Introduction
A seizure is an involuntary body movement caused by abnormal signals from the brain. Depending on the mechanism and localization, several types of seizures are identified. The following paper provides a comparison of generalized and complex partial seizures by contrasting their pathophysiology, typical EEG findings, physical presentations, and the common medications for each of the conditions.
Pathophysiology
Generalized seizures usually start in several parts of the brain and cannot be identified as pertinent to a specific area. Certain hyperexcitable neurons within an epileptogenic focus receive a high-voltage paroxysmal discharge and, as a result of this, remain partially depolarized (Ko & Sahai-Srivastava, 2015). Once the inhibitory influence of the surrounding tissue is overcome, the seizure impulse spreads to the nearby cortical and subcortical structures as well as structures of the brain stem.
In contrast, complex partial seizures start in a specific area of the brain and, as a result, affect a corresponding area of the body. Importantly, complex partial seizures affect consciousness. Physiologically, they are caused by the hypoperfusion of the mediodorsal thalamus or the bilateral frontal and parietal association. The dispersion of these discharges eventually generates ictal effects that are likely responsible for the altered consciousness (Carroll & Benbadis, 2016). Neuroexcitability of the mesial temporal lobes increases over time in patients with complex partial seizures, leading in some cases to temporal lobe epilepsy.
Examples
Generalized seizures have many subtypes. Examples of generalized seizures include tonic-clonic and absence seizures, formerly known as grand mal and petit mal, respectively. Lesser-known examples include tonic seizures, myoclonic seizures, clonic seizures, and atonic seizures. Complex partial seizures are less varied and differ only by their secondary generalization. Thus, the examples include secondarily generalizable and non-generalizable seizures.
Typical EEG Findings
Generalized seizures are most commonly represented on an EEG as spikes and sharp waves. They vary in duration and share a set of common characteristics, such as their complex nature. Specifically, a spike is usually followed by a slow wave (Fischetti, 2012). The complex may occur in discreet bursts of high regularity, with normal EEG readings between them (3-Hz spike-wave complex) or less predictable and monomorphic patterns, with occasional abnormalities between spikes (slow spike-wave complex).
Complex partial seizures produce sharp focal waves, temporal spikes, and occasional focal slowing (Fischetti, 2012). Most commonly, the pattern of waves and slowing is highly systemic and sustained within a 10-30 Hz activity. Importantly, depending on the subtype, slowing can be either localized or generalized.
Physical Presentation
Generalized seizures are known to be preceded by prodromes – symptoms that occur several days before the seizure onset. Prodromes include anxiety, disruption of sleep patterns, irritability, and mood disorders. Headaches and abdominal pain are less common.
Complex partial seizures are preceded by auras – small-scale, simple partial seizures that last for several seconds and can be used to determine the onset site. The most widespread auras are psychic (e.g. déjà vu) and abdominal. In addition, complex partial seizures are accompanied by the alteration of consciousness, such as decreased awareness and responsiveness. Finally, a set of automatisms (unconscious repetitive behaviors) can be observed after the onset. These behaviors range in complexity and location, with oral and manual being the most common (Carroll & Benbadis, 2016).
Common Medications
Generalized seizures are commonly treated by broad-spectrum antiepileptic drugs (AEDs) that target several areas of the brain. Common AEDs include Ezogabine, Lamictal, Lorazepam, and Klonopin.
Complex partial seizures are more commonly treated by medications that target a specific area of the brain (narrow-spectrum antiepileptic drugs). These medications include Diazepam, Clobazam, Zarontin, Gabapentin, Methsuximide, and Phenobarbital, among others.
Conclusion
A seizure is a complex condition that originates from a complex set of factors. The subjectivity of some of its symptoms complicates the self-diagnosis process and requires the assistance of a healthcare professional and sophisticated equipment. Due to this fact, the provided list of medications is neither exhaustive nor definitive and can be used interchangeably depending on the individual needs of the patients.
References
Carroll, E., & Benbadis, S. R. (2016). Complex partial seizures.
Fischetti, E. R. (2012). Seizure types – clinical correlation and EEG findings.
Ko, D. Y., & Sahai-Srivastava, S. (2015). Generalized tonic-clonic seizures.