A Look at the Role of Functional Near-Infrared Spectroscopy on Mitochondrial Disorders

Functional near-infrared (fNIRS) spectroscopy could be a valuable tool to detect epilepsy in patients with mitochondrial disorders, according to a recent study published in Neurotherapeutics (1).

Epilepsy is a common neurological manifestation in individuals with mitochondrial diseases, which are a group of inherited disorders that disrupt the mitochondria's ability to produce energy for cells. The disease results in the affected individual to recurrent seizures, which is a result of excessive electrical discharges in a group of brain cells (2). Approximately 50 million people worldwide have epilepsy, making it one of the most common neurological diseases globally (2). Although epilepsy is quite common, 70% of people afflicted with it can live seizure-free lives if properly diagnosed and treated (2). Unfortunately, approximately 75% of people with epilepsy in low-income countries do not get the treatment needed (2).

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This is why developing and discovering new ways to detect epilepsy are important. Traditionally, electroencephalography (EEG) serves as the gold standard for seizure diagnosis and localization, often complemented by additional imaging modalities for enhanced source localization (1). However, EEG limitations exist, particularly in infants and children, where motion artifacts can significantly impact data interpretation (1).

As a result of EEG’s limitations, fNIRS emerges as a promising alternative technique because of its portability and insensitivity to motion. This non-invasive technique measures changes in blood oxygenation levels by NIR light, providing valuable insights into energy metabolism and neuronal activity (1). fNIRS offers real-time monitoring with high spatial resolution, complementing traditional diagnostic tools like EEG and providing a more comprehensive understanding of seizure and epileptogenesis (1).

As a technique, fNIRS has an important advantage over traditional techniques in that it can detect changes in Cytochrome c oxidase (CcO), a key enzyme in cellular respiration (1). This unique feature sheds light on the metabolic dimension of epilepsy related to mitochondrial dysfunction (1). By simultaneously capturing information on both energy metabolism and neuronal activity, fNIRS offers a multifaceted approach for investigating the complexities of epilepsy in mitochondrial disorders (1).

Another advantage of fNIRS is its instrumentation. Because of the general push in spectroscopy to miniaturize instruments, fNIRS technology was created with an eye on this trend. As a result, fNIRS has portable instrumentation compatible with infants, which means it can be used as a tool for seizure detection in a vulnerable population (1). Being able to test infants is important, because the early detection of seizures in neonates is essential for determining whether someone has severe mitochondrial dysfunction (1).

The combined application of fNIRS with EEG and other imaging techniques offers a comprehensive approach that could significantly impact early diagnosis and treatment planning for neonatal epilepsy (1). Furthermore, the integration of machine learning with fNIRS and EEG data holds promise for improved seizure recognition in neonates (1).

With improvements in spatial resolution and the exploration of additional biomarkers, fNIRS is a technique that can deliver enormous benefit to routine clinical practice. This deeper understanding of the underlying pathophysiology can lead to the development of more personalized and effective therapeutic strategies (1). Collaborative research efforts utilizing fNIRS alongside traditional methods are poised to significantly contribute to the evolution of diagnostics and treatment modalities for individuals affected by epilepsy and mitochondrial disorders (1).

References

(1) Khaksari, K.; Chen, W.-L.; Chanvanichtrakool, M.; et al. Applications of Near-Infrared Spectroscopy in Epilepsy, with a Focus on Mitochondrial Disorders. Neurotherapeutics 2024, 21 (1), e00323. DOI: 10.1016/j.neurot.2024.e00323

(2) World Health Organization, Epilepsy. WHO. Available at: https://www.who.int/news-room/fact-sheets/detail/epilepsy (accessed 2024-06-04).