Spasticity

Spasticity is a motor disorder characterized by increased muscle tone and exaggerated reflexes, resulting from damage to the central nervous system (CNS). It is commonly associated with conditions such as stroke, multiple sclerosis, cerebral palsy, and spinal cord injury.

Definition of Spasticity

Spasticity is defined as a condition in which certain muscles are continuously contracted, leading to stiffness or tightness of the affected muscles. This increased muscle tone can result in:

1. Hypertonia: Increased resistance to passive movement, which can vary with the speed of movement.
2. Exaggerated Deep Tendon Reflexes: Heightened reflex responses, such as the knee-jerk reflex.
3. Clonus: Involuntary, rhythmic muscle contractions that can occur in response to sudden stretching of the muscle.

Spasticity can affect various muscle groups and may lead to functional impairments, pain, and decreased quality of life.

Mechanisms of Spasticity

1. Upper Motor Neuron Damage: Spasticity typically results from damage to upper motor neurons, which originate in the brain and descend to the spinal cord. This damage disrupts the normal inhibitory control of spinal reflexes, leading to increased excitability of the spinal reflex arcs.
2. Imbalance of Excitatory and Inhibitory Inputs: In a healthy nervous system, there is a balance between excitatory (e.g., glutamate) and inhibitory (e.g., gamma-aminobutyric acid, or GABA) neurotransmitters. Damage to upper motor neurons can lead to an imbalance, resulting in excessive excitatory input and reduced inhibitory control.
3. Changes in Muscle Spindle Sensitivity: Muscle spindles, which are sensory receptors located within muscles, become more sensitive following CNS injury. This increased sensitivity can lead to exaggerated reflex responses and contribute to spasticity.
4. Neuroplasticity: Following CNS injury, the nervous system may undergo neuroplastic changes that can exacerbate spasticity. These changes can include the reorganization of neural pathways and alterations in synaptic connections.

Clinical Significance of Spasticity

1. Functional Impairment: Increased muscle tone and stiffness can lead to difficulties with movement, coordination, and daily activities, significantly impacting a person’s quality of life.
2. Pain and Discomfort: Spasticity can be associated with muscle pain, discomfort, and secondary complications such as joint deformities and contractures.
3. Indicator of Neurological Conditions: The presence of spasticity can indicate underlying neurological conditions, such as stroke, multiple sclerosis, cerebral palsy, or spinal cord injury, and may help guide diagnosis and management.
4. Impact on Rehabilitation: Spasticity can complicate rehabilitation efforts, making it more challenging to achieve functional goals in physical therapy and occupational therapy.

Assessment of Spasticity

1. Clinical History: Gathering information about the patient’s medical history, onset, and progression of symptoms, as well as any relevant neurological events (e.g., stroke, trauma).
2. Neurological Examination: A thorough examination to assess muscle tone, strength, and reflexes. Key assessments include:
   • Modified Ashworth Scale (MAS): A widely used scale to quantify spasticity based on resistance to passive movement.
   • Tardieu Scale: An assessment tool that evaluates spasticity based on the angle of muscle reaction and the speed of passive movement.
3. Functional Assessment: Evaluating the impact of spasticity on daily activities and functional mobility, often using standardized assessments such as the Barthel Index or the Functional Independence Measure (FIM).
4. Documentation: The results of the assessment should be documented, noting the severity and distribution of spasticity.

Management of Spasticity

1. Pharmacological Treatments:
   • Baclofen: A muscle relaxant that acts on the central nervous system to reduce spasticity.
   • Tizanidine: An alpha-2 adrenergic agonist that can help decrease muscle tone.
   • Dantrolene: A muscle relaxant that acts directly on muscle fibers to reduce spasticity.
   • Botulinum Toxin Injections: Localized injections can help reduce spasticity in specific muscle groups.
2. Physical Therapy: Targeted physical therapy can help improve mobility, flexibility, and strength, as well as reduce the impact of spasticity on daily activities.
3. Occupational Therapy: Occupational therapists can provide strategies and adaptive equipment to help individuals manage daily tasks more effectively.
4. Surgical Interventions: In severe cases, surgical options such as selective dorsal rhizotomy or orthopedic procedures may be considered to alleviate spasticity and improve function.
5. Assistive Devices: The use of braces, splints, or other assistive devices can help manage spasticity and improve mobility.

References

• Adams, R. D., Victor, M., & Ropper, A. H. (2014). Principles of Neurology (10th ed.). McGraw-Hill.
• Merritt, H. H., & McDonald, J. W. (2010). Neurology (12th ed.). Lippincott Williams & Wilkins.
• Kandel, E. R., Schwartz, J. H., & Jessell, T. M. (2013). Principles of Neural Science. McGraw-Hill.
• Pandyan, A. D., et al. (2005). Spasticity: A review of its properties and measurement. Disability and Rehabilitation, 27(1), 2-10.