Spasticity: Symptoms, Causes and Treatment

Spasticity is a complex, multifaceted condition frequently encountered in people with injuries or diseases affecting the brain or spinal cord. It is characterized by abnormal muscle stiffness and involuntary muscle contractions that significantly impact daily life, movement, and function. Understanding spasticity—its symptoms, underlying causes, and available treatments—is essential for patients, caregivers, and healthcare professionals seeking to improve quality of life and optimize management strategies.

Symptoms of Spasticity

Spasticity manifests in a variety of ways, and its presentation can differ significantly from person to person. Recognizing the core symptoms is the first step in managing and treating spasticity effectively. These symptoms not only affect movement but can also disrupt daily living and cause significant discomfort.

Symptom	Description	Impact	Source
Stiffness	Increased muscle tone, resistance to movement	Limits mobility, daily activities	3 4 7 8 10
Spasms	Sudden, involuntary muscle contractions	Disrupts movement, causes pain	3 4 2 8 10
Clonus	Rapid, rhythmic muscle contractions	Interferes with function	4 8
Pain	Associated with muscle overactivity	Reduces quality of life	3 4

Table 1: Key Symptoms

Understanding the Main Symptoms

Spasticity is most commonly described as a velocity-dependent increase in muscle tone—meaning muscles become more resistant the faster you try to move them. This resistance often appears as stiffness, making it difficult to move the affected limb or body part. Many individuals also report frequent muscle spasms, which are sudden, involuntary contractions that can be painful and unpredictable 3 4 2.

Clonus is another hallmark symptom. It involves rapid, repetitive, rhythmic contractions, especially noticeable during attempts to stretch or move a limb 4 8. For some, spasticity includes pain, either directly from muscle overactivity or from secondary complications like contractures and abnormal posture 3 4.

How Symptoms Affect Life

The impact of these symptoms goes far beyond physical discomfort. For individuals with conditions such as multiple sclerosis or spinal cord injury, spasticity can interfere with essential daily activities. Tasks like walking, climbing stairs, and even sleeping may become challenging 3 4. In fact, surveys show that more than 80% of people with multiple sclerosis report spasticity, and over a third find it significantly bothersome 3.

Stiffness is often cited as the most disruptive symptom, correlating strongly with limitations in daily activities and the need for assistance 4. Spasms and clonus, while sometimes less problematic, can still cause considerable distress and functional impairment. The distribution and severity of symptoms are highly individualized, with some experiencing issues in the limbs, trunk, or both 4.

Associated Signs

In addition to the main symptoms, spasticity is often accompanied by:

• Exaggerated tendon reflexes
• The "clasp-knife" response (a sudden decrease in resistance during passive stretching)
• Spastic dystonia (persistent muscle contraction)
• Weakness and loss of dexterity (part of the broader upper motor neuron syndrome) 8 10

Understanding these symptoms—how they present and how they impact daily life—is essential for effective assessment and management.

Causes of Spasticity

Spasticity does not arise in isolation; it is a consequence of injury or disease impacting the central nervous system. The mechanisms behind spasticity are complex and involve both neurological and muscular changes. Unpacking these causes can help patients and families make sense of the condition and its challenges.

Cause	Mechanism/Description	Typical Conditions	Source
Upper Motor Neuron (UMN) Lesion	Damage to brain or spinal cord pathways	Stroke, SCI, MS, TBI, CP	1 5 7 8 9 10 12 14
Reflex Hyperexcitability	Increased stretch reflex activity	UMN syndrome	7 8 9 10 12
Loss of Inhibition	Disruption of inhibitory control over reflexes	After CNS injury	5 7 8 9
Soft Tissue Changes	Muscle shortening, contracture, fibrosis	Chronic spasticity	6 9 10 12

Table 2: Key Causes

Neurological Origins

The vast majority of spasticity cases are traced back to upper motor neuron (UMN) lesions—damage to the pathways in the brain or spinal cord that control movement. This damage is seen in conditions such as:

• Spinal cord injury (SCI)
• Stroke
• Multiple sclerosis (MS)
• Cerebral palsy (CP)
• Traumatic brain injury (TBI) 1 5 8 14

When these pathways are injured, the balance between excitatory and inhibitory signals sent to the spinal cord is disrupted. Normally, inhibitory signals from the brain act as a brake on the reflexes that control muscle tone. After an injury, this brake is lost or weakened, leading to hyperexcitability of spinal reflexes—the core of spasticity 7 8 9.

Reflex Changes and Plasticity

A defining feature of spasticity is the increased sensitivity of the stretch reflex. When a muscle is stretched quickly, the reflex that resists this stretch becomes exaggerated. This is not just a simple loss of inhibition; over time, the spinal cord and even the brain undergo plastic changes—adaptive but often maladaptive rewiring—that further enhance reflex responsiveness 7 8 9.

For example, studies reveal that after spinal cord injury, the reticulospinal tract (another descending pathway) may become more influential, while the main corticospinal tract's control weakens. This imbalance contributes to the overactivity seen in spastic muscles 5.

Muscle and Soft Tissue Changes

Chronic spasticity does not just affect the nervous system. Over time, muscles themselves adapt:

• Muscle fibers may lose the ability to grow properly in length
• Sarcomere (muscle unit) length may become abnormally long
• Fibrosis and contractures—permanent shortening of muscles and tendons—can develop, further restricting movement and complicating management 6 9 10 12

These changes make it even harder to move the affected limb and can themselves become sources of pain and disability.

The Complexity of Spasticity's Causes

It is important to understand that spasticity is not caused by a single mechanism or process. Instead, it emerges from a multifactorial interaction of neurological lesions, altered reflexes, changes in muscle and joint properties, and even the duration and location of the injury. The variable presentation and progression of spasticity reflect this underlying complexity 1 4 8 9 10.

Treatment of Spasticity

Managing spasticity is a highly individualized process that requires a multifaceted approach. Treatments aim to reduce symptoms, improve function, and enhance quality of life. No single therapy works for everyone—effective management often combines physical, pharmacological, and sometimes surgical interventions, tailored to the patient’s needs and goals.

Treatment Type	Methods/Examples	Key Consideration	Source
Physical & Rehabilitative	Stretching, exercise, physiotherapy, casting	Foundational for all patients	11 13 14 15
Pharmacological	Oral medications, botulinum toxin, nerve blocks	Adjunct to physical therapy	12 14
Non-Pharmacological	Neuromuscular stimulation, acupuncture, vibration therapy	Varying evidence for efficacy	11 13 15
Surgical	Tendon releases, intrathecal baclofen pumps	For severe, refractory cases	14

Table 3: Key Treatments

Physical and Rehabilitative Interventions

Physical therapies form the cornerstone of spasticity management. They include:

• Stretching routines to maintain muscle length and joint flexibility
• Strengthening of antagonist muscles (opposite to spastic muscles)
• Physical and occupational therapy to promote functional movement
• Casting, splinting, and taping to maintain limb positioning and prevent contractures 13 14 15

These interventions help prevent secondary complications and improve independence. Evidence supports combining these approaches with medications or injections for optimal results 13 14 15. For example, casting after botulinum toxin injections can enhance the effect and improve outcomes 15.

Pharmacological Treatments

Medications are used to reduce muscle overactivity and manage symptoms:

• Oral agents: Baclofen, tizanidine, diazepam, and dantrolene are commonly prescribed. Each has benefits and potential side effects, and their effectiveness can vary 12 14.
• Botulinum toxin injections: Highly effective for focal (localized) spasticity, these injections weaken overactive muscles, providing a window for physical therapy to achieve better function 14 15.
• Nerve blocks: Local anesthetics or neurolytic agents (alcohol, phenol) can be injected to temporarily or permanently reduce spasticity in targeted muscles. These are often used for diagnostic purposes or when other treatments are insufficient 12.

It’s important to note that pharmacological treatments are adjunctive—they work best when combined with physical interventions 13 14.

Non-Pharmacological and Adjunctive Therapies

A variety of non-drug interventions have been studied, including:

• Electro-neuromuscular stimulation
• Acupuncture
• Vibration therapy
• Extracorporeal shock wave therapy
• Transcranial magnetic or direct current stimulation 11 15

Evidence for these approaches varies, with moderate support for some (like electro-neuromuscular stimulation and acupuncture) as adjuncts, and lower or inconclusive evidence for others. More research is needed to determine the most effective protocols and combinations 11 15.

Surgical Interventions

For severe, treatment-resistant spasticity, surgical options may be considered:

• Tendon releases or lengthening procedures to relieve contractures
• Intrathecal baclofen pump implantation: delivers medication directly to the spinal cord, providing effective control with fewer systemic side effects 14

These approaches are reserved for cases where less invasive treatments have failed or when spasticity causes significant harm.

The Importance of Individualized, Multimodal Care

Spasticity varies widely in its presentation and impact. Successful management requires:

• Careful assessment and characterization of symptoms
• Goal setting with the patient
• Ongoing monitoring and adaptation of the treatment plan
• Integration of multiple therapies for the best chance of meaningful improvement 4 13 14 15

Conclusion

Spasticity is a challenging condition that demands a nuanced, patient-centered approach. Understanding its symptoms, underlying causes, and treatment options empowers individuals and their care teams to make informed decisions and improve quality of life.

Key Points:

• Symptoms: Spasticity presents as muscle stiffness, spasms, clonus, and pain, significantly affecting daily function 3 4 8 10.
• Causes: It is rooted in upper motor neuron lesions, loss of inhibitory control, reflex hyperexcitability, and soft tissue changes 1 5 7 8 9 10 12 14.
• Treatment: Management is multimodal—combining physical therapy, pharmacological agents (like botulinum toxin), adjunctive non-drug therapies, and surgery for severe cases. Individualized assessment and care planning are essential 11 12 13 14 15.

By integrating the latest evidence with personalized care, individuals living with spasticity can achieve better function, reduced discomfort, and improved participation in everyday life.