Overview of Reflex Epilepsy
The most common type of reflex epilepsy, the patient is often caused by light stimulation of epileptic seizures, seizures can be manifested as limb twitching, eyes upward, loss of consciousness, or briefly froze, often accompanied by flashes of light in front of the eyes, blurred vision, the cause of the disease is not known, and may be related to heredity, excitability of the brain, visual signal processing abnormalities, etc. The wearing of blue-light glasses and medication as the main treatment method.
Definition
Photosensitive epilepsy is the most common type of reflex epilepsy. Patients can have seizures triggered by specific types of light stimuli, such as watching television, playing video games, or fast flashing lights at a dance party [1].
Patients often present with myoclonic seizures, generalized tonic clonic seizures, focal epileptic seizures or catatonic seizures, etc., and myoclonic seizures.
Typology or classification
The term “photosensitivity” refers to the abnormal electrical response of the human brain to intermittent flash stimuli [2]. Photosensitive epilepsy can be categorized into simple photosensitive epilepsy and epilepsy with photosensitivity [1].
Simple photosensitive epilepsy: seizures occur only during light stimulation and not normally.
Epilepsy combined with photosensitivity: the patient himself/herself has seizures and can also be triggered by light stimulation.
Incidence
There is no authoritative incidence of photosensitive epilepsy in China.
Foreign data show that the incidence of photosensitive epilepsy is about 1/3000, accounting for 2% of new epilepsies [1].
The incidence is higher in children and adolescents aged 7 to 19 years [1].
Female incidence is more than male, and the male to female ratio is about 1:1.5 to 2 [1].
Etiology
Causes
The cause of photosensitive epilepsy is not well understood and is currently thought to be related to factors such as genetics, abnormal visual signal processing, cortical hyperexcitability, and structural brain abnormalities [3].
When light strikes the human eye, it is received by retinal photoreceptor cells and converted into electrical signals, which are transmitted to the visual cortex of the brain through the visual conduction pathway to produce excitation, and when the signal processing is abnormal in this process, the cerebral cortex will be abnormally discharged, and seizures may be induced [4].
Genetic studies have shown that neuronal hyperexcitability due to abnormal ion channels in the brain is also an important causative factor in many patients [5].
Microstructural abnormalities in the hippocampus and other parts of the brain (e.g., the nucleus accumbens) are also thought to be important in the pathogenesis of the disease.
Predisposing factors
Light changes
Rapidly changing lights: e.g., watching television, playing video games, flashing lights in dance halls and nightclubs.
Seizures may also be triggered by sunlight passing through gaps in the foliage of trees, sparkling light on water, glare through blinds, and flashing neon lights at night.
Highly saturated red light, multiple clearly recognizable striped shapes, light and dark stripes, and frequently changing shapes.
Other triggering factors
Alcohol consumption, overexertion, sleep deprivation.
Symptoms
Main Symptoms
Seizure manifestations
Patients with photosensitive epilepsy often present with myoclonic seizures, generalized tonic-clonic seizures focal seizures, and cataplexy with eyelid myoclonic seizures. During seizures, patients often have transient visual symptoms, such as flashes of light, blurring, defocusing, and narrowing of the visual field.
Myoclonic seizures
A sudden, rapid, forceful jerking of a part of the body.
Generalized tonic clonic seizure
It is characterized by sudden loss of consciousness, sudden collapse, limb straightening, and twitching of the limbs.
It may be accompanied by screaming, rolling eyes, purple lips, foaming at the mouth, tongue biting, incontinence and so on.
Consciousness gradually returns after a few minutes, but the course of the seizure cannot be recalled [6-7].
Focal seizures
Abnormal involuntary movements or sensations in one part of the body, mostly in one eyelid, corner of the mouth, hand or toe, but may also spread to one side of the face or limb. It may or may not be accompanied by loss of consciousness.
Loss of consciousness with eyelid myoclonic seizures
Similar to a brief seizure, this is often characterized by a sudden cessation of ongoing activities, a blank stare in the eyes, and staring ahead or upwards, sometimes accompanied by involuntary eyelid twitching.
Focal seizures
Abnormal involuntary movements or sensations in one part of the body, usually in the eyelids, corners of the mouth, hands or toes on one side, but may also affect one side of the face or limbs. They may or may not be accompanied by loss of consciousness.
Myoclonic seizure
A sudden, rapid, forceful jerking of a part of the body.
Other symptoms
Hyperactivity, inattention, and motor incoordination.
Cognitive (including memory, executive functioning, etc.), language, and emotional deficits.
Medical Treatment
Department of Medicine
Neurology
If seizures are induced by changes in light, a prompt visit to the Department of Neurology is preferred. Pediatric patients are referred to the Department of Pediatrics and Pediatric Neurology.
Emergency Department
If the seizure occurs continuously within a short period of time and cannot be relieved on its own, it is recommended to call 120 emergency number to the Emergency Department as soon as possible.
Preparation for medical treatment
Preparation for medical consultation: registration, preparation of documents, frequently asked questions
Tips for seeking medical treatment
Be accompanied by family members to the hospital, do not go by yourself to avoid accidents such as trauma caused by sudden onset of epilepsy on the way.
When the patient has a sustained seizure and is unconscious, tilt his/her head to one side to prevent aspiration of vomit.
Preparation Checklist for Medical Attendance
Symptom checklist
Particular attention should be paid to the time of onset of symptoms, special manifestations, etc.
Is there any sudden loss of consciousness, sudden collapse?
Is there any hardening of the body, twitching of the limbs, accompanied by screaming and rolling of the eyes?
Are there any purple lips, foaming at the mouth, tongue bite, incontinence, etc.?
Can you recall the course of the seizure after consciousness is restored?
Is there a sudden cessation of ongoing activities, similar to a brief period of freezing?
Is there any involuntary rapid twitching of the eyelids or other parts of the body?
Is there any abnormal sensation in a certain part of the body?
Do the above symptoms occur after light stimulation such as watching TV or playing games?
Was there excessive alcohol consumption or severe sleep deprivation prior to the onset of the symptoms?
Are there any other deficits in memory, attention, language, mood, etc.?
Medical History Checklist
Any history of difficult labor or ischemic hypoxia at birth?
Any history of cranial trauma, intracranial infections, etc.?
Is there a family history of epilepsy?
Any previous seizures or diagnosis of epilepsy?
Checklist
Test results from the last six months, which can be brought with you to the doctor’s office
Imaging tests: cranial CT, cranial MRI.
Electroencephalography.
Other tests: blood test, liver and kidney function, electrocardiogram.
List of medications used
Medication used in the last 3 months, if available in boxes or packages, bring with you to the doctor’s appointment
Antiepileptic drugs: sodium valproate, lamotrigine, phenobarbital, etc.
Diagnosis
Diagnosis based on
Medical history
The patient has a history of seizures or seizures induced by flash stimuli.
There may be a family history of epileptic patients or similar symptomatic episodes.
Symptoms
Seizures are transient in nature, and the patient is usually unable to recall what happened during the seizure, so a witness account of the seizure is critical.
Seizures may include multiple or partial convulsions of the limbs, rolling of the eyes, loss of consciousness, incontinence, falling, transient disorientation, sensory abnormalities, and other symptoms.
Normally, patients may show hyperactivity or motor incoordination, memory, attention, executive function, language and emotional deficits.
Physical Examination
The doctor may examine the patient for injuries due to seizures, make an initial assessment of physical activity, and mental and psychological state.
Examine the patient’s mouth and tongue for any bite injuries from the seizure.
Check the coordination of the patient’s activities, for example, let the patient touch the doctor’s outstretched finger with the tip of the finger, and then return to touch the tip of the patient’s own nose, repeated in different directions, speeds, with eyes open and closed, and compare the two sides to check whether the patient has ataxia.
Let the patient do some psychological scale examination to know specifically about the patient’s psycho-psychological condition.
Examination Tests
Laboratory tests
These include routine blood tests, liver and kidney functions, and blood electrolyte measurements.
The purpose is to assess the overall physical condition and help formulate a treatment plan.
During the course of treatment, some of the items may need to be reviewed periodically in order to monitor drug side effects.
Imaging Tests
Cranial magnetic resonance imaging (MRI) can clarify whether there are organic lesions in the skull, such as tumors and vascular malformations that cause seizures.
Functional magnetic resonance examination: such as magnetic resonance spectroscopy can detect abnormal metabolism in the cerebral cortex, and magnetic resonance diffusion tensor examination can detect microstructural alterations in the cerebral white matter fiber bundles.
Precautions:
CT has a certain degree of radiation, children and pregnant women need to be cautious of the examination.
Before the MRI examination, if you have metal dentures, cardiac stents and other metal implants in your body, consult your doctor whether you can perform the examination.
Electroencephalography
Electroencephalography (EEG) can detect abnormal brain waves in and around the lesion area.
If needed, video EEG or intermittent flash stimulation-induced EEG can also be done.
Typical EEG abnormalities in patients with this disease can be categorized into 4 groups (Waltz classification), with abnormal EEG (epileptic waves) located in the occipital, parieto-occipital, frontal, frontal and central regions.
Differential diagnosis
Syncope
Similarities: Both can present as a sudden loss of consciousness and a fall.
Differences: Syncope manifests as sudden collapse, loss of consciousness and quick recovery. It is usually induced by change of body position, emotional excitement, urination, etc.. No manifestations of seizures such as limb convulsions, disorientation, etc., and no epileptic waves on EEG.
Hypoglycemia
Similarities: Both may manifest as loss of consciousness, limb twitching or limb tonus.
Differences: Patients with hypoglycemia usually have a history of diabetes mellitus, the onset of blood glucose tests is often below 2 mmol/L, and the onset is not related to light stimulation.
Episodic sleeping sickness
Similarities: Both can present with sudden loss of consciousness and falls.
Differences: Seizure sleep disorder is not associated with light stimulation and there are no clinical signs of seizures. There are no epileptic waves on the EEG.
Treatment
Treatment aims: to reduce or control the frequency of seizures, to avoid trauma and accidents, and to improve the quality of life.
Treatment principle: wear special glasses and medication combination.
Wearing special glasses
Reducing the stimulation of light changes through special glasses can reduce seizures.
Wearing cross-polarized glasses can control two-thirds of seizures [1].
Blue light glasses can also reduce seizures in patients who are sensitive to sunlight.
Specialized smart glasses made of black material can also reduce seizures [1].
Medication.
For patients with simple photosensitive epilepsy, prevention and wearing special glasses are the mainstay, with medication in a few severe cases; for patients with epilepsy with photosensitivity, oral antiepileptic drugs are needed while avoiding triggers.
The treatment of photosensitive epilepsy should be classified according to the patient’s seizures with medication, and antiepileptic drugs are preferred for generalized seizures, such as sodium valproate as the preferred drug for myoclonus[8] .
Two drugs are ineffective, levetiracetam, phenobarbital, clonidine, clobazam or ethosuximide can be used as the second choice drug, lamotrigine can be used as valproic acid to add therapeutic drugs.
Clomiphene can be used for photosensitive seizures associated with menstruation.
Adverse effects such as cardiac arrhythmias, bone marrow suppression, liver and kidney impairment, and rash need to be watched for.
The medication needs to be taken strictly in accordance with the doctor’s requirements, on time, in the right amount and regularly, and unauthorized stopping, reducing or changing the medication is prohibited.
Prognosis
Cure
Photosensitive epileptic seizures are age-related, with about 30% of patients remitting on their own as they age, with an average age of remission of 24 years.
The prognosis for photosensitive epilepsy is relatively good, with oral medication controlling seizures in about 80% of patients [2].
Prognostic factors
The severity of the patient’s photosensitivity, alertness to their exposure to light stimuli, and adherence to treatment are strongly associated with prognosis [9].
Hazard.
Recurrent seizures or prolonged medication can lead to impaired intellectual development in pediatric patients.
Repeated seizures can affect normal life and work and can lead to low self-esteem, anxiety and depression.
Seizures are prone to accidents such as falls, car accidents and burns, leading to fractures and traumatic brain injuries.
In rare cases of persistent status epilepticus, which is not terminated in time, sudden death may occur.
Daily
Daily Management
Dietary management
Balanced nutrition, focusing on high-quality protein, low-fat, low-salt, low oil, high-fiber diet.
Avoid spicy and stimulating, too oily food, and do not overeat.
Abstain from alcohol, strong tea and coffee.
Life Management
Live a regular life and avoid staying up late.
Avoid gazing at fast-flashing objects.
Psychological support
Family members should cooperate with doctors to guide patients to correctly understand the disease and establish confidence in the treatment of the disease.
In case of emotional instability and depression, seek help from relatives, friends and medical staff, and psychological counseling if necessary.
Disease monitoring
The form, frequency and duration of seizures can be recorded by means of taking videos, keeping diaries or journals, etc., so as to assist the doctor in understanding the condition and treatment effect, and formulating and adjusting the treatment plan.
Patients taking oral antiepileptic drugs need regular monitoring of blood and liver functions.
During the process of reducing or stopping antiepileptic drugs, the EEG changes should be monitored.
Prevention
The risk of photosensitive seizures can be effectively reduced by the following methods
Avoiding environments with rapidly changing lights, such as nightclubs and dance clubs.
Avoid looking at objects with high brightness that change frequently, such as playing video games [10].
When watching TV, the distance between your eyes and the TV should be at least three times the width of the screen [1].
Wearing blue light glasses, viewing fluorescent screens with graphic stimuli, walking up and down stairs outdoors, or looking out of a moving car, patients can close one eye and look with a single eye to minimize light stimuli.
Stop smoking and drinking, live a regular life, and get enough sleep.