Spasticity Symptoms & Diagnosis

Spasticity develops after damage to pathways in the brain or spinal cord that help regulate movement. The classic feature is a velocity-dependent increase in resistance: when an affected muscle is stretched more quickly, resistance tends to increase. In everyday life, however, people usually notice the consequences rather than the examination definition. A hand may remain clenched, the elbow may pull toward the body, the toes may curl, or a leg may become difficult to advance while walking.

Not every stiff or difficult-to-move limb is spastic. Weakness, pain, swelling, joint disease, fixed muscle shortening, dystonia and rigidity can look similar. A careful evaluation matters because these problems are treated differently and often occur together.

Common symptoms and signs

• Muscles that feel tight, stiff or difficult to relax
• Resistance when someone moves the limb, especially during faster movement
• Sudden involuntary contractions or spasms
• Rhythmic repeated movement called clonus, often seen at the ankle
• A clenched hand, flexed wrist or bent elbow
• A pointed or inward-turning foot, stiff knee or scissoring pattern of the legs
• Difficulty reaching, opening the hand, releasing an object or placing the heel
• Pain, cramping, disturbed sleep or difficulty finding a comfortable position
• Problems with dressing, bathing, nail care, palm hygiene or applying a brace
• Skin pressure, moisture or injury in a tightly closed hand or flexed joint

The pattern depends on the neurological condition and the location of injury. After stroke, one side of the body is often affected. Multiple sclerosis or spinal cord injury may produce symptoms in both legs, although patterns vary. Cerebral palsy may affect one limb, one side, both legs or all four limbs.

Spasticity, spasms, clonus and hypertonia

These terms are related but not interchangeable. Hypertonia is a broad description of abnormally increased resistance to passive movement. Spasticity is a neurological form of muscle overactivity in which resistance has a speed-dependent component. A spasm is an involuntary muscle contraction that may occur at rest or with movement. Clonus is a series of rhythmic contractions triggered by stretch.

A person can have spasticity without frequent spontaneous spasms, or spasms that cause more disruption than the background stiffness. Describing when symptoms occur and what they interfere with is often more useful than using a single label.

Spasticity versus contracture

A contracture is a loss of passive joint movement caused by changes in muscle, tendon, capsule or other soft tissue. Spasticity is dynamic neural overactivity; contracture is a mechanical limitation, although the two frequently coexist. A joint with mostly dynamic resistance may move farther when the muscle is stretched slowly or under different conditions. A fixed contracture remains limited.

This distinction influences treatment. An injection that reduces muscle activity cannot by itself reverse major fixed shortening. Conversely, assuming every limitation is a contracture may overlook treatable overactivity. Examination at different speeds, range-of-motion measurement and sometimes diagnostic blocks help the team understand the contribution of each factor.

Spasticity versus rigidity and dystonia

Rigidity is typically associated with disorders such as Parkinson disease and produces resistance that is less dependent on movement speed. Dystonia causes sustained or intermittent muscle contractions that produce patterned, twisting movements or postures and may vary with task or position. Mixed forms of hypertonia can occur, particularly in cerebral palsy and acquired brain injury. Specialist assessment may be needed when the movement pattern is unclear.

How spasticity is diagnosed

There is no blood test or scan that measures spasticity directly. Diagnosis is based on the history, neurological examination and the way the limb responds to movement. Imaging or laboratory tests may be used to identify an underlying condition or investigate a sudden change, not to replace the clinical examination.

The clinician may ask when stiffness or spasms began, whether symptoms fluctuate, which activities are affected and what makes them better or worse. The examination commonly includes:

• Passive movement at slow and faster speeds
• Active range of motion and selective motor control
• Muscle strength and endurance
• Reflexes, sensation and coordination
• Joint range and evidence of fixed shortening
• Pain, swelling, skin condition and limb position
• Walking, balance, transfers, reach and hand use
• Sleep, hygiene, dressing, caregiving and equipment fit

The Modified Ashworth Scale

The Modified Ashworth Scale is the most widely used bedside measure of resistance during passive movement. Scores range from no increase in tone to a limb that is rigid in flexion or extension. It is quick and requires no equipment, which helps explain its popularity.

Its limitations are important. The examiner feels total resistance, which can reflect neural activity, joint stiffness, soft-tissue changes and technique. The scale does not isolate spasticity perfectly, describe pain or show whether a person can walk, dress or use the hand. A change in score is therefore only one part of outcome assessment.

The Tardieu and Modified Tardieu Scales

The Tardieu approach examines the response to movement at different velocities and records the angle at which a muscle reaction occurs. Comparing the reaction during a fast stretch with the available range during slow movement may help distinguish a dynamic component from fixed limitation. Like all clinical scales, it depends on positioning, technique and examiner consistency.

Function and personal goals are part of diagnosis

Two people with the same tone score may have very different problems. One may be unable to clean the palm; another may walk safely but wake repeatedly with painful spasms. Assessment should document the activity or symptom that matters and establish how it will be measured. Goal Attainment Scaling, pain scores, range measurements, gait tests and upper-limb function measures may complement tone scales.

Spasticity does not always require treatment. Increased tone can sometimes support standing, transfers or grip. The team should ask whether the disadvantages outweigh any benefit and whether reducing tone is likely to help the chosen goal.

Symptoms can fluctuate

Pain, fatigue, emotional stress, cold, constipation, urinary problems, infection, skin irritation, pressure injury, tight clothing and poorly fitting equipment can worsen spasms or stiffness. In spinal cord injury, an increase in spasticity may be an early sign of a problem below an area with reduced sensation.

Preparing for an appointment

A short record can make the assessment more useful. Note which body areas are affected, when symptoms occur, possible triggers, pain, sleep disruption and the activities that have become harder. A brief video of an intermittent spasm or walking pattern may help if it can be recorded safely. Bring an up-to-date medication list and information about braces, splints or mobility equipment.

Most importantly, identify one or two outcomes that would improve daily life. “Less tone” is difficult to translate into a treatment decision. “Open the hand for cleaning without pain” or “reduce spasms that wake me three times a night” gives the team a clearer target.

Sources

1. American Academy of Physical Medicine and Rehabilitation. Spasticity. PM&R KnowledgeNow.
2. American Stroke Association. Spasticity: symptoms and assessment. Updated 2025.
3. Harb A, Kishner S. Modified Ashworth Scale. StatPearls. Updated 2025.
4. Gal O, et al. Clinical Outcome Assessments for Spasticity: Review, Critique and Recommendations. Mov Disord. 2024.
5. Hugos CL, Cameron MH. Assessment and Measurement of Spasticity in Multiple Sclerosis. Rehabil Res Pract. 2019.
6. Balci BP. Spasticity Measurement. Noro Psikiyatr Ars. 2018.

For an overview of available management options, continue to Spasticity Treatment.

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Public-service medical disclaimer: this page offers general education and cannot diagnose the cause of stiffness or involuntary movement. Do not rely on it for diagnosis, treatment or an individualized medical decision.