Abnormally high muscle tone, known as hypertonia or spasticity, commonly affects the upper extremity following a neurological event such as a stroke or traumatic brain injury. This increased stiffness hinders daily activities and can lead to painful joint contractures over time. Managing this condition requires a comprehensive strategy involving various effective techniques for reducing excessive muscle tone and maintaining limb usability.
Physical and Rehabilitative Techniques
Physical and occupational therapists use hands-on, non-invasive methods to modulate excessive muscle tone in the upper limb. A primary technique is Passive Range of Motion (PROM) stretching, where the limb is gently moved through its available range to counteract muscle shortening. For example, stretching the common flexor muscles requires stabilizing the arm while slowly extending the wrist and opening the fingers. This sustained stretch should be held for 30 to 40 seconds at the point of mild tension, avoiding quick movements that could trigger a stronger reflex response.
Repetition of goal-directed, active movement exercises is paramount in driving changes in the nervous system. Performing functional tasks, such as reaching or grasping, promotes neuroplasticity and normalizes muscle activation patterns. High-repetition practice of these activities, guided by a therapist, improves functional recovery of the upper limb.
Specialized sensory input can temporarily alter the muscle’s response. For example, applying a cold stimulus or vibration to a muscle belly offers a temporary reduction in tone. Vibration stimulates muscle spindle receptors, reducing tone in the opposing muscle group, which creates a short window of reduced stiffness for performing stretching or functional exercises immediately afterward.
Pharmacological and Injectable Treatments
Medical interventions reduce muscle tone chemically, either systemically or locally. Oral muscle relaxants, such as baclofen and tizanidine, are often prescribed for generalized hypertonia affecting multiple limbs. Baclofen mimics the neurotransmitter GABA to decrease nerve signal excitability in the spinal cord, relaxing the muscles. Tizanidine, an alpha-2 agonist, reduces tone by increasing presynaptic inhibition of motor neurons.
These systemic medications are effective but may cause side effects like sedation, generalized weakness, or dry mouth, which can limit the dosage. For severe, refractory cases, Intrathecal Baclofen Therapy involves surgically implanting a pump to deliver baclofen directly into the spinal fluid. This bypasses the blood-brain barrier, allowing for a lower, more targeted dose that minimizes systemic side effects.
Focal spasticity, confined to specific muscle groups in the upper extremity, is treated with targeted injections. Botulinum toxin type A (BoNT-A) is the first-line pharmacological treatment, often using products specifically approved for upper limb spasticity. The neurotoxin is injected directly into overactive muscles, such as the wrist or finger flexors, blocking the release of acetylcholine at the neuromuscular junction. This temporary chemical denervation weakens the targeted muscle, reducing tone and providing relief for 12 to 20 weeks.
Orthotics and Positioning Strategies
External devices and careful limb placement maintain therapeutic gains and prevent long-term complications. Orthotic devices, commonly known as splints or braces, are custom-made or prefabricated tools used to support the upper limb. Resting splints are static devices designed to hold the wrist and hand in a functional, lengthened position to preserve joint range of motion. A common wrist-hand orthosis positions the wrist in slight extension and the thumb abducted, facilitating functional hand architecture.
Splints may be static, simply stabilizing the joint, or dynamic, allowing or assisting movement with a spring or elastic component. For limbs with high tone, splints require additional padding and a carefully monitored wearing schedule to avoid excessive tissue pressure or skin breakdown. The static progressive orthosis applies a sustained, gentle force to the joint’s end range, aiming to stretch shortened soft tissues and improve passive range of motion.
Proper positioning of the limb during rest, sitting, and sleep is a continuous intervention that prevents tone from escalating. When sitting, the arm should be supported on a table or pillow to prevent hanging in a flexed, gravity-dependent position. During sleep, positioning the arm away from the body with the palm down and the elbow extended helps stretch the common flexor muscles. Avoiding prolonged positions that encourage the limb to curl up maintains muscle length and prevents the development of fixed joint contractures.