Introduction

Brief overview of nystagmus¹

Nystagmus is when the eye moves in a way you can't control. They might go slow one way, then quickly back. It can show up due to many reasons, like: 

1. Inner ear or balance issues(Vestibular)
2. Brain or nerve problems(Central Nervous System)
3. Born with it (Congenital)
4. Some drugs or bad stuff

Nystagmus can mess with how you see, your balance, and how you live your life. To solve the problem, you need to know the reason for the causation. There are kinds of nystagmus:

1. Pendular nystagmus: eyes move like waves
2. Jerk nystagmus: eyes drift slowly, then snap back fast
3. Rotary nystagmus: eyes turn in circles. Knowing about nystagmus can help find and handle health problems

Importance of distinguishing between central and peripheral nystagmus²

Telling apart the two types of nystagmus, central and peripheral, is key for many reasons:

1. They come from different causes: Central nystagmus often points to a brain or nerve issue, while peripheral nystagmus is usually about problems in the inner ear or balance system
2. Varied Treatment Approach: Treatments for central nystagmus often involve neurologists (brain and nerve doctors) or neurosurgeons. In contrast, peripheral nystagmus can typically be managed with approaches like balance therapy or by an ENT (ear, nose, and throat) specialist 
3. They mean different things for the patient:  Central nystagmus can signal a serious underlying condition, such as a brain tumour or multiple sclerosis, and requires immediate medical attention. Peripheral nystagmus, while it often impacts quality of life, generally has a better outlook for improvement with appropriate treatment 
4. Specific test choices:  Identifying whether nystagmus is central or peripheral is crucial for selecting the appropriate diagnostic tests. For instance, central nystagmus may warrant an MRI, while peripheral nystagmus might require tests of inner ear balance. Accurate differentiation between central and peripheral nystagmus allows healthcare professionals to:
   • Give the right treatment
   • Make the patient’s results better
   • Improve quality of life

By recognising the distinct characteristics and clinical presentations of central and peripheral nystagmus, doctors can provide more effective care.

Definition and characteristics

Central nystagmus: origin, features, and types³

Origin

 Central nystagmus originates from damage or lesions within the central nervous system (CNS), specifically affecting areas like the brainstem or cerebellum. These regions are critical for processing signals related to balance, eye movements, and maintaining posture.

Features

1. Changes in way and size: Central nystagmus may appear in different ways (side to side, up and down, round, or mixed) and sizes
2. Not stopped by looking fixed: Not like the nystagmus on the outer side, central nystagmus doesn’t stop when you look at something still
3. Might show with other brain issues: Central nystagmus might come with other brain problems like weak muscles, speech issues, or clumsy moves

Types

1. Downbeat nystagmus: A type of vertical nystagmus with the fast phase beating downward
2. Upbeat nystagmus: A type of vertical nystagmus with the fast phase beating upward
3. Periodic alternating nystagmus: A type of nystagmus that changes direction periodically
4. See-saw nystagmus: A type of torsional nystagmus with a see-saw type movement

Common causes 

1. Cerebrovascular disease: Stroke or transient ischemic attack
2. Multiple sclerosis: Demyelinating disease affecting the CNS
3. Tumours: Brainstem or cerebellar tumours
4. Degenerative disorders: Conditions like spinocerebellar ataxia

Peripheral nystagmus: origin, features, and types³

Origin 

Peripheral nystagmus shakes come from wrongs or breaks in the inner ear's balance part, specifically : 

1.  Labyrinth: This deep ear part controls our stance and balance
2. Vestibular nerve (balance nerve): This nerve sends balance information from the inner ear to the head

Features

1. Unidirectional: Side eye shakes mostly go one way, slow on one side and quick on the other
2. Suppressed with fixation: Staring at something can calm or cut down these eye shakes
3. Associated with vertigo: These eye shakes often come with head spins, feeling off, and balance issues

Types

1. Unilateral peripheral vestibular nystagmus: Comes from one side, ear pain or injury
2. Benign Paroxysmal Positional vertigo (BPPV) nystagmus: Set off by head moves or moves
3. Ménière's sickness nystagmus: Tied to Ménière's sickness, a health issue of the inner ear

Common cause

1. Benign Paroxysmal Positional Vertigo(BPPV): A health case that brings short, strong dizzy spells
2. Vestibular neuronitis: Swelling of the balance nerve
3. Labyrinthitis: Swelling of the inner ear
4. Ménière's disease: A health issue of the inner ear that affects balance and hearing

Origin and pathophysiology

Central nystagmus: brainstem, cerebellum, or other central nervous system structures⁴

The following CNS structures play a role in central nystagmus:

1. Brainstem: Hurt to the brainstem, chiefly the pons or medulla, may bring on central nystagmus. The brainstem joins up with info from the inner ear and helps guide eye movements
2. Cerebellum: Cuts or harm in the cerebellum, mainly the flocculonodular lobe or vermis, may lead to central nystagmus. The cerebellum works to keep eye movements and balance fine movements
3. Vestibular nuclei: The vestibular nuclei, set in the brainstem, take in and sort out info from the inner ear. Hurt to these nuclei may bring on central nystagmus
4. Cerebellar peduncles: The cerebellar peduncles that link the cerebellum to the brainstem might also play a part in central nystagmus

Common reasons for central nystagmus

1. Stroke or a short-term block in blood flow: Harm to the brain's base or back part due to less blood flow
2. Multiple sclerosis: Loss of the protective cover on brain nerves, which hits the brain's base or back part
3. Tumours: Growths in the brain's base, back part, or nearby can lead to central nystagmus
4. Degenerative diseases: Issues like spin twists stop or shrink in the parts linked to the brain's base

Peripheral nystagmus: vestibular system, inner ear, or cranial nerve VIII⁵

1. Vestibular Labyrinth: The inside ear part that helps keep balance, made of curved tubes and balance sacs (utricle and saccule)
2. Vestibular nerve (Cranial Nerve VIII): The nerve that sends balance info from the inside ear to the brainstem
3. Inner ear: Also called the labyrinth, it has the balance system and the cochlea (for hearing)

Common causes

1. Benign Paroxysmal Positional Vertigo (BPPV): A state that gives short, strong dizzy spells set off by certain head moves
2. Inflamed balance nerve: Swelling of the balance nerve
3. Labyrinthitis: The inside ear gets inflamed
4. Ménière's illness: An inner ear issue that upsets balance and hearing
5. Balanceschwannoma: A harmless growth on the balance nerve

Diagnostic clues⁶

Clinical examination of nystagmus

History

1. When it started and how long it lasted.
2. Other issues (feeling off balance, hearing issues, etc.)
3. Past health (brain issues, pills taken, etc.)

Observation

1. Kind of nystagmus (quick, swinging, etc.)
2. How it moves and how big it is
3. Changes with where the eye looks, the head sits, or if the eye stays still

Physical examination

1. Central Nystagmus:
   • Often linked with brain issues (brain attack, nerve disease, etc.)
   • Usually moves one way or many ways
   • It can show up when looking straight
   • Often with other brain signs
2. Peripheral Nystagmus:
   • Often linked with inner ear issues (ear rocks, ear swelling, etc.)
   • Mostly moves one way and side to side
   • Often with dizziness, ear noise, or hearing loss
   • It can change with how the head is moved or placed

Key difference⁷

1. Way and Kind: Central nystagmus can shift and vary more in the way it moves, while the side nystagmus usually goes one way and stays flat
2. Linked Signs: Central nystagmus often goes with other brain signs, while side nystagmus is mostly seen with inner ear signs like dizziness
3. Look and Place: Central nystagmus can show when you look straight and may switch with where you look, while side nystagmus may move with the way your head turns or moves

Diagnostic evaluation

Diagnostic tests: electronystagmography (ENG), videonystagmography (VNG), rotational chair testing

To see if you have nystagmus, doctors run many tests to check eye movement and find out why it happens. Here are some tests and scans they might use: 

Tests⁸

Electronystagmography (ENG): This uses tiny wires to track eye movement, helping find nystagmus and other issues

Videonystagmography (VNG): This uses small cameras to follow eye movement, checking both nystagmus and balance

Rotational Chair Testing: Puts you in a spinning chair to study your eye movement as you turn, checking the balance system.

Spontaneous Nystagmus Test: Looks at eye  movement without any prompts or holds

Positional Nystagmus Test (Dix-Hallpike Test): Tests for the eye movement brought on by moving your head in certain ways.

Optokinetic Nystagmus Test: Sees how eyes react to moving objects

Imaging studies⁹

MRI (Magnetic Resonance Imaging): Takes clear brain pictures to check for problems like stroke, big growths, or multiple sclerosis.

CT Scans (Computed Tomography): Make brain pictures to find out why nystagmus may be happening.

These checks let doctors figure out why nystagmus is there, helping them plan how to treat and manage it.

FAQs

What is nystagmus?

Nystagmus is when your eyes move on their own in a steady and repeating way.

What are the types of nystagmus?

There are two main kinds: central nystagmus (from the brain) and peripheral nystagmus (from inner ear problems).

What causes nystagmus?

It can come from brain issues, ear troubles, or other nerve conditions.

How is nystagmus found?

Doctors check it by looking at your eyes, doing tests (like ENG, VNG, chair tests), and sometimes by taking scans (MRI, CT).

Why know the difference between central and peripheral nystagmus?

Knowing the type helps find the cause, plan treatment, and guess what might happen next, as brain-linked nystagmus may point to a bigger issue.

Conclusion 

Summary of key differences between central and peripheral nystagmus

There are two ways eyes may shake, known as nystagmus, each has its own mark. The kind that happens on the sides, or peripheral nystagmus, goes one way, jerks, and gets tired. It's often linked to ear problems like BPPV or Meniere's disease. But, the central kind moves in more ways, might jerk or swing, and doesn’t get tired. It's tied to brain troubles like stroke, multiple sclerosis, or growths in the brainstem or cerebellum. Tests like the head impulse test and skew deviation test can tell them apart. Knowing the type of nystagmus is the key to good care and treatment.