Exploring Transcranial Photobiomodulation for Aphasia

This article will explore two key concepts: aphasia, a language disorder, and transcranial photobiomodulation (tPBM), a therapeutic technique utilizing light.

 

What is Aphasia?

Aphasia is a neurological disorder that impairs a person's ability to communicate effectively. It can affect various language skills, including:

• Speaking: Difficulty forming words or sentences, expressing thoughts clearly;
• Listening: Problems understanding spoken language;
• Reading: Difficulty comprehending written words or sentences;
• Writing: Challenges with writing words or expressing thoughts through writing.

Aphasia typically arises due to damage in specific brain regions responsible for language processing. Common causes include:

• Stroke: A blood clot blocking or a blood vessel bursting in the brain can damage language areas;
• Head injury: Traumatic brain injury (TBI) can disrupt communication pathways;
• Brain tumors: Tumors growing in language centers can cause aphasia symptoms;
• Degenerative diseases: Alzheimer's disease and other degenerative conditions can affect language function.

The severity and type of aphasia vary depending on the location and extent of brain damage. There are several types of aphasia, each with distinct characteristics:

• Broca's aphasia: Difficulty speaking fluently, with short and grammatically incorrect sentences;
• Wernicke's aphasia: Problems understanding spoken language and difficulty forming coherent speech;
• Anomic aphasia: Difficulty finding the right words to express oneself;
• Global aphasia: A severe form affecting all aspects of language communication.

 

What is Transcranial Photobiomodulation?

Transcranial photobiomodulation (tPBM) is a therapeutic approach that employs near-infrared (NIR) or red light delivered through light-emitting diodes (LEDs) to target specific areas of the brain. The light is believed to interact with cellular components within the brain, potentially leading to various benefits:

• Improved cellular function: Light exposure might influence cellular energy production (ATP) and stimulate repair mechanisms;
• Reduced inflammation: tPBM might modulate the activity of immune cells and signaling molecules, potentially leading to decreased inflammation within brain tissues;
• Enhanced blood flow: Some research suggests tPBM could improve blood flow to the brain, delivering more oxygen and nutrients to brain cells;
• Neurotransmitter activity: Light therapy might influence the production and release of neurotransmitters, chemical messengers crucial for brain function.

Transcranial Photobiomodulation for Aphasia

A 2018 research paper, titled "Transcranial, red/near-infrared light-emitting diode therapy for chronic traumatic brain injury and poststroke aphasia: clinical studies," [1] investigated the potential benefits of transcranial photobiomodulation (tPBM) for three distinct patient groups:

• Chronic Traumatic Brain Injury (TBI): This group included patients with closed-head injuries and resulting cognitive dysfunction. The time since their injury ranged from 10 months to 8 years;
• Post-Stroke Aphasia: This group consisted of individuals who developed aphasia as a consequence of a stroke;
• Chronic Traumatic Encephalopathy (CTE): This section involved a single participant, a retired professional football player suspected of having early-stage CTE.

All participants received tPBM using LED clusters emitting red/near-infrared light. Each treatment session involved applying the LED clusters to 11 specific scalp locations for 9.75 minutes, delivering a total dose of 13 J/cm2. The treatment regimen consisted of 18 outpatient sessions delivered three times a week.

While all groups exhibited improvements, the study revealed a critical factor specifically affecting those with post-stroke aphasia: LED cluster placement. Delivering transcranial photobiomodulation (tPBM) ipsilaterally (on the same side of the body) to the stroke lesion resulted in a significant improvement in picture-naming ability.

Another study from 2023 [2] investigated the potential of combining transcranial photobiomodulation (tPBM) with speech-language therapy for aphasia recovery after stroke. A 38-year-old woman with aphasia from a left-hemisphere stroke received two 5-month treatment phases:

• Phase 1 (5 months): Traditional speech-language therapy alone;
• Phase 2 (5 months): tPBM combined with speech-language therapy. tPBM targeted specific brain areas associated with language using red and near-infrared light.

After phase 1, the patient showed minimal improvement in speech fluency and expression. However, phase 2 (with combined tPBM and therapy) led to significant improvement. Speech rate increased from 25-30 words per minute to over 80 words per minute, and utterance length and complexity grew noticeably.

This case suggests that tPBM may accelerate speech and language recovery in aphasia patients when combined with traditional therapy.

References

1. Margaret A. Naeser, Paula I. Martin, Michael D. Ho, Maxine H. Krengel, Yelena Bogdanova, Jeffrey A. Knight, Andrea Fedoruk, Michael R. Hamblin, Bang-Bon Koo, Chapter 25 - Transcranial, red/near-infrared light-emitting diode therapy for chronic traumatic brain injury and poststroke aphasia: clinical studies. Photobiomodulation in the Brain. Academic Press, 2019, pages 309-331, ISBN 9780128153055, https://doi.org/10.1016/B978-0-12-815305-5.00025-7.
2. Estrada-Rojas, K., & Cedeño Ortiz, N. P. (2023). Increased Improvement in Speech-Language Skills After Transcranial Photobiomodulation Plus Speech-Language Therapy, Compared to Speech-Language Therapy Alone: Case Report with Aphasia. Photobiomodulation, photomedicine, and laser surgery, 41(5), 234–240. https://doi.org/10.1089/photob.2022.0024