Hypertonia
   HOME

TheInfoList



OR:

Hypertonia is a term sometimes used synonymously with ''
spasticity Spasticity () is a feature of altered skeletal muscle performance with a combination of paralysis, increased tendon reflex activity, and hypertonia. It is also colloquially referred to as an unusual "tightness", stiffness, or "pull" of muscles. ...
'' and ''rigidity'' in the literature surrounding damage to the
central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...
, namely upper motor neuron lesions. Impaired ability of damaged
motor neurons A motor neuron (or motoneuron), also known as efferent neuron is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or ...
to regulate descending pathways gives rise to disordered spinal reflexes, increased excitability of muscle spindles, and decreased synaptic inhibition. These consequences result in abnormally increased
muscle tone In physiology, medicine, and anatomy, muscle tone (residual muscle tension or tonus) is the continuous and passive partial contraction of the muscles, or the muscle's resistance to passive stretch during resting state.O’Sullivan, S. B. (2007) ...
of symptomatic muscles. Some authors suggest that the current definition for spasticity, the velocity-dependent overactivity of the stretch reflex, is not sufficient as it fails to take into account patients exhibiting increased muscle tone in the absence of stretch reflex over-activity. They instead suggest that "reversible hypertonia" is more appropriate and represents a treatable condition that is responsive to various therapy modalities like drug or physical therapy.


Presentation

Symptoms associated with central nervous systems disorders are classified into positive and negative categories. Positive symptoms include those that increase muscle activity through hyper-excitability of the stretch reflex (i.e., rigidity and spasticity) where negative symptoms include those of insufficient muscle activity (i.e. weakness) and reduced motor function. Often the two classifications are thought to be separate entities of a disorder; however, some authors propose that they may be closely related.


Pathophysiology

Hypertonia is caused by upper motor neuron lesions that may result from injury, disease, or conditions that involve damage to the central nervous system. The lack of or decrease in upper motor neuron function leads to loss of inhibition with resultant hyperactivity of
lower motor neuron Lower motor neurons (LMNs) are motor neurons located in either the anterior grey column, anterior nerve roots (spinal lower motor neurons) or the cranial nerve nuclei of the brainstem and cranial nerves with motor function (cranial nerve lower ...
s. Different patterns of muscle weakness or hyperactivity can occur based on the location of the lesion, causing a multitude of neurological symptoms, including
spasticity Spasticity () is a feature of altered skeletal muscle performance with a combination of paralysis, increased tendon reflex activity, and hypertonia. It is also colloquially referred to as an unusual "tightness", stiffness, or "pull" of muscles. ...
, rigidity, or dystonia. Spastic hypertonia involves uncontrollable muscle spasms, stiffening or straightening out of muscles, shock-like contractions of all or part of a group of muscles, and abnormal
muscle tone In physiology, medicine, and anatomy, muscle tone (residual muscle tension or tonus) is the continuous and passive partial contraction of the muscles, or the muscle's resistance to passive stretch during resting state.O’Sullivan, S. B. (2007) ...
. It is seen in disorders such as
cerebral palsy Cerebral palsy (CP) is a group of movement disorders that appear in early childhood. Signs and symptoms vary among people and over time, but include poor coordination, spasticity, stiff muscles, Paresis, weak muscles, and tremors. There may b ...
,
stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...
, and
spinal cord injury A spinal cord injury (SCI) is damage to the spinal cord that causes temporary or permanent changes in its function. It is a destructive neurological and pathological state that causes major motor, sensory and autonomic dysfunctions. Symptoms of ...
. Rigidity is a severe state of hypertonia where muscle resistance occurs throughout the entire range of motion of the affected joint independent of velocity. It is frequently associated with lesions of the
basal ganglia The basal ganglia (BG) or basal nuclei are a group of subcortical Nucleus (neuroanatomy), nuclei found in the brains of vertebrates. In humans and other primates, differences exist, primarily in the division of the globus pallidus into externa ...
. Individuals with rigidity present with stiffness, decreased range of motion, and loss of motor control. Rigidity is a nonselective increase in the tone of agonist and antagonist without velocity dependence, and the increased tone remains uniform throughout the range of movement. On the contrary, spasticity is a velocity-dependent increase in tone resulting from the hyper excitability of stretch reflexes. It primarily involves the antigravity muscles – flexors of the upper limb and extensors of the lower limb. During the passive stretch, a brief "free interval" is appreciated in spasticity but not in rigidity because the resting muscle is electromyographically silent in spasticity. In contrast, in rigidity, the resting muscle shows firing. Dystonic hypertonia refers to muscle resistance to passive stretching (in which a therapist gently stretches the inactive contracted muscle to a comfortable length at very low speeds of movement) and a tendency of a limb to return to a fixed involuntary (and sometimes abnormal) posture following movement.


Management

Therapeutic interventions are best individualized to particular patients. Basic principles of treatment for hypertonia are to avoid noxious stimuli and provide frequent range of motion exercise.


Physical interventions

Physiotherapy Physical therapy (PT), also known as physiotherapy, is a healthcare profession, as well as the care provided by physical therapists who promote, maintain, or restore health through patient education, physical intervention, disease preventio ...
has been shown to be effective in controlling hypertonia through the use of stretching aimed to reduce
motor neuron A motor neuron (or motoneuron), also known as efferent neuron is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly o ...
excitability. The aim of a physical therapy session could be to inhibit excessive tone as far as possible, give the patient a sensation of normal position and movement, and to facilitate normal movement patterns. While static stretch has been the classical means to increase range of motion, PNF stretching has been used in many clinical settings to effectively reduce muscle spasticity. Icing and other
topical anesthetic A topical anesthetic is a local anesthetic that is used to numb the surface of a body part. They can be used to numb any area of the skin as well as the front of the eyeball, the inside of the nose, ear or throat, the anus and the genital area. ...
s may decrease the reflexive activity for short period of time in order to facilitate motor function. Inhibitory pressure (applying firm pressure over muscle tendon) and promoting body heat retention and rhythmic rotation (slow repeated rotation of affected body part to stimulate relaxation) have also been proposed as potential methods to decrease hypertonia. Aside from static stretch casting, splinting techniques are extremely valuable to extend joint range of motion lost to hypertonicity. A more unconventional method for limiting tone is to deploy quick repeated passive movements to an involved joint in cyclical fashion; this approach has also been demonstrated to show results on persons without physical disabilities. For a more permanent state of improvement, exercise and patient education is imperative. Isokinetic, aerobic, and
strength training Strength training, also known as weight training or resistance training, is exercise designed to improve physical strength. It is often associated with the lifting of Weightlifting, weights. It can also incorporate techniques such as bodyweigh ...
exercises should be performed as prescribed by a physiotherapist, and stressful situations that may cause increased tone should be minimized or avoided.


Pharmaceutical interventions

Baclofen,
diazepam Diazepam, sold under the brand name Valium among others, is a medicine of the benzodiazepine family that acts as an anxiolytic. It is used to treat a range of conditions, including anxiety disorder, anxiety, seizures, alcohol withdrawal syndr ...
, and dantrolene remain the three most commonly used pharmacologic agents in the treatment of spastic hypertonia. Baclofen is generally the drug of choice for spinal cord types of spasticity, while sodium dantrolene is the only agent which acts directly on muscle tissue.
Tizanidine Tizanidine, sold under the brand name Zanaflex among others, is an alpha-2 (α2) adrenergic receptor agonist, similar to clonidine, that is used to treat muscle spasticity due to spinal cord injury, multiple sclerosis, and spastic cerebral ...
is also available. Phenytoin with
chlorpromazine Chlorpromazine (CPZ), marketed under the brand names Thorazine and Largactil among others, is an antipsychotic medication. It is primarily used to treat psychotic disorders such as schizophrenia. Other uses include the treatment of bipolar d ...
may be potentially useful if sedation does not limit their use. Ketazolam, not yet available in the United States, may be a significant addition to the pharmacologic set of options. Intrathecal administration of antispastic medications allows for high concentrations of drug near the site of action, which limits side effects.


See also

* Dystonia *
Hypotonia Hypotonia is a state of low muscle tone (the amount of tension or resistance to stretch in a muscle), often involving reduced muscle strength. Hypotonia is not a specific medical disorder, but it is a potential manifestation of many different dis ...
* Paratonia *
Spasticity Spasticity () is a feature of altered skeletal muscle performance with a combination of paralysis, increased tendon reflex activity, and hypertonia. It is also colloquially referred to as an unusual "tightness", stiffness, or "pull" of muscles. ...
* Clasp-knife response


References


External links

{{Authority control Cerebral palsy types Symptoms and signs: Nervous system Muscular disorders Pediatrics