Spasticity

What is spasticity?

It is a motor disorder characterized by increased muscle tone (hypertonia) with permanent contraction of the affected muscles.

In the exploration, an increase in resistance is observed when stretching a muscle. This resistance varies according to the speed at which the stretching is performed; the faster the speed, the greater the resistance.

Spasticity makes it difficult to control the movement of the limbs, resulting in significant limitations in the quality of life and autonomy of people.

It is estimated that, in Spain, it affects one out of every 1000 inhabitants and in the world, more than 12 million people suffer from spasticity.

It is caused by an alteration in the functioning of the pyramidal pathway, located in the central nervous system (brain, brainstem and spinal cord). This motor pathway is responsible for voluntary movements, carrying information from the brain to the muscles of the extremities. It consists mainly of two types of neurons, an upper motor neuron located in the cerebral cortex, whose axon connects with a lower motor neuron located in the medulla. Spasticity is caused by diseases affecting the upper motor neuron, resulting in increased activity of the lower motor neuron. These lesions may be located in the brain, brainstem or spinal cord.

The most frequent cause of spasticity in adults is acquired brain damage, appearing in 20-40% of patients with stroke and in up to 60% of patients with moderate-severe head injury. Other diseases include multiple sclerosis, brain tumors, hypoxic brain damage secondary to cardiorespiratory arrest, spinal cord injury and neurodegenerative diseases such as amyotrophic lateral sclerosis. In childhood, cerebral palsy is the pathology most frequently associated with spasticity.

Spasticity appears accompanied by other symptoms, forming what is known as upper motor neuron syndrome or pyramidal syndrome, which presents with:

• Weakness of one or more extremities

The clinical pattern will depend on the location and extent of the lesion. If it occurs at the cerebral level, it generally affects the contralateral arm and leg. In the case of the spinal cord, depending on whether the lesion is at the cervical, dorsal or lumbar level, it may affect all 4 limbs (tetraparesis or tetraplegia, depending on the severity), an arm and a leg on one side (hemiparesis or hemiplegia) or both legs (paraparesis or paraplegia).

• Sustained, involuntary contraction of muscles with difficulty in relaxing them

This contraction usually predominates over the flexor musculature in the upper extremity resulting in a posture with flexed fingers, wrist and elbow, pronated forearm and with internal rotation and approximation of the arm to the trunk. In the lower extremity it mainly affects the extensor musculature, causing a posture when walking with little flexion of the knee, bringing the tip of the foot downwards and bringing the legs together.

• Increased osteotendinous reflexes, when explored with the hammer.

Sometimes what is known as clonus appears, which consists of the appearance of rhythmic and involuntary muscular contractions, when stretching a muscle or tendon. The most common clonus is achilles, which often manifests itself as a “slight tremor” of the foot, which appears while the person is seated, when resting the toe of the foot on the floor.

• Appearance of pathological reflexes

Reflexes such as Babinski’s sign which consists in the extension of the 1st toe when stimulating the lateral side of the sole of the foot.

Spasticity is a symptom that generally appears progressively over weeks or months; unlike weakness which can be acute in onset. It is dynamic, so it can vary in the same person over time.

Increased muscle tone secondary to spasticity has both positive and negative effects on the health and autonomy of individuals.

On the other hand, if an abrupt worsening of spasticity is observed in a patient, we must take into account several factors that may cause it:

• Infections (urinary tract infections, pneumonia, otitis…)
• Pressure ulcers
• Painful stimuli of various causes (ingrown toenail, ill-fitting orthoses, etc.).
• Deep vein thrombosis
• Urinary retention
• Exposure to cold (e.g. swimming in a pool with cold water)
• Fatigue
• Stress
• Maintaining an inadequate posture

First appraisal

In the first evaluation of the patient with spasticity, a medical history should be taken, including personal history, current disease and an examination.

The following aspects will be recorded in the clinical history:

• Topographical distribution of symptoms (focal, regional or generalized)
• Time of evolution
• Existence of other accompanying symptoms such as loss of strength in the extremities, altered sensation, balance or gait, or the presence of sphincter incontinence.
• Presence of pain secondary to muscle stiffness
• The evolution of spasticity over time.
• Aggravating factors of spasticity. For example, urinary tract infections or skin pressure ulcers may aggravate spasticity.
• Limitations secondary to spasticity in basic activities, work, family and social activities.
• Etiology of spasticity
• Previous and current treatments

Once this information has been collected, a general physical and neurological examination should be performed. In the neurological examination, muscle tone is evaluated by passively mobilizing the limbs, joint balance which can be quantified with a goniometer and motor balance or strength in the limbs. This is evaluated bilaterally and systematically starting with the upper extremities, in which shoulder abduction, elbow flexion and extension, wrist dorsal and palmar flexion and finger flexion-extension are explored. Subsequently, hip flexion and extension, knee flexion and extension and dorsal and plantar flexion of the ankle are explored. The strength of each muscle group will be quantified with a score from 0 to 5, according to the following criteria:

• Grade 0, no contraction is visualized or palpable.
• Grade 1, slight visible or palpable contraction, although no movement of the limb is observed.
• Grade 2, movement performed without gravity with all or more than half of the range of motion.
• Grade 3, movement against gravity in all or more than half of the range of motion.
• Grade 4, movement against light to moderate resistance throughout the full range of motion.
• Grade 5, normal contraction power

Subsequently, the patient’s ability to perform some movements and to walk is explored .

Spasticity can affect any muscle, but there are some typical patterns that help us to predict the functional limitations of each patient and the orthopedic deformities that may develop.

1. Cerebral palsy: Children with cerebral palsy may develop one of the following patterns:
   1. Diplegia or spastic diparesis, when affecting both lower limbs, manifested by a “scissors gait” characterized by the crossing of the lower limbs at each step as a result of hypertonia of the adductor musculature and with support of the tips of the feet.
   2. Tetraplegia or spastic tetraparesis, which is the most severe form of cerebral palsy because it affects all 4 limbs. Apart from the “scissors gait”, the arms maintain a posture with flexed elbows, wrists and fingers, approximation of the first finger, pronation of the forearm and adduction and internal rotation of the arm.
   3. Hemiplegia or spastic hemiparesis, with involvement of one arm and one leg on the same side.

In the 3 patterns, the foot can adopt an equinovarus posture with plantar flexion and inversion. This posture causes them to walk on their toes and with the child’s development can lead to contractures that will limit standing and ambulation.

2. In adults
   1. Stroke and traumatic brain injury usually present with spastic hemiparesis, which is the most common pattern. However, a brainstem lesion may produce a tetraparesis.
   2. The spinal cord injury, depending on its course, will be paraparesis (dorsal cord injury) or spastic tetraparesis (cervical cord injury).

In the clinical history it is convenient to use scales that allow us to quantify the degree of spasticity, pain and functional status of the patient. The scales should be reproducible, intra and interobserver, simple and not time consuming. The most commonly used are:

• Modified Asworth scale measures the degree of spasticity or increased muscle tone on examination, classifying it into 5 grades ranging from 0 to 4.

0: Normal muscle tone.

1: Mild hypertonia. Increased muscle tone with “arrest” in the passive movement of the limb, minimal resistance in less than half of its arc of movement.

2: Moderate hypertonia. Increased muscle tone during most of the arc of movement, but can passively move the affected part with ease.

3: Intense hypertonia. Prominent increase in muscle tone, with difficulty in performing passive movements.

4: Extreme hypertonia. The affected part remains rigid, both for flexion and extension.

• Visual analog pain scale (VAS), measures pain intensity from 0 to 10. It consists of a horizontal line of 10 centimeters. The left end represents the absence or lesser intensity of pain and the right end the greater intensity. The patient is asked to mark on the line the point that indicates the intensity and it is measured with a millimeter ruler. The assessment will be: mild pain if the patient scores the pain as less than 3, moderate pain if the assessment is between 4 and 7, and severe pain if the assessment is equal to or greater than 8.

• Scales measuring gait (Timed Up and Go or 6-minute gait test)
• Functional scales to assess participation and activity level: FIM, Rankin and Barthel.
• Quality of life scales (SF-36 questionnaire).

Spasticity is a chronic disorder that interferes with the functioning and quality of life of people who suffer from it. The management of the patient with spasticity will be carried out by a multidisciplinary team, with specific training in neurorehabilitation, in which neurologists or rehabilitation physicians, physiotherapists and occupational therapists participate. In each case, in agreement with the patient and/or family members, specific objectives should be established, which may be one or more of the following:

• Decrease the muscle tone of the extremities.
• Improve posture at rest to prevent the onset of joint stiffness and deformity
• Improve standing and walking
• Reducing pain caused by increased muscle tone
• Decrease spasms
• Facilitating basic activities of daily living (e.g., dressing, toileting)
• Facilitating hygiene
• Facilitating the use of orthoses
• Improve response to rehabilitation

Depending on the objectives, the type of therapy is individualized, which may include pharmacological treatment, physical therapy, use of orthoses, technical aids and/or invasive treatments such as surgery. It should be started early, before the appearance of joint contractures or limitations that worsen the response to treatment. The following aspects should be taken into account:

• Time of evolution of spasticity
• Severity and location of spasticity
• Response to previous treatments
• Cause of spasticity
• Patient’s ability to cooperate with treatment

The different types of treatment for spasticity are:

1. Physiotherapy: uses different techniques, such as ensuring proper positioning, passive mobilization of the joints and facilitating a normal movement pattern (Bobath technique).
2. Occupational therapy through the indication of orthopedic devices that help improve function or prevent joint deformities. Some studies have shown that the use of serial casts can reduce spasticity.
3. Oral drugs: they are effective in reducing the increase in tone, but their use is sometimes limited by side effects such as sedation or negative cognitive effects. Initiation is usually progressive, starting with a low dose, which is increased depending on clinical response and tolerance. These include baclofen, tizanidine, benzodiazepines (diazepam, clonazepam), gabapetin, pregabalin and cannabinoids.
4. Botulinum toxin injections: this is the treatment of choice for focal spasticity in adults and children, both in upper and lower limbs. It has been shown in several clinical trials to be a safe and effective treatment. Treatment with botulinum toxin should be accompanied by a neurorehabilitation program, including stretching and exercises after infiltration and in some cases the use of splints. The effect is transitory and starts 48-72 hours after infiltration, reaches its maximum peak after 2 weeks and lasts 3-4 months. The dose is variable in each patient and depends on the muscles involved, the objectives of the treatment and the response to previous infiltrations. Side effects appear in approximately 16% of patients, days after infiltration and are transient. They are generally local and are produced by diffusion of the toxin to muscles close to the infiltrated muscles, producing weakness.
5. Intrathecal baclofen: indicated in patients with severe spasticity affecting the lower extremities or all 4 extremities, who have not responded to conservative treatments or who have not tolerated oral baclofen due to side effects. By administering the treatment directly to the central nervous system (subarachnoid space), the effective doses are lower than those required when used orally. It consists of a pump and a reservoir that is implanted subcutaneously in the abdominal wall and a catheter that releases the medication into the subarachnoid space, located in the spine. Before implanting the pump, the efficacy of the treatment must be verified by performing a baclofen test, which consists of administering the medication by means of a lumbar puncture and assessing the clinical response.
6. Neurosurgical procedures:
   1. Selective rhizotomy, which consists of the section of posterior nerve roots between the lumbar (L2) and sacral (S1 or S2) regions. It is performed under general anesthesia and is indicated in patients with severe spasticity, usually children with cerebral palsy, who have not responded to less invasive treatments.
   2. Medullary neurostimulation: consists of stimulation of the medulla or posterior roots by epidural route.
7. Orthopedic surgery: indicated primarily for children with cerebral palsy who have bone deformities or muscle or tendon shortening. This surgery aims to reduce spasticity, increase range of motion, facilitate activities such as hygiene, increase tolerance to orthoses and/or reduce pain.

For more information about this pathology and the resources available in our country through the associations of patients (e.g. www. fedace.org, www.aspace.org, www.ictusfederacion.es, www.aspaym.org )

AUTHOR AND DATE OF ISSUE

Dr. Elena Riva

30/03/2021