life

OBJECTIVE

This study aimed to investigate (1) the prevalence of self-reported sensory hypersensitivity (noise [NS] and light [LS]) over 1 year after mild traumatic brain injury (mTBI) in adults and (2) the impact of NS and LS measured 2 weeks after injury on long-term outcomes 12 months postinjury, while controlling for postconcussion symptoms.

SETTING

Participants were recruited from 6 hospitals in the south of the Netherlands and were tested 4 times (2 weeks, 3 months, 6 months, and 12 months postinjury), using self-report questionnaires.

PARTICIPANTS

In total, 186 mTBI participants (diagnosed using WHO [World Health Organization]/EFNS [European Federation of Neurological Societies] criteria at the neurology/emergency department) and 181 participants with a minor orthopedic injury in their extremities (control group).

DESIGN

An observational, longitudinal, multicenter cohort study.

MAIN MEASURES

NS and LS items (Rivermead Post-Concussion Symptoms Questionnaire) were used as main outcome variables to determine sensory hypersensitivity symptoms. Additional outcomes included anxiety, depression, health-related quality of life (HRQoL), and life satisfaction.

RESULTS

There was an elevated prevalence of NS and LS between 2 weeks and 3 months after injury in the mTBI group compared with controls. Approximately 3% of mTBI patients had persistent hypersensitivity symptoms during the whole course of the study. At 12 months postinjury, the mTBI and control groups did not differ in the prevalence of persistent hypersensitivity symptoms. There was no evidence of a predictive value of hypersensitivity within 2 weeks postinjury on anxiety, depression, HRQoL, or life satisfaction, 12 months later after controlling for postconcussion symptoms.

CONCLUSIONS

These results not only confirm the presence of hypersensitivity symptoms after mTBI in the subacute stage but also provide assurance about the small size of the group that experiences persistent symptoms. Furthermore, there was no evidence that early NS and LS are uniquely associated with long-term emotional and quality-of-life outcomes, over and above general levels of postconcussion symptoms.

Traumatic Brain Injury and Vision

Traumatic brain injury disrupts the complex anatomy of the afferent and efferent visual pathways. Injury to the afferent pathway can result in vision loss, visual field deficits, and photophobia. Injury to the efferent pathway primarily causes eye movement abnormalities resulting in ocular misalignment and double vision. Injury to both the afferent and efferent systems can result in significant visual disability.

Optometric Brain Injury Curriculum in Federal Residency Training Programs: A Consensus Report

INTRODUCTION

Brain injury often impacts the visual system. Diagnosis and treatment of visual system problems related to brain injury is a field with less settled science and more variation in practice than most specialty fields. Most optometric brain injury residency programs are in federal clinics (VA and DoD). A consensus core curriculum has been created that will allow some consistency while facilitating program strengths.

MATERIALS AND METHODS

Kern's curriculum development model and a focus group of subject matter experts were used to reach consensus in producing a core curriculum to provide a common framework for brain injury optometric residency programs.

RESULTS

A common high-level curriculum was developed with educational goals through consensus.

CONCLUSIONS

In a relatively new subspeciality without a firm foundation of settled science, a common curriculum will help provide a common framework to facilitate clinical and research progress in this field. The process sought out expertise and community building to help improve the adoption of this curriculum. This core curriculum will provide a framework for educating optometric residents in the diagnosis, management, and rehabilitation of patients with visual sequelae because of brain injury. It is intended to ensure that appropriate topics are covered while allowing for flexibility according to each program's strengths and resources.

Structure and function of retinal ganglion cells in subjects with a history of repeated traumatic brain injury

This study tested whether repeated traumatic brain injuries (TBIs) alter the objective structure or the objective function of retinal ganglion cells (RGCs) in human subjects recruited from an optometry clinic. Case subjects (n = 25) with a history of repeated TBIs (4.12 ± 2.76 TBIs over 0-41 years) and healthy pair-matched control subjects (n = 30) were prospectively recruited. Retinal nerve fiber layer (RNFL) thickness was quantified with spectral-domain optical coherence tomography, and scanning laser polarimetry measured RNFL phase retardation. Measurements of the photopic negative response were made using full-field flash electroretinography. There was no statistically significant difference (p = 0.42) in global RNFL thickness between the case cohort (96.6 ± 9.4 microns) and the control cohort (94.9 ± 7.0 microns). There was no statistically significant difference (p = 0.80) in global RNFL phase retardation between the case cohort (57.9 ± 5.7 nm) and the control cohort (58.2 ± 4.6 nm). There were no statistically significant differences in the peak time (p = 0.95) of the PhNR or in the amplitude (p = 0.11) of the PhNR between the case cohort (69.9 ± 6.9 ms and 24.1 ± 5.1 μV, respectively) and the control cohort (70.1 ± 8.9 ms and 27.8 ± 9.1 μV, respectively). However, PhNR amplitude was more variable (p < 0.025) in the control cohort than in the case cohort. Within the case cohort, there was a strong positive (r = 0.53), but not statistically significant (p = 0.02), association between time since last TBI and PhNR amplitude. There was also a modest positive (r = 0.45), but not statistically significant (p = 0.04), association between time since first TBI and PhNR amplitude. Our results suggest that there were no statistically significant differences in the objective structure or in the objective function of RGCs between the case cohort and the control cohort. Future large, longitudinal studies will be necessary to confirm our negative results and to more fully investigate the potential interaction between PhNR amplitude and time since first or last TBI.

Montreal Brain Injury Vision Screening Test for General Practitioners

Visual disturbances are amongst the most commonly reported symptoms after a traumatic brain injury (TBI) despite vision testing being uncommon at initial clinical evaluation. TBI patients consistently present a wide range of visual complaints, including photophobia, double vision, blurred vision, and loss of vision which can detrimentally affect reading abilities, postural balance, and mobility. In most cases, especially in rural areas, visual disturbances of TBI would have to be diagnosed and assessed by primary care physicians, who lack the specialized training of optometry. Given that TBI patients have a restricted set of visual concerns, an opportunity exists to develop a screening protocol for specialized evaluation by optometrists—one that a primary care physician could comfortably carry out and do so in a short time. Here, we designed a quick screening protocol that assesses the presence of core visual symptoms present post-TBI. The MOBIVIS (Montreal Brain Injury Vision Screening) protocol takes on average 5 min to perform and is composed of only “high-yield” tests that could be performed in the context of a primary care practice and questions most likely to reveal symptoms needing further vision care management. The composition of our proposed protocol and questionnaire are explained and discussed in light of existing protocols. Its potential impact and ability to shape a better collaboration and an integrative approach in the management of mild TBI (mTBI) patients is also discussed.

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.