Nystagmus - Types, Causes, Symptoms, Diagnosis, and Management

Introduction

The eyes are the source of vision. It is the most delicate sense organ, and any injury, infection, or function change will result in adverse effects. Nystagmus is an involuntary condition in which the eyes produce repetitive and rapid movements that affect vision, balance, and coordination. This condition is also called dancing eyes. The movements will be from side to side, up and down (vertical nystagmus), and circulatory movements. It can be acquired from parents or caused by some medical conditions and toxicity. Even certain medications can cause this condition.

Nystagmus is not a very dangerous condition itself; however, it can be associated with some serious health conditions, such as toxicity, stroke, inflammatory diseases, brain tumors, and head injury or trauma. The condition is commonly seen in children and adults and affects six to 24 people in every 10,000, per studies. Therefore, treating nystagmus at the earliest is vital as it might result in vision loss.

What Are the Types of Nystagmus?

Based on the path of movements, nystagmus is divided into three types.

• Horizontal Nystagmus: Shows side-to-side eye movements.

• Vertical Nystagmus: Shows up and down eye movements.

• Rotary Nystagmus: Also known as torsional nystagmus, it shows circular eye movements.

Based on the onset of the condition. Nystagmus is divided into two types.

• Congenital Nystagmus: Also called infantile or early-onset nystagmus. It starts in infants between six weeks and three months of age. The symptoms are present in both eyes, with horizontal to and fro movements seen predominantly. Still, vertical and rotational movements are seen sometimes. The underlying cause is unknown, but scientists suggest the genetic link to albinism could be a reason. This condition does not require management as it is mostly mild, but the parents might opt for corrective surgery to avoid further complications.

• Acquired Nystagmus: This type of nystagmus is acquired later in life due to an injury or an infection. The episodes occur due to a problem in the inner ear or brain. A few underlying conditions, like stroke, multiple sclerosis, and drug usage, can aggravate the condition.

Voluntary Nystagmus: It is one of the subtypes of nystagmus that temporarily induces nystagmus-like eye movements. The condition is rare and not a cause for concern. Voluntary nystagmus is usually described as a conjugate, benign, pendular, and primarily horizontal nystagmus.

What Are the Symptoms of Nystagmus?

Uncontrolled Eye Movement: A disorderly combination of slower and faster eye movements occurs.

• Problems with vision.

• Sensitive to light.

• Dizziness.

• Issues with balancing the body.

• Tilting head often when trying to focus on things.

• Blurry vision.

What Are the Causes of Nystagmus?

• Infantile Nystagmus:

  • Albinism - It is an inherited condition with less or no melanin pigment production. Melanin pigment determines the color of the skin, eyes, and hair.

  • Optic nerve disease.

  • Rod monochromatism.

  • Leber's Congenital Amaurosis - The retinal structure of the eye in children will be affected.

  • Congenital Cataract - A cloudy lens present at the time of birth.

  • Optic Nerve Hypoplasia - The optic nerve is underdeveloped.

  • Noonan Syndrome - It is a genetic disorder characterized by the underdevelopment of various body parts, including facial structures.

  • Nystagmus Blockage Syndrome.

• Conditions That Present Nystagmus as a Sign or Symptom:

  • Trauma to the head.

  • Optic Nerve Hypoplasia - Optic nerves are not developed completely.

  • Multiple Sclerosis - The protective covers of the nerves are damaged.

  • Tullio Phenomenon - Sound causing dizziness.

  • Meniere's Disease - This inner ear disorder causes dizziness (vertigo).

  • Canavan Disease - The inability of the brain's nerves to send and receive messages. This is an inherited disorder.

  • Aniridia - Partial or complete absence of the iris (colored part of the eye).

  • Tumors of the brain.

  • Whipple's Disease - In this condition, the joints and the digestive system are affected by the bacteria Tropheryma whipplei. It will affect the absorption of nutrients by the body.

  • Pelizaeus-Merzbacher Disease - The central nervous system of the male group is affected. It is an inherited condition.

  • Superior Canal Dehiscence Syndrome - There is an abnormal opening between the inner ear and the brain, causing hearing impairment.

• Toxic Substances Poisoning Leading to Nystagmus:

  • Intoxication by alcohol.

  • Barbiturates.

  • Ketamine.

  • Lithium.

  • Nitrous oxide.

  • Salicylates.

  • Phenytoin.

  • Benzodiazepines.

  • Pregabalin.

  • Phencyclidine.

  • Amphetamines.

What Are the Risk Factors of Nystagmus?

• Family history of nystagmus.

• Albinism condition.

• Astigmatism.

• Diseases of the retina and optic nerve.

• Multiple sclerosis.

• History of strokes.

• Consumption of alcohol.

• Vitamin B12 deficiency.

What Are the Possible Complications of Nystagmus?

• Reduced vision.

• Impaired coordination of the eyes.

Most cases, especially the acquired ones, are associated with an underlying medical condition like head trauma, stroke, or drug abuse. In that case, if the conditions are left untreated, complications will occur.

They are,

• Brain damage.

• Difficulty walking.

• Imbalance.

• Paralysis.

How to Diagnose Nystagmus?

A physical examination is done to diagnose the causative factors to plan appropriate treatment. For example, a standard test to diagnose nystagmus makes the patient spin around for 30 seconds, stop, and look at an object. If nystagmus is present, rapid movements will be seen.

The patient will be put through the following tests for nystagmus.

• Electro-oculography: This is done to measure eye movements.

• Electronystagmography: This test shows how the eyes react to different stimuli.

• Magnetic Resonance Imaging (MRI) And Computed Tomography Scans (CT Scan) - These tests capture pictures of the brain for analysis.

• Examination of the ear.

• Neurological examination.

• Vision acuity will be tested.

• A genetic test is also done to rule out any inherited genetic mutation associated with the congenital form of nystagmus.

How to Treat Nystagmus?

Once the causative underlying medical condition is diagnosed, it can be cured, as in the case of acquired nystagmus. However, congenital nystagmus cannot be wholly treated, and only its symptoms can be managed to some extent. The different treatment modalities available are,

• Contact Lenses and Eyeglasses: Contact lenses and eyeglasses will be prescribed to correct the vision, which will help resolve the rapid movements of the eye.

• Medications: Certain medications like Gabapentin (anticonvulsant), Baclofen (muscle relaxant), Memantine, and Acetazolamide are proven to be good for curing nystagmus.

• Surgical Procedures:

  • Tenotomy - This surgery removes particular eye muscles and repositions them in the eyeball at the exact spot. This surgery aims to control the eye oscillations and, in turn, improve vision.

  • Vision Correction - If nystagmus is not controlled, a laser surgery called LASIK (laser-assisted in-situ keratomileusis) can improve vision. The improved vision will, in turn, control the nystagmus.

Conclusion

Therefore, nystagmus is the circular, up-and-down, and side-to-side movement of the eyes that is found to make everyday activities challenging. Since these involuntary movements can only be controlled with proper management and control over time. An appropriate treatment plan is essential for a good prognosis, so it becomes necessary to consult an ophthalmologist at the earliest.