Thought insertion is defined by the ICD-10 as feeling as if one's thoughts are not one's own, but rather belong to someone else and have been inserted into one's mind. The person experiencing thought insertion will not necessarily know where the thought is coming from, but is able to distinguish between their own thoughts and those inserted into their minds. However, patients do not experience all thoughts as inserted, only certain ones, normally following a similar content or pattern. This phenomenon is classified as a delusion. A person with this delusional belief is convinced of the veracity of their beliefs and is unwilling to accept such diagnosis.

Thought insertion is a common symptom of psychosis and occurs in many mental disorders and other medical conditions. However, thought insertion is most commonly associated with schizophrenia. Thought insertion, along with thought broadcasting, thought withdrawal, thought blocking and other first rank symptoms, is a primary symptom and should not be confused with the delusional explanation given by the respondent. Although normally associated with some form of psychopathology, thought insertion can also be experienced in those considered nonpathological, usually in spiritual contexts, but also in culturally influenced practices such as mediumship and automatic writing.

Examples of thought insertion:

"She said that sometimes it seemed to be her own thought 'but I don't get the feeling that it is'. She said her 'own thoughts might say the same thing', 'but the feeling isn't the same', 'the feeling is that it is somebody else's'"

"I look out the window and I think that the garden looks nice and the grass looks cool, but the thoughts of Eamonn Andrews come into my mind. There are no other thoughts there, only his. He treats my mind like a screen and flashes thoughts onto it like you flash a picture"

"The subject has thoughts that she thinks are the thoughts of other people, somehow occurring in her own mind. It is not that the subject thinks that other people are making her think certain thoughts as if by hypnosis or psychokinesis, but that other people think the thoughts using the subject's mind as a psychological medium."

Unbidden thoughts are thoughts that come to mind without the subject directly or consciously meaning to think them. Inserted thoughts, while sharing the characteristic of unconsciously or indirectly being conjured, are distinct from unbidden thoughts because of the author of the thoughts. During an experience of unbidden thinking, the subject knows that they are the author of the thought even though they may not have consciously meant to think it. During the feeling of thought insertion, however, the subject feels as though the thought belongs to another person and was inserted into their own mind, making the author of the thought someone other than themselves.

These symptoms are not due to situations such as, person is depressed because of difficulty making friends. It is normal to experience dysfunctional emotions and behaviors at times.

Criteria are met for a neurotic or personality disorder, preferably at least two.

Some symptoms may include:

1. Depression.

2. Mania.

3. Anxiety.

4. Anger.

5. Dissociative symptoms such as depersonalization, derealization, deja vu, etc.

6. Emotional instability.

7. Psychopathic behavior.

8. Narcissism.

9. Paranoia.

10. Obsessive-compulsive behavior.

Criteria are met for a psychotic disorder.

Some symptoms may include:

1. Delusions, such as thought insertion, paranoid preoccupations, fantasies of personal omnipotence, over engagement with fantasy figures, grandiose fantasies of special powers, referential ideation, and confusion between fantasy and real life.

2. Hallucinations and/or unusual perceptual experiences.

3. Negative symptoms (anhedonia, affective flattening, alogia, avolition)

4. Disorganized behavior and/or speech such as thought disorder, easy confusability, inappropriate emotions/facial expressions, uncontrollable laughter, etc.

5. Catatonic behavior.

In Scientology, an implant is a form of Thought insertion, similar to an engram but done deliberately and with evil intent. It is "an intentional installation of fixed ideas, contra-survival to the thetan".

The intention in the original engram or incident is to implant an idea or emotion or sensation, regarding some phenomenon etc. The intention in Scientology and Dianetics is to erase the compulsive or command effect of the idea, emotion, sensation, etc. so that the person can make a rational judgment and decision in the affected areas of life.

Scientology practices often have to do with addressing implants prior to the current lifetime — one of the most notable is the "R6 implant"; but in some cases current life implants are addressed. Examples of implants according to Scientology include Aversion therapy, Electroconvulsive therapy, hypnosis, various attempts at brainwashing, and the inducing of fear or terror. Note that this is not a complete list, as many kinds of incidents can include implants as an element.

Other important implants in Scientology doctrine include the Helatrobus implants, which Hubbard claimed occurred 382 trillion years ago to 52 trillion years ago by an alien nation called the Helatrobans, who sought to restrain human minds by capturing and brainwashing thetans. These implants are said to be responsible for the concept of Heaven.

Medical fetishism refers to a number of sexual fetishes involving objects, practices, environments, and situations of a medical or clinical nature. In sexual roleplay a hospital or medical scene involves the sex partners assuming the roles of doctors, nurses, surgeons and patients to act out specific or general medical fetishes. Medical fantasy is a genre in pornography, though the fantasy may not necessarily involve pornography or sexual activity.

Medical fetishism may involve sexual attraction to respiratory therapy involving oxygen via nasal cannula or any sort of masks, medical practitioners, medical uniforms, hospital gowns, anaesthesia, intimate examinations (such as rectal examination, gynecological examination, urological examination, andrological examination, rectal temperature-taking), catheterization, diapering, enemas, injections, insertion (such as suppository insertion, menstrual-cup insertion, and prostatic massage), medical devices (such as orthopedic casts and orthopedic braces; see also "Abasiophilia"), dental objects (such as dental braces, retainers, and headgear), medical restraints, and medical gags.

Some people eroticize about intimate examinations as part of a medical fetish, and as such are a common service offered by professional dominants.

An intimate examination can form part of a scene in medical play where the nurse or doctor inflicts one or more embarrassing and humiliating quasi-medical procedures on the patient. Often frozen or heated objects are introduced to the patient's body to simulate the uncomfortable sensations that can occur during a real examination. Examinations may include an examination and intrusion of the anus, urethra, or vagina, as well as handling and twisting of the penis, testicles, clitoris, and nipples. Quite often, strap on play is also incorporated, as this can heighten the intimacy, and also the sensations of the patient. This may be a prelude to masturbation or administration of an enema. Before examination, the patient can be placed in physical restraints and gagged, and wear some form of embarrassing clothing.

Sexual dysfunction (or sexual malfunction or sexual disorder) is difficulty experienced by an individual or a couple during any stage of a normal sexual activity, including physical pleasure, desire, preference, arousal or orgasm. According to the DSM-5, sexual dysfunction requires a person to feel extreme distress and interpersonal strain for a minimum of 6 months (excluding substance or medication-induced sexual dysfunction). Sexual dysfunctions can have a profound impact on an individual's perceived quality of sexual life. The term "sexual disorder" may not only refer to physical sexual dysfunction, but to paraphilias as well; this is sometimes termed "disorder of sexual preference".

A thorough sexual history and assessment of general health and other sexual problems (if any) are very important. Assessing performance anxiety, guilt, stress and worry are integral to the optimal management of sexual dysfunction. Many of the sexual dysfunctions that are defined are based on the human sexual response cycle, proposed by William H. Masters and Virginia E. Johnson, and then modified by Helen Singer Kaplan.

Sexual arousal disorders were previously known as frigidity in women and impotence in men, though these have now been replaced with less judgmental terms. Impotence is now known as erectile dysfunction, and frigidity has been replaced with a number of terms describing specific problems that can be broken down into four categories as described by the American Psychiatric Association's "Diagnostic and Statistical Manual of Mental Disorders": lack of desire, lack of arousal, pain during intercourse, and lack of orgasm.

For both men and women, these conditions can manifest themselves as an aversion to, and avoidance of, sexual contact with a partner. In men, there may be partial or complete failure to attain or maintain an erection, or a lack of sexual excitement and pleasure in sexual activity.

There may be physiological origins to these disorders, such as decreased blood flow or lack of vaginal lubrication. Chronic disease can also contribute, as well as the nature of the relationship between the partners.

Additionally, the condition Post-Orgasm illness Syndrome (POIS) may cause symptoms when aroused, including adrenergic-type presentation; Rapid breathing, paraesthesia, palpitations, headaches, aphasia, nausea, itchy eyes, fever, muscle pain/weakness and fatigue.

From the onset of arousal, symptoms can persist for up to a week in patients.

The aetiology of this condition is unknown, however it is believed to be a pathology of either the immune system or autonomic nervous systems. It is defined as a rare disease by the NIH but the prevalence is unknown. It is not thought to be psychiatric in nature, but it may present as anxiety relating to coital activities and thus may be incorrectly diagnosed as such. There is no known cure or treatment.

Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is an epileptic disorder that causes frequent violent seizures during sleep. These seizures often involve complex motor movements, such as hand clenching, arm raising/lowering, and knee bending. Vocalizations such as shouting, moaning, or crying are also common. ADNFLE is often misdiagnosed as nightmares. Attacks often occur in clusters and typically first manifest in childhood. There are four known loci for ADNFLE, three with known causative genes. These genes, "CHRNA4", "CHRNB2", and "CHRNA2", encode various nicotinic acetylcholine receptor α and β subunits.

Hapnes Boman Skeie syndrome is a rare genetic disorder first described by Sveln Hapnes et al. in 1980. It is characterized by subcutaneous angiolipomas around the wrists, knees, and ankles. It is also known as "anomalous insertion of extensor tendons of fingers", a name derived from the condition that the tendons of the fingers are attached in such a way that the fingers cannot open or close normally. Though the tumors extend deeply into the muscle tissue, joints, and tendons, the tumors did not invade these structures.

ADNFLE is a partial epilepsy disorder characterized by brief violent seizures during sleep. Seizures are complex, consisting of arm and leg movements, fist clenching, and vocalizations such as yelling and moaning. These seizures often occur in clusters and can first manifest in childhood. Diagnosis is often initially incorrectly made as nightmares, night terrors, parasomnias and various psychiatric disorders.

It most often occurs in the middle of the night and lasts from seconds to minutes, an indicator for the differential diagnosis of levator ani syndrome, which presents as pain and aching lasting twenty minutes or longer. In a study published in 2007 involving 1809 patients, the attacks occurred in the daytime (33 per cent) as well as at night (33 per cent) and the average number of attacks was 13. Onset can be in childhood; however, in multiple studies the average age of onset was 45. Many studies showed that women are affected more commonly than men. This can be at least partly explained by men's reluctance to seek medical advice concerning such a delicate case as rectal pain.

During an episode, the patient feels spasm-like, sometimes excruciating, pain in the anus, often misinterpreted as a need to defecate. The pain must arise de novo, that is in absence of clear cause. As such, pain associated with penetrative anal intercourse, trauma or rectal foreign body insertion preclude a diagnosis of proctalgia fugax. Simultaneous stimulation of the local autonomic system can cause erection in males. In some people, twinges sometimes occur shortly after orgasm. Because of the high incidence of internal anal sphincter thickening with the disorder, it is thought to be a disorder of the internal anal sphincter or that it is a neuralgia of pudendal nerves. It is recurrent and there is also no known cure. However, some studies show effective use of botulinum toxin, pudendal nerve block, and calcium channel blockers. It is not known to be linked to any disease process and data on the number of people afflicted vary, but prevalence may be as high as 8–18%. It is thought that only 17–20% of sufferers consult a physician, so obtaining accurate data on occurrence presents a challenge.

The pain episode subsides by itself as the spasm disappears on its own, but may reoccur.

Proctalgia fugax (a variant of levator ani syndrome) is a severe, episodic pain in the regions of the rectum and anus. It can be caused by cramp of the levator ani muscle, particularly in the pubococcygeal part.

Doctors have documented numerous cases of insertion of foreign bodies into the urethra, typically as the result of auto-erotic activities. This can result in infections and serious internal bleeding.

A wide variety of solid objects have been reported to have been inserted into the urethra, including batteries, safety pins, straws, and telephone wires. Liquefied objects have also been inserted into the urethra, such as an injection of cocaine (which, arguably, had harmful results).

The Chuck Palahniuk story "Guts", from the novel "Haunted", includes the story of a boy in his early teens inserting candle wax into his urethra.

Symptoms categorized as physically visible symptoms include chorea, dystonia, spasticity, and rigidity, all physical symptoms of the body associated with movement disorders. The symptoms accompanying neuroferritinopathy affecting movement are also progressive, becoming more generalized with time. Usually during the first ten years of onset of the disease only one or two limbs are directly affected.

Distinctive symptoms of neuroferritinopathy are chorea, found in 50% of diagnosed patients, dystonia, found in 43% of patients, and parkinsonism, found in 7.5% of patients. Full control of upper limbs on the body generally remains until late onset of the disease. Over time, symptoms seen in a patient can change from one side of the body to the opposite side of the body, jumping from left to right or vice versa. Another route that the physically visible symptoms have been observed to take is the appearance, disappearance, and then reappearance once more of specific symptoms.

While these symptoms are the classic indicators of neuroferritinopathy, symptoms will vary from patient to patient.

Symptoms categorized as medically tested and diagnosed include iron accumulation in the brain, basal ganglia cavitation, and neurodegeneration. Patients who are diagnosed with neuroferritinopathy have abnormal iron accumulation in the brain within the neurons and glia of the striatum and cerebellar cortices. Along with the accumulation of iron in the brain, neuroferritinopathy typically causes severe neuronal loss as well.

Secondary symptoms may also arise. It is possible that the initial iron accumulation will cause additional neuronal damage and neuronal death. The damaged neurons may be replaced by other cells in an effort to reverse the neurodegeneration. These cells often have a higher iron content. The breakdown of the blood brain barrier may also occur due to the loss of neurons and will subsequently allow more iron to access the brain and accumulate over time.

Neuroferritinopathy is mainly seen in those who have reached late adulthood and is generally seen to slowly progress throughout many decades in a lifetime with the mean age of onset being 39 years old. A loss of cognition is generally only seen with late stages of the disease. Diagnosed patients are seen to retain most of their cognitive functioning until the most progressive stages of the illness sets in.

Myringosclerosis rarely causes any symptoms. Tympanosclerosis, on the other hand, can cause significant hearing loss or chalky, white patches on the middle ear or tympanic membrane.

The Huntington's disease-like syndromes (often abbreviated as HD-like or "HDL" syndromes) are a family of inherited neurodegenerative diseases that closely resemble Huntington's disease (HD) in that they typically produce a combination of chorea, cognitive decline or dementia and behavioural or psychiatric problems.

Tympanosclerosis (also known as myringosclerosis or intratympanic tympanosclerosis) is a condition caused by hyalinization and subsequent calcification of subepithelial connective tissue of TM and middle ear, sometimes resulting in a detrimental effect to hearing.

Caustic ingestion occurs when someone accidentally or deliberately ingests a caustic or corrosive substance. Depending on the nature of the substance, the duration of exposure and other factors it can lead to varying degrees of damage to the oral mucosa, the oesophagus, and the lining of the stomach.

The severity of the injury can be determined by endoscopy of the upper digestive tract, although CT scanning may be more useful to determine whether surgery may be required.

During the healing process, strictures of the oesophagus may form, which may require therapeutic dilatation and insertion of a stent.

Symptoms of ML III are often not noticed until the child is 3–5 years of age. Patients with ML III are generally of normal intelligence (trait) or have only mild mental retardation. These patients usually have skeletal abnormalities, coarse facial features, short height, corneal clouding, carpal tunnel syndrome, aortic valve disease and mild enlargement of organs. Some children with severe forms of this disease do not live beyond childhood. However, there is a great variability among patients - there are diagnosed individuals with ML III living in their sixties.

A Stener lesion is a type of traumatic injury to the thumb. It occurs when the aponeurosis of the adductor pollicis muscle becomes interposed between the ruptured ulnar collateral ligament (UCL) of the thumb and its site of insertion at the base of the proximal phalanx. No longer in contact with its insertion site, the UCL cannot spontaneously heal.

In terms of the signs/symptoms of Fukuyama congenital muscular dystrophy it is characterized by a decrease in skeletal muscle tone as well as an impairment in brain and eye development.Initial symptoms of FCMD present in early infancy as decreased ability to feed. Marked differences in facial appearance occur due to decreased muscle tone. Further characteristics include:

- Seizures

- Delay in developmental

- Cardiac issues

- Swallowing difficulty

- Neurological problems

Fukuyama congenital muscular dystrophy also affects the nervous system and various associated parts. FCMD affects normal development of the brain producing a broadly smooth, bumpy shaped cortex named cobblestone lissencephaly as well as various other malformations, notably micropolygyria. Children also experience delayed myelination in the brain.

Symptoms of gamekeeper's thumb are instability of the MCP joint of the thumb, accompanied by pain and weakness of the pinch grasp. The severity of the symptoms are related to the extent of the initial tear of the UCL (in the case of Skier's thumb), or how long the injury has been allowed to progress (in the case of gamekeeper's thumb).

Characteristic signs include pain, swelling, and ecchymosis around the thenar eminence, and especially over the MCP joint of the thumb. Physical examination demonstrates instability of the MCP joint of the thumb.

The patient will often manifest a weakened ability to grasp objects or perform such tasks as tying shoes and tearing a piece of paper. Other complaints include intense pain experienced upon catching the thumb on an object, such as when reaching into a pants pocket.