The process of epileptogenesis tends to be gradual, and it is during this process that the brain develops epilepsy. Still, this process is not entirely understood. Epilepsy is a serious health problem that affects millions of people all around the world. It is one of the most common neurological disorders. By learning more about the process, medical experts can help to develop better strategies and treatments that are aimed at preventing the development of epilepsy.
Post-traumatic epilepsy, called PTE, is responsible for 20% of all of the acquired epilepsy cases. The use of experimental models could be helpful when it comes to studying epileptogenesis. Previous research found that “repetitive high-frequency oscillations with spikes (rHFOSs) occur early after lateral fluid percussion injury (FPI) and may be a biomarker for PTE.” The goal of the study was to utilize “multiple electrodes in rat hippocampal and neocortical regions to describe the long-term electroencephalographic and behavioral evolution of rHFOSs and epileptic seizures after traumatic brain injury (TBI).”
The Methods Used for the Study
The researchers used adult male rats for their experiments. Specifically, they used Sprague-Dawley rats that weighed between 300 and 350 grams and were approximately 65 days old at the time of the experiment. These rats were subjected to “mild, moderate, or severe FPI or sham injury followed by video–electroencephalography (EEG) recordings with a combination of 16 neocortical and hippocampal electrodes at an early, intermediate, or late time-point after injury, up to 52 weeks. Recordings were analyzed for the presence of rHFOSs and seizures.”
When the experiment started, there were 34 rats in all. However, during the procedure, four of the rats died. In addition, there were two rats that were excluded due to dural breech. This left a total of 28 rats to be analyzed.
The Results of the Study
According to the researchers, “perilesional rHFOSs were recorded in significantly more rats after severe (70.3%) than mild (20%) injury or shams (14.3%). Frequency of occurrence was significantly highest in the early (10.8/h) versus late group (3.2/h). Late focal seizures originating from the same electrodes were recorded in significantly more rats in the late (87.5%) versus early period (22.2%), occurring almost exclusively in injured rats. Seizure duration increased significantly over time, averaging 19 s at the beginning of the early period and 27 s at the end of the late period.”
In addition, they found that the frequency of the seizures that were suffered by the rats went up over time. In the early group, the rats were suffering an average of 4.4 seizures per week. However, in the late group, they were suffering 26.4 seizures per week on average.
Researchers found that the “gross inspection of brains after perfusion did not reveal any non–TBI-related causes of seizures such as abscess or infection, including in rats with status epilepticus.” There were also no lesions found in any of the sham-injured animals.
The researchers believe that the “association between early rHFOSs and later focal seizures suggests that rHFOSs may be a potential noninvasive biomarker of PTE.” While PTE might not be the only relevant issue from a clinical perspective, it does seem that it could be a good way to study epileptogenesis and how it relates to various forms of epilepsy.
Of course, as with any study, the researchers know that more work and more research will need to be done in this area to determine the full association and whether the rHFOSs could truly be a good option as a noninvasive biomarker for epileptogenesis.
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