In diseases affecting CNS there are two types of findings on motor exams. Spasticity and rigidity. Rigidity can be of continuous type and intermittent or cogwheel rigidity.
What is rigidity?
Rigidity is a phenomenon seen in diseases affecting the nervous system. In this phenomenon the symptoms like stiffness of muscle are seen.
Because of this stiffness of the muscle, the limbs are held in a particular posture. There is generally no loss of power in the limb.
Rigidity can be experienced by the examiner when he/she tries to extend the limbs of the patient at the joint.
This rigidity is experienced as involuntary resistance by the patient to the passive extension of the limbs.
Rigidity can be cogwheel type or continuous type.
What is cogwheel rigidity?
Cogwheel rigidity is a type of rigidity. In this rigidity examiner can experience intermittent resistance to the passive movement of the limb in patients.
For example when the examiner tries to extend the limb at the elbow, he/she has to apply the force. The limb extends with force but there are jerky movements like ritcheting.
The limb starts extending and suddenly resistance is reduced, again resistance increases and decreases during range of the motion intermittently.
Most common disease with cogwheel rigidity?
Parkinson’s disease causes rigidity. Cogwheeling is the most common classical symptom of Parkinson’s disease.
This disease was first described by James Parkinson in his handbook ‘Shaky disease’ in 1817.
Chinese sources had described this disease in 1000 BC.
What are other findings of Parkinson’s disease?
Parkinson’s is a disorder of movement but mental findings are also seen in it. It is characterized by the following features.
- Inability to start movement like a patient has to stoop forward to start walking and finds difficulty in stopping again may collide with the wall.
- Bradykinesia is slow movement or reduced movement.
- A face with no emotions.
- Loss of bladder control.
- Cogwheel rigidity.
- Emotional instability.
- Loss of balance.
- Loss of automatic movements like blinking of eyes.
- Altered posture.
Why does cogwheeling occur?
Cogwheeling in Parkinson disease is because of changes in basal ganglia, a part of the brain. This part of the brain plays an important role in most body movements.
Basal ganglia functions to start and maintain automatic movements. Also the extrapyramidal tract maintains the tone of antagonistic muscles while movement. They help in carrying out movements smoothly without intermittent jerks.
The function of this part of the brain is balancing the force of different groups of muscles during movement.
In Parkinson disease a neurotransmitter chemical dopamine level is reduced.
This alters the posture, tone and character of the muscle while moving.
What is treatment?
Parkinson desease is almost always the cause of cogwheel rigidity. The treatment of cogwheel rigidity involves the treatment of the underlying cause.
As the dopamine level has reduced in this disease, the treatment is providing dopamine like drugs.
L-dopa is given in treatment of Parkinson’s disease. It is combined with carbidopa as both combined are found to reduce the side effects of the L-dopa.
These both drugs together make the life of the affected person simple to some extent.
In addition to these drugs, dopamine antagonists can be used for the treatment.
Those patients who do not respond to medical treatment may get help from deep brain stimulation.
What are other ways to deal with cogwheel rigidity?
Along with above said medications following techniques help in dealing with cogwheel rigidity.
- Stretching exercises.
- Relaxing meditation.
Your physiotherapist may help you in teaching and performing those