From the Guidelines
Ischemic stroke in the medial right cerebral artery typically causes hypotonia (decreased muscle tone) in the left side of the body due to damage to motor pathways. When this stroke occurs, blood flow is interrupted to the right hemisphere's motor cortex and corticospinal tracts, which control voluntary movement and muscle tone on the contralateral (opposite) side of the body. Initially, patients experience flaccid hypotonia in the affected limbs, characterized by reduced resistance to passive movement and diminished deep tendon reflexes. Over time, this hypotonia often transitions to spasticity (increased muscle tone) as the brain attempts to compensate for the damage.
Management of Hypotonia and Spasticity
Management includes early physical therapy starting within 24-48 hours post-stroke, focusing on passive range of motion exercises and proper positioning to prevent contractures. According to the guidelines for adult stroke rehabilitation and recovery from the American Heart Association/American Stroke Association 1,
- Targeted injection of botulinum toxin into localized upper limb muscles is recommended to reduce spasticity, to improve passive or active range of motion, and to improve dressing, hygiene, and limb positioning.
- Oral antispasticity agents can be useful for generalized spastic dystonia but may result in dose-limiting sedation or other side effects.
- Physical modalities such as NMES or vibration applied to spastic muscles may be reasonable to improve spasticity temporarily as an adjunct to rehabilitation therapy.
Medication and Therapy
Medications like baclofen or tizanidine may be prescribed if spasticity develops. Botulinum toxin injections can target specific muscle groups with severe spasticity. This pattern occurs because upper motor neurons in the cerebral cortex normally inhibit lower motor neurons in the spinal cord; when damaged by stroke, this inhibition is lost, eventually leading to hyperactive reflexes and increased tone after the initial hypotonic phase. The use of intrathecal baclofen therapy may be useful for severe spastic hypertonia that does not respond to other interventions, as recommended by the guidelines 1.
From the Research
Effects of Ischemic Stroke on Hypotonia and Muscular Tone
- Ischemic stroke in the medial right cerebral artery can lead to various effects on muscular tone, including hypotonia, which is a condition characterized by reduced muscle tone [ 2 ].
- Studies have shown that patients with acute stroke can experience improvements in arm functions, including muscle tone, with the use of Theta Burst Stimulation (TBS) or Functional Electrical Stimulation (FES) combined with physical therapy [ 2 ].
- However, the specific effects of ischemic stroke on hypotonia and muscular tone can vary depending on the location and severity of the stroke, as well as individual patient factors [ 3 ].
Treatment Options for Hypotonia and Muscular Tone
- Oral delivery of baclofen has been shown to be effective in reducing spastic hypertonia in patients with acquired brain injury, including stroke [ 3 ].
- Intrathecal baclofen (ITB) therapy has also been used to manage spastic dystonia in patients with stroke, with significant improvements in gait pattern and muscular tone [ 4 ].
- Other treatment options, such as physical therapy and rehabilitation, can also be effective in improving muscular tone and reducing hypotonia in patients with ischemic stroke [ 2 ].
Case Studies and Research Findings
- A case study reported the complete resolution of restless legs syndrome (RLS) following an ischemic stroke of the right middle cerebral artery, highlighting the complex relationship between stroke and muscular tone [ 5 ].
- Another case study demonstrated the effectiveness of ITB therapy in improving gait pattern and reducing spastic dystonia in a patient with stroke [ 4 ].
- These findings suggest that individualized treatment approaches may be necessary to address the unique effects of ischemic stroke on hypotonia and muscular tone [ 6 ].