Hyperkinesia


Hyperkinesia refers to an increase in muscular activity that can result in excessive abnormal movements, excessive normal movements, or a combination of both. Hyperkinesia is a state of excessive restlessness which is featured in a large variety of disorders that affect the ability to control motor movement, such as Huntington's disease. It is the opposite of hypokinesia, which refers to decreased bodily movement, as commonly manifested in Parkinson's disease.
Many hyperkinetic movements are the result of improper regulation of the basal ganglia–thalamocortical circuitry. Overactivity of a direct pathway combined with decreased activity of indirect pathway results in activation of thalamic neurons and excitation of cortical neurons, resulting in increased motor output. Often, hyperkinesia is paired with hypotonia, a decrease in muscle tone. Many hyperkinetic disorders are psychological in nature and are typically prominent in childhood. Depending on the specific type of hyperkinetic movement, there are different treatment options available to minimize the symptoms, including different medical and surgical therapies. The word hyperkinesis comes from the Greek hyper, meaning "increased," and kinisis, meaning "movement."

Classification

Basic hyperkinetic movements can be defined as any unwanted, excess movement. Such abnormal movements can be distinguished from each other on the basis of whether or not, or to what degree they are, rhythmic, discrete, repeated, and random. In evaluating the individual with a suspected form of hyperkinesia, the physician will record a thorough medical history, including a clear description of the movements in question, medications prescribed in the past and present, family history of similar diseases, medical history, including past infections, and any past exposure to toxic chemicals. Hyperkinesia is a defining feature of many childhood movement disorders, yet distinctly differs from both hypertonia and negative signs, which are also typically involved in such disorders. Several prominent forms of hyperkinetic movements include:

Ataxia

The term ataxia refers to a group of progressive neurological diseases that alter coordination and balance. Ataxias are often characterized by poor coordination of hand and eye movements, speech problems, and a wide-set, unsteady gait. Possible causes of ataxias may include stroke, tumor, infection, trauma, or degenerative changes in the cerebellum. These types of hyperkinetic movements can be further classified into two groups. The first group, hereditary ataxias, affect the cerebellum and spinal cord and are passed from one generation to the next through a defective gene. A common hereditary ataxia is Friedreich's ataxia. in contrast, sporadic ataxias occur spontaneously in individuals with no known family history of such movement disorders.

Athetosis

is defined as a slow, continuous, involuntary writhing movement that prevents the individual from maintaining a stable posture. These are smooth, nonrhythmic movements that appear random and are not composed of any recognizable sub-movements. They mainly involve the distal extremities, but can also involve the face, neck, and trunk. Athetosis can occur in the resting state, as well as in conjunction with chorea and dystonia. When combined with chorea, as in cerebral palsy, the term "choreoathetosis" is frequently used.

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 the 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 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.

Hemiballismus

Typically caused by damage to the subthalamic nucleus or nuclei, hemiballismus movements are nonrhythmic, rapid, nonsuppressible, and violent. They usually occur in an isolated body part, such as the proximal arm.

Hemifacial spasm

is characterized by involuntary contraction of facial muscles, typically occurring only on one side of the face. Like blepharospasm, the frequency of contractions in hemifacial spasm may range from intermittent to frequent and constant. The unilateral blepharospasm of HFS may interfere with routine tasks such as driving. In addition to medication, patients may respond well to treatment with Botox. HFS may be due to vascular compression of the nerves going to the muscles of the face. For these patients, surgical decompression may be a viable option for the improvement of symptoms.

Myoclonus

is defined as a sequence of repeated, often nonrhythmic, brief, shock-like jerks due to sudden involuntary contraction or relaxation of one or more muscles. These movements may be asynchronous, in which several muscles contract variably in time, synchronous, in which muscles contract simultaneously, or spreading, in which several muscles contract sequentially. It is characterized by a sudden, unidirectional movement due to muscle contraction, followed by a relaxation period in which the muscle is no longer contracted. However, when this relaxation phase is decreased, as when muscle contractions become faster, a myoclonic tremor results. Myoclonus can often be associated with seizures, delirium, dementia, and other signs of neurological disease and gray matter damage.

Stereotypies

are repetitive, rhythmic, simple movements that can be voluntarily suppressed. Like tremors, they are typically back and forth movements, and most commonly occur bilaterally. They often involve fingers, wrists, or proximal portions of the upper extremities. Although, like tics, they can stem from stress or excitement, there is no underlying urge to move associated with stereotypies and these movements can be stopped with distraction. When aware of the movements, the child can also suppress them voluntarily. Stereotypies are often associated with developmental syndromes, including the autism spectrum disorders. Stereotypies are quite common in preschool-aged children and for this reason are not necessarily indicative of neurological pathology on their own.

Tardive dyskinesia / tardive dystonia

or tardive dystonia, both referred to as "TD", refers to a wide variety of involuntary stereotypical movements caused by the prolonged use of dopamine receptor-blocking agents. The most common types of these agents are antipsychotics and anti-nausea agents. The classic form of TD refers to stereotypic movements of the mouth, which resemble chewing. However, TD can also appear as other involuntary movements such as chorea, dystonia, or tics.

Tics

A tic can be defined as a repeated, individually recognizable, intermittent movement or movement fragments that are almost always briefly suppressible and are usually associated with awareness of an urge to perform the movement. These abnormal movements occur with intervening periods of normal movement. These movements are predictable, often triggered by stress, excitement, suggestion, or brief voluntary suppressibility. Many children say that the onset of tics can stem from the strong urge to move. Tics can be either muscular or vocal in nature and most commonly involve the face, mouth, eyes, head, neck or shoulder muscles. Tics can also be classified as simple motor tics, complex motor tics, or phonic tics.
When both motor and vocal tics are present and persist for more than one year, a diagnosis of Tourette syndrome is likely. TS is an inherited neurobehavioral disorder characterized by both motor and vocal tics. Many individuals with TS may also develop obsessions, compulsions, inattention and hyperactivity. TS usually begins in childhood. Up to 5% of the population has tics, but at least 20% of boys will have developed tics at some point in their lifetimes.