New Research on Eye Movement and Memory May Impact Chronic Neck Pain Patients
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Exactly how we create memories has always been an evolving science. Now a new research study pulls back the curtain on a really interesting part of the puzzle involving eye movements. In fact, this new data may explain why many patients with chronic upper neck pain have brain fog and memory issues. Let’s dig in.
Memory 101
There are various parts to the process of creating and recalling memories:
- Encoding
- Storage
- Retrieval
This new research focuses on encoding and recall.
EMD
My first experience with Eye Movement Desensitization as a therapy was in the 90s when I was a young physician in practice. Some of the car crash injury patients I was seeing had PTSD and were seeing a local neurologist who was big into EMD. As I understood it, they were retraining their eyes to reduce PTSD. Frankly, to my understanding of neurophysiology at the time, the whole thing sounded like voodoo.
The history of this therapy began in 1987 when Francine Shapiro. Ph.D. noted that eye movements appeared to decrease the negative emotions associated with her own memories of distressing events. She then performed a small randomized trial that showed that this technique of eye movement retraining seemed to help PTSD patients. Other research followed an EMD was born.
At this point, you’re probably like me, thinking, this sounds like some serious alternative medicine mumbo jumbo. Others have had the same criticism. However, we’ve had research for 50 years that suggest that eye movements are linked somehow to memory encoding (1).
The New Research
Scandanavian researchers took 62 healthy adults and recorded their eye movements while remembering various scenes (2). The participants then recalled all of the scenes while looking at a blank screen while also having their eye movements tracked. The researchers found that the sequence in which the subjects looked at the objects on the screen was replayed in the same order when they later recalled the scene. In addition, being instructed to replicate those same eye movements helped to recall the scene more thoroughly.
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For example, if yesterday you saw a series of car crashes and looked suddenly to the left at one and then suddenly to the right at the other, when you recall those crashes, your eyes subtly repeat that pattern. In addition, getting you to recall it better is as simple as repeating those exact eye movements. It therefore also follows that if you wanted to reduce your recall, you would remember it while forcing a new eye pattern different than the original, which is what EMD does. Does it sound less like voodoo now?
Implications for Patients with Upper Neck Problems who Report Brain Fog and Memory Problems
Patients who get hit in the head or in a car crash often injure the upper neck (C0-C3). This could be an injury to the facet joints, nerves, or ligaments. In the latter case, that could represent craniocervical instability.
Credit: See Citation #4 Below
We’ve also known for decades that patients with traumatic neck injuries have altered eye movements when they stress their neck (3,4). This is called altered smooth pursuit neck torsion. That test is a different version of a smooth pursuit test, which tracks eye movements as the patient tracks a target from left to right. In someone with a traumatic upper neck injury, when they turn their neck or trunk, the accuracy of tracking an object goes down, often due to uncontrollable eye movements. Patients often describe this as having to concentrate to read, words moving on the page, blurred vision, difficulty judging distance, and eye strain.
Why does this happen? Because the upper neck is linked directly to eye movements through the cervical ocular reflex (COR) (5). When the upper neck is injured, bad information is provided to the brain about head and eye position, causing the eyes to move abnormally.
What are the implications for memory and recall in patients with an upper neck injury? Given that repeating the eye movements involved with the memory is critical for accurate recall and that upper neck injury patients have a hard time with normal eye movements, it’s not a big stretch to think that this could be the reason they often report brain fog or memory problems.
How Does this Change the Treatment Picture for Upper Neck Injury Patients?
To me, these findings mean that the first order of business for patients with an upper neck facet joint or nerve injury is to fix that problem. For example, we often use precise imaged guided injections of platelet-rich plasma to help those injuries. Or for a patient with craniocervical instability (CCI), the focus is to treat that instability through an advanced injection like the PICL procedure. However, if brain fog and memory issues don’t resolve, then retraining eye movements may be the next step. There are various physical therapists and vision therapy optometrists that can help that process.
The upshot? Eye movements and memory are linked. If you have problems with memory after a neck injury, there may be a really good reason.
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(1) Damiano C, Walther DB. Distinct roles of eye movements during memory encoding and retrieval. Cognition. 2019 Mar;184:119-129. doi: 10.1016/j.cognition.2018.12.014. Epub 2018 Dec 27. PMID: 30594878.
(2) Johansson R, Nyström M, Dewhurst R, Johansson M. Eye-movement replay supports episodic remembering. Proc Biol Sci. 2022 Jun 8;289(1976):20220964. doi: 10.1098/rspb.2022.0964. Epub 2022 Jun 15. PMID: 35703049; PMCID: PMC9198773.
(3) Treleaven J, Jull G, LowChoy N. Smooth pursuit neck torsion test in whiplash-associated disorders: relationship to self-reports of neck pain and disability, dizziness and anxiety. J Rehabil Med. 2005 Jul;37(4):219-23. doi: 10.1080/16501970410024299. PMID: 16024477.
(4) Majcen Rosker Z, Vodicar M, Kristjansson E. Is Altered Oculomotor Control during Smooth Pursuit Neck Torsion Test Related to Subjective Visual Complaints in Patients with Neck Pain Disorders? Int J Environ Res Public Health. 2022 Mar 23;19(7):3788. doi: 10.3390/ijerph19073788. PMID: 35409472; PMCID: PMC8997387.
(5) Ischebeck, B.K., de Vries, J., Van der Geest, J.N. et al. Eye movements in patients with Whiplash Associated Disorders: a systematic review. BMC Musculoskelet Disord 17, 441 (2016). https://doi.org/10.1186/s12891-016-1284-4
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