Spasticity

1. A state of spasm.

2. The tendency to, or capability of suffering, spasm.

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Spasticity is an abnormal physiological state of increased muscle tone with exaggeration of the tendon jerks or reflexes. The definition implies comparison with normal muscle tone, and therein lies the importance of clinical experience. Physicians use their own ‘proprioceptive’ sense to assess whether muscular tone is normal, by slowly moving the patient's limbs at the knee, ankle, and wrist joints so as to stretch the muscles acting on them — the quadriceps at the knee for example, and the biceps at the elbow. The slight resistance to movement in a normal subject is attributable to the intrinsic, passive mechanical properties of the muscles, tendons, joints, and ligaments, because in a resting and, equally important, relaxed subject, there is no muscle activity to generate an opposing force. However, in a spastic limb, for all but the very slowest of joint movements the physician perceives an opposing resistance to movement, the immediate cause of which is an exaggerated ‘stretch’ reflex. This spinal reflex, which arises in muscle receptors exquisitely sensitive to muscle stretch, is notable for the fact that the relevant afferent fibres pass directly to the motor neurons innervating the same and closely related (agonist) muscles. Thus, when muscle tone is enhanced, so also are the tendon jerks; if the patellar or other tendons are tapped, which applies a brief stretch to the muscles, the reflex jerk is larger or more ‘brisk’ than usual. Indeed, brisk jerks may be the earliest indication of a developing spasticity.

Spasticity results from loss of the control of the spinal reflex centres that normally descends from higher parts of the central nervous system, via several different nerve pathways. Thus, for example, a stroke can interrupt the pathway descending from the cerebral cortex, resulting in spasticity of the limbs on the affected side of the body; or a complete transection of the spinal cord can leave the reflex centres for both legs uncontrolled, so that they become spastic (after recovery from an initial period of ‘spinal shock’). The importance of such descending control over the reflex pathways within the spinal cord has been known for many years. However, the fine detail concerning the many different types of interneuron that subserve such control has only been established over the last 20-30 years through experiments on anaesthetized animals. From these, new concepts have emerged which in turn have led to the development of sophisticated, electrophysiolgical measurements for use in man. These will be important in establishing the usefulness of the concepts in the search for symptomatic therapies that might ease the mobility problems resulting from spasticity. Meanwhile, direct recording in man of the electrical activity of the muscle receptors, using the technique of microneuronography, in which ultra-fine electrodes are inserted into the relevant peripheral nerves, has proved to be a valuable technique. It has been established, with respect to the muscle nerves so far examined, that spasticity is not due to an exaggerated sensitivity of the muscle receptors (‘spindles’) to stretch. This factor had preoccupied much of the thinking about the cause of spasticity since the early 1950s, following the discovery that the sensitivity of muscle spindles depends on central nervous system control over the ‘gamma’ motor neurons that innervate the special types of muscle fibre within the muscle spindles.

— Tom Sears

See also cerebral palsy; muscle tone; paralysis; reflexes; stroke.

Definition

Spasticity is an abnormal increase in muscle tone. It may be associated with involuntary muscle spasms, sustained muscle contractions (dystonia), and exaggerated deep tendon reflexes that make movement difficult or uncontrollable. Although it most commonly affects the legs and arms, spasticity can affect any part of the body including the trunk, neck, eyelids, face, or vocal cords.

Description

Spastic muscles are resistant to the normal stretching that occurs during use and may remain contracted for long periods. Spasticity may not be present all the time and varies based on initial muscle tone; length of responding muscle groups; and the person's position, posture, and state of relaxation. Spasticity may increase with anxiety, emotions, pain, or sensory stimulation. It may worsen with movement of the involved muscles. Spasticity may be aggravated by temperature extremes, humidity, skin problems such as a pressure ulcer or ingrown toenail, bladder or bowel problems, infections, and sometimes tight clothing.

The severity of spasticity ranges from slight muscle stiffness to spasms that come and go, to permanent contracture. Spasticity-induced contracture can be treated with medications. If muscle contractures are not treated, fixed contracture can occur, leaving the muscle permanently shortened.

Severe spasticity can interfere with a child's normal functioning, motor and speech development, and/or comfort. Spasticity can be painful, especially if joints are pulled into abnormal positions or if range of motion is limited.

Simple activities of daily living (such as walking, eating, dressing, and bathing) may become time-consuming and difficult for both the child and caregiver. When spasticity limits activity for long periods, it can cause additional medical problems such as sleep disturbances, pressure sores, and pneumonia.

Demographics

The exact incidence of spasticity is not known. Estimates report spasticity may affect over 500,000 Americans and over 12 million people world-wide.

Causes and Symptoms

Causes

Spasticity occurs when certain nerve signals do not reach the muscles because of injury or disease that affects parts of the brain or spinal cord. With spasticity, muscles receive improper nerve signals, causing them to contract, while the brain is unable to communicate with the motor nerves to stop the muscles from contracting.

Common neurological conditions associated with spasticity include cerebral palsy, brain injury or trauma, severe head injury, stroke, multiple sclerosis, spinal cord injury, and some metabolic diseases.

Symptoms

Spasticity is characterized by increased muscle tone (hypertonicity) and by muscle stiffness.

Symptoms associated with spasticity include the following:

• increased muscle stretch reflexes
• involuntary contraction and relaxation of muscles (spasms)
• prolonged muscle contractions (dystonia)
• rapid, repetitive jerky motions (clonus)
• exaggerated deep tendon jerks or reflexes
• involuntary crossing of the legs (also called scissoring reflex)
• abnormal posture or abnormal positioning of the shoulder, arm, wrist, or finger
• increased resistance to movement of certain muscle groups

When to Call the Doctor

If a child has any of the following symptoms, the parent or caregiver should call the child's doctor:

• worsening spasticity
• apparent development of muscle contractures
• worsening overall health

Diagnosis

A diagnosis of spasticity is often made with the diagnosis of cerebral palsy or following a brain or spinal cord injury. A multi-disciplinary team may be consulted to provide an accurate diagnosis of spasticity so the proper treatment can be planned.

The diagnosis of spasticity includes:

• review of personal and family medical history
• review of current medications
• review of other health problems
• physical examination
• diagnostic tests

The medical history helps the physician evaluate the presence of other conditions or disorders that might contribute to or cause the spasticity. Records of previous diagnoses, surgeries, and treatments are reviewed. The child's family medical history is evaluated to determine if there is a history of muscular or neurological disorders.

Questions about the child's medical history may include:

• When were the symptoms first noticed?
• How long have the symptoms lasted?
• Are the symptoms always present?
• What muscles are affected?
• What makes the symptoms improve?
• What specific treatments or techniques have been tried?
• What makes the symptoms worse?
• Do certain activities, emotions, or events seem to aggravate the symptoms?
• Are other symptoms present?
• Is the spasticity preventing function or independence?

The doctor will review the presence of other health problems such as swallowing function, bowel and bladder function, and learning difficulties.

The physical exam may include an evaluation of the child's motor reflexes including muscle tone, mobility, strength, balance and endurance; heart and lung function; cranial nerve function; and an examination of the child's abdomen, spine, throat, and ears. The child's height and weight and blood pressure also are checked and recorded.

To confirm the diagnosis of spasticity, the following tests can be performed to evaluate the child's arm and leg movements, muscular activity, range of motion, and ability to perform self-care activities:

• x rays of the spine and hips
• occupational and physical therapy evaluations to determine upper and lower extremity movement patterns and passive range of motion
• diagnostic blocks with local anesthetics to provide information on the effectiveness of potential treatments
• nerve conduction studies to evaluate muscle or nerve damage
• electromyogram (EMG or myogram) to detect abnormal muscle electrical activity.

Nerve conduction studies and an electromyogram (EMG) are usually performed together to provide a comprehensive assessment of nerve and muscle function. In both tests, the examiner uses a computer, monitor, amplifier, loudspeaker, stimulator and high-tech filters to see and hear how the muscles and nerves are responding during the test.

In the nerve conduction study, small electrodes are placed on the skin over the muscles to be examined. A stimulator delivers a very small electrical current (that does not cause damage to the body) through the electrodes, causing the nerves to fire. In the electromyogram, a very thin, sterilized needle is inserted into various muscles, usually those affected most by spasticity symptoms. The needle is attached by wires to a recording machine. The patient is asked to relax and contract the muscles being examined. The electrical signals produced by the nerves and muscles during these tests are measured and recorded by a computer and displayed as electrical waves on the monitor. The test results are interpreted by a specially trained physician.

Treatment

There is no cure for spasticity, but it can be managed with the appropriate treatment. Treatment options include physical and occupational therapy, medications, surgery, or a combination of these treatments. The goals of treatment are to increase the child's comfort, decrease pain, ease mobility, help with activities of daily living including hygiene, ease rehabilitation procedures, and prevent or decrease the risk of developing a joint contracture. The type of treatment recommended will depend upon the severity of the spasticity; the patient's overall health; the potential benefits, limitations, and side effects of the treatment; and the impact of the treatment on the child's quality of life.

In some cases, treatment is not recommended or desired, because it would actually interfere with the patient's current mobility and not improve function. For example, some people with multiple sclerosis who experience significant leg weakness find that spasticity makes their legs more rigid, helping them to stand, transfer to a chair or bed, or walk.

Clinicians should work with the child and the parents or caregivers to develop an individual treatment plan. Specific treatment goals will vary from one person to the next. Treatment should be provided by a pediatric neurologist and a multi-disciplinary team of specialists that may include a physiatrist, physical therapist, occupational therapist, gait and movement specialists, social worker, and surgical specialists as applicable, such as a pediatric orthopedic surgeon or pediatric neurosurgeon.

Physical and Occupational Therapy

Physical therapy includes stretching exercises, muscle group strengthening exercises, and range of motion exercises to prevent muscles from shortening (contracture), preserve flexibility and range of motion, and reduce the severity of symptoms. Exercises should be practiced daily, as recommended by the physical therapist. Prolonged stretching can lengthen muscles to help decrease spasticity. Strengthening exercises can restore the proper strength to muscles affected by spasticity. Aquatic therapy also may be recommended, since in water there is less stress on the body.

A physical therapist can instruct the patient on proper posture guidelines. Proper posture is critical, especially while sitting and sleeping, to maintain proper alignment of the hips and back. Balancing rest and exercise is also important.

Occupational therapy may include splints, casts, or braces on the affected arm or leg to enable proper limb positioning and maintain flexibility and range of motion. It may also include training for proper limb positioning while seated in a wheelchair or lying in bed.

Physical and occupational therapists can provide guidelines on how to adapt the child's environment to ensure safety and comfort.

Other Treatments

Brief application (about 10 minutes) of cold packs to spastic muscles may help ease pain and improve function for a short period of time.

Electrical stimulation may be used to reduce spasticity for a short period of time or to stimulate a weak muscle to counteract the action of a stronger, spastic muscle.

Biofeedback training may be used to teach the patient how to consciously reduce muscle tension. Biofeedback uses an electrical signal that indicates when a spastic muscle relaxes. The patient may be able to use biofeedback to learn how to consciously reduce muscle tension and possibly reduce spasticity. However, little research had been conducted as of 2004 to determine the effectiveness of biofeedback on reducing spasticity.

Medications

Medications to treat spasticity are taken by mouth, injected, or received through continuous delivery systems. These medications work by preventing nerves from signaling the muscles to contract, thereby preventing muscle contractions.

If treatment with a single medicine fails to effectively treat spasticity, a different medicine may be tried or an additional medicine may be prescribed. The most important medication guidelines include making sure the child takes the medicine exactly as prescribed and not discontinuing medication without first talking to the child's doctor, even if the medication does not seem to be working or is causing unwanted side effects.

ORAL MEDICATIONS. The most commonly prescribed oral medication is baclofen (Lioresal). Baclofen is a muscle relaxant that works on nerves in the spinal cord to reduce spasticity. The benefits of baclofen include decreased stretch reflexes, improved passive range of motion, and reduced muscle spasms, pain, and tightness. Side effects include drowsiness and sedation, as well as weakness, decreased muscle tone, confusion, fatigue, nausea, and dizziness. Baclofen should not be taken with central nervous system depressants or alcohol.

Benzodiazepines, such as diazepam (Valium), clonazepam (Klonopin, Rivotril), and lorazepam (Ativan) reduce spasticity by acting on the central nervous system. The benefits of benzodiazepines include improved passive range of motion, less muscle overactivity, fewer painful spasms, and overall relaxation. These medications are often taken at night because they cause drowsiness. They are also taken at night to relieve muscle spasms that interrupt sleep. Side effects include unsteadiness, loss of strength, low blood pressure, gastrointestinal symptoms, memory problems, confusion, and behavioral problems.

Datrolene sodium (Dantrium) acts on the muscles to directly interfere with the chemistry of the muscle contraction. It is generally used when other medications are not effective. Benefits may include improved passive movement, decreased muscle tone, and reduced muscle spasms, tightness, and pain. Side effects include generalized weakness, including weakness of the respiratory muscles, as well as drowsiness, fatigue, diarrhea, and sensitivity to the sun. Liver problems may occur with this medication, so frequent lab tests are performed to evaluate liver function.

Tizanidine (Zanaflex) reduces spasticity by acting on the central nervous system. It does not usually cause reduced muscle strength. The most common side effect is sedation, and other side effects include low blood pressure, dry mouth, dizziness, and hallucinations. Liver problems may occur with this medication, so frequent lab tests are performed to evaluate liver function.

INJECTED MEDICATIONS. Botulinum toxin type A (Botox, Dysport) or type B (Myobloc) is injected locally into the affected muscle group to relax the muscles. It works by preventing nerves from sending signals to the muscles that cause them to contract. Although the treatment takes one to two weeks to reach its full effectiveness, the beneficial effects last three to four months. Botulinum-toxin allows more normal limb positioning and improved mobility. In some patients, the injections also decrease pain. Injections may be used to make casting easier, ease the adjustment of a new brace, or delay surgery.

Botulinum toxin is made by the bacteria that cause botulism. However, the amount of botulinum toxin injected to treat spasticity is so small that it would not cause botulism poisoning. This treatment is very safe, and the injections can be given in a doctor's office without the use of sedation or anesthesia. Injections can be repeated but should be spaced apart from three to six months to avoid exceeding the recommended dose. Botulinum-toxin injections can be used in combination with oral medications or intrathecal baclofen to treat spasticity.

Botulinum-toxin injections are typically expensive and may not be covered by insurance. A Reimbursement Hotline established by Allergan, the manufacturer of Botox, is a resource for reimbursement questions: available online at www.botox.com. Elan, the manufacturer of Myobloc, also has resources available to answer questions about reimbursement: available online at www.botox.com. Elan, the manufacturer of Myobloc, also has resources available to answer questions about reimbursement: available online at www.elan.com.

Alcohol and phenol are injected in combination but are less commonly used to treat spasticity. The medications are injected directly onto nerves that supply spastic muscles to destroy them. The injections cut off the signals to those muscles, allowing them to relax. This treatment may be used to treat spasticity in larger muscle groups closer to the trunk, such as the thigh muscles. Although this treatment is generally less expensive than botulinum-toxin injections, there are more serious side effects.

Short-term medications such as lidocaine, a local anesthetic, can be used to assess the potential benefit of botulinum toxin or alcohol and phenol injections.

CONTINUOUS DELIVERY MEDICATIONS. Baclofen usually is taken as an oral medication but also can be delivered directly into the spinal fluid when the oral medication does not effectively control symptoms. An intrathecal baclofen delivery system continuously releases prescribed amounts of baclofen in small doses directly into the spinal fluid via a small catheter and pump. This type of delivery system causes fewer and less severe side effects than the oral baclofen.

To determine the potential effectiveness of the system, an initial trial of the intraspinal therapy is conducted. During this trial, the medication is delivered into the spinal fluid via a lumbar puncture procedure. The medication usually reaches its peak effectiveness within four hours. If the patient responds favorably to the trial, the intrathecal system can be considered.

The intrathecal baclofen delivery system is placed by a neurosurgeon during a surgical procedure under local or general anesthesia. First, a catheter (thin, flexible tube) is inserted through a needle and guided into the spinal canal, close to where pain pathways enter the spinal cord. The other end of the catheter is tunneled under the skin to the abdomen where a pocket is created. There, the pump is implanted under the skin (epidermal area) through an incision in the abdomen. The baclofen pump is a round, titanium disc about one inch thick and about three inches in diameter. The pump is anchored to surrounding tissue and connected to the catheter. The incision is then closed.

The pump reservoir is filled with the prescribed amount of medication. Medication can be filled and refilled in the pump by inserting a needle through the skin into a filling port (called a diaphragm) in the center of the pump.

The medication is dispensed, either continuously or at certain intervals as determined by the doctor, via a tiny motor in the pump that moves the medication from the pump reservoir through the catheter. Baclofen flows freely in the spinal canal, affecting the nerves to control hyperactive muscles. The system contains a computer chip, so adjustments to the dose, rate, and timing of the medication can be made by the physician using an external programmer. The system also has an alarm to indicate when the reservoir needs to be refilled, the battery is low, or the pump is not delivering the medication. If the system does not appear to be effective in treating spasticity, it can be turned off and eventually removed.

Pump refills and medication adjustments are generally made once every two to three months after the initial dosage is established. The pump system lasts from three to five years, at which time the system needs to be replaced.

Surgery

Surgery is only recommended when all other treatments have been tried and have not effectively controlled the child's spasticity symptoms. Surgical options for chronic spasticity include selective dorsal rhizotomy and tendon release surgery.

Selective dorsal rhizotomy surgery, also called selective posterior rhizotomy, involves a surgical resection of part of the spinal nerve. By cutting the sensory nerve rootlets that cause the spasticity, muscle stiffness is decreased while other functions are maintained. Potential benefits of this surgical procedure include pain relief, reduced spasticity to improve walking or aid sitting in a wheelchair, increased ability to bend at the waist, and improved use of the hands. Sometimes, rhizotomy results in improved breathing and better control of the arms, legs, and head.

Orthopedic surgery for spasticity may be performed to correct a contracture. During contracture release surgery, the tendon of a contractured muscle is cut, the joint is repositioned to a more normal angle, and a cast is applied. Regrowth of the tendon to this new length occurs over several weeks following surgery. After the cast is removed, physical therapy can help strengthen the muscles and improve range of motion. This procedure is most commonly performed on the Achilles tendon but may also be performed on the knees, hips, shoulders, elbows, and wrists.

Tendon transfer surgery is another technique to treat contractures. During this procedure, the tendon attached to a spastic muscle is cut and transferred to a different site, preventing the muscle from being pulled into an abnormal position.

The disadvantages of these orthopedic procedures are that they are irreversible and that they may need to be repeated.

Other orthopedic surgeries that may accompany contracture release surgery include osteotomy, in which a small wedge is removed from a bone to allow repositioning. A cast is applied while the bone heals in a more natural position. Osteotomy is more commonly performed on the bones in the hips or feet. Arthrodesis is a fusing of bones that normally move independently to limit the ability of a spastic muscle to pull the joint into an abnormal position. Arthrodesis is more commonly performed on the bones in the ankle.

Nutritional Concerns

Dietary guidelines are individualized, based on the child's age, diagnosis, overall health, severity of disability, and level of functioning. Specific nutritional problems, such as swallowing or feeding difficulties, may be a concern in some patients and should be managed by a team of specialists including a speech therapist. Early identification, treatment, and correction of specific feeding problems will improve the health and nutritional status of the patient.

A well-balanced and carefully planned diet will help maintain general good health for people with spasticity. Specialists recommend that people with multiple sclerosis and other movement disorders adhere to the same low-fat, high-fiber diet that is recommended for the general population.

Children with spasticity may have different energy needs, depending on their condition. One study indicated that ambulatory and non-ambulatory adolescents with cerebral palsy had decreased energy needs compared with a control group of normal adolescents. Therefore, a child's specific calorie needs should be evaluated by a registered dietitian who can work with the parents to develop an individualized meal plan. The child's weight should be obtained once a week or at least once a month to determine if caloric intake is adequate.

A child's self-feeding skills can impact his or her health outcome. One study indicated that 90 percent of children with good to fair motor and feeding skills reached adulthood. In contrast, a lack of self-feeding skills was associated with a six-fold increase in mortality (rate of death).

Maintaining a healthy weight is important to prevent the development of chronic diseases such as diabetes, high blood pressure (hypertension), and heart disease.

Tube feedings may be required in some patients with failure to thrive, aspiration pneumonia, difficulty swallowing, or an inability to ingest adequate calories orally to maintain nutritional status or promote growth.

Alternative Treatment

Alternative and complementary therapies include approaches that are considered to be outside the mainstream of traditional health care.

Techniques that reduce stress, such as yoga, Tai Chi, meditation, deep breathing exercises, guided imagery, and relaxation training, may be helpful to induce relaxation and manage spasticity. Acupuncture and biofeedback training also may help induce relaxation. Before learning or practicing any particular technique, it is important for the parent/caregiver and child to learn about the therapy, its safety and effectiveness, potential side effects, and the expertise and qualifications of the practitioner. Although some practices are beneficial, others may be harmful to certain patients.

Initial trials of cannabinoids, the active ingredient in marijuana, have shown promise in the treatment of muscle stiffness and limb straightening associated with multiple sclerosis. Further research is needed to determine the beneficial effects of marijuana-derived substances on neuromuscular symptoms associated with movement disorders. Researchers caution that smoking marijuana is dangerous, especially since there may be other harmful substances mixed in with the illegal drug.

Relaxation techniques and dietary supplements should not be used as a substitute for medical therapies prescribed by a doctor. Parents should discuss these alternative treatments with the child's doctor to determine the techniques and remedies that may be beneficial for the child.

Prognosis

There is no cure for spasticity, and it cannot be prevented. However, it can be well-managed with the proper combination of physical and occupational therapy, medication, and surgery. The long-term outlook for those with spasticity depends on the severity of the spasticity and the associated disorder.

Parental Concerns

Parents should work closely with the child's therapists and doctors to create an effective treatment plan. It is important for parents to communicate their treatment goals with the healthcare team. Parents should take an active role in the child's exercise program and help the child practice the exercises as prescribed every day. Raising a child with a movement disorder can be challenging. There are several support groups available to provide information and assistance.

Resources

Books

Barnes, Michael P., and Garth R. Johnson. Upper Motor Neuron Syndrome & Spasticity: Clinical Management & Neurophysiology. Cambridge, UK: Cambridge University Press, 2001.

Gelber, David A., and Douglas R. Jeffery. Clinical Evaluation and Management of Spasticity. Totowa, NJ: Humana Press Inc., 2001.

Periodicals

"Position of the American Dietetic Association: Providing Nutrition Services for Infants, Children, and Adults with Developmental Disabilities and Special Health Care Needs." Journal of the American Dietetic Association 104, no. 1 (2004): 97–107.

Organizations

Brain Injury Association of America. 8201 Greensboro Dr., Ste. 611, McLean, VA 22102. Web site: www.biausa.org.

National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control. 4770 Buford Hwy., NE, Ste. F-35, Atlanta, GA 30341. Web site: .

National Institute on Disability and Rehabilitation Research, Office of Special Education and Rehabilitative Services. U.S. Department of Education, 400 Maryland Ave., SW, Washington, DC 20202–7100. Web site: www.ed.gov/about/offices/list/osers/nidrr/.

National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health. PO Box 5801, Bethesda, MD 20824. Web site: www.ninds.nih.gov/about_ninds/.

National Rehabilitation Information Center (NARIC). 4200 Forbes Blvd., Ste. 202, Lanham, MD 20700. Web site: www.naric.com.

National Spinal Cord Injury Association. 6701 Democracy Blvd., #300–9, Bethesda, MD 20817. Web site: www.spinalcord.org.

Worldwide Education and Awareness for Movement Disorders (WE MOVE). 204 W. 84th St. New York, NY 10024. Web site: www.wemove.org.

Web Sites

"Electromyogram and Nerve Conduction Study." North American Spine Society. Available online at www.spine.org/articles/emg_test.cfm (accessed October 17, 2004).

"Severe Spasticity." Medtronic. Available online at www.medtronic.com/neuro/spasticity/spasticity.html (accessed October 17, 2004).

Spinal Cord Injury Information Network. Available online at www.spinalcord.uab.edu (accessed October 17, 2004).

"Task Force on Childhood Motor Disorders Consensus Report of a Meeting at the National Institutes of Health, April 22–24, 2001." Available online at www.ninds.nih.gov/news_and_events/hypertonia_meeting_2001.htm. (accessed October 17, 2004).

"What you need to know about Electromyograms." The Cleveland Clinic Health Information Center. Available online at www.clevelandclinic.org/health/health-info/docs/0200/0225.asp?index=4825 (accessed October 17, 2004.)

[Article by: Angela M. Costello]

Resistance to passive movements of a limb that is maximal at the beginning of the movement and becomes less as more pressure is applied. Spasticity is a symptom of spinal injuries. It is usually accompanied by weakness in the affected limb (spastic paralysis).

The state of being spastic.

• inherited neonatal s. — signs appear in calves at 2 to 5 days of age. Unable to stand; if lifted rigidity of all muscles with extension of limbs.
• inherited periodic s. — see inherited periodic spasticity.
• inherited progressive s. — possibly inherited disease of Angora goats; characterized by development of lethargy and ataxia at about 2 months of age, followed by paresis, recumbency and euthanasia and necropsy lesions of vacuolation in neurons of the brain and spinal cord.

A form of muscular hy-pertonicity with increased resistance to stretch.

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