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Spasticity is one of the most common neurological symptoms in children with brain injury. It is linked to a dysfunction of the central nervous system which can be genetic or acquired. Explanations from Dr Julie Bonheur, pediatric neurologist specializing in abnormal movements and spasticity within the DYSPA Unit (Rare Diseases Competence Center) at the Adolphe de Rothschild Foundation Hospital.
What is spasticity?
Spasticity is characterized by involuntary contractions of agonist and antagonist muscles (muscles that contract at different times during a movement), associated with an increase in muscle tone and an exacerbation of deep tendon reflexes. It is due to central nervous system dysfunction which can be secondary to an injury (acquired) or intrinsic (genetic or metabolic origin).
What is spastic diplegia or Little syndrome?
We speak of spastic diplegia when spasticity only affects the lower limbs, and quadriplegia when all four limbs are affected. Little syndrome is the old name given to spastic diplegia in the context of premature birth.
What are the causes of spasticity?
There are many causes that can lead to spasticity.
Acquired causes
In children, “cerebral palsy” is the primary cause of spasticity. This generic term designates early acquired lesions (before 2 years) of the central nervous system. “The most common are the after-effects of prematurity, strokes which occur in the perinatal period (from the last trimester of pregnancy, to the first days of life). Among the other causes which can cause spasticity, we find : meningitis or severe infection in the first months of life, or during pregnancy (toxoplasmosis, CMV, etc.), head trauma and perinatal anoxia (when the brain is temporarily deprived of oxygen at birth)”illustrates Dr Julie Bonheur.
Spasticity can appear later in childhood or adolescence, or even in adulthoodfollowing damage to the central nervous system (brain and marrow): autoimmune diseases (multiple sclerosis, etc.), tumoral, vascular, inflammatory, infectious, surgical or post-traumatic lesions.
Genetic causes: paraplegia
In children, genetic causes of spasticity are rare. They concern children with abnormalities of the white matter, nerves or marrow (notably hereditary spastic paraplegia), or with a metabolic disease (disorder in the functioning of cells modifying energy production).
What are the symptoms associated with spasticity?
Spasticity manifests itself as muscle tone increased and hyperreflexia. As the central nervous system is no longer able to carry out its regulatory action (inhibitory role), the tendon reflexes are exacerbated. “When we test the reflexes by tapping on different places of the muscle, we find this reflex on unusual areas. These reflexes are said to be vivid, diffused. In addition to this hyperreflexia, muscular co-contraction of agonist and antagonist muscles (i.e. a simultaneous contraction of the muscles allowing different movements of the arm or leg) is responsible for “stiffness of the legs” (hypertonia). This results in an inability to have fluid movement, or even an absence of movement. Children with spasticity have motor function (walking for example) impaired to varying degrees depending on the severity of the spasticity and associated disorders.develops the pediatric neurologist.
Which muscles are affected by spasticity?
Spasticity can be focal, meaning that only one muscle or limb is affected, or diffuse, in which case all of the muscles of the lower limbs or even all four limbs are affected. This depends on the location of the initial neurological lesion or the disease involved.
What are the consequences of spasticity? Does it hurt ?
Spasticity has an impact on quality of life. It causes a loss of function which results in discomfort in movement which cannot be achieved fluidly. When spasticity affects the lower limbs, the gait is modified, with or without the need for equipment, or even impossible. Spasticity also causes pains (muscular, joint or neuropathic). Long-term, muscle, tendon and bone deformities can occur, especially during growth.
“The pathology does not progress in the event of an acquired lesion but consequences evolve over time, especially during adolescence with the acceleration of growth. Treatment must be done as early as possible to avoid complications. specifies the specialist.
Diagnosis: how to test for spasticity?
The diagnosis of spasticity is essentially based on clinical examination.
The doctor collects the patient’s history (pregnancy and childbirth history), family history (if other family members are affected), to determine the cause of the spasticity. Additional tests can be carried out: a brain MRI, blood tests, genetic samples or even a lumbar puncture.
“We look for signs of spasticity: lively, diffuse osteo-tendinous reflexes, clonus of the ankle, stiffness appearing when stretching, and the presence of deformities (particularly bony)”informs Dr. Julie Bonheur.
The modified Ashworth scale
The modified Ashworth scale is sometimes used to assess muscle tone and quantify spasticity. It is rated on 6 points ranging from 0 to 4. The lowest scores represent normal muscle tone, and the highest scores confirm spasticity, or increased resistance to stretching from passive movement, when the doctor manipulates the patient’s leg or arm.
How to treat spasticity?
In most cases, the cause of spasticity has no cure. Treatment is then symptomatic. This involves multidisciplinary care including: rehabilitation coordinated by the physical medicine and rehabilitation doctor (MPR), motor physiotherapy, psychomotor skills (depending on the child’s age), occupational therapy , speech therapy (in the event of language impairment), and the installation of devices. “Motor physiotherapy has an important place for maintain muscle flexibility which are constantly contracted, try to preserve joint range of motion and improve motor function“indicates Dr Julie Bonheur.
The rehabilitation doctor prescribes devices to the patient if necessary (wheelchair, compression splints, etc.) in order to contain bone deformities and stabilize the child so that he can walk better.
Botulinum toxin injections in certain muscles can also be offered to reduce the contraction of these muscles and protect the child from deformations during this growth period.
In addition, painkillers can be prescribed for pain. “There are oral drug treatments to limit spasticity (Baclofen or Rivotril) but their effect is limited and they often cause side effects,” regrets the expert.
When medical care is not sufficient, surgical treatment may be offered:
- A neurosurgical intervention to intervene on the “spasticity symptom” by modulating the functioning of the central nervous system;
- Orthopedic surgery to correct the consequences of spasticity (modify the bone, lengthen the muscles, modify what has been deformed) and prevent the deformations from getting worse.
What neurosurgical treatment?
In cases of focal spasticity, that is to say there is only one spastic limb, a neurotomy may be considered. This intervention consists of cutting part of the nerve that innervates this region to try to reduce spasticity downstream.
In the event of diffuse spasticity, that is to say which has affected the lower limbs or even all four limbs, several treatments can be offered:
- The Baclofen pump: this reversible technique consists of inserting a catheter in contact with the spinal cord and nerve roots to deliver Baclofen continuously. This procedure is carried out in the operating room. “If the treatment does not work or causes too many side effects, it is possible to withdraw it, reassures the neuropediatrician. This treatment aims to reduce exacerbated reflexes as well as hypertonia (too strong and constant contraction of the muscles). It is often used in tetraparetic patients”.
- Selective dorsal rhizotomy: this irreversible technique consists of cutting part of the sensory roots which innervate the lower limbs and “go up” towards the spinal cord. The intervention is carried out under electrophysiological guidance “Following this surgery, spasticity in the lower limbs disappears. However, it has no action on the motor deficit (control) and muscle weakness which remain impaired in the spastic patient. Reinforced rehabilitation is necessary following this…