What is a stroke?
A stroke occurs when the blood supply to a part of your brain is suddenly reduced. This prevents that part of your brain from getting oxygen and other nutrients from your blood. A stroke is a medical emergency.
Your brain needs a continuous supply of oxygen and nutrients from blood, supplied by your arteries — without oxygen or nutrients, your brain cells will die ('infarct') and the affected area can suffer permanent damage.
There are 2 main reasons for reduced blood supply: a blood clot or a bleed.
How can tVNS using a TENS Machine aid in Stroke Recovery?
Stroke is one of the leading causes of death and disability globally. A significant proportion of stroke survivors are left with long term neurological deficits that have a detrimental effect on personal wellbeing and wider socioeconomic impacts.
As such, there is an unmet need for novel therapies that improve neurological recovery after stroke. Invasive vagus nerve stimulation (VNS) paired with rehabilitation has been shown to improve upper limb motor function in chronic stroke.
However, invasive VNS requires a surgical procedure and therefore may not be suitable for all stroke patients.
Non-invasive, transcutaneous VNS (tVNS) via auricular vagus nerve stimulation in the ear (taVNS) and cervical vagus nerve stimulation in the neck (tcVNS) have been shown to activate similar vagal nerve projections in the central nervous system to invasive VNS.
A number of pre-clinical studies indicate that tVNS delivered in acute middle cerebral artery occlusion reduces infarct size through anti-inflammatory effects, reduced excitotoxicity and increased blood-brain barrier integrity. Longer term effects of tVNS in stroke that may mediate neuroplasticity include microglial polarisation, angiogenesis and neurogenesis.
Pilot clinical trials of taVNS indicate that taVNS paired with rehabilitation may improve upper limb motor and sensory function in patients with chronic stroke.
Suggested TENS Machine Settings for tVNS:
Pulse Width: 200us
Pulse Rate: 15-30us/step.
Duration: 15 min/day for 2 weeks.