Measuring Spasticity

The assessment of spasticity can provide information that will help in making a diagnosis of the cause of spasticity, as well as in measuring response to treatment. If a strong increase in spasticity occurs suddenly, potential causes such as a blood clot, urinary tract infection, sprain, pressure sore, or broken bone should be ruled out or treated, if necessary.

When physicians or therapists assess spasticity, they focus on three main areas: the clinical pattern of motor function, the patient's ability to control her or his muscles, and how muscle stiffness and any contractures worsen the functional problems. Functional problems may include difficulty with bathing, toileting, eating, sleeping, dressing, sitting, transferring (such as from a chair to a bed), walking, or standing. Both the clinical history and a physical examination should evaluate the stretch reflex, passive and active motion, and function. The healthcare professional who is doing the evaluation must also distinguish between spasticity and rigidity in a muscle. Both rigidity and spasticity cause an increased tone in muscles, but spasticity is typically only present during stretching of the muscle, and rigidity is present even when the muscle is at rest.

Because two or more muscles cross most joints, identifying the muscles affected by spasticity requires isolating the muscles. The identification can take place through clinical evaluation, that is, observing movements and palpating (feeling) the muscles, or by laboratory evaluations, such as biomechanical methods or electrophysiologic tests. The results of this testing can help the clinician to form an opinion about what muscles or activity may be working against the intended movement. Once the clinician has an idea about which muscles are causing the problems, she or he may choose to inject a local anesthetic into those muscles to block their effect and see if the spasticity improves. In some cases, the blocking will reveal underlying weakness and the fact that the spastic muscle was supporting a weak muscle, and intervention would worsen the situation instead of making it better.

Clinical Examination
A standard evaluation of the nervous system forms the basis of the clinical examination in spasticity. Strength and reflexes are both assessed in this examination. The clinician asks the patient to relax and then moves the joints through their full range of motion at various speeds. Spastic muscles may have a "spastic catch," exhibit the "clasped knife" phenomenon, or both. Observing the person with spasticity perform activities such as walking, drinking from an open cup, and moving from one position to another often yields valuable information.

The clinical examination also includes an evaluation of deep tendon reflexes. The most commonly used method of testing these reflexes is the tapping technique. With the patient sitting on the examination table and his or her legs hanging freely, the examiner gently but firmly taps below the knee (testing the patellar reflex), first on one leg and then the other. The responses should be the same in the two legs. Similar techniques may be used to test reflexes in the Achilles tendon (behind the ankle), and reflexes may also be checked in the biceps, triceps, and brachioradialis muscles of the arms.

Rating Scales
Rating scales may also be used to measure spasticity and the response to treatment. The original and modified versions of the Ashworth Scale are both widely used measures of treatment response and have been validated in patients with MS and other causes of spasticity. To use these scales, the clinician moves the patient's limbs through the range of motion and scores the muscle tone for each limb, resulting in a subjective measure. The Ashworth scales are easy to use, but they do not distinguish the cause of the resistance. Another scale that has been used in measuring response to treatment is a spasm scale. This scale simply requires the assessor to count the number of spasms that the patient has in a set period of time—typically one hour.

Biomechanical Studies
The pendulum test and most other biomechanical tests are typically used only in research to measure spasticity; the equipment that is needed to perform these tests is not available in most doctors' offices, so they are not used in routine practice. To perform the pendulum test, the patient sits on an examination table and the examiner holds the patient's foot with the knee fully extended (as straight as possible). The examiner drops the leg, and a computer records the motion and vibration.

Other than the fact that they are bulky, expensive to use, and not readily available in clinical practice, the other problem with biomechanical tests is that they can not tell the difference between the various factors, such as the stretch reflex and contractures, that have an impact on muscle tone. These devices have been used in research to measure response to medications and other treatments of spasticity.

Electrophysiologic Studies
The measurement of electrical activity in muscles, or electromyography, can also be recorded to determine the number and length of contractions that occur in response to stimuli or movement. Recordings are usually made of agonist and antagonist muscles at the same time.

The most frequently used technique is called dynamic multichannel electromyography, which is often combined with gait-laboratory technology. This technique captures the electrical activity from sensors placed on multiple muscles and records the information while the person is moving. In addition, gait analysis records the force and angle of the legs from video recordings and sensors on the ground, called force plates. Gait analysis is used most often when planning operations to relieve spasticity in children with cerebral palsy.

Another electrophysiologic test that is used primarily in research studies to evaluate response to treatment is the measurement of a reflex called the H reflex (also called the Hoffman reflex in honor of the discoverer of this reflex). The H reflex is brought about by stimulating a nerve, particularly the tibial nerve, with an electric shock and is essentially measuring deep tendon reflexes. A measurement known as the H/M ratio is higher in people with spasticity than in those with normal reflexes.

Functional Measurements
Spasticity almost universally has at least some impact on a person's ability to function. However, tests of general functional ability such as the Barthel Index and the Functional Independence Measure do not have sufficient sensitivity to measure functional changes in people with spasticity. The Fugl-Meyer Assessment of Sensorimotor Impairment (commonly referred to as the Fugl-Meyer scale) uses a three-step approach to systematically test function in the arms and legs. The maximum score is 100, and a score of less than 50 indicates severe motor impairment, although not necessarily from spasticity alone.

	The Spasticity Management Team