Spasticity (muscle spasm): causes, symptoms and modern treatment approaches

Spasticity is a movement disorder characterised by abnormally high muscle tension (muscle tone). It is caused by damage to the central nervous system (CNS) – that is, the brain or spinal cord. The muscles are stiff, difficult to move and prone to involuntary, often painful spasms. Spasticity is not a disease in its own right, but is always a symptom of an underlying neurological condition such as a stroke or multiple sclerosis.

What exactly is spasticity? – Definition of increased muscle tone

Spasticity is a form of increased muscle tone that is felt as resistance during passive movement, the degree of which depends on the speed of the movement. You can think of it as a handbrake that is constantly applied within the muscle: the faster you try to extend a joint (e.g. the elbow), the more strongly the muscle „resists“ this. This phenomenon is also known as „velocity-dependent stretch resistance“. Often, after an initial tightening, the resistance suddenly subsides; this is known as the ‘penknife phenomenon’. Spasticity can range from mild stiffness to severe, painful and uncontrollable muscle spasms.

The neurological cause: Why does spasticity develop?

The cause of spasticity always lies in damage to the central nervous system (CNS). In a healthy state, the brain sends signals via the spinal cord to the muscles, which not only control movement but also finely regulate and dampen muscle tone. If this part of the CNS – the so-called upper motor neuron – is damaged, these dampening signals are lost. The consequence is that the muscles become hyperexcitable. Reflexes are heightened, and the muscles effectively receive too many „accelerator commands“ without the „brake“ functioning properly. The result is uncontrolled, increased baseline muscle tone.

Common underlying conditions that can cause spasticity

As spasticity is always a symptom, it occurs in association with various neurological conditions and injuries. The most common causes include:

• Stroke: one of the most common causes of spasticity in adults.
• Multiple sclerosis (MS): This chronic inflammatory disease of the central nervous system often leads to spasticity, particularly in the legs.
• Traumatic brain injury: injuries to the brain caused by accidents.
• Spinal cord injuries: For example, following an accident (paraplegia).
• Cerebral palsy: A brain injury sustained in early childhood, which is often accompanied by spastic paralysis.
• Lack of oxygen in the brain (hypoxia).

Typical symptoms and signs of spasticity

The symptoms of spasticity can vary greatly and have a significant impact on quality of life:

• Increased muscle stiffness: The limbs feel stiff and are difficult to move.
• Painful muscle cramps (spasms): Sudden, involuntary and often painful muscle contractions.
• Clonus: Rhythmic, twitching movements, often visible at the ankle.
• Poor posture: Constant tension can cause joints to remain in an unnatural position (e.g. a clenched fist, a bent arm, or a pointed foot).
• Impaired fine motor skills: Activities such as grasping, writing or eating become more difficult.
• Problems with walking: A stiff leg or pes planus can significantly affect your gait.
• Difficulties with personal hygiene: for example, it may become impossible to open one’s hand to wash it.

Diagnosis: How is spasticity diagnosed?

A diagnosis of spasticity is usually made by a neurologist following a clinical examination. The doctor assesses muscle tone by passively moving the patient’s limbs. In doing so, they pay attention to the speed-dependent resistance. Reflexes are tested; these are often exaggerated. The Ashworth scale is frequently used to classify the severity of the condition. In addition, investigations are carried out to determine the underlying cause, if this is not yet known (e.g. by means of an MRI scan of the brain or spinal cord).

Modern treatment options in detail: from physiotherapy to botulinum toxin

The main pillars of spasticity treatment are:

• Physiotherapy and occupational therapy: This forms the very basis of any treatment. Through targeted stretching, movement exercises, positioning and training in everyday activities, the aim is to keep the muscles supple, prevent poor posture and improve function.
• Drug therapy (oral): Medicines such as baclofen, tizanidine or tolperisone can reduce muscle tone throughout the body. The downside is that they often cause drowsiness and can also weaken muscles in areas where this is not desirable. They are therefore often used to treat generalised spasticity.
• Focal treatment with botulinum toxin: This therapy is one of the most effective methods for treating localised spasticity. Botulinum toxin (e.g. Botox®), which is well known in the field of aesthetics, is injected directly into the overactive muscles. There, it blocks the release of the neurotransmitter acetylcholine, thereby preventing the nerve from stimulating the muscle to contract. The muscle remains relaxed for around three to six months. The treatment must be repeated regularly, but it is very effective and has virtually no systemic side effects.
• Intrathecal baclofen pump (ITB): In cases of severe, generalised spasticity that does not respond to oral medication, a small pump can be implanted under the abdominal skin. This delivers the drug baclofen directly into the cerebrospinal fluid via a catheter. This achieves a high level of efficacy with significantly lower doses and fewer side effects.
• Surgical procedures: In rare, severe cases, surgical procedures (e.g. tendon lengthening) may also be considered.

Living with spasticity: What does the diagnosis mean for everyday life?

Spasticity is a chronic condition that can have a significant impact on everyday life. It can lead to pain, restricted movement and social withdrawal. Consistent and individually tailored therapy is key to managing the symptoms, maintaining independence for as long as possible and significantly improving quality of life. Sharing experiences in self-help groups can also provide important support for those affected and their families.