Morrison’s Laryngeal Gutters: Why treat the retrolaryngeal region with manual therapy?

Manual therapy, of all types, has been included in the voice (and later swallowing) professional literature since 1985 (Aronson 1). Early on, aggressive laryngeal manipulation was the norm, as it was seen to break up and reduce local muscle tension in the perilaryngeal musculature and related areas. Research began in 1993 (Roy and Leeper 2), standardizing laryngeal manipulation with muscle tension dysphonia and associated voice disorders. Later, manual therapy drifted into the treatment of head and neck cancer-related disorders and myofunctional models of care.

One of the targets of traditional laryngeal manipulation (LMT) is a reduction in tension in the inferior constrictor muscles. The contraction of these muscles is seen to propel the food bolus down the esophagus and indirectly restrict airflow. When tension or other described problems occur in this region, laryngeal motion is diminished, potentially impacting the voice. LMT was seen as targeting that tension, allowing for a normalization in laryngeal movement.

I learned treatment to what was described in physical therapy continuing education as treatment to the “anterior cervical” region. I’d used it successfully for decades before being invited into the SLP community to teach manual therapy. Accidentally, I drifted from the area of the vertebrae and cervical nerve roots into the retrolaryngeal space. Without realizing where I was, patients began to report a replication of issues they’d not told me during their intake. They were seeing a PT for their neck pain. Why would they mention a voice or swallowing concern? I never thought to ask. But those early experiences led to my current vocation of teaching manual therapy to this and other areas for those very specific voice, swallowing, oral motor, and related concerns.

As I originally learned, the work was often uncomfortable for the patient. We were pressing on the vertebrae and nerve roots, feeling like we were putting the spine back into proper alignment and helping to reduce cervical disc herniations. I look back at my beliefs in those days (the 90s) and shake my head at what I learned and repeated as fact. No evidence was presented in my original training in the 90s, but evidence was thin in those classes. Since then, my touch has become much lighter, and my understanding of this region’s anatomy (and dangers) has grown immensely.

As I undertook an effort to improve the quality of my continuing education workshops, I worked to build the blended, multifactorial narrative I’ve incorporated into my classes today. Though my technique style differs from that of LMT, there were parallels in both works. The wording varies greatly, as I see the effects of manual therapy having less of a local-only effect than mechanisms from central aspects of the nervous system(s). I speak in-depth about these factors in this paper 3.

If the scientific literature shows that (to me) aggressive LMT is efficacious in improving voice problems, why deviate? I’ve undergone in-depth training in LMT but intensely disliked many aspects of that work, namely how powerless I felt when another person was wrangling my neck from side to side, with little chance of meaningful input on my part. I learned a lot in that training, though few of the actual hands-on components made it into my bag of treatment tricks.

After that LMT training, I stumbled upon a 1997 paper by Murray Morrison, MD, “Pattern recognition in muscle misuse voice disorders: how I do it” 4. A Google Scholar search identified this paper based on a few keywords. Since I was first exposed to the basics of this technique in 1994, I’d never seen a study mention the benefit/need of treatment to this space, much less assign a specific technique. Morrison spoke of the benefits of accessing the inferior constrictors in the “laryngeal gutter,” which can be viewed as the space between the posterior thyroid cartilage and the anterior spine/transverse processes. While the technique differed from mine, the underlying rationale fit nicely. I’d finally located credible evidence, supported not only by Morrison’s paper but also by the existing and later studies demonstrating the benefits of accessing and intervening in this zone to reduce muscle tension dysphonia.

The area surrounding these gutters is often considered a danger zone. Many massage therapy programs advise against ever treating this zone due to the presence of the carotid arteries, vagus nerve, etc. In a recent study I conducted among SLPs who have taken my training, many report that while in graduate school, they were warned not to use manual therapy due to safety concerns. While these cautions and concerns are understandable, they overlook the depth of data reporting positive outcomes derived from manual therapy interventions. However, with inadequate training or training that presents success from the need to “break things up,” therapists who work with too heavy of a hand do risk potential injury.

Regarding treatment of Morrison’s gutters, can we access this space and improve mobility? Quite easily, yes. Whether it is from the more traditional LMT or the gentler form of therapy I propose, access can be simple and relatively safe. We dive deeply into these steps in the training. Based on numerous FEES videos filmed while this gentler form of manual therapy was being performed, we can see the effects of externally applied touch and pressures on the internal responses to the vocal folds, etc., all done with complete patient input and control. No work should be done with the clinician completely leading the treatment without patient input. Ideally, shared decision-making tempers the therapist’s beliefs to allow the individual patient’s values and expectations.

Accessibility to quality evidence is essential, but what sort of evidence counts? Most manual therapy studies may be categorized as “outcome-based” studies. Apply an intervention and show the treatment was successful. Such studies are often thin on the underlying narratives and mechanisms of action. Still, researchers seem to be given a pass so long as they state a previous study/paper that spoke of their perspectives on the underlying mechanisms. Comparative papers on the potential mechanisms of action at play are sorely lacking in manual therapy research, both inside and outside the voice/swallowing domain. Just because something “works” does not validate the stated mechanism. Such stories tend to follow post hoc fallacy perspectives.

I have gratitude for Morrison’s establishing a rationale for intervening in the retrolaryngeal space, as it gave me a degree of confidence that I was not an outlier or exploring areas that were seen as unsafe. A deep understanding of the region’s anatomy is essential, as is training and mentoring to ensure pressures are not only generally safe for everyone receiving the work. I enjoy hanging out in gutters, determining if I can replicate or connect with my patient’s issues. We’ve had evidence for many years on the efficacy of intervention to those gutters, and I’m happy to provide an option to those who feel work need not be aggressive to be helpful.

 

Walt Fritz, PT

Foundations in Manual Therapy Seminars

 

1 Aronson, A. E. (1985). Clinical voice disorders. An interdisciplinary approach, 157-197.

2 Roy, N., & Leeper, H. A. (1993). Effects of the manual laryngeal musculoskeletal tension reduction technique as a treatment for functional voice disorders: perceptual and acoustic measures. Journal of voice, 7(3), 242-249.

3 Fritz W. (2024). The mechanism of action for laryngeal manual therapies: the need for an update. Current opinion in otolaryngology & head and neck surgery, 32(3), 151–155.

4 Morrison M. (1997). Pattern recognition in muscle misuse voice disorders: how I do it. Journal of voice: official journal of the Voice Foundation, 11(1), 108–114. https://doi.org/10.1016/s0892-1997(97)80031-8