Symptoms vary according to the kind of dystonia involved. In most cases, dystonia tends to lead to abnormal posturing, in particular on movement. Many sufferers have continuous pain, cramping, and relentless muscle spasms due to involuntary muscle movements. Other motor symptoms are possible including lip smacking.

Early symptoms may include loss of precision muscle coordination (sometimes first manifested in declining penmanship, frequent small injuries to the hands, and dropped items), 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 temporomandibular joint disorder. The voice may crack frequently or become harsh, triggering frequent throat clearing. Swallowing can become difficult and accompanied by painful cramping.

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 some cases with patients who already have dystonia, a subsequent tramatic injury or the effects of general anethesia during an unrelated surgery can cause the symptoms to progress rapidly.

An accurate diagnosis may be difficult because of the way the disorder manifests itself. Sufferers may be diagnosed as having similar and perhaps related disorders including Parkinson's disease, essential tremor, carpal tunnel syndrome, TMD, Tourette's syndrome, conversion disorder or other neuromuscular movement disorders. It has been found that the prevalence of dystonia is high in individuals with Huntington's disease, where the most common clinical presentations are internal shoulder rotation, sustained fist clenching, knee flexion, and foot inversion. Risk factors for increased dystonia in patients with Huntington's disease include long disease duration and use of antidopaminergic medication.

Chorea is a continuous, random-appearing sequence of one or more discrete involuntary movements or movement fragments. Although chorea consists of discrete movements, many are often strung together in time, thus making it difficult to identify each movement's start and end point. These movements can involve the face, trunk, neck, tongue, and extremities. Unlike dystonic movements, chorea-associated movements are often more rapid, random and unpredictable. Movements are repeated, but not rhythmic in nature. Children with chorea appear fidgety and will often try to disguise the random movements by voluntarily turning the involuntary, abnormal movement into a seemingly more normal, purposeful motion. Chorea may result specifically from disorders of the basal ganglia, cerebral cortex, thalamus, and cerebellum. It has also been associated with encephalitis, hyperthyroidism, anticholinergic toxicity, and other genetic and metabolic disorders. Chorea is also the prominent movement featured in Huntington's disease.

Dystonia is a movement disorder in which involuntarily sustained or intermittent muscle contractions cause twisting or repetitive movements, abnormal postures, or both. Such abnormal postures include foot inversion, wrist ulnar deviation, or lordotic trunk twisting. They can be localized to specific parts of the body or be generalized to many different muscle groups. These postures are often sustained for long periods of time and can be combined in time. Dystonic movements can augment hyperkinetic movements, especially when linked to voluntary movements.

Blepharospasm is a type of dystonia characterized by involuntary contraction of the muscles controlling the eyelids. Symptoms can range from a simple increased frequency of blinking to constant, painful eye closure leading to functional blindness.

Oromandibular dystonia is a type of dystonia marked by forceful contractions of the lower face, which causes the mouth to open or close. Chewing motions and unusual tongue movements may also occur with this type of dystonia.

Laryngeal dystonia or spasmodic dysphonia results from abnormal contraction of muscles in the voice box, resulting in altered voice production. Patients may have a strained-strangled quality to their voice or, in some cases, a whispering or breathy quality.

Cervical dystonia (CD) or spasmodic torticollis is characterized by muscle spasms of the head and neck, which may be painful and cause the neck to twist into unusual positions or postures.

Writer's cramp and musician’s cramp is a task-specific dystonia, meaning that it only occurs when performing certain tasks. Writer’s cramp is a contraction of hand and/or arm muscles that happens only when a patient is writing. It does not occur in other situations, such as when a patient is typing or eating. Musician’s cramp occurs only when a musician plays an instrument, and the type of cramp experienced is specific to the instrument. For example, pianists may experience cramping of their hands when playing, while brass players may have cramping or contractions of their mouth muscles.

Myoclonus dystonia includes the rapid contractions of myoclonus alongside the abnormal postures classified under dystonia, as well as neurological and psychiatric issues. This disease typically begins during childhood with symptoms of myoclonus and slight dystonia, most commonly cervical dystonia or writer’s cramp. Dystonia symptoms tend to not get exaggerated over the course of the disease and is rarely the only associated symptom, while the myoclonus symptoms can become more severe. Psychiatric issues are clinically diagnosed with the aforementioned symptoms and include depression, anxiety, personality disorders and addiction. Obsessive-compulsive disorder is associated with myoclonus dystonia as both have been found to have a commonality on chromosome 7 in various studies.

Neurological symptoms are relatively common in those with myoclonus dystonia. Any neurological abnormalities won’t normally be present in those affected at a young age. Neurological testing has been performed to determine the origins of these symptoms and multiple parts of the brain have been pinpointed including the brainstem, neocortex, pallidum, and thalamus. These cause various effects in those diagnosed with myoclonus dystonia including changes in posture and tremors, and very rarely dementia and ataxia.

Myoclonus is characterized by rapid contractions that affect the upper body including the neck, torso and arms, but may also affect the legs. These movements are stimulated by various factors including stress, noise, caffeine, and physical stimuli. Myoclonus can be characterized in multiple ways including neurological basis, muscular activity, and by stimuli. Myoclonus can be positive or negative; positive myoclonus results from brief spurts of muscle activity and negative myoclonus occurs when there is a lack of any muscular activity. Myoclonus is usually classified physiologically to optimize treatment. Myoclonus is a precursor effect to myoclonus dystonia and most commonly begins in childhood or adolescence.

Myoclonus is classified as cortical, subcortical, peripheral or spinal. Cortical myoclonus is the most common of these four and affects the upper limbs and face. Myoclonus dystonia has been characterized under subcortical origin, specifically under nonsegmented myoclonus or brainstem myoclonus. Symptoms within this classification include the startle response and reticular reflex myoclonus. Sudden stimuli like noise or touch to areas around the head or chest cause the startle response which will go up the brain stem and down the spinal cord causing jerk-like movements. Hyperekplexia is a heightened brainstem response where an affected person will continue to elicit the same response to a repeated stimuli. In contrast, reticular reflex myoclonus occurs spontaneously to stimuli applied to distal limbs. Spinal myoclonus is caused by defects in spinal organization or connections, and peripheral myoclonus has symptoms of rhythmic jerks due to a neuron-the most common being the hemifacial spasm.

Tremor is the uncontrollable shaking of an arm or a leg. Twitches or jerks of body parts may occur due to a startling sound or unexpected, sudden pain. Spasms and contractions are temporary abnormal resting positions of hands or feet. Spasms are temporary while contractions could be permanent. Gait problems are problems with the way one walks or runs. This can mean an unsteady pace or dragging of the feet along with other possible irregularities (Stone).

Initial symptoms of spasmodic torticollis are usually mild. Some feel an invisible tremor of their head for a few months at onset. Then the head may turn, pull or tilt in jerky movements, or sustain a prolonged position involuntarily. Over time, the involuntary spasm of the neck muscles will increase in frequency and strength until it reaches a plateau. Symptoms can also worsen while the patient is walking or during periods of increased stress. Other symptoms include muscle hypertrophy, neck pain, dysarthria and tremor. Studies have shown that over 75% of patients report neck pain, and 33% to 40% experience tremor of the head.

Late-onset dyskinesia, also known as tardive dyskinesia, occurs after long-term treatment with an antipsychotic drug such as haloperidol (Haldol) or amoxapine (Asendin). The symptoms include tremors and writhing movements of the body and limbs, and abnormal movements in the face, mouth, and tongue including involuntary lip smacking, repetitive pouting of the lips, and tongue protrusions.

Rabbit syndrome is another type of chronic dyskinesia, while orofacial dyskinesia may be related to persistent replication of Herpes simplex virus type 1.

Motor disorders are malfunctions of the nervous system that cause involuntary or uncontrollable movements or actions of the body (Stone). These disorders can cause lack of intended movement or an excess of involuntary movement (Mandal). Symptoms of motor disorders include tremors, jerks, twitches, spasms, contractions, or gait problems.

These are the most common dystonias and tend to be classified as follows:

The combination of blepharospasmodic contractions and oromandibular dystonia is called cranial dystonia or Meige's syndrome.

Acute dystonia is a sustained muscle contraction that sometimes appears soon after administration of antipsychotic medications. Any muscle in the body may be affected, including the jaw, tongue, throat, arms, or legs. When the throat muscles are involved, this type of dystonia is called an acute laryngospasm and is a medical emergency because it can impair breathing. Older antipsychotics such as Haloperidol or Fluphenazine are more likely to cause acute dystonia than newer agents. Giving high doses of antipsychotics by injection also increases the risk of developing acute dystonia.

Methamphetamine, other amphetamines and dopaminergic stimulants including cocaine and pemoline can produce choreoathetoid dyskinesias; the prevalence, time-frame and prognosis are not well established. Amphetamines also cause a dramatic increase in choreoathetoid symptoms in patients with underlying chorea such as Sydenham’s, Huntington’s, and Lupus. Long-term use of amphetamines may increase the risk of Parkinson's disease (PD): in one retrospective study with over 40,000 participants it was concluded that amphetamine abusers generally had a 200% higher chance of developing PD versus those with no history of abuse; the risk was much higher in women, almost 400%. There remains some controversy as of 2017.

Levodopa-induced dyskinesia (LID) is evident in patients with Parkinson's disease who have been on levodopa () for prolonged periods of time. LID commonly first appears in the foot, on the most affected side of the body. There are three main types that can be classified on the basis of their course and clinical presentation following an oral dose of :

- Off-period dystonia – correlated to the akinesia that occurs before the full effect of sets in, when the plasma levels of are low. In general, it occurs as painful spasms in the foot. Patients respond to therapy.

- Diphasic dyskinesia – occurs when plasma L-DOPA levels are rising or falling. This form occurs primarily in the lower limbs (though they can happen elsewhere) and is usually dystonic (characterized by apparent rigidity within muscles or groups thereof) or (characterized by involuntary movement of muscles) and will not respond to dosage reductions.

- Peak-dose dyskinesia – the most common form of levodopa-induced dyskinesia; it correlates with the plateau plasma level. This type usually involves the upper limbs more (but could also affect the head, trunk and respiratory muscles), is choreic (of chorea), and less disabling. Patients will respond to reduction but may be accompanied by deterioration of parkinsonism. Peak-dose L-DOPA-induced dyskinesia has been suggested to be associated with cortical dysregulation of dopamine signaling.

Spasmodic torticollis is a form of focal dystonia, a neuromuscular disorder that consists of sustained muscle contractions causing repetitive and twisting movements and abnormal postures in a single body region. There are two main ways to categorize spasmodic torticollis: age of onset, and cause. The disorder is categorized as early onset if the patient is diagnosed before the age of 27, and late onset thereafter. The causes are categorized as either primary (idiopathic) or secondary (symptomatic). Spasmodic torticollis can be further categorized by the direction and rotation of head movement.

In mild cases, ET can manifest as the inability to stop the tongue or hands from shaking, the ability to sing only in vibrato, and difficulty doing small precise tasks such as threading a needle. Even simple tasks like cutting in a straight line or using a ruler can range from difficult to impossible, depending on the severity of the condition. In disabling cases, ET can interfere with a person's activities of daily living, including feeding, dressing, and taking care of personal hygiene. Essential tremor generally presents as a rhythmic tremor (4–12 Hz) that occurs only when the affected muscle is exerting effort. Any sort of physical or mental stress will tend to make the tremor worse.

The tremor may also occur in the head (neck), jaw and voice as well as other body regions, with the general pattern being that the tremor begins in the arms and then spreads to these other regions in some people. Women are more likely to develop the head tremor than are men. Other types of tremor may also occur, including postural tremor of the outstretched arms, intention tremor of the arms and rest tremor in the arms. Some people may have unsteadiness and problems with gait and balance.

ET-related tremors do not occur during sleep, but people with ET sometimes complain of an especially coarse tremor upon awakening that becomes noticeably less coarse within the first few minutes of wakefulness. Tremor and disease activity/intensity can worsen in response to fatigue, strong emotions, low blood sugar, cold and heat, caffeine, lithium salts, some antidepressants, and other factors. It is typical for the tremor to worsen in "performance" situations, such as when writing a check for payment at a store or giving a presentation.

Parkinson's disease and Parkinsonism can also occur simultaneously with ET. In those cases the degree of tremor, rigidity, and functional disability does not differ from those people with idiopathic Parkinson's disease. Hand tremor predominates (as it does in Parkinson’s disease), and occurs in nearly all cases, followed by head tremor, voice tremor, neck, face, leg, tongue and trunk tremor. Most other tremors occur in association with hand tremor. Walking difficulties in essential tremor are common. About half of patients have associated dystonia, including cervical dystonia, writer's cramp, spasmodic dysphonia, and cranial dystonia, and 20% of the patients had associated parkinsonism. Olfactory dysfunction (loss of sense of smell) is common in Parkinson’s disease, and has also been reported to occur in patients with essential tremor. A number of patients with essential tremor also exhibit many of the same neuropsychiatric disturbances seen in idiopathic Parkinson's disease.

Essential tremor with tremor onset after the age of 65 is associated with Mild cognitive impairement and dementia.

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".

This type of tremor is often referred to as "kinetic tremor".

Essential tremor has been known as "benign essential tremor", but the adjective "benign" has been removed in recognition of the sometimes disabling nature of the disorder.

There are several types of torsion dystonia that affect different areas of the body. However, it is unknown if the gene that causes Early Onset Torsion Dystonia is responsible for the other dystonias as well.

- Cervical dystonia (spasmodic torticollis): A type of dystonia that affects the head, neck and spine. It can create problems by the characteristic turning of the head and neck from side to side.

- Blepharospasm: This type of dystonia causes involuntary contraction of the eyelids. The main concern for this dystonia is that it can cause the eyelids to close involuntarily and for indefinite periods of time.

- Oromandibular dystonia: A dystonia of the jaw, lips, and/or the tongue. It can make eating and swallowing very complicated due to the jaw being held open or shut for periods of time.

- Spasmodic dysphonia: A dystonia of the vocal cords. The complications surrounding this form of dystonia are speech related and can cause symptoms such as speech that wavers, speech that sounds like a whisper, or speech that is hesitant.

- Writer's cramp (occupational dystonia): A dystonia that affects the muscles of the hand and forearm. It is triggered by attempting to write or execute other fine-motor hand functions.

- Orofacial-Buccal dystonia (Meige's or Brueghal's Syndrome): A combination of blepharospasm and oromandibular dystonia.

- Early-onset torsion dystonia: The most severe type of dystonia, it begins in an arm or leg and progresses to the rest of the body until the person — in most cases, a child — is confined to a wheel chair.

The Greek word "blepharon" means "eyelid". Spasm means "uncontrolled muscle contraction". The term blepharospasm ['blef-a-ro-spaz-m] can be applied to any abnormal blinking or eyelid tic or twitch resulting from any cause, ranging from dry eyes to Tourette's syndrome to tardive dyskinesia. The blepharospasm referred to here is officially called benign essential blepharospasm (BEB) to distinguish it from the less serious secondary blinking disorders. "Benign" indicates the condition is not life-threatening, and "essential" is a medical term meaning "of unknown cause". It is both a cranial and a focal dystonia. Cranial refers to the head and focal indicates confinement to one part. The word dystonia describes abnormal involuntary sustained muscle contractions and spasms. Patients with blepharospasm have normal eyes. The visual disturbance is due solely to the forced closure of the eyelids.

Oromandibular dystonia (OMD) is a form of focal dystonia that affects varying areas of the head and neck including the lower face, jaw, tongue and larynx. The spasms may cause the mouth to pull open, shut tight, or move repetitively. Speech and swallowing may be distorted. It is often associated with dystonia of the cervical muscles (Spasmodic Torticollis), eyelids (Blepharospasm), or larynx (Spasmodic Dysphonia).

In patients with OMD, involuntary contractions may involve the muscles used for chewing (masticatory muscles). These may include the thick muscle in the cheek that closes the jaw (masseter muscle) and the broad muscle that draws back the lower jaw and closes the mouth (temporalis muscle). Some patients may also experience involuntary contractions of the wide muscle at the side of the neck (platysmal muscle). This muscle draws down the corner of the mouth and lower lip or other muscle groups.

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 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.

PED attacks are characterized in multiple ways. One distinguishing characteristic of PED patients is that they typically experience longer durations of dystonia during their attacks. The most frequent target of attacks are both legs bilaterally, rather than unilateral symptoms. The attacks have also been known to affect the upper half of the body as well. In some cases, patients have had attacks that affected the posturing of their neck and shoulder. Usually there is not an indicative aura symptom prior to a PED attack, which has to do with the nature of the onset of attacks.

The duration and frequency of PED attacks fall between those of PKD and PNKD. The attacks can be relieved with rest, typically taking about 10 minutes from cessation of the exercise. Attacks usually do not last longer than 30 minutes. Attacks typically occur at intervals of between a day and a month, however, there is a great deal of variability here. This variability can be contributed to the nature of the onset of attacks.

The attacks consist of dystonia, chorea, and athetosis just like PKD. They are mostly of the limbs, and are usually unilateral or asymmetric. What sets PNKD apart from PKD is that the attacks can last anywhere from four minutes to four hours, but shorter and longer attacks have been reported as well.

The attacks also affect the limbs, usually unilaterally, but bilateral symptoms have also been experienced. PNKD patients usually report the presence of an aura before an attack as well; however they are usually different from those of PKD patients. Once again the aura varies, but is typically felt in the target limb. Another frequently noted aura is dizziness

PNKD patients experience attacks that last much longer than those of PKD. These attacks vary in length and can last anywhere between four minutes and four hours. Similar to the difference between length of attacks, the intervals between attacks are much longer. The Interval between PNKD patients’ attacks is from one day to several months.

Tardive dyskinesia is characterized by repetitive, involuntary movements. Some examples of these types of involuntary movements include:

- Grimacing

- Tongue movements

- Lip smacking

- Lip puckering

- Pursing of the lips

- Excessive eye blinking

Rapid, involuntary movements of the limbs, torso, and fingers may also occur. In some cases, an individual's legs can be so affected that walking becomes difficult or impossible. These symptoms are the opposite of patients who are diagnosed with Parkinson's disease. Parkinson's patients have difficulty moving, whereas tardive dyskinesia patients have difficulty not moving.

Respiratory irregularity, such as grunting and difficulty breathing, is another symptom associated with tardive dyskinesia, although studies have shown that the prevalence rate is relatively low.

Tardive dyskinesia is often misdiagnosed as a mental illness rather than a neurological disorder, and as a result patients are prescribed neuroleptic drugs, which increase the probability that the patient will develop a severe and disabling case, and shortening the typical survival period.

Other closely related neurological disorders have been recognized as variants of tardive dyskinesia. Tardive dystonia is similar to standard dystonia but permanent. Tardive akathisia involves painful feelings of inner tension and anxiety and a compulsive drive to move the body. In some extreme cases, afflicted individuals experience so much internal torture that they lose their ability to sit still. Tardive tourettism is a tic disorder featuring the same symptoms as Tourette syndrome. The two disorders are extremely close in nature and often can only be differentiated by the details of their respective onsets. Tardive myoclonus, a rare disorder, presents as brief jerks of muscles in the face, neck, trunk, and extremities.

"AIMS Examination": This test is used when psychotropic medications have been prescribed because patients sometimes develop tardive dyskinesia due to prolonged use of antipsychotic medications. The Abnormal Involuntary Movement Scale (AIMS) examination is a test used to identify the symptoms of tardive dyskinesia (TD). The test is not meant to tell whether there is an absence or presence of tardive dyskinesia. It just scales to level of symptoms indicated by the actions observed. The levels range from none to severe. The AIMS examination was constructed in the 1970s to measure involuntary facial, trunk, and limb movements. It is best to do this test before and after the administration of the psychotropic drugs. Taking the AIMS consistently can help to track severity of TD over time.

Tremor is most commonly classified by clinical features and cause or origin. Some of the better known forms of tremor, with their symptoms, include the following:

- Cerebellar tremor (also known as intention tremor) is a slow, broad tremor of the extremities that occurs at the end of a purposeful movement, such as trying to press a button or touching a finger to the tip of one’s nose. Cerebellar tremor is caused by lesions in or damage to the cerebellum resulting from stroke, tumor, or disease such as multiple sclerosis or some inherited degenerative disorder. It can also result from chronic alcoholism or overuse of some medicines. In classic cerebellar tremor, a lesion on one side of the brain produces a tremor in that same side of the body that worsens with directed movement. Cerebellar damage can also produce a “wing-beating” type of tremor called rubral or Holmes’ tremor — a combination of rest, action, and postural tremors. The tremor is often most prominent when the affected person is active or is maintaining a particular posture. Cerebellar tremor may be accompanied by other manifestations of ataxia, including dysarthria (speech problems), nystagmus (rapid, involuntary rolling of the eyes), gait problems and postural tremor of the trunk and neck. "Titubation" is tremor of the head and is of cerebellar origin.

- Dystonic tremor occurs in individuals of all ages who are affected by dystonia, a movement disorder in which sustained involuntary muscle contractions cause twisting and repetitive motions and/or painful and abnormal postures or positions. Dystonic tremor may affect any muscle in the body and is seen most often when the patient is in a certain position or moves a certain way. The pattern of dystonic tremor may differ from essential tremor. Dystonic tremors occur irregularly and often can be relieved by complete rest. Touching the affected body part or muscle may reduce tremor severity (a geste antagoniste). The tremor may be the initial sign of dystonia localized to a particular part of the body.

- Essential tremor (sometimes called benign essential tremor) is the most common of the more than 20 types of tremor. Although the tremor may be mild and nonprogressive in some people, in others, the tremor is slowly progressive, starting on one side of the body but affecting both sides within 3 years. The hands are most often affected but the head, voice, tongue, legs, and trunk may also be involved. Head tremor may be seen as a vertical or horizontal motion. Essential tremor may be accompanied by mild gait disturbance. Tremor frequency may decrease as the person ages, but the severity may increase, affecting the person’s ability to perform certain tasks or activities of daily living. Heightened emotion, stress, fever, physical exhaustion, or low blood sugar may trigger tremors or increase their severity. Onset is most common after age 40, although symptoms can appear at any age. It may occur in more than one family member. Children of a parent who has essential tremor have a 50 percent chance of inheriting the condition. Essential tremor is not associated with any known pathology.

- Orthostatic tremor is characterized by fast (>12 Hz) rhythmic muscle contractions that occur in the legs and trunk immediately after standing. Cramps are felt in the thighs and legs and the patient may shake uncontrollably when asked to stand in one spot. No other clinical signs or symptoms are present and the shaking ceases when the patient sits or is lifted off the ground. The high frequency of the tremor often makes the tremor look like rippling of leg muscles while standing. Orthostatic tremor may also occur in patients who have essential tremor, and there might be an overlap between these categories of tremor.

- Parkinsonian tremor is caused by damage to structures within the brain that control movement. This resting tremor, which can occur as an isolated symptom or be seen in other disorders, is often a precursor to Parkinson's disease (more than 25 percent of patients with Parkinson’s disease have an associated action tremor). The tremor, which is classically seen as a "pill-rolling" action of the hands that may also affect the chin, lips, legs, and trunk, can be markedly increased by stress or emotion. Onset is generally after age 60. Movement starts in one limb or on one side of the body and usually progresses to include the other side.

- Physiological tremor occurs in every normal individual and has no clinical significance. It is rarely visible and may be heightened by strong emotion (such as anxiety or fear), physical exhaustion, hypoglycemia, hyperthyroidism, heavy metal poisoning, stimulants, alcohol withdrawal or fever. It can be seen in all voluntary muscle groups and can be detected by extending the arms and placing a piece of paper on top of the hands. Enhanced physiological tremor is a strengthening of physiological tremor to more visible levels. It is generally not caused by a neurological disease but by reaction to certain drugs, alcohol withdrawal, or medical conditions including an overactive thyroid and hypoglycemia. It is usually reversible once the cause is corrected. This tremor classically has a frequency of about 10 Hz

- tremor (also called hysterical tremor) can occur at rest or during postural or kinetic movement. The characteristics of this kind of tremor may vary but generally include sudden onset and remission, increased incidence with stress, change in tremor direction and/or body part affected, and greatly decreased or disappearing tremor activity when the patient is distracted. Many patients with psychogenic tremor have a conversion disorder (see Posttraumatic stress disorder) or another psychiatric disease.

- Rubral tremor is characterized by coarse slow tremor which is present at rest, at posture and with intention. This tremor is associated with conditions which affect the red nucleus in the midbrain, classically unusual strokes.

Tremor can result from other conditions as well

- Alcoholism, excessive alcohol consumption, or alcohol withdrawal can kill certain nerve cells, resulting in a tremor known as asterixis. Conversely, small amounts of alcohol may help to decrease familial and essential tremor, but the mechanism behind it is unknown. Alcohol potentiates GABAergic transmission and might act at the level of the inferior olive.

- Tremor in peripheral neuropathy may occur when the nerves that supply the body’s muscles are traumatized by injury, disease, abnormality in the central nervous system, or as the result of systemic illnesses. Peripheral neuropathy can affect the whole body or certain areas, such as the hands, and may be progressive. Resulting sensory loss may be seen as a tremor or ataxia (inability to coordinate voluntary muscle movement) of the affected limbs and problems with gait and balance. Clinical characteristics may be similar to those seen in patients with essential tremor.

- Tobacco withdrawal symptoms include tremor.

- Most of the symptoms can also occur randomly when panicked.

Torsion dystonia, also known as dystonia musculorum deformans, is a disease characterized by painful muscle contractions resulting in uncontrollable distortions. This specific type of dystonia is frequently found in children, with symptoms starting around the ages of 11 or 12. It commonly begins with contractions in one general area such as an arm or a leg that continue to progress throughout the rest of the body. It takes roughly 5 years for the symptoms to completely progress to a debilitating state.

Symptoms of spasmodic dysphonia can come on suddenly or gradually appear over the span of years. They can come and go for hours or even weeks at a time, or remain consistent. Gradual onset can begin with the manifestation of a hoarse voice quality, which may later transform into a voice quality described as strained and breaks in phonation. These phonation breaks have been compared to stuttering in the past, but there is a lack of research in support of spasmodic dysphonia being classified as a fluency disorder. It is commonly reported by people with spasmodic dysphonia that symptoms almost only occur on vocal/speech sounds that require phonation. Symptoms are less likely to occur at rest, while whispering, and/or on speech sounds that do not require phonation. It is hypothesized this occurs because of an increase in sporadic, sudden, and prolonged tension found in the muscles around the larynx during phonation. This tension affects the abduction and adduction (opening and closing) of the vocal folds. Consequently, the vocal folds are unable to retain subglottal air pressure (required for phonation) and breaks in phonation can be heard throughout the speech of people with spasmodic dysphonia.

Regarding types of spasmodic dysphonia, the main characteristic of spasmodic dysphonia, breaks in phonation, is found along with other varying symptoms. The voice quality of adductor spasmodic dysphonia can be described as “strained-strangled” from tension in the glottal region. Voice quality for abductor spasmodic dysphonia can be described as breathy from variable widening of the glottal region. Vocal tremor may also be seen in spasmodic dysphonia. A mix and variance of these symptoms are found in mixed spasmodic dysphonia.

Symptoms of spasmodic dysphonia typically appear in middle aged people, but have also been seen in people in their twenties, with symptoms emerging as young as teenage years.