Tension myositis syndrome (TMS), also known as tension myoneural syndrome or mindbody syndrome is a name given by John E. Sarno to a condition he describes as characterized by musculoskeletal and nerve symptoms, most notably back pain. Sarno, a Professor of Clinical Rehabilitation Medicine at New York University School of Medicine and Attending Physician at The Rusk Institute of Rehabilitation Medicine at New York University Medical Center, has described TMS in four books, and has stated that the condition may be involved in other pain disorders as well. The treatment protocol for TMS includes education, writing about emotional issues, resumption of a normal lifestyle and, for some patients, support meetings and/or psychotherapy. In 2007, David Schechter (a medical doctor and former student and research assistant of Sarno's) published a peer-reviewed study of TMS treatment showing a 54% success rate for chronic back pain. In terms of statistical significance and success rate, the study outperformed similar studies of other psychological interventions for chronic back pain.

The TMS diagnosis and treatment protocol are not accepted by the mainstream medical community. However, TMS and Sarno's treatment methods have received national attention, including a segment on ABC's "20/20"; an episode of "Larry King Live"; an interview with "Medscape"; and articles in "Newsweek", "The Seattle Times", and "The New York Times". Prominent medical doctors who support TMS treatment include Andrew Weil and Mehmet Oz. Notable patients treated for tension myositis syndrome include Senator Tom Harkin, John Stossel, Howard Stern, and Anne Bancroft.

People vary in their tendency to get MSDs. Gender is a factor with a higher rate in women than men. Obesity is also a factor, with overweight individuals having a higher risk of some MSDs, specifically lower back.

There is a growing consensus that psychosocial factors are another cause of some MSDs. Some theories for this causal relationship found by many researchers include increased muscle tension, increased blood and fluid pressure, reduction of growth functions, pain sensitivity reduction, pupil dilation, body remaining at heightened state of sensitivity. Although research findings are inconsistent at this stage, some of the workplace stressors found to be associated with MSDs in the workplace include high job demands, low social support, and overall job strain. Researchers have consistently identified causal relationships between job dissatisfaction and MSDs. For example, improving job satisfaction can reduce 17-69 per cent of work-related back disorders and improving job control can reduce 37-84 per cent of work-related wrist disorders.

Back pain is frequently mentioned as a TMS symptom, but Sarno defines TMS symptoms much more broadly than that:

- "Symptom type:" TMS symptoms include pain, stiffness, weakness, tingling, numbness, muscle contractures, cramps and other negative sensations, according to Sarno.

- "Symptom location:" In addition to the back, Sarno states that TMS symptoms can occur in the neck, knee, arms, wrists, and other parts of the body. Schechter states that the symptoms have a tendency to move to other parts of the body. He considers symptom movement an important indicator that the pain is from TMS.

Functional somatic syndromes may occur in 6 to 36% of the population.

BFS has been reported in other African cultures, and also in Brazil, Argentina, and Ethiopian Jews. Historic higher reported prevalence among males may be due to more males being present in higher education in African countries. Studies since the 1990s have not verified gender differences. Other studies found a possible association with low socioeconomic status, an association with average or higher intelligence, and a high association with neuroticism. Individuals with BFS have been found to have problems with isolation, poor study habits, and the use of psychostimulants as well as physical changes including in muscle tension and heart rate.

The most common causes of myalgia by injury are: sprains and strains.

Treatment may involve investigation, reassurance and explanation, and possibly specialist treatment such as antidepressants or cognitive behavioral therapy.

Anumonye reported treatment success with lorazepam; others found benefit with antidepressants and relaxation exercises.

Overuse of a muscle is using it too much, too soon and/or too often. Examples are:

- Repetitive strain injury.

As of 2013 tension headaches affect about 1.6 billion people (20.8% of the population) and are more common in women than men (23% to 18% respectively). Despite its benign character, tension-type headache, especially in its chronic form, can impart significant disability on patients as well as burden on society at large.

BII phobia is one of the more common psychiatric disorders, affecting about 3 to 4% of the general population, and in about 80% of the BII phobia cases, the patient experiences syncope or presyncope. After a random survey was completed in Aligarh, India, with 1648 male and 1613 female, it was found that a significantly higher percentage of females compared to males had BII phobia; 23.36% of females were diagnosed with BII phobia while only 11.19% of males were diagnosed. Females also fainted more often than males, at 64.09% compared to a male rate of 39.4%.

Furthermore, only 5.3% of BII phobia patients reported to have visited the hospital once or twice for consultation about BII phobia, however, without engaging in any kind of treatment.

Another study, involving participants from all 50 states and the District of Columbia, ages 65 years and older, found that a total of 386 participants disclosed having BII Phobia throughout their whole lifetime, 90% of those cases consisted of patients dealing with BII Phobia as well as other lifetime fears.

The lateral femoral cutaneous nerve most often becomes injured by entrapment or compression where it passes between the upper front hip bone (ilium) and the inguinal ligament near the attachment at the anterior superior iliac spine (the upper point of the hip bone). Less commonly, the nerve may be entrapped by other anatomical or abnormal structures, or damaged by diabetic or other neuropathy or trauma such as from seat belt injury in an accident.

The nerve may become painful over a period of time as weight gain makes underwear, belting or the waistband of pants gradually exert higher levels of pressure. Pain may be acute and radiate into the rib cage, and into the groin, thigh, and knee. Alternately, weight loss or aging may remove protective fat layers under the skin, so the nerve can compress against underwear, outer clothing, and—most commonly— by belting. Long periods of standing or leg exercise that increases tension on the inguinal ligament may also cause pressure.

The entire distribution of the nerve is rarely affected. Usually, the unpleasant sensation(s) affect only part of the skin supplied by the nerve.

Most cases of back pain are related to issues in human musculoskeletal system and are not related to severe diseases. Musculoskeletal problems also called mechanical because many of them linked to vertebrae physical motions. Back pain itself is not considered a diagnosis, but rather a symptom of underlying (in most cases musculoskeletal) problems.

following:

- Vertebrae misalignment, which can cause nerve interference (also called subluxation), muscle tension, or muscle spasm

- Strained muscles

- Sprained ligaments

- Ruptured disks, which also called "slipped", or herniated disks

- Degenerative discs (lose their cushioning ability). The degeneration usually caused by repetitive strain, or injury, or aging.

- Irritated joints

Jumping Frenchmen of Maine syndrome must be distinguished from other conditions involving the startle reflex or tics.

Tourette syndrome is characterized by multiple physical (motor) tics and at least one vocal (phonic) tic. There are many overlaps when compared clinically, but the abnormal "jumping" response is always provoked, unlike the involuntary tics in Tourette syndrome.

Latah from Southeast Asia is a disorder where one's startle response is similar to a state of trance with repetitive speech or movements. Miryachit is a disorder found in Siberia that also displays an action similar to "jumping". Neurasthenia is a disorder with a startle response during periods of great fatigue.

Hyperekplexia is an extremely rare autosomal dominant neurological disease. The symptoms start in infancy with hypertonia, an abnormal muscle tension that decreases flexibility, and an exaggerated startle in all ages of life.

The cause of BII phobia is not well known. Some studies show that specific genes make one more vulnerable to the phobia. Other studies suggest that just like any other phobia, BII phobia could be caused by a traumatic experience (Chapman). It has been proved that social stress amplifies BII symptoms, however, it is not a main cause.

The cause of Jumping Frenchmen syndrome is unknown. One theory is that it is a genetic condition. Observation of 50 cases found the disorder to be remotely located and concentrated in the northern regions of Maine. Fourteen of these cases were found in four families. Another set of cases were found in a single family where the father, his two sons, and his two grandchildren exhibited "jumping" behavior.

It may also be a culture-bound syndrome or a formed habit. These French "jumpers" lived in a very remote region and most were lumberjacks. This type of small community would allow for a majority to adapt to this sort of reaction. Also, instances of many being shy may imply that the "jumper" was positively reinforced by the sudden attention as the entertainment for a group.

In 1885, Georges Gilles de la Tourette included Jumping Frenchmen syndrome in the typology of "convulsive tic illness"; studies of the condition in the 1980s cast doubt on whether the phenomenon was in fact a physical condition similar to Tourette syndrome. Documentation of direct observation of "Jumping Frenchmen" has been scarce, and while videotape evidence was recorded by several researchers that showed the condition to be real, MH and JM Saint-Hilaire concluded from studying eight affected people that it was brought on by conditions at their lumber camps and was psychological, not neurological.

Chronic headache, or chronic daily headache (CDH), is classified as experiencing fifteen or more days with a headache per month. It is estimated that chronic headaches affect "4% to 5% of the general population". Chronic headaches consist of different sub-groups, primarily categorized as chronic tension-type headaches and chronic migraine headaches. The treatments for chronic headache are vast and varied. Medicinal and non-medicinal methods exist to help patients cope with chronic headache, because chronic headaches cannot be cured. Whether pharmacological or not, treatment plans are often created on an individual basis. Multiple sources recommend "multimodal treatment", which is a combination of medicinal and non-medicinal remedies. Some treatments are controversial and are still being tested for effectiveness. Suggested treatments for chronic headaches include medication, physical therapy, acupuncture, relaxation training, and biofeedback. In addition, dietary alteration and behavioral therapy or psychological therapy are other possible treatments for chronic headaches.

BSS is not limited to the elderly but has an average age of onset of 66 years and is more common amongst men. This late age of onset is largely due to the increased preponderance of the conditions causing the symptom in older individuals – such as muscular weakness and neurological disorders like Parkinson's disease. While BSS doesn’t have any negative stigma in and of itself, those affected by it may be perceived differently due to the condition. For example, an elderly individual afflicted with the condition may be viewed as very physically weak, because of the severe bending of the back caused by the condition.

A multitude of neurological disorders cause BSS, including motor neuron disease, CNS disorders, and early amyotrophic lateral sclerosis. Usually, the bent spine is caused by dysfunctioning extensor spinal muscles with a neurological cause.

Neurological origin BSS may also result from damage to the basal ganglia nuclei that are a part of the cerebral cortex, which play a major role in bodily positioning. Damage to this part of the brain can inhibit proper flexion and extension in the muscles necessary for maintaining an upright position. Additionally, the neurotransmitter dopamine plays a key role in the operation of basal ganglia. An abnormally low dopamine concentration, such as that associated with Parkinson’s disease, causes dysfunction in the basal ganglia and the associated muscle groups, leading to BSS. Studies have estimated the prevalence of BSS in people affected by Parkinson's to be between 3% and 18%.

Many physicians also recommend changes in diet to treat chronic headaches. Many chronic headache sufferers fail to recognize foods or beverages as headache factors, because the consumption may not consistently cause headaches or the headaches may be delayed. Many of the chemicals in certain foods can cause chronic headaches, including caffeine, monosodium glutamate (MSG), nitrites, nitrates, tyramine, and alcohols. Some of the foods and beverages that chronic headache sufferers are advised to avoid include caffeinated beverages, chocolate, processed meats, cheese and fermented dairy products, fresh yeast-risen baked goods, nuts, and alcohol as well as certain fruits and vegetables. Additionally, people may have differing dietary triggers on an individualized basis, because not all foods affect people the same way. Different medical professionals suggest different ways of testing or changing diets. Some may suggest eliminating a few of the potentially headache-causing foods at a time for a short period of time, while others suggest removing all the threatening foods from a person's diet and slowly adding a couple back at a time. Yet, others may not suggest diet modification at all. The treatment of chronic headaches through changes in diet is based on personal opinion, and, therefore, controversial.

Many doctors commonly recommend a combined treatment of: a warm compress applied to the eyes (to relieve muscle tension, relax the muscles, and reduce swelling); a small dosage of antihistamine (to reduce any swelling that may be caused by an allergic reaction); increase bed rest (to allow muscles to rest); decrease exposure to computer screens, televisions, or harsh lighting (to allow muscles to rest); and monitor caffeine intake (too much caffeine can cause an adverse reaction such as eye twitching, but a controlled dose can serve as an effective treatment by increasing blood flow).

Frequent contributing factors include: too much caffeine, high levels of anxiety, fatigue, dehydration, stress, overwork, and a lack of sleep. Use of certain drugs or alcohol may also be factors.

Magnesium deficiency.

20-30% of people who menstruate experience symptoms severe enough to meet PMS criteria and 3-8% of people who are of reproductive age meet the PMDD criteria.

Bipolar depression, anxiety disorders, and other Axis I disorders are more common in people with PMDD than in the general population. In people with PMDD, there is a 50-78% lifetime incidence of various psychiatric disorders such as generalized anxiety disorder, seasonal affective disorder and major depressive disorder.

The symptoms in which coincide with mood disorders, such as major depressive disorder or bipolar disorder, may worsen during the premenstrual period and thus may mimic PMDD. This phenomenon is known as premenstrual exacerbation (PME) and refers to the worsening of mood disorder symptoms during the premenstrual phase. An estimated 40% of people who seek treatment for PMDD are found to not have PMDD, but rather a PME of an underlying mood disorder.

Medical personnel can avoid misdiagnosis by having people seeking treatment for PMDD use a daily charting method to record their symptoms. Daily charting helps distinguish when mood disturbances are experienced and allows PMDD to be distinguished from other mood disorders. With PMDD, mood symptoms are present only during the luteal phase, or last two weeks, of the menstrual cycle. While PMDD mood symptoms are of a cyclical nature, other mood disorders are variable or constant over time. Although the medical community lacks a consensus on the most efficient instrument by which to confirm a PMDD diagnosis, several well-validated scales for recording premenstrual symptoms include the Calendar of Premenstrual Experiences (COPE), Daily Record of Severity of Problems (DRSP), and Prospective Record of the Severity of Menstruation (PRISM).

PMDD mood symptoms are only present in people who are menstruating. Thus, symptoms do not occur during pregnancy and after menopause. Other mood disorders typically persist across all reproductive life events and are independent of a person's menstrual cycle or lack thereof.

In addition to AXIS I disorders, several other medical illnesses such as chronic fatigue syndrome, fibromyalgia, irritable bowel syndrome and migraine disorder may present symptoms similar or identical to those of PMDD. Clinicians must distinguish between PMDD and other medical and/or psychiatric conditions.