Muscle hypertonia is a pathological increase in muscle tone. It is of neurological origin and often the consequence of a pathology.

Hypertonia is a disorder of muscle tone. The tone of a muscle is measured by the resistance it opposes when it is passively mobilized. In some cases, this resistance is considered too low, so we speak of hypotonia. In the opposite case, the resistance is too great, we then speak of hypertonia.

Hypertonia is defined as a permanent exaggeration of the tone of a muscle. Muscle tone is increased, causing stiffness and difficulty in moving the joints. Often of neurological origin, hypertonia is the consequence of an injury to the central nervous system.

There are two main types of muscle hypertonia:

• Spastic hypertonia or spasticity. It is the most frequently encountered tone disorder. It is also called elastic hypertonia because it is characterized by a return to its starting position of the mobilized limb once it is no longer manipulated. If, for example, the doctor tries to bend a patient’s elbow, resistance builds up, becomes more and more important, and does not stop until the arm has returned to its original position. We also speak of pyramidal hypertension because associated with other symptoms such as muscle paralysis or hemiplegia, it constitutes pyramidal syndrome. Spasticity can be variable throughout the day, often more severe in the morning upon waking. It can also be influenced by weather conditions, emotion or stress. Its intensity can vary enormously. It can range from a simple stiffness in a joint to a total inability to mobilize the joint;
• Plastic hypertonicity or rigidity. It is characterized by the feeling of a constant resistance during the passive mobilization of a limb, whatever the direction or the speed of the manipulation, and an absence of return to the initial position when the manipulation is finished. Here, if the doctor tries to straighten the elbow, the resistance is the same throughout the movement and the arm does not return to the starting position when released. It is also called extrapyramidal hypertonia because it is caused by a malfunction of the extrapyramidal nervous system. Along with other symptoms, it constitutes extrapyramidal syndrome.

The word hypertonia is also used to refer to two independent conditions of muscle tone. Vagal discomfort is also called vagal hypertonia. This is too much stress on the vagus nerve which causes discomfort and a brief loss of consciousness. Vagal hypertension is caused by a slowing of the heart rate associated with a drop in blood pressure. If it is a benign condition, it is still important to find the cause.

We also speak of ocular hypertonia. This is an abnormal rise in pressure inside the eyeball. The risk in the long term is the deterioration of the optic nerve and the appearance of glaucoma.

Hypertonia is the consequence of an injury to the central nervous system. This lesion can have several causes:

• degenerative disease of the nervous system. The hypertonia can for example be due to a Parkinson’s disease or parkinsonian syndrome;
• a vascular or cardiovascular condition. Muscle hypertension can be the result of a stroke. Indeed, following a stroke, it is possible to preserve a lesion in the area of ​​the brain that controls motor skills;
• a tumor ;
• an infection ;
• a genetic or congenital disease.

Hypertonia is often associated with reduced motive power and causes difficulty in making precise movements. It can cause discomfort when walking due to instability in the ankle joint or difficulty moving the hip or knee joints. If muscle hypertonicity affects a joint in the upper limb, it can interfere with the ability to grasp the hand or lift the arm to reach for an object high up.

Due to muscle contractures, hypertonia can cause severe pain in the affected limbs.

As seen above, muscle hypertonia can be caused by different pathologies. Its first treatment will therefore be that of the pathology of which it is the symptom.

In some cases, this is not sufficient or the discomfort due to hypertonia is too great. It is then possible to relieve the patient by muscle relaxants or physiotherapy. Hypertonia can also be treated with botulinum toxin injections. In the case of stiffness due to Parkinson’s disease, this can also be reduced by surgery.

Whether it is a simple stiffness or a more important discomfort, it is important to discuss it with your doctor so that he can investigate and find the cause of this discomfort.