The hypothalamic-pituitary-adrenal (HPA) axis function is known to be an important consideration in development of symptomatic TMD.

There are three types of stresses in TMD patients, the first is emotional or life stress as described by Hans Selye in “Stress of Life”.

The second type of Stress is biological stress and includes nutrition, vitamins , hormones , exposure to light and effects on circadian rhythms, the air we breathe, alcohol, allergies, thyroids and iodine levels, our Biome both in our gut and other body cavities and the medications and side effects of medications.

Third are structural stresses anywhere in our body including postural issues, repetitive strain injuries, habits, ergometrics, structral issue such as short leg, scoliosis, missing teeth, micrognathia, crossbites, airway size, tongue tie and deviate swallows to name a few.

Our bodies are designed to deal with stresses of all sorts to preserve our health and function. When the stresses are more than are ability to cope failure of systems occurs. H-P-A axis addresses not the stresses but what happens when they exceed our abilities to compensate and continue to function.

Some patients have healthier coping mechanisms that others. All patients with high stress do not develop high cortisol levels as shown by “Chronic HPA Axis Response to Stress in Temporomandibular Disorder”

When patient’s coping mechanisms fail professional help is often sought. This can come from Structural corrections such as orthotic for short leg or missing teeth or bite issue. It may aim toward correcting biochemical or psychological stresses. The stress is part of the problem, how the patient handles the stress is often a bigger issue.

The Autonomic Nervous System has two divisions, the Sympathetic Division responsible for the “Fight or Flight ” reflex and the Parasympathetic Division respnsible for the “Rest and Digest” reflex or “Feed and Breed” reflex. Sympathetic survival of individual and Parasympathetic survival of the species.

The Sphenopalatine Ganglion is the largest Parasympathetic Ganglion of the Cranium and is found on the maxillary division (sensory) of the Trigeminal Nerve where it exits through the foramen Rotunda into the Pterygopalatine Fossa. The maxillary artery is also found in the fossa.

The Trigeminal nerves are actually brain cells as are the Parasympathetic fibers of the Sphenopalatine Ganglion. The ganglion also contains post-ganglionic sympathetic fibers from the Stellate Ganglion, the Sympathetic Cervical chain via the Superior Cervical Sympathetic Ganglion. There are also Somato-Sensory fibers from the Trigeminal nerve passing thru the Ganglion.

The trigeminal afferent nerves are amplified in the Reticular Activating System and are part of the Limbic System and travel to the Hypothalamus and the Amydyla. Pain is percieved in the Limbic System and is an emotional response to stimuli.

The fibers of the Trigeminal nerve and the Sphenopalatine Ganglion control the blood flow to the anterior two thirds of the meninges of the brain.

Physical stresses are responded to by the musculoskeletal systems and as muscles “sacrifice themselves” to protect the whole they can develop taut bands and trigger points of Myofascial Pain and Dysfunction (MPD) and Fibromyalgia. The article “Postural alterations as a risk factor for temporomandibular disorders” states ” Alterations in head posture, vertebral curves and lower limbs could be considered risk factors for muscular TMD. The most frequent postural alterations were lumbar hyperlordosis, forward head posture and genu valgus (knock knee).”

These taut bands and trigger points of MPD and Fibromyalgia develop under combined forces of autonomic and somatosensory nerve function. Structural stresses are controlled by the muscles but overuse becomes a problem. Muscle Splinting is a valuable protection for an injury but long term muscle shorten creates new problems. This is why physical therapy is necessary to return to a normal state. Without correction of function we again see the taut bands and trigger points of MPD.

Following an injury Muscle Splinting is protective but if it is maintained too long it leads to chronic muscle shortening and taut bands and trigger points as described by Travell in “Myofascial Pain and Dysfunction: A Trigger Point Manual” Frequently doctors and physical therapists will utilize trigger point injections and dry needling in their treatment as described in “Effects of myofascial trigger point dry needling in patients with sleep bruxism and temporomandibular disorders: a prospective case series” which concluded “Deep DN of active MTrPs in the masseter and temporalis in patients with myofascial TMD and SB was associated with immediate and 1-week improvements in pain, sensitivity, jaw opening and TMD-related disability.”

Sphenopalatine Ganglion Blocks were first described by Dr Greenfield Sluder in 1908 who later wrote the medical textbook “Nasal Neurology” when he was Chair of Otolaryngology at Washington University School of Medicine in Sant Louis, Missouri. He described the block for treating Sluder’s Neuralgia or Sphenopalatine Neuralgia. It is now believed that may have been a TMJ disorder, Cluster headache or related Trigeminal disorder like migraine or a TAC, Trigeminal Autonomic Cephalgia.

Byrd looked at 10,000 SPG Blocks in 2000 patients in a 1929 article in the “Annals of Internal Medicine” now JAMA. Almost 100% had success with a very wide range of disorders many of which have strong overlaps to TMD, Migraine, Trigeminal Neuralgia and sinus headaches. The anatomical and neurologic connections are often not obvious and rather are subject to the diversity of the Limbic System, especially the Hypothalamus, the Amygdala and the Reticular Activating System. TMJ has often been called “The Great Imposter” as described in Cranio Journal “TMJ Alias, The Great Imposter, Has a Co- Conspirator: Poor Sleep” which can be found at: Poor Sleep can be related to many different problems and cause and effect is often difficult to ascertain. This was reported in CARDIOVASCULAR AND SLEEP-RELATED CONSEQUENCES OF TEMPOROMANDIBULAR DISORDERS. NHLBI WORKSHOP
Sponsors: National Heart, Lung and Blood Institute (NHLBI), NHLBI Division of Heart and Vascular Diseases (DHVD), NHLBI National Center on Sleep Disorders Research (NCSDR)

Shimshak demonstrated in his two articles in Cranio that TMD patients have a three fold increase in medical spending in all fields of medicine. The second article was, “Health care utilization by patients with temporomandibular joint disorders”. Abstract below:
The claims data base of a large New England managed care organization was used to compare the health care utilization patterns of patients with TMJ disorders to non-TMJ subjects. Inpatient, outpatient and psychiatric claims data were examined over a wide range of diagnostic categories. Age and sex adjusted results showed that, overall, patients with TMJ disorders were greater utilizers of health care services and had higher associated costs than non-TMJ subjects. For some of the major diagnostic categories, such as nervous, respiratory, circulatory, and digestive, the inpatient and outpatient claims differences in utilization and costs were as large as 3 to 1. For only one diagnostic category, pregnancy and childbirth, were utilization and costs greater for non-TMJ subjects than TMJ patients. The psychiatric claims for TMJ patients exhibited differences that were at least twice as large as those for the non-TMJ subjects.

The evidence is for a major input of the Limbic System in TMJ Disorders. The wide spread symptoms that are often hard to pinpoint cause and effect is similar what is found in Functional Neurological Disorders (FND).

According to Mayo Clinic: “Symptoms of functional neurologic disorders(FND) may vary, depending on the type of functional neurologic disorder, and they’re significant enough to cause impairment and warrant medical evaluation. Symptoms can affect body movement and function and the senses.

Signs and symptoms that affect body movement and function may include:

Weakness or paralysis
Abnormal movement, such as tremors or difficulty walking
Loss of balance
Difficulty swallowing or feeling “a lump in the throat”
Seizures or episodes of shaking and apparent loss of consciousness (nonepileptic seizures)
Episodes of unresponsiveness
Signs and symptoms that affect the senses may include:

Numbness or loss of the touch sensation
Speech problems, such as inability to speak or slurred speech
Vision problems, such as double vision or blindness
Hearing problems or deafness”

`This does not mean TMD is a psychological problem but rather it is a problem with huge connections into the CNS due to the Trigemninal nerve input. Correction of the nociceptive input to the brain can give amazing relief, especially when it is combined with a reset of the autonomic nervous system, both sympathetic and parasympathetic with a sphenopalatine ganglion (SPG) Block. It is important that all stresses be addressed, not just the structural stresses. It is extremely important to address the noxious inputs from structural stresses to correct the entire system and prevent future development of FND

A great deal of information can be found in my Cranio Article: Neuromuscular dentistry and the role of the autonomic nervous system: Sphenopalatine ganglion blocks and neuromodulation. An International College of Cranio Mandibular Orthopedics (ICCMO) position paper. The paper has been reprinted on this site.

Scientific American published and excellent article on Functional Neurologic Disorders in November 2020. The article is “Decoding a Disorder at the Interface of Mind and Brain
A mysterious condition once dismissed as hysteria is challenging the divide between neurology and psychiatry”

SASPGB or Self-Administration of SPG Blocks is a game changer for many patients and should always be considered as part of a first line treatment protocol along with other procedures.