Postural instability in Parkinson’s disease: cause, symptoms, treatment

As the disease progresses, people with Parkinson’s often develop balance problems and a crooked posture, which is referred to in technical jargon as postural instability. It is a very noticeable symptom of Parkinson’s disease, as both upright gait and balance are impaired, increasing the risk of falls – a dangerous consequence of the disease. Compared to other motor symptoms such as muscle tremors (tremor), muscle stiffness (rigor) or slowness of movement (bradykinesia), drug therapy is less effective for postural instability. For this reason, other therapeutic treatments are the main focus for postural instability, which we would like to inform you about below.

You can also find out what is behind this particular symptom, what causes are taken into consideration, how postural instability manifests itself and what effects it has on life with Parkinson’s disease.

Postural instability: what is it?

Postural instability in conjunction with gait difficulties and falls is a symptom of various neurological diseases, but is particularly common in Parkinson’s disease. In the course of Parkinson’s disease, the following so-called cardinal symptoms are the focus for patients: tremor (muscle tremor), rigor (muscle stiffness) and bradykinesia (slowness of movement), which mainly occur on one side of the body at the beginning of the neurodegenerative disease. According to the current guideline (2025), postural instability is no longer one of the four cardinal symptoms of Parkinson’s disease.

Disturbance of holding and positioning reflexes and balance

Postural instability in Parkinson’s disease is a disorder of upright posture caused by inadequately functioning postural reflexes. Those affected have to adjust their posture when sitting or standing because the transmission of signals via the sensors of the skeletal muscles does not function properly via the spinal cord. Our organ of balance – the inner ear – also reports the change in stability to our brain, whereby the posture is consciously corrected instead of being unconscious, automatic and invisible to others. As the disease progresses, the balance reflexes are also disturbed as part of the postural instability.

As a result, the mobility of those affected is more or less impaired and the risk of falling is increased because the body no longer reacts adequately to sudden turns or jolts in order to maintain balance. This poses a particular risk for Parkinson’s patients, because it is not only the lack of stability of the upright posture, but also falls that make it difficult or impossible to live independently with Parkinson’s disease.

Frequency of postural instability in Parkinson’s disease

Postural instability occurs in around 16 percent of Parkinson’s patients. The risk of falls increases with the duration of the disease and the impairment of balance. Falls occur in around 60 percent of people with postural instability as the disease progresses.

Causes: How does postural instability develop in Parkinson’s disease?

To better understand what causes postural instability in Parkinson’s, let’s first look at natural (physiological) balance control, which is completely involuntary in healthy people.

Physiological and pathological balance control

Controlling our balance is actually an involuntary activity. If our posture is stable, we can maintain our balance even when our stance is disturbed or when preparing and executing movements. And this requires good coordination of our sensory system – i.e. perception and evaluation with the sensory organs (hearing, smelling, seeing, touching, tasting) – and motor skills. We use our sensory system to take in information (stimulus reception) and transmit it to our central nervous system, or CNS for short (brain, spinal cord). Thanks to our motor skills, the muscles can be activated and tensed to perform movements (stimulus response).

Impaired function of the basal ganglia in Parkinson’s disease

The basal ganglia (nuclei basales), a group of cerebral and diencephalic nuclei that are important for our movement processes, also form nerve pathways that influence the activation (tension) and inhibition (relaxation) of the muscles. The basal ganglia are also important for maintaining our balance. In Parkinson’s disease, a lack of dopamine in the brain disrupts the function of the basal ganglia. And this has a negative effect on muscle activity and our balance.

Postural stability therefore depends on the interaction of sensory, motor, visual (relating to vision), vestibular (relating to our sense of balance) and cognitive (relating to perception, thinking and cognition) circuits. If there is a disruption here, a pathological balance control called postural instability develops.

Disorders in the white matter (substantia alba)

Parkinson’s disease is a progressive movement disorder caused by the degeneration of dopaminergic nerve cells in the substantia nigra (black matter). In some Parkinson’s patients with postural instability, however, dopamine replacement therapy does not respond despite the dopamine deficiency.

In this case, the postural instability could be caused by disorders not in the black substance (substantia nigra) but in the white substance (substantia alba) in the brain, such as periventricular hyperintensities, in which the composition of the brain tissue around a cerebral ventricle (fluid-filled cavities in the brain) changes, or disorders of the transverse fiber connections (corpus callosum fibers) between the two cerebral hemispheres.

Symptoms: How does postural instability manifest itself in Parkinson’s disease?

The clinical picture of postural instability manifests itself in the form of gait disorders and balance problems. Patients often adopt a stooped posture with slightly bent knees, which makes walking increasingly difficult over time. A shuffling gait and many small steps are also noticeable, which are sometimes accelerated quite unintentionally, but the stride length becomes shorter and shorter. This gives them a slightly rushed impression. This type of gait disorder is also known as festination.

People with unstable posture often have problems starting to walk at all. They turn and pause for a moment and then start again with short, faltering steps. The arms swing only slightly or not at all when walking. Sometimes they also hold their arms around their waist.

There is also a tendency to shift the body’s center of gravity backwards (retropulsion) or forwards (propulsion). The reason for this lies in the disturbance of the postural and positioning reflexes. You have to constantly correct your posture when standing or sitting. Many other symptoms of Parkinson’s disease can occur alongside postural instability, are individual and vary from person to person.

What exacerbates postural instability?

Postural instability can be exacerbated by other Parkinson’s symptoms. Especially if sensory perception is impaired, such as in the case of visual-spatial orientation disorders (visual disturbances) or dizziness.

Complication: increased risk of falling due to postural instability

A dangerous complication of postural instability is the increased risk of falls caused by a lack of coordination and balance in movement sequences. Falls can be accompanied by broken bones, fear of new falls and significantly reduced mobility, which can have a detrimental effect on quality of life. Limited mobility can lead to social isolation, which in turn can trigger depressive phases, depression and anxiety disorders.

Due to this complication, postural instability also has a poor prognosis. It is associated with physical, psychological and social components and can lead to a need for care. As a result, it significantly jeopardizes independence for a life with Parkinson’s.

Diagnosis: How is postural instability diagnosed?

Your treating neurologist will diagnose postural instability in Parkinson’s disease. In most cases, the symptom occurs in the later stages of the disease. If the symptom develops earlier, neurologists must therefore also clarify other neurological causes. Postural instability is a subjective diagnosis, as it depends primarily on the findings of the patient interview and physical examination.

A detailed discussion with the patient about the symptoms and accompanying signs of postural instability and a thorough physical examination therefore form an important basis for the diagnosis. Information on modifiable factors such as environmental stress, unhealthy lifestyle (e.g. alcohol consumption, cigarettes, unhealthy diet), chemical exposure to pesticides or stress and non-modifiable risk factors such as increasing age are also important for individualized treatment.

Neurological examination: tests and imaging procedures

In addition, laboratory tests and other tests as well as imaging procedures such as magnetic resonance imaging (MRI) can be used to support the diagnosis. The following tests can be used to check balance in postural instability:

• Retropulsion test (pull test): This test checks balance and postural reflexes. Doctors initiate a sudden push or pull on the patient’s shoulders from behind. If this is followed by several corrective steps backwards (> 1 step), there is a reflex disorder.
• Functional Reach Test: The test is a method of measuring static balance in an “extreme” position with maximum forward movement. Patients hold their feet in one place and try to reach forward horizontally with their arm as far as possible.
• Timed-up-and-go test (TUG test): The TUG test is used to assess mobility, muscle strength and balance as well as the risk of falling. Patients stand up from a sitting position on command, walk along a marked line on the floor (about three meters) with as normal and safe a gait as possible, turn around, walk back to the chair and sit down again. During the test, the time is recorded in seconds and the results are interpreted using a scale, e.g. over 30 seconds indicates a pronounced mobility restriction.
• Romberg test: This test checks balance with eyes closed. Patients stand upright and place their feet next to each other. First, the position is held for 30 seconds with eyes open, then for 30 seconds with eyes closed. If the closed eyes lead to a significant decrease in stability, the Romberg sign is positive and indicates a sensory disorder.
• Stance and gait tests: Various standing and walking tests also provide information about balance. In the so-called tandem stand, patients place their feet one behind the other to challenge their balance, or in the one-leg stand, they have to try to maintain their balance. A walking test with changes of direction can also check balance.

Treatment of postural instability in Parkinson’s disease

The treatment of postural instability in Parkinson’s is difficult, as dopamine replacement therapy often does not have the same positive effect as with other motor symptoms of Parkinson’s disease. Tremor, rigor, bradykinesia and akinesia (severe lack of movement) respond well to medications such as levodopa (L-dopa), dopamine agonists, MAO inhibitors or COMT inhibitors. Even surgical interventions such as deep brain stimulation (DBS) or pump therapy are often unable to help with postural instability. So what can you do if you suffer from postural instability with balance disorders and medical support is difficult?

Fall prevention is the be-all and end-all for postural instability

Good fall prevention is a very important part of therapy, as it can help you to maintain your independence for as long as possible. To avoid dangerous falls, you should consider the following tips:

• Remove tripping hazards: Remove carpets, door thresholds and other tripping hazards (steps, stairs) in your own four walls.
• Install lighting: Provide good lighting in all rooms of your home. This will help you keep your bearings at night.
• Use aids: There are many different aids available to you. They help to make your home environment safer. Stair lifts, grab rails and walking aids are ideal for keeping your balance and preventing falls.

Supportive therapies for postural instability

Supportive measures such as physiotherapy and occupational therapy or psychotherapy can also be helpful in minimizing the risk of falls and tailoring treatment to individual needs.

• Physiotherapy: Balance exercises can improve postural stability and reduce the risk of falling if the exercises are practiced regularly – even in everyday life. Physiotherapists adapt the treatment and training to individual needs and create appropriate training plans.
• Occupational therapy: Balance exercises should also be trained as part of occupational therapy, e.g. in the form of sitting quietly, standing balance and other endurance activities.
• Psychotherapy: Another important aspect of postural instability is the fear of (further) falls, which can be very pronounced and interfere with social life. Out of fear, activities become less frequent and those affected withdraw from social life. This can result in depression and loneliness. Psychotherapeutic support can then be very helpful in overcoming fears and coping better with postural instability and Parkinson’s disease.

Good to know: Both physiotherapy and occupational therapy train Parkinson’s patients with postural instability to “fall correctly” in the event of a fall in order to minimize the risk of injury and get back on their feet after a fall.

Medication for postural instability

Dopamine replacement therapy has a minor effect on postural instability. The avoidance of benzodiazepines, i.e. prescription drugs used as sleeping pills or tranquillizers, or anticholinergics, which inhibit the parasympathetic nervous system, has been shown to be positive in studies.

Drugs such as Droxidopa, a prodrug, may be helpful against Parkinson’s and can prevent the number of falls. Prodrugs are drugs in an inactive form that are first converted and become effective in the body. Droxidopa is converted to the neurotransmitter noradrenaline when it crosses the blood-brain barrier. The medication is used, for example, to treat dizziness or if blood pressure drops when standing up (from lying or sitting) due to a lack of noradrenaline release (neurogenic orthostatic hypotension) – both are symptoms of Parkinson’s disease that reduce the risk of falling. Further research is needed into the medicinal treatment of postural instability.

Transcranial direct current stimulation for postural instability?

Clinical studies and meta-analyses indicate that transcranial direct current stimulation (tDCS) can be used as an adjunct to various neurological and psychiatric disorders and may lead to improvement. These include the treatment of migraines to reduce pain, Parkinson’s disease and postural instability to improve cognitive function, and anxiety disorders to improve symptoms.

tDCS is a form of electrical therapy (electrical stimulation) and a non-invasive procedure in which two electrodes are placed on the scalp, which transmit a weak, constant current through the skull to the nerve cells of the brain.