From the Guidelines
Upper motor neuron lesions are characterized by a set of symptoms including spasticity, hyperreflexia, clonus, and positive Babinski sign, with spasticity being a key component that affects quality of life and increases caregiver burden 1. These symptoms result from damage to neurons in the brain or spinal cord that control voluntary movement. The symptoms typically include:
- Spasticity (increased muscle tone), which is correlated with activity limitations associated with hygiene, dressing, and pain 1
- Hyperreflexia (exaggerated reflexes)
- Clonus (rhythmic muscle contractions)
- Positive Babinski sign (upward movement of the big toe when the sole is stimulated) Patients also experience muscle weakness, particularly in the extensors of the upper limbs and flexors of the lower limbs, creating a characteristic posture. Coordination is impaired, but muscle atrophy is minimal compared to lower motor neuron lesions. These symptoms occur because upper motor neurons normally inhibit lower motor neurons, and when this inhibition is lost, there is excessive activation of muscles. The prevalence of poststroke spasticity in any limb is in the range of 25% to 43% over the first year after stroke, highlighting the importance of early rehabilitation to prevent contractures and optimize functional recovery 1. Management typically involves physical therapy to maintain range of motion, medications like baclofen or tizanidine to reduce spasticity, and addressing the underlying cause when possible. It is essential to note that the cost of care is significantly higher when spasticity is present, emphasizing the need for effective management strategies to improve quality of life and reduce healthcare costs 1.
From the Research
Symptoms of Upper Motor Neuron (UMN) Lesion
The symptoms of an upper motor neuron (UMN) lesion include:
- Spasticity, which is a common and disabling symptom for many patients with upper motor neuron dysfunction 2
- Velocity-dependent increase in muscle tone and uncontrolled, repetitive, involuntary contractions of skeletal muscles 3
- Hypertonia, which can lead to significant pain and limited mobility, resulting in decreased quality of life and difficulty maintaining personal care 3
- Muscle spasms, which can be painful and distressing 4
- Soft tissue shortening (fixed contractures) if left untreated 4
Clinical Presentation
The clinical presentation of UMN lesion can vary depending on the location and severity of the lesion. However, common features include:
- Increased excitability of the alpha motor neurons due to an imbalance between the excitatory and inhibitory influences of the vestibulospinal and reticulospinal tracts 4
- Changes in the structure and mechanical properties of the paralyzed muscles and the effect of thixotropy, which can contribute to hypertonia 4
- Interference with motor function or causing distressing symptoms, such as painful muscle spasms 4
Associated Conditions
UMN lesions can be caused by various neurological conditions, including: