Understanding Nystagmus in Stroke
Nystagmus, one of the many side effects of an intense stroke, is a condition that pertains to a patient’s vision. Also called ‘dancing eyes’, Nystagmus in stroke is characterized by the involuntary, rapid movement of the eyes that have a reduced vision as a result. These movements vary in pace. At times they are fast, and other times they are slow.
Nystagmus usually affects both eyes, hence it is very noticeable. Patients who go through this condition after a stroke have a long recovery road ahead of them. They have to undergo a number of tests and treatments to make it better.
How do Rapid Eye Movements Occur?
How and why do these rapid eye movements occur? To understand the pathophysiology of Nystagmus, it helps to take a look at the relationship between vision and the brain. Every sensory or motor reaction in the body is controlled by a specific section of the cerebellum. Packed with small arteries that supply blood to it, the cerebellum is the main control room that neurons report to.
In the event of a stroke, sections of the cerebellum get damaged due to lack of oxygen. When one of the small arteries get blocked, oxygenated blood supply is hindered, leading to instant suffocation for the sensitive neurons. If the affected neurons belong to the part of the brain that controls normal vision, Nystagmus in stroke is a possible result.
In healthy individuals, the head rotates about an axis. Along with this movement, the eyes also rotate about the same axis in the opposite direction to keep a distant image in clear view. Such angular acceleration is detected by the semicircular canals in the inner eye. Next, a signal is sent to the nuclei in the brain, and then to the extraocular muscles that make the eyes fix their gaze on one object.
With Nystagmus after stroke, the semicircular canals are stimulated even when the head is not moving. The result? Rapid eye movements that are not coherent with the movement of the head. It is clear that the abnormal stimulation of the semicircular canals is owing to improper communication between the brain and the extraocular muscles. Hence, indicating that the stroke affected regular muscle and nerve coordination in the eye area.
It is interesting to note that patients with Nystagmus in stroke are not actually aware of their own rapid eye movements. While other can see the irregularity in the motion of the pupils, the person himself doesn’t feel anything except for a blurred vision because the eyes are unable to fix on one object and process a clear view.
Types of Nystagmus
There are many types of rapid eye movement conditions. According to research, there are close to 45 different types of Nystagmus because this condition results from a number of causes, apart from being a side effect of stroke.
The following are some types of Nystagmus, each of which comes with its own problems and difficulties.
Acquired Nystagmus: The term Acquired Nystagmus indicates that the patient was not born with this condition. Nystagmus in stroke is a type of acquired condition.
Congenital Nystagmus: This type of Nystagmus is present at birth and is characterized by the oscillation of both pupils that never work together.
Manifest Nystagmus: Manifest Nystagmus is a variation of this condition in which rapid eye movement is recorded all the time.
Manifest Latent Nystagmus: A type of Nystagmus in which rapid eye movements worsen when one eye is covered.
Another classification of the types of Nystagmus can be made on the basis of the type of movement of the eyes. These include:
Horizontal Nystagmus: Rapid eye movements happen from right to left.
Vertical Nystagmus: Rapid eye movements happen from top to bottom.
Circular Nystagmus: Rapid eye movements happen in a circle.
Treating the Pathophysiology of Nystagmus
Nystagmus in stroke can be treated using a number of treatment options. While it may be impossible to reverse Nystagmus after stroke, a lot can be done to improve it. It should be taken into consideration that while Nystagmus in stroke only affects the movements of the eye, it actually has damaging implications on the patient’s life as a whole.
A huge blow to self-concept and self-confidence is the most notable drawback. Patients with Nystagmus in stroke are always in doubt of what they see because the connection between their eyes and mind is so weak. For this reason, those who have the worst extent of Nystagmus after stroke, are called Legally Blind.
Moreover, Nystagmus in stroke also has cosmetic affects. An individual’s eyes are a focal point of concentration during conversations and are an attractive feature on the face. With uncontrollable, rapid eye movements, the cosmetic appeal of the eyes, and the face in general, is lost. Hence, low self esteem and confidence is also a product of this effect.
Therefore, the treatment options for Nystagmus in stroke focus on making eye movements better for clearer vision and improving the overall cosmetic appeal as well. Patient with Nystagmus usually tilt their head in different directions to find a position that minimizes the rapid movement in their eyes. This position is called the Null Position.
Using surgery, doctors are able to improve Nystagmus in stroke by reducing the need to tilt the head and stay in the null position to get a clear image of an object. Medicines like Botox and Baclofen are known to reduce Nystagmus in stroke as well. Medicine prescription for Nystagmus in stroke is done very carefully because various medications are also a cause of this condition, which means they may end up worsening eye movements instead of making them better.
Moreover, regular eye exams and tests are prescribed for those with Nystagmus after stroke so that the extent of the oscillation can be monitored. Contact lens and spectacles have proved very helpful in this regard as well. Patients with this condition are given contact lens post surgery so their eyes can get accustomed to the change.