How the origin of seizures dictates treatment strategy
By Edwige Smague
INTRODUCTION
Following a general overview of epilepsy subtypes and epileptic encephalopathies, we now turn to idiopathic and symptomatic epilepsy. Distinguishing between the two allows us to target diagnostic and therapeutic approaches better and thus improve patient care. We also examine the clinical implications and treatment options adapted to each form.
The neurologist Russell Reynolds, known for his contributions to the understanding of epilepsy, made significant distinctions in the classification of epilepsies, distinguishing idiopathic epilepsies, which have no identifiable cause, from symptomatic epilepsies, which are linked to identifiable brain lesions [2].
Idiopathic epilepsy has a genetic or hereditary cause, with no visible lesion or abnormality in the brain. This form of epilepsy often occurs in children or adolescents and tends to be less severe. Idiopathic epilepsies with a genetic cause but for which a mutation in a gene has not been identified are defined by the absence of a cerebral lesion detectable on MRI. By contrast, when gene mutations are identified, brain abnormalities can be observed depending on which gene is mutated, such as Bourneville Tuberous Sclerosis [3].
Tonic-clonic seizures
Also known as 'Grand mal,' these seizures have two phases: a period of intense muscular contraction (tonic phase) and a period of convulsion (clonic phase). When the person regains consciousness, they are disoriented, tired, and feel a strong need to sleep. Seizures often affect both hemispheres of the brain [4].
Diagnosis and Treatment
Electroencephalograms (EEG) detect specific abnormalities, and family history investigations determine the diagnosis of idiopathic epilepsy. The doctor then adapts a protocol of an anti-epileptic drug to the particular patient. Usually, the seizures are well controlled and diminish or even disappear with age in some patients [5].
Versus, epilepsy symptomatic has identifiable causes such as intracranial infection (meningitis or encephalitis) or trauma that can trigger convulsions. Strokes can also lead to epilepsy. Elderly persons can also have seizures when their brain no longer receives sufficient blood flow. In all cases, it is important that specialists make a thorough diagnosis [6].
Partial or generalised seizures
Symptomatic epileptic seizures vary considerably, depending on the location and nature of the lesion in the brain. This is why they are called focal seizures, meaning focus or central point, from the Latin focus. In neurology, focal refers to a concentration of activity in a specific brain area. We can observe seizures affecting only one part of the body, such as sudden chewing for no reason or an arm contracting involuntarily. However, they may spread throughout the brain, leading to loss of consciousness and generalised convulsions. Some people are aware of their seizures, while others are not. They often have no memory of what happened and may feel very tired after the seizure. Myoclonic seizures can also be linked to symptomatic epilepsy due to the hyperexcitability of neurons in regions of the motor cortex. Factors such as fatigue, stress, hypoglycaemia or alcohol can trigger seizures. They are characterised by uncontrolled jerking and sudden muscle contractions that last only a few seconds. They can sometimes be confused with nervous spasms, as they are not very violent, and the person does not lose consciousness during them. They usually occur in the morning but can also appear during the night. These seizures are difficult to predict and prevent and can sometimes lead to falls. Seizures can lead to complications due to subjacent conditions such as neurological problems, infections or cognitive deficits [7].
Diagnosis and Treatment of symptomatic epilepsy
Not all symptomatic epilepsies are considered acquired (some may be linked to genetic abnormalities or brain dysfunction without structural damage). Russell Reynolds' work led to a better understanding that not all symptomatic epilepsies should be considered as acquired, i.e. with identifiable causes. This distinction has important implications for the diagnosis, treatment and management of patients with epilepsy.
When the lesion is visible on a brain MRI scan, symptomatic epilepsy can be diagnosed.
Similar to idiopathic epilepsy, specialists will seek appropriate treatment for the patient with anti-epileptic drugs.
However, sometimes, these treatments do not work, in which case an intervention may be considered to remove or treat the lesion responsible for the seizures. Approaches such as vagus nerve stimulation or specific diets (ketogenic diet) are often used in cases of drug resistance [8].
Pronostic
Idiopathic epilepsy, although often more challenging to detect, generally has a better prognosis due to the effectiveness of treatments in controlling seizures. Conversely, symptomatic epilepsy, which is easier to identify, is more complex to manage because of the severity of the underlying brain damage.
Conclusion
Whether the condition is a mystery to be solved or, on the contrary, crystal clear, the key lies not in obviousness but in the ability to spot the small details.
REFERENCES
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[2]Eadie M. J. (2007). The neurological legacy of John Russell Reynolds (1828-1896). Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia, 14(4), 309–316. [PubMed]
[3]Panayiotopoulos CP. The Epilepsies: Seizures, Syndromes and Management. Oxfordshire (UK): Bladon Medical Publishing; 2005. Chapter 10, Idiopathic Generalised Epilepsies. Available from: [NCBI]
[4]Kodankandath TV, Theodore D, Samanta D. Generalized Tonic-Clonic Seizure. [Updated 2023 Jul 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: [NCBI]
[5]Rathore, C., Patel, K. Y., & Satishchandra, P. (2022). Current Concepts in the Management of Idiopathic Generalized Epilepsies. Annals of Indian Academy of Neurology, 25(1), 35–42. [NCBI]
[6]Simon Shorvon (2014), The concept of symptomatic epilepsy and the complexities of assigning cause in epilepsy; Epilepsy & Behavior [Direct Science]
[7] McWilliam M, Asuncion RMD, Al Khalili Y. Idiopathic (Genetic) Generalized Epilepsy. [Updated 2024 Feb 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: [PubMed]
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