Conditions & DBS
Learn more about the conditions which Deep Brain Stimulation might be used to treat.
How Can DBS Assist Certain
Medical Conditions?
Deep brain stimulation (DBS) is used to treat disabling symptoms of neurological disorders such as dystonia, epilepsy, essential tremor, and Parkinson's disease.
Every patient is unique. Treatment recommendations can only be made on a considered assessment of an individual’s specific medical circumstances.
Parkinson'sDisease
Parkinson’s Disease (PD) is a neurological disease that causes a variety of typical changes of human movement.
People with Parkinson’s disease may also experience changes in mood, behaviour, sleep, speech, swallowing, bladder and bowel function.
Late in the disease, PD can be associated with cognitive change.
What causes PD?
The cause of PD is still unknown, but emerging research suggests a combination of genetic and environmental factors may play a role in the development of the disease.
How does PD develop?
The pathologic changes of PD first begin in the nerves of the intestines and nose.
Current medical evidence suggests that these changes might make their way up into the brain by transport through the nerves that arise from the brain to the gut and the nose.
The changes in the brain of patients with PD appear first at the lower end of the brain (brainstem) and make their way over years to decades to the outer surface of the brain (cortex).
What are the symptoms of PD?
PD can cause movement-related (motor) symptoms as well as symptoms unrelated to movement (non-motor).
Common motor symptoms of PD include:
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Shaking of the hands, arms, legs, jaw and face – also known as tremor
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Stiffness of the limbs or trunk
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Slowness of movement
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Gait or balance problems
These symptoms develop when a midbrain structure, called the Substantia Nigra, becomes affected by the condition.
The Substantia Nigra is responsible for the majority of the brain’s production of a chemical called dopamine.
Dopamine is an important modulator of the processes in the brain that control co-ordination and movement.
When the cells of the Substantia Nigra are affected by PD, they begin to degenerate and die.
When dopamine production becomes critically depleted, the physical symptoms of PD develop.
The non-motor symptoms of PD can include:
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Loss of sense of smell and constipation – this is thought to occur as a result of the changes that first develop in the nerves of the nose and gut
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Mood, behaviour and sleep disturbances – likely caused by the reduction in dopamine production and changes in other brainstem structures
Non-motor symptoms may develop before the motor symptoms of PD.
PD is a progressive disease, meaning it develops slowly – usually over a number of years – and gets worse over time. In many cases, symptoms begin on one side of the body and spread to the other side over time.
While the disease itself isn’t fatal, complications can be serious.
How common is PD?
PD is the second most common degenerative neurological disease in Australia after dementia, affecting an estimated 70,000 Australians.
Every day, 32 Australians are diagnosed with PD. Around 20% of people diagnosed with PD are aged under 50 years, and 10% will be diagnosed before age 40.
DBS for Parkinson’s Disease
The most common indication for DBS is Parkinson’s disease.
In the early stages of PD, patients experience substantial benefit with medication therapy, usually achieving 60-80% improvement of physical symptoms with consistent control through the day. This has been termed the ‘Honeymoon phase’ (see below figure)
Over years however, symptom control can become inconsistent and is sometimes accompanied by periods of excessive movement termed dyskinesia. Medication adjustments can be effective in ironing out these variations in physical performance and dyskinesia, but over time some patients find that irrespective of the alterations made to their medications, consistent symptom control cannot be achieved. It is usually at this point that patients consider advanced therapy interventions for their Parkinson’s disease including DBS.
In this situation, DBS achieves significant improvements in consistency of physical performance over and above that achieved by medication. DBS reduces dyskinesia by more than 75% and generally achieves substantially improved tremor control.
Some patients with Parkinson’s disease find medication is ineffective for their tremor from the beginning. Due to the significant impact of DBS on tremor, patients with severe medication refractory tremor may consider DBS in the first few years after diagnosis.
Occasionally patients simply do not tolerate medication treatment of their PD. Whilst there may be a variety of causes for this, DBS can be effective in this population too.
Tourette
Syndrome
Tourette syndrome is a condition affecting movement and behaviour. It is characterised by the presence of involuntary movements and vocalisations referred to as tics.
Tics are brief, intermittent, often repetitive, partially suppressible involuntary movements which may affect any body part. Vocal tics present with repeated involuntary vocalisations.
Tics are usually suppressible, but suppression leads to progressively increasing urge, which is relieved by tic performance. In Tourette syndrome, tics maybe accompanied by one or a variety of behavioural abnormalities including Attention Deficit Hyperactivity Disorder, Obsessive Compulsive Disorder and Autism. Anxiety and Depression are also more common in Tourette’s syndrome.
What causes Tourette syndrome?
The cause of Tourette syndrome is not known, however genetic factors have a considerable impact. The risk of a family with one affected child, having a second child with Tourette’s is about 25%.
How does Tourette’s develop?
Tics tend to first present between 2 & 15 years of age (average 7 years). They tend to worsen in teenage years, but then generally improve spontaneously in adulthood.
What are the symptoms of Tourette syndrome?
Tourette syndrome usually presents with motor or vocal tics. The behavioural elements of the condition may become apparent due to interpersonal or academic difficulties, anxiety or depression.
How common is Tourette syndrome?
Tourette syndrome is much more common in males then females. The estimated prevalence is between 0.03-1.6% of the population.
Treatment for Tourette syndrome
Treatment for Tourette syndrome depends on the nature and severity of the symptoms. In mild cases, education and counselling for the patient and family may be all that is required. Tics may respond to a variety of medications. Behavioural, psychologic and psychiatric conditions may require specific interventions.
DBS for Tourette syndrome
Surgery is rarely required for the treatment of Tourette syndrome. DBS is considered in cases where tics are severe and not responding sufficiently to tablet treatment.
Ref: Harrison’s Internal Medicine 21st edition; Chapter 436
Tremor
Tremor refers to involuntary rhythmic oscillatory movements of body parts, manifesting as shaking. Tremor may be intermittent or persistent, and be maximal at rest, in particular postures or with movement.
Tremor can occur as an isolated syndrome in conditions such as Essential Tremor, or along with other symptoms in conditions such as Parkinson’s disease.
What causes tremor?
Tremor is thought to arrive from abnormal oscillatory neural signals in the brain. What causes these abnormal brain oscillations to occur is not known.
How does tremor develop?
The rate of progression of Tremor syndromes depends on the underlying cause. Tremor syndromes usually progress over months to years.
What are the symptoms tremor?
People with tremor present with complaints of shaking movements, most commonly affecting the fingers or hands. Tremor can however affect any body part or multiple body parts in the same individual.
Common tremor syndromes
Essential tremor is by far the most common tremor syndrome. Patients typically present to medical attention complaining of rhythmic fine shaking involving the hands or fingers. Tremor is most evident in particular postures or with action. Tremor can be first evident at any stage of life and tends to worsen slowly, usually over decades. Tremor can spread to involve the chin, neck and lower limbs. In severe cases, slurred speech and imbalance can occur after many years of the condition.
How common is tremor?
Tremor syndromes, particularly Essential tremor are common in the community particularly in older age groups. Tremor syndromes can be caused by metabolic conditions such as overactivity of the thyroid gland or certain medications. Medical review is recommended in the context of any new onset tremor syndrome.
Treatment for tremor.
Many tremor syndromes can be at least partially treated with oral medications. In Essential tremor for example, tremor control improves by approximately 50% with tablet treatment in around 50% of patients.
DBS for tremor
DBS is utilised in the management of patients with severe tremor causing functional impairment (eg difficulty writing or doing up buttons) who have not achieved sufficient improvement with tablet therapy.
Ref: Harrison’s Internal Medicine 21st edition; Chapter 436
Dystonia
Dystonia refers to involuntary sustained or intermittent muscle contractions which result in abnormal postures or repetitive movements.
Dystonia can affect one body part (focal), adjacent body parts (segmental) or be generalised-affecting many or all body parts. Dystonia can occur as an isolated symptom or part of a more generalised neurologic syndrome.
What causes dystonia?
There are many causes of dystonia. Dystonia can be caused by genetic or structural disorders of the nervous system, metabolic and inflammatory conditions, or as a side effect of certain types of medicine. In many instances, the cause of the dystonia is not established. These conditions are referred to as idiopathic dystonia
How does dystonia develop?
Dystonia can develop quickly, over days, in the context of metabolic or structural abnormalities of the nervous system. More commonly, dystonia develops slowly over months or even years. In many cases, symptom progression will plateau, resulting in symptoms no longer progressing over time.
What are the symptoms of dystonia?
Dystonia results in abnormal postures or repetitive movements. It can be associated with pain or functional impairment depending on the extent and body parts involved. Dystonia can be aggravated by stress or fatigue and improved with relaxation or so called sensory tricks, when touching an involved body part results in reduction of dystonic movements.
Common dystonia syndromes
Blepharospasm: Involuntary eye closure, sometimes accompanied by excessive blinking.
Cervical dystonia: This relates to involuntary abnormal posturing of the neck, typically characterised by twisting movements of the neck. Pain and abnormal shoulder posturing are common accompaniments.
Generalised dystonia: This refers to repetitive stereotyped posturing or repetitive movements of the neck, trunk and/ or limbs.
How common is dystonia?
The condition is rare but there are many causes of dystonia. Certain types of dystonia occur at particular stages of life. Metabolic and genetic dystonias most commonly develop in the first two decades of life. Cervical dystonia usually develops in the fifth decade of life, whereas facial dystonia syndromes occur more typically in the sixth decade.
Treatment for dystonia.
Most focal dystonias respond well to targeted injection of botulinum toxin. Focal and generalised dystonia may respond to a range of oral medications.
DBS for dystonia
DBS is considered in the treatment of dystonia when symptoms remain severe despite treatment with botulinum toxin +/-medications. Efficacy of DBS for dystonia depends on the cause, extent and duration of the underlying condition.
Ref: Harrison’s Internal Medicine 21st edition; Chapter 436