# Terson syndrome

Terson syndrome or Terson's syndrome is a condition where eye haemorrhages occur due to intracranial bleeding, most often associated with subarachnoid haemorrhage (SAH), commonly from a ruptured cerebral aneurysm. Patients may experience blurred vision, floaters, or complete vision loss due to retinal or vitreous haemorrhage, and neurological symptoms like severe headaches, nausea, seizures, and confusion may also arise. Diagnosis is challenging as the eye bleeding can resemble other conditions, such as diabetic retinopathy or retinal vein occlusion. A fundoscopic exam is the primary diagnostic method, but imaging like CT, MRI, and OCT can aid in confirming the diagnosis. Treatment involves managing intracranial pressure and haemorrhage, with options like vitrectomy or anti-VEGF injections for persistent eye bleeds. The prognosis depends on the severity of both neurological and ocular damage, with early intervention improving recovery chances. However, recurrence risks exist depending on the underlying cause of the haemorrhage. Research continues on improving early diagnosis, surgical approaches, and understanding the genetic and molecular factors influencing the disease.

## History

An instance of intraretinal hemorrhage coexisting with subarachnoid hemorrhage (SAH) was initially documented by German ophthalmologist Moritz Litten in 1881. In 1900, French ophthalmologist Albert Terson reported a link between SAH—later known as Terson syndrome—and vitreous hemorrhage. This syndrome includes many kinds of intraocular hemorrhages, usually caused by a sudden increase in intracranial pressure (ICP), which can happen in combination with SAH, intracerebral hemorrhage, or traumatic brain injury.
The vitreous, sub-hyaloid, subretinal space, intraretinal regions, or beneath the internal limiting membrane are some of the locations where the hemorrhages may occur in the eye. According to Sohan Hayreh, the rupture of capillaries in the optic nerve, which is most likely brought on by elevated retinal venous pressure from central retinal vein compression, is the source of these retinal hemorrhages. The intricate vascular connections between the brain and the eye are highlighted by the fact that Terson syndrome is most frequently observed after aneurysmal subarachnoid hemorrhages. This emphasizes how crucial it is to diagnose and treat the illness using a thorough, interdisciplinary approach. Terson syndrome occurs in about 13% of SAH patients, especially in more severe instances (shown by a higher Hunt-Hess score), and these cases are linked to a higher risk of death. Persistent vision impairment can cause problems carrying out daily tasks, which might lower one's quality of life or cause psychological suffering like anxiety or depression. In certain instances, vision may return to almost normal levels as the blood in the eye gradually clears itself without the need for major treatment. However, depending on how severe the initial bleeding was, this procedure may take weeks or months.

## Signs and symptoms

Temporary Terson's Syndrome symptoms and indicators include abrupt vision loss or blurred vision in one or both eyes, being the most obvious signs of Terson's syndrome. The reason behind this is that blood in the vitreous or retinal layers blocks light from reaching the retina. The extent and location of the intraocular hemorrhage determine the degree of vision impairment. Because of clots or debris in the vitreous cavity, patients may suffer floaters, which are spots or threads in their field of vision. In extreme situations, extensive vitreous bleeding may result in a total loss of the red reflex. Patients frequently exhibit signs of Terson's syndrome because the illness frequently coexists with cerebral hemorrhages such as subarachnoid hemorrhage (SAH). These could include a severe headache (referred to as a "thunderclap headache" in situations of SAH), nausea and vomiting, changed mental status or confusion, and stiff neck (caused by meningism connected to SAH). The symptoms and indicators of Terson's syndrome that persist throughout time are Long-term vision impairments may result if the intraocular hemorrhage is not treated or resorbed naturally. These could include irreversible vision loss, particularly in cases of retinal detachment or macula damage. Retinal fibrosis or tractional retinal detachment can result from persistent, untreated intraocular bleeding. This scarring may necessitate surgery and significantly compromise vision. The fact that Terson's illness mostly affects the brain and eyes highlights the intimate relationship between intracranial pressure and ocular structures. Intraocular bleeding, which can happen in the retina, subhyaloid space (beyond the vitreous membrane), or vitreous body, is the main cause of ocular involvement. If treatment is not received, this bleeding can cause long-term problems such retinal detachment or scarring in addition to impairing eyesight.
The underlying pathology originates in the brain and usually involves an intracranial hemorrhage, such as a subarachnoid hemorrhage (SAH), or several types of elevated intracranial pressure. The abrupt increase in intracranial pressure causes the condition, which is then communicated to the eyes through the optic nerve sheath. Furthermore, symptoms like headaches, nausea, or neurological abnormalities resulting from the main intracranial trauma may be caused by the syndrome's indirect impact on neurological function. The significance of a comprehensive approach to diagnosis and therapy is underscored by these interrelated effects, which show how systemic illnesses can appear in localized areas like the eyes.

## Causes

It appears as an aftereffect of an intracranial hemorrhage (such as traumatic brain injury or subarachnoid hemorrhage). Intraocular bleeding results from the condition's abrupt and severe rise in intracranial pressure, which is then conveyed to the eyes through the optic nerve sheath. Terson's syndrome's most frequent cause. A ruptured cerebral aneurysm is usually the cause of SAH, which can result in visual problems and elevated intracranial pressure. An increased risk of Terson's syndrome can result from severe head trauma that causes intracranial bleeding. elevated intracranial pressure brought on by diseases such as brain tumors, arteriovenous malformations, or extreme hypertension.

## Standard diagnostic criteria and methods

Terson's syndrome is frequently diagnosed by combining neurological and ophthalmological testing. Fundoscopy, which enables direct evaluation of the retina for indications of bleeding, usually in the vitreous or retinal areas, is the main diagnostic technique. Further confirmation of intraocular and cerebral hemorrhages can be obtained using further imaging modalities. Ocular ultrasonography can be used to evaluate the anatomy of the eye when the hemorrhage prevents retinal vision. Terson's syndrome is characterized by hemorrhages beneath the internal limiting membrane, which can be detected by optical coherence tomography (OCT).
Despite being uncommon, fluorescein angiography may be useful in assessing retinal blood flow and detecting issues. To verify whether brain hemorrhages are present, neurological imaging is essential. In order to identify subarachnoid hemorrhage and other forms of cerebral bleeding, a CT scan is frequently the initial step. While MRA or CTA (magnetic resonance or computed tomography angiography) can be useful in identifying vascular abnormalities, such as aneurysms, that may have contributed to the hemorrhage, MRI can offer better detailed imaging of mild brain hemorrhages. An important diagnostic criterion is the temporal correlation between the cerebral hemorrhage and the commencement of ocular bleeding; because of increased intracranial pressure, the eye hemorrhage usually happens soon after the brain bleed.
Other diagnostic assessments include visual acuity tests to measure the impact on vision and lumbar puncture to confirm subarachnoid hemorrhage when imaging results are unclear. This comprehensive approach ensures that Terson’s syndrome is accurately diagnosed and managed.

### Challenges in diagnosis

Due to its symptoms' overlap with those of other eye disorders such diabetic retinopathy, retinal vein occlusion, or hypertensive retinopathy—all of which can result in retinal or vitreous hemorrhages—diagnosing Terson's syndrome can be difficult. If the neurological history of a patient is not carefully taken into account, these similarities may result in a misdiagnosis. Furthermore, during fundoscopy, thick vitreous hemorrhage may obscure the retina, making it challenging to locate the bleeding source. To confirm the intraocular hemorrhage and prevent a delayed diagnosis, further imaging, like as ultrasound, may be required in some situations.
Intraocular hemorrhages may be mild or asymptomatic in certain patients, particularly if the bleeding is not severe. Because these people might not exhibit visual symptoms, medical professionals might simply concentrate on neurological evaluation, ignoring the necessity of an ocular examination. Furthermore, Terson's syndrome is somewhat uncommon and might not be identified right once, especially in non-specialized contexts. Delays in diagnosis and treatment may result from professionals' lack of awareness.
Assessing ocular involvement may be delayed in emergency settings involving patients who have experienced traumatic brain injuries because the focus frequently moves to stabilizing the patient's neurological status. Intraocular hemorrhage can also result from elevated intracranial pressure caused by tumors or brain swelling, but this may go unnoticed if Terson's disease is not diagnosed. In order to treat the neurological and ocular components of the illness and avoid long-term visual impairment, early detection and timely intervention are essential.

### Common misdiagnoses

* Diabetic retinopathy: This condition can induce confusion, particularly in diabetic patients, by causing retinal and vitreous hemorrhages that resemble those in Terson's syndrome. Diabetic retinopathy might be the first thing considered in the absence of a complete neurological history.
* Hypertensive retinopathy: Because it also results in retinal hemorrhages, hypertensive retinopathy may be misdiagnosed in individuals with hypertension. This may cause a neurological bleed to go unnoticed, postponing the proper diagnosis.
* Retinal vein occlusion: Especially in older people or those with cardiovascular risk factors, retinal vein occlusion, which is a blockage in the retina's veins, causes retinal hemorrhage and visual loss that resembles the symptoms of Terson's syndrome.
* Primary vitreous hemorrhage: If there is no evident neurological event or other neurological symptoms at presentation, intraocular bleeding may be caused by primary vitreous hemorrhage or other isolated eye disorders.
* Ocular trauma: If a healthcare provider fails to take into account the likelihood that concurrent cerebral bleeding may be contributing to Terson's syndrome, intraocular hemorrhage in a patient with a history of head trauma may be mistakenly diagnosed as a direct eye injury.

## Current treatment options and their effectiveness
### Management of intracranial hemorrhage

* Surgical Intervention: Clipping or coiling to prevent re-bleeding and lower intracranial pressure.
* ICP Management: Medications or drainage to reduce pressure.
* Effectiveness: Crucial for preventing further ocular damage and stabilizing neurological function.

### Observation and monitoring of intraocular hemorrhage

* Watchful Waiting: For mild cases, allowing natural blood reabsorption.
* Effectiveness: Effective in mild cases but not suitable for severe hemorrhages.

### Vitrectomy (surgical removal of vitreous hemorrhage)

* Procedure: Removal of vitreous gel and blood to improve vision.
* When Used: Recommended for persistent or dense hemorrhages.
* Effectiveness: Highly effective for vision restoration; carries some risks.

### Intravitreal anti-VEGF injections

* Medication: Off-label use of anti-VEGF injections to reduce inflammation.
* Effectiveness: Mixed results; beneficial for some cases, not standard.

### Laser photocoagulation (rarely used)

* Procedure: Cauterizing blood vessels in cases of recurrent retinal bleeding.
* Effectiveness: Limited in Terson’s syndrome; more suited for vascular retinal diseases.

### Ocular rehabilitation and visual aids

* Supportive Measures: Low-vision aids and rehabilitative services for lasting impairment.
* Effectiveness: Improves quality of life for patients with residual vision loss.

## Phases
### Initial onset

A subarachnoid hemorrhage brought on by a ruptured aneurysm, or less frequently, other forms of brain hemorrhages (such intracerebral or subdural hemorrhages), is usually the origin of the abrupt increase in intracranial pressure that frequently precedes the onset of Turner's syndrome.
This rise in pressure causes intraocular hemorrhage, typically in the retina or vitreous, which causes symptoms including impaired vision, vision loss, or "floaters."

### Development of symptoms

* Depending on the size of the brain hemorrhage, neurological symptoms may include headaches, altered mental status, seizures, or unconsciousness.
* Ocular Symptoms: Severe, thick hemorrhages that drastically impair vision can occur, as well as moderate occurrences that go away on their own. In the days or weeks after the initial brain trauma, symptoms could get worse.

### Settlement or therapy

* Natural Resolution: In less severe situations, the eye's blood may reabsorb itself over the course of weeks to months, progressively enhancing vision.
* Surgical Intervention: To remove the blood and restore vision, surgery (such as a vitrectomy) may be necessary if bleeding is severe or ongoing.

## Recovery potential
### Vision recovery

* Patients with mild hemorrhages often regain full or near-full vision.
* Those with severe hemorrhages who undergo vitrectomy also have a strong chance of visual improvement, though outcomes depend on timely treatment.
* Permanent vision loss can occur if there’s retinal damage or complications like retinal detachment.

### Neurological recovery

* Overall recovery is influenced by the severity of the intracranial hemorrhage and the effectiveness of treatment. Treating the underlying cause, such as aneurysm clipping or coiling, improves neurological recovery prospects.
* Neurological impairments may persist if the brain injury was severe or if complications arose, affecting long-term quality of life.

## Risk of recurrence

The underlying cause of the original episode has a significant impact on the recurrence of intracranial and intraocular hemorrhages in Terson's syndrome. For instance, the chance of rebleeding is greatly decreased in situations with ruptured aneurysms once the aneurysm is treated using techniques like coiling or clipping. Other factors, such poorly controlled hypertension, could raise the chance of more brain hemorrhages in the future, though. Similarly, if intracranial pressure is regulated, intraocular bleeding from a single brain event usually does not repeat. Recurrent intraocular bleeding, however, may result from any further bouts of elevated intracranial pressure, such as those caused by a fresh or recurrent brain hemorrhage. To reduce the chance of recurrence, the underlying ailment must be well managed.

## Factors that influence prognosis

The prognosis for Terson's syndrome is influenced by several factors, including the patient's age, overall health, the severity and location of the intracranial hemorrhage, the timeliness of treatment, and the extent of intraocular hemorrhage. Younger patients generally experience better recovery outcomes due to stronger healing capacities and fewer complications. In contrast, older patients may face a higher risk of complications, such as hypertension, diabetes, and age-related changes in the brain and eyes, which can reduce their recovery potential.
Chronic health conditions like hypertension, diabetes, and cardiovascular disease increase the risk of recurrence and hinder recovery. Healthy vascular and immune systems are essential for healing and blood reabsorption; poor vascular health can lead to slower or incomplete recovery. The severity and location of the intracranial hemorrhage play a significant role in the prognosis, with severe hemorrhages and those in critical brain regions, such as the brainstem, leading to worse outcomes. Elevated intracranial pressure (ICP) exacerbates both neurological and visual complications.
Timely treatment is crucial for improving recovery. Early neurosurgical intervention and prompt ophthalmologic treatment, such as vitrectomy for severe intraocular hemorrhages, can significantly improve both neurological and visual outcomes. Access to specialized care that integrates neurology and ophthalmology expertise is also vital for optimal recovery.
Intraocular hemorrhage severity further affects prognosis. Mild hemorrhages may resolve naturally, but severe, dense hemorrhages, if left untreated, can lead to permanent vision impairment and complications such as retinal detachment. Ongoing rehabilitation and follow-up care are essential to maximize recovery, and lifestyle adjustments—such as controlling blood pressure, managing blood sugar, and avoiding smoking—can improve long-term outcomes and reduce the risk of recurrence.

## Epidemiology

Terson syndrome is relatively rare, and exact prevalence and incidence rates remain uncertain due to frequent underreporting, especially in patients with severe intracranial injuries. Estimates suggest that 8-15% of patients with subarachnoid hemorrhage (SAH) develop Terson syndrome, though detection methods and study populations can cause this rate to vary. Terson syndrome (TS) is characterized by intraocular hemorrhage following an intracranial bleed, such as SAH. Reported incidence rates for TS following SAH range from 8% to as high as 46%, depending on the study and patient demographics. In one study, up to 21% of SAH patients were found to have TS. However, the true prevalence may be underestimated due to the high mortality rate linked to SAH and other brain hemorrhages, which can limit the number of patients surviving long enough to receive a diagnosis. Although TS is uncommon, it is most often associated with ruptures of the anterior communicating artery (ACommA) aneurysms.

### Demographic variations

Several factors can impact both the frequency and outcomes of Terson syndrome. Terson syndrome can affect individuals of all ages, but it is more commonly observed in middle-aged and older adults, particularly those at an elevated risk for subarachnoid hemorrhage due to aneurysms. While the condition is most frequently reported in adults between the ages of 30 and 60, it can also occur in children, typically following traumatic brain injuries or less common causes like arteriovenous malformations. Pediatric cases tend to have better outcomes, owing to the faster healing capacity of younger individuals, though untreated cases can still lead to permanent visual impairments. In older adults, outcomes are generally poorer due to the prevalence of chronic conditions such as hypertension, diabetes, and cerebrovascular disease, which increase susceptibility to both intracranial and ocular hemorrhages. There is a slight male predominance in Terson syndrome, as seen in studies like one from Policlinico Gemelli in Rome, where 53% of patients were male. This may be attributed to higher rates of aneurysm rupture, which occur more frequently in men, particularly with subarachnoid hemorrhage (SAH). However, women are also affected, with factors such as hormonal changes, pregnancy-related complications, and a higher likelihood of aneurysms in certain areas of the posterior circulation playing a role. Geographically, Terson syndrome is diagnosed worldwide but is more frequently observed in regions with higher rates of subarachnoid hemorrhage, such as North America and Europe, where advanced imaging technologies like CT and MRI improve detection and management. In contrast, regions with limited healthcare resources may experience underreporting of Terson syndrome due to misdiagnosis or lack of diagnostic capabilities, particularly in settings where cerebrovascular diseases and trauma are less comprehensively managed. The scarcity of large-scale data on Terson syndrome underscores the need for further research to better understand its prevalence, risk factors, and outcomes across diverse populations.

## Research directions
### Improved early diagnosis

* Research is increasingly focused on identifying reliable biomarkers or imaging techniques that could lead to earlier detection of intraocular hemorrhage in patients with intracranial hemorrhages. Given that timely diagnosis is crucial for effective intervention and visual outcomes, exploring the role of advanced imaging techniques, such as OCT (Optical Coherence Tomography) and high-definition B-scan ultrasonography, is a promising research avenue.

### Surgical advances in treatment

* The effectiveness of vitrectomy and the timing of the procedure continue to be key areas of study. Several studies suggest that early vitrectomy improves visual outcomes, but there is no universal consensus on the optimal timing for surgery. Research is exploring whether minimally invasive techniques and newer surgical tools can reduce complications and improve outcomes.
* Further investigation into alternative or adjunct therapies, such as intravitreal injections (anti-VEGF agents), is also ongoing to determine their role in treating retinal hemorrhages secondary to TS.

### Pathophysiology and genetic factors

* Understanding the underlying pathophysiology of TS is still evolving. Research is investigating the genetic and molecular factors that may predispose certain individuals to both intracranial and ocular hemorrhages. This could help identify at-risk populations or provide insight into why some patients recover fully while others experience permanent visual impairment.

### Long-term prognosis and rehabilitation

* Studies focusing on long-term outcomes of TS, including visual rehabilitation and the impact of sustained visual impairment, are essential for improving quality of life for affected individuals. The role of rehabilitation services, including the use of visual aids and therapy for those with permanent vision loss, is another emerging area of research.

### Predictive models and risk stratification

* Developing predictive models that incorporate demographic, clinical, and radiological factors to better stratify risk and guide clinical decision-making is another active area of research. These models could help clinicians anticipate outcomes and personalize treatment plans for patients with TS.