Can Musical Tones Played in the Ear Help with Gait-Freezing in Parkinson’s Patients?
Parkinson’s Disease is the second most common degenerative neurological disorder. The incidence Parkinson’s Disease, let’s called it PD for short, is growing rapidly with an aging population. The fundamental cause of PD is the death of nerve cells that produce a chemical called dopamine. The loss of these dopamine producing cells occurs in a part of the brain known generally as the basal ganglia and specifically the substantia nigra.
This part of the brain, the basal ganglia is known to influence movement and diseases or injury of the basal ganglia produce what are known as movement disorders which include Parkinson’s Disease. Parkinson’s Disease is characterized by slow movements known as bradykinesia (brady = slow, kinesis = movements). Tremor and other signs of abnormal muscle function are seen. One of the more disturbing symptoms that can occur in patients suffering with PD is called freezing of gait.
See voluntary movement takes place in two basic steps. To move we create the intention to move in one part of the brain. Thus one part of the brain plans the movement and the actual movement commands that activates the muscles occurs in a different part of the brain. So we plan a movement and that plan is carried out by other circuits in the brain which then executes that plan.
In many patients with Parkinson’s Disease, planned movements like walking have delayed or failed execution. This is called Freezing-of-gait and it can severely diminish the quality of life in Parkinson’s patients. Although we call this symptom freezing of gait, it can actually occur with any voluntary movement, like reaching for a glass, brushing your hair or getting up from a seated position to stand. It often leaves the Parkinson’s patient unable to initiate a movement or stuck in the middle of a planned action. It not hard to realize how freezing can severely diminishes a patient’s functional abilities and interfere with daily activities. Freezing is also linked to fails and injuries in PD patients,
The medical treatments for PD include drugs that replace the dopamine that is lost with degeneration of the substantia nigra. As a general rule dopamine replacement therapies are quite effective for patients suffering with PD with two notable exceptions:
- They usually are not specially effective for freezing-type symptoms and
- They usually loose their effectiveness over time
Several groups of researchers believe they have identified the specific part of the brain which malfunctions and causes freezing symptoms in Parkinson’s patients. It is known as the pedunculopontine nucleus (let’s call it the PPN for short) in the brainstem. Studies of electrical stimulation of the PPN through the use of surgically implanted deep brain electrodes have produced some promising results. This technique appears to activate the PPN and reduce gait-freezing in patients suffering from Parkinson’s Disease.
However, it now may be possible to activate the PPN and improve gait-freezing without resorting to brain surgery using special headphones and specific musical tones.
Research has shown that structures in the inner ear called otoliths can be stimulated by musical tones of a specific frequency. These inner ear structures have direct connections with the PPN. Stimulating the otoliths with a tone played through special bone-conducting headphones appears to activate the PPN and reduce gait-freezing in our patients. We have developed a computer program that uses these otolith activating tone bursts with neurological rehabilitation that has improved movement and reduced freezing symptoms in a number of our patients suffering from Parkinson’s Disease.