Although essential tremor is often mild, people with severe tremor have difficulty performing many of their routine activities of daily living. ET is generally progressive in most cases (sometimes rapidly, sometimes very slowly), and can be disabling in severe cases.

Surgery, such as the denervation of selected muscles, may also provide some relief; however, the destruction of nerves in the limbs or brain is not reversible and should be considered only in the most extreme cases. Recently, the procedure of deep brain stimulation (DBS) has proven successful in a number of cases of severe generalised dystonia. DBS as treatment for medication-refractory dystonia, on the other hand, may increase the risk of suicide in patients. However, reference data of patients without DBS therapy are lacking.

ET is one of the most common neurological diseases, with a prevalence of approximately 4% in persons age 40 and older and considerably higher among persons in their 60s, 70s, 80s, with an estimated 20% of individuals in their 90s and over. Aside from enhanced physiological tremor, it is the most common type of tremor and one of the most commonly observed movement disorders.

"Primary dystonia" is suspected when the dystonia is the only sign and there is no identifiable cause or structural abnormality in the central nervous system. It is suspected to be caused by a pathology of the central nervous system, likely originating in those parts of the brain concerned with motor function, such as the basal ganglia, and the GABA (gamma-aminobutyric acid) producing Purkinje neurons. The precise cause of primary dystonia is unknown. In many cases it may involve some genetic predisposition towards the disorder combined with environmental conditions.

"Secondary dystonia" refers to dystonia brought on by some identified cause, such as head injury, drug side effect (e.g. tardive dystonia), or neurological disease (e.g. Wilson's disease).

Meningitis and encephalitis caused by viral, bacterial, and fungal infections of the brain have been associated with dystonia. The main mechanism is inflammation of the blood vessels, causing restriction of blood flow to the basal ganglia. Other mechanisms include direct nerve injury by the organism or a toxin, or autoimmune mechanisms.

Environmental and task-related factors are suspected to trigger the development of focal dystonias because they appear disproportionately in individuals who perform high precision hand movements such as musicians, engineers, architects, and artists. Chlorpromazine can also cause dystonia, which can be often misjudged as a seizure.

Neuroleptic drugs often cause dystonia, including oculogyric crisis.

Misfunction of the sodium-potassium pump may be a factor in some dystonias. The - pump has been shown to control and set the intrinsic activity mode of cerebellar Purkinje neurons. This suggests that the pump might not simply be a homeostatic, "housekeeping" molecule for ionic gradients; but could be a computational element in the cerebellum and the brain. Indeed, an ouabain block of - pumps in the cerebellum of a live mouse results in it displaying ataxia and dystonia. Ataxia is observed for lower ouabain concentrations, dystonia is observed at higher ouabain concentrations. A mutation in the - pump (ATP1A3 gene) can cause rapid onset dystonia parkinsonism. The parkinsonism aspect of this disease is thought to be attributable to malfunctioning - pumps in the basal ganglia; the dystonia aspect is thought to be attributable to malfunctioning - pumps in the cerebellum (that act to corrupt its input to the basal ganglia) possibly in Purkinje neurons.

Cerebellum issues causing dystonia is described by Filip et al. 2013: "Although dystonia has traditionally been regarded as a basal ganglia dysfunction, recent provocative evidence has emerged of cerebellar involvement in the pathophysiology of this enigmatic disease. It has been suggested that the cerebellum plays an important role in dystonia etiology, from neuroanatomical research of complex networks showing that the cerebellum is connected to a wide range of other central nervous system structures involved in movement control to animal models indicating that signs of dystonia are due to cerebellum dysfunction and completely disappear after cerebellectomy, and finally to clinical observations in secondary dystonia patients with various types of cerebellar lesions. It is proposed that dystonia is a large-scale dysfunction, involving not only cortico-basal ganglia-thalamo-cortical pathways, but the cortico-ponto-cerebello-thalamo-cortical loop as well. Even in the absence of traditional "cerebellar signs" in most dystonia patients, there are more subtle indications of cerebellar dysfunction. It is clear that as long as the cerebellum's role in dystonia genesis remains unexamined, it will be difficult to significantly improve the current standards of dystonia treatment or to provide curative treatment."

Current medical science does not precisely describe the causes of dystonia. Misfiring of neurons in the sensorimotor cortex, a thin layer of neural tissue that covers the brain, is thought to cause contractions. This misfiring may result from impaired inhibitory mechanisms during muscle contraction. When the brain tells a given muscle to contract, it simultaneously silences muscles that would oppose the intended movement. It appears that dystonia interferes with the brain's ability to inhibit those surrounding muscles, leading to loss of selectivity.

The sensorimotor cortex is organized as discrete "maps" of the human body. Under normal conditions, each body part (such as individual fingers) occupies a distinct area on these cortical maps. In dystonia, these maps lose their distinct borders and overlap occurs. Exploration of this initially involved over-training particular finger movements in non-human primates, which resulted in the development of focal hand dystonia. Examination of the primary somatosensory cortex in the trained animals showed grossly distorted representations of the maps pertaining to the fingers when compared to the untrained animals. Additionally, these maps in the dystonic animals had lost the distinct borders that were noted in the untrained animals.

Imaging studies in humans with focal dystonia have confirmed this finding. Also, synchronous afferent stimulation of peripheral muscles induces organizational changes in motor representations, characterized both by an increase in map size of stimulated muscles and a reduction in map separation, as assessed using transcranial magnetic stimulation.

The cross-connectivity between areas that are normally segregated in the sensory cortex may prevent normal sensorimotor feedback and so contribute to the observed co-contraction of antagonist muscle groups, and inappropriately timed and sequenced movements that underlie the symptoms of focal dystonia. It is hypothesized that a deficit in inhibition caused by a genetically mediated loss of inhibitory interneurons may be the underlying cause of the deficits observed in dystonia.

While usually painless, in some instances the sustained contraction and abnormal posturing in dystonia cause pain. Focal dystonia most typically affects people who rely on fine motor skills—musicians, writers, surgeons, etc. It is thought that the excessive motor training those skills require may contribute to the development of dystonia as their cortical maps become enlarged and begin to overlap. Focal dystonia is generally "task-specific," meaning that it is only problematic during certain activities.

Although dystonias may be induced by chemical exposure/ingestion, brain injury, or hereditary/genetic predisposition, the task-specific focal dystonias such as writer's cramp are a unique challenge to diagnose and treat. Some cases may respond to chemical injections - botulinum toxin (botox) is often cited, though it is not helpful in all cases. Behavioral retraining attempts may include writing devices, switching hands, physical therapy, biofeedback, constraint-induced motion therapy, and others. Some writing instruments allow variations of pressure application for use. None of these are effective in all cases, however. The work of Dr. Joaquin Farias has shown that proprioceptive stimulation can induce neuroplasticity, making it possible for patients to recover substantial function that was lost from focal dystonia.

Anticholinergics such as Artane can be prescribed for off-label use, as some sufferers have had success.

A 1969 study of torsion dystonia patients found an average IQ 10 points higher than controls matched for age, sex and ethnic background.

Focal dystonia is a neurological condition, a type of "dystonia", that affects a muscle or group of muscles in a specific part of the body, causing involuntary muscular contractions and abnormal postures. For example, in focal hand dystonia, the fingers either curl into the palm or extend outward without control. In musicians, the condition is called "musician's focal dystonia", or simply, "musician's dystonia". In sports, it is commonly referred to as the "yips".

The medical treatment of essential tremor at the Movement Disorders Clinic at Baylor College of Medicine begins with minimizing stress and tremorgenic drugs along with recommending a restricted intake of beverages containing caffeine as a precaution, although caffeine has not been shown to significantly intensify the presentation of essential tremor. Alcohol amounting to a blood concentration of only 0.3% has been shown to reduce the amplitude of essential tremor in two-thirds of patients; for this reason it may be used as a prophylactic treatment before events during which one would be embarrassed by the tremor presenting itself. Using alcohol regularly and/or in excess to treat tremors is highly unadvisable, as there is a purported correlation between tremor and alcoholism. Alcohol is thought to stabilize neuronal membranes via potentiation of GABA receptor-mediated chloride influx. It has been demonstrated in essential tremor animal models that the food additive 1-octanol suppresses tremors induced by harmaline, and decreases the amplitude of essential tremor for about 90 minutes.

Two of the most valuable drug treatments for essential tremor are propranolol, a beta blocker, and primidone, an anticonvulsant. Propranolol is much more effective for hand tremor than head and voice tremor. Some beta-adrenergic blockers (beta blockers) are not lipid-soluble and therefore cannot cross the blood–brain barrier (propranolol being an exception), but can still act against tremors; this indicates that this drug’s mechanism of therapy may be influenced by peripheral beta-adrenergic receptors. Primidone’s mechanism of tremor prevention has been shown significantly in controlled clinical studies. The benzodiazepine drugs such as diazepam and barbiturates have been shown to reduce presentation of several types of tremor, including the essential variety. Controlled clinical trials of gabapentin yielded mixed results in efficacy against essential tremor while topiramate was shown to be effective in a larger double-blind controlled study, resulting in both lower Fahn-Tolosa-Marin tremor scale ratings and better function and disability as compared to placebo.

It has been shown in two double-blind controlled studies that injection of botulinum toxin into muscles used to produce oscillatory movements of essential tremors, such as forearm, wrist and finger flexors, may decrease the amplitude of hand tremor for approximately three months and that injections of the toxin may reduce essential tremor presenting in the head and voice. The toxin also may help tremor causing difficulty in writing, although properly adapted writing devices may be more efficient. Due to high incidence of side effects, use of botulinum toxin has only received a C level of support from the scientific community.

Deep brain stimulation toward the ventral intermediate nucleus of the thalamus and potentially the subthalamic nucleus and caudal zona incerta nucleus have been shown to reduce tremor in numerous studies. That toward the ventral intermediate nucleus of the thalamus has been shown to reduce contralateral and some ipsilateral tremor along with tremors of the cerebellar outflow, head, resting state and those related to hand tasks; however, the treatment has been shown to induce difficulty articulating thoughts (dysarthria), and loss of coordination and balance in long-term studies. Motor cortex stimulation is another option shown to be viable in numerous clinical trials.

To date, there is no single, universal treatment that has been found to cure myoclonus dystonia. However, there are several treatment methods that have been found to be effective for helping to reduce the symptoms associated with the syndrome.

Although the cause of writer's cramp is not well known, it was historically believed to be the result of excessive fine motor activity, possibly complicated by a tense or otherwise inappropriate writing technique. More recently, Karin Rosenkranz et al. have suggested that this is not necessarily the case. Musician's cramp (a similar focal dystonia which affects some 1% of instrumentalists) has historically been grouped together with writer's cramp because of this and their common task-specificity. Rosenkranz et al. have more recently identified significant differences between the two populations, however. No matter exactly how it arises, researchers generally agree that these types of focal dystonia are the result of a basal ganglia and/or sensorimotor cortex malfunction in the brain.

Early symptoms may include loss of precision muscle coordination (sometimes first manifested in declining penmanship, frequent small injuries to the hands, dropped items and a noticeable increase in dropped or chipped dishes), cramping pain with sustained use and trembling. Significant muscle pain and cramping may result from very minor exertions like holding a book and turning pages. It may become difficult to find a comfortable position for arms and legs with even the minor exertions associated with holding arms crossed causing significant pain similar to restless leg syndrome. Affected persons may notice trembling in the diaphragm while breathing, or the need to place hands in pockets, under legs while sitting or under pillows while sleeping to keep them still and to reduce pain. Trembling in the jaw may be felt and heard while lying down, and the constant movement to avoid pain may result in the grinding and wearing down of teeth, or symptoms similar to TMD. The voice may crack frequently or become harsh, triggering frequent throat clearing. Swallowing can become difficult and accompanied by painful cramping. Patients may also present with varying degree of disability and symptoms, such as experiencing more difficulty writing down-stroke as compared to writing upstroke.

Electrical sensors (EMG) inserted into affected muscle groups, while painful, can provide a definitive diagnosis by showing pulsating nerve signals being transmitted to the muscles even when they are at rest. The brain appears to signal portions of fibers within the affected muscle groups at a firing speed of about 10 Hz causing them to pulsate, tremble and contort. When called upon to perform an intentional activity, the muscles fatigue very quickly and some portions of the muscle groups do not respond (causing weakness) while other portions over-respond or become rigid (causing micro-tears under load). The symptoms worsen significantly with use, especially in the case of focal dystonia, and a "mirror effect" is often observed in other body parts: use of the right hand may cause pain and cramping in that hand as well as in the other hand and legs that were not being used. Stress, anxiety, lack of sleep, sustained use and cold temperatures can worsen symptoms.

Direct symptoms may be accompanied by secondary effects of the continuous muscle and brain activity, including disturbed sleep patterns, exhaustion, mood swings, mental stress, difficulty concentrating, blurred vision, digestive problems and short temper. People with dystonia may also become depressed and find great difficulty adapting their activities and livelihood to a progressing disability. Side effects from treatment and medications can also present challenges in normal activities.

In some cases, symptoms may progress and then plateau for years, or stop progressing entirely. The progression may be delayed by treatment or adaptive lifestyle changes, while forced continued use may make symptoms progress more rapidly. In others, the symptoms may progress to total disability, making some of the more risky forms of treatment worth considering in the future.

Myoclonic dystonia or Myoclonus dystonia syndrome is a rare movement disorder that induces spontaneous muscle contraction causing abnormal posture. The prevalence of myoclonus dystonia has not been reported, however, this disorder falls under the umbrella of movement disorders which affect thousands worldwide. Myoclonus dystonia results from mutations in the SGCE gene coding for an integral membrane protein found in both neurons and muscle fibers. Those suffering from this disease exhibit symptoms of rapid, jerky movements of the upper limbs (myoclonus), as well as distortion of the body's orientation due to simultaneous activation of agonist and antagonist muscles (dystonia).

Myoclonus dystonia is caused by loss-of-function-mutations in the epsilon sarcoglycan gene (SGCE). The disease is dominantly inherited, however SGCE is an imprinted gene, so only the paternal allele is expressed. Therefore, children suffering from this disease inherit the mutation from the father. If the mutated allele is inherited from the mother, the child is not likely to exhibit symptoms.

While no cure has been found for myoclonus dystonia, treatment options are available to those suffering from the disease. Ethanol often ameliorates the symptoms well, and so the syndrome is also called "Alcohol-responsive dystonia". Alcohol may be substituted by benzodiazepines, such as clonazepam, which work through the same mechanism. Deep brain stimulation (DBS) is another viable option that can alleviate symptoms without the unwanted side effects of medications, and has been successful in treating other movement disorders.

Treatment of primary dystonia is aimed at reducing symptoms such as involuntary movements, pain, contracture, embarrassment, and to restore normal posture and improve the patient’s function. This treatment is therefore not neuroprotective. According to the European Federation of Neurological Sciences and Movement Disorder Society, there is no evidence-based recommendation for treating primary dystonia with antidopaminergic or anticholinergic drugs although recommendations have been based on empirical evidence. Anticholinergic drugs prove to be most effective in treating generalized and segmental dystonia, especially if dose starts out low and increases gradually. Generalized dystonia has also been treated with such muscle relaxants as the benzodiazepines. Another muscle relaxant, baclofen, can help reduce spasticity seen in cerebral palsy such as dystonia in the leg and trunk. Treatment of secondary dystonia by administering levodopa in dopamine-responsive dystonia, copper chelation in Wilson’s disease, or stopping the administration of drugs that may induce dystonia have been proven effective in a small number of cases. Physical therapy has been used to improve posture and prevent contractures via braces and casting, although in some cases, immobilization of limbs can induce dystonia, which is by definition known as peripherally induced dystonia. There are not many clinical trials that show significant efficacy for particular drugs, so medical of dystonia must be planned on a case-by-case basis. Botulinum toxin B, or Myobloc, has been approved by the US Food and Drug Administration to treat cervical dystonia due to level A evidential support by the scientific community. Surgery known as GPi DBS (Globus Pallidus Pars Interna Deep Brain Stimulation) has come to be popular in treating phasic forms of dystonia, although cases involving posturing and tonic contractions have improved to a lesser extent with this surgery. A follow-up study has found that movement score improvements observed one year after the surgery was maintained after three years in 58% of the cases. It has also been proven effective in treating cervical and cranial-cervical dystonia.

The disease is more commonly found amongst Ashkenazi Jews. The occurrence of torsion dystonia in the Ashkenazi Jewish population as stated by the Department of Epidemiology and Public Health of Yale University School of Medicine in New Haven, CT; "Reports dating to the beginning of this century describe Ashkenazi Jewish (AJ) families with multiple cases of ITD either in siblings (Schwalbe 1908; Bernstein 1912; Abrahamson 1920) or in parents and offspring (Wechsler and Brock 1922; Mankowsky and Czerny 1929; Regensberg 1930). The first comprehensive evaluation of the mode of inheritance of ITD in Jewish and non-Jewish families was described by Zeman and Dyken (1967), who concluded that the disorder was inherited as an autosomal dominant with incomplete penetrance in both populations. Although they concluded that the gene frequency was higher in the AJ population than in non-Jews, no difference in mode of inheritance or disease mechanism was construed."

The long-term prognosis is uncertain, and has mostly to do with the underlying cause; i.e. autoimmune, paraneoplastic, etc. However, in recent years increased understanding of the basic mechanisms of NMT and autoimmunity has led to the development of novel treatment strategies. NMT disorders are now amenable to treatment and their prognoses are good. Many patients respond well to treatment, which usually provide significant relief of symptoms. Some cases of spontaneous remission have been noted, including Isaac's original two patients when followed up 14 years later.

While NMT symptoms may fluctuate, they generally don't deteriorate into anything more serious, and with the correct treatment the symptoms are manageable.

A very small proportion of cases with NMT may develop central nervous system findings in their clinical course, causing a disorder called Morvan's syndrome, and they may also have antibodies against potassium channels in their serum samples. Sleep disorder is only one of a variety of clinical conditions observed in Morvan's syndrome cases ranging from confusion and memory loss to hallucinations and delusions. However, this is a separate disorder.

Some studies have linked NMT with certain types of cancers, mostly lung and thymus, suggesting that NMT may be paraneoplastic in some cases. In these cases, the underlying cancer will determine prognosis. However, most examples of NMT are autoimmune and not associated with cancer.

The three causes of NMT are:

1. Acquired

2. Paraneoplastic

3. Hereditary

The acquired form is the most common, accounting for up to 80 percent of all cases and is suspected to be autoimmune-mediated, which is usually caused by antibodies against the neuromuscular junction.

The exact cause is unknown. However, autoreactive antibodies can be detected in a variety of peripheral (e.g. myasthenia gravis, Lambert-Eaton myasthenic syndrome) and central nervous system (e.g. paraneoplastic cerebellar degeneration, paraneoplastic limbic encephalitis) disorders. Their causative role has been established in some of these diseases but not all. Neuromyotonia is considered to be one of these with accumulating evidence for autoimmune origin over the last few years. Autoimmune neuromyotonia is typically caused by antibodies that bind to potassium channels on the motor nerve resulting in continuous/hyper-excitability. Onset is typically seen between the ages of 15–60, with most experiencing symptoms before the age of 40. Some neuromyotonia cases do not only improve after plasma exchange but they may also have antibodies in their serum samples against voltage-gated potassium channels. Moreover, these antibodies have been demonstrated to reduce potassium channel function in neuronal cell lines.

Symptoms are very similar to those found in benign fasciculation syndrome and include:

- Fasciculations (Primary Symptom)

- Muscle cramping (Primary Symptom)

- Muscle pain

- Muscle Stiffness

- Generalized fatigue

- Anxiety

- Exercise intolerance

- Globus sensations

- Paraesthesias.

- Hyperreflexia

Cramp fasciculation syndrome (CFS) is a rare peripheral nerve hyperexcitability disorder. It is more severe than the related (and common) disorder known as benign fasciculation syndrome; it causes fasciculations, cramps, pain, fatigue, and muscle stiffness similar to those seen in neuromyotonia (another related condition). Patients with CFS, like those with neuromyotonia, may also experience paresthesias.

Most cases of cramp fasciculation syndrome are idiopathic.

Cramp fasciculation syndrome is diagnosed by clinical examination and electromyography (EMG). Fasciculation is the only abnormality (if any) seen with EMG.

Cramp fasciculation syndrome is a chronic condition. Treatment options include anti-seizure medications such as carbamazepine, immunosuppressive drugs and plasmapheresis.

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.

High-voltage pulsed galvanic stimulation (HGVS) has been shown to be of prophylactic benefit, to reduce the incidence of attacks. The patient is usually placed in the left lateral decubitus position and a sterile probe is inserted into the anus. The negative electrode is used and the stimulator is set with a pulse frequency of 80 to 120 cycles per second. The voltage (intensity) is started at 0, progressively raised to a threshold of patient discomfort, and then is decreased to a level that the patient finds comfortable. As the patient's tolerance increases, the voltage can be gradually increased to 250 to 350 Volts. Each treatment session usually lasts between 15 and 60 minutes. Several studies have reported short-term success rates that ranged from 65 to 91%.

Atherosclerosis affects up to 10% of the Western population older than 65 years and for intermittent claudication this number is around 5%. Intermittent claudication most commonly manifests in men older than 50 years.

One in five of the middle-aged (65–75 years) population of the United Kingdom have evidence of peripheral arterial disease on clinical examination, although only a quarter of them have symptoms. The most common symptom is muscle pain in the lower limbs on exercise—intermittent claudication.

The most common cause of Erb's palsy is dystocia, an abnormal or difficult childbirth or labor. For example, it can occur if the infant's head and neck are pulled toward the side at the same time as the shoulders pass through the birth canal. The condition can also be caused by excessive pulling on the shoulders during a cephalic presentation (head first delivery), or by pressure on the raised arms during a breech (feet first) delivery. Erb's palsy can also affect neonates affected by a clavicle fracture unrelated to dystocia.

A similar injury may be observed at any age following trauma to the head and shoulder, which cause the nerves of the plexus to violently stretch, with the upper trunk of the plexus sustaining the greatest injury. Injury may also occur as the result of direct violence, including gunshot wounds and traction on the arm, or attempting to diminish shoulder joint dislocation. The level of damage to the constituent nerves is related to the amount of paralysis.

Some babies recover on their own; however, some may require specialist intervention.

Neonatal/pediatric neurosurgery is often required for avulsion fracture repair. Lesions may heal over time and function return. Physiotherapeutic care is often required to regain muscle usage.

Although range of motion is recovered in many children under one year in age, individuals who have not yet healed after this point will rarely gain full function in their arm and may develop arthritis.

The three most common treatments for Erb's Palsy are: Nerve transfers (usually from the opposite arm or limb), Sub Scapularis releases and Latissimus Dorsi Tendon Transfers.

Nerve transfers are usually performed on babies under the age of 9 months since the fast development of younger babies increases the effectiveness of the procedure. They are not usually carried out on patients older than this because when the procedure is done on older infants, more harm than good is done and can result in nerve damage in the area where the nerves were taken from. Scarring can vary from faint scars along the lines of the neck to full "T" shapes across the whole shoulder depending on the training of the surgeon and the nature of the transplant.

Subscapularis releases, however, are not time limited. Since it is merely cutting a "Z" shape into the subscapularis muscle to provide stretch within the arm, it can be carried out at almost any age and can be carried out repeatedly on the same arm; however, this will compromise the integrity of the muscle.

Latissimus Dorsi Tendon Transfers involve cutting the Latissimus Dorsi in half horizontally in order to 'pull' part of the muscle around and attach it to the outside of the biceps. This procedure provides external rotation with varying degrees of success. A side effect may be increased sensitivity of the part of the biceps where the muscle will now lie, since the Latissimus Dorsi has roughly twice the number of nerve endings per square inch of other muscles.

Most commonly, intermittent (or vascular or arterial) claudication is due to peripheral arterial disease which implies significant atherosclerotic blockages resulting in arterial insufficiency. It is distinct from neurogenic claudication, which is associated with lumbar spinal stenosis. It is strongly associated with smoking, hypertension, and diabetes.

Scotty Cramp is a disease in Scottish Terriers causing spasms and hyperflexion and hyperextension of the legs. It is caused by a disorder in serotonin metabolism that causes a deficiency of available serotonin. It is inherited as an autosomal recessive trait.

Scotty Cramp occurs in puppies and young dogs. Symptoms present after exercise or excitement and last a few minutes. A goose-stepping gait and arched spine are often seen, and the dogs may turn somersaults as it runs. The symptoms usually resolve after ten minutes, but they may repeat several times in a day. If the diagnosis is unsure, a dose of methysergide can be given. In affected dogs, this will block serotonin and increase the frequence and severity of the symptoms. Diazepam or acepromazine is used to control the symptoms of Scotty Cramp. Vitamin E may also be of some benefit. Because Scotty Cramp is inherited, affected dogs and their parents and siblings should not be bred.