Effectiveness of gaze stabilization therapy with vestibular adaptation exercises in motion sickness: A Randomized Controlled Trial

Introduction

Motion sensitivity, also referred to as motion sickness, is a common condition, with a prevalence of 28% in the general population and more common in women (27.3%) than in men (16.8%). Symptoms of motion sensitivity can be experienced during land, air, sea, or space travel, resulting in impaired function. According to the neural mismatch model proposed by Reason et al, motion sensitivity can be defined as “a self-inflicted maladaptation phenomenon that occurs at the onset and cessation of conditions of sensory rearrangement when the prevailing inputs from the visual and vestibular systems are at variance with stored patterns derived from previous transactions with the spatial environment.”1

Motion is sensed by the brain through three different pathways of the nervous system that send signals coming from the inner ear (sensing motion, acceleration, and gravity), the eyes (vision), and the deeper tissues of the body surface (proprioceptors). When the body is moved intentionally, for example, when we walk, the input from all three pathways is coordinated by our brain. When there is unintentional movement of the body, as occurs during motion when driving in a car, the brain is not coordinating the input, and there is thought to be incoordination or conflict among the inputs from the three pathways. It is hypothesized that the conflict among the inputs is responsible for motion sickness. Many of the drugs that are used to treat motion sickness act by influencing or affecting the levels of these compounds within the brain. Without the motion-sensing organs of the inner ear, motion sickness does not occur, suggesting that the inner ear is critical for the development of motion sickness. Visual input seems to be of lesser importance, since blind people can develop motion sickness. Motion sickness is more likely to occur with complex types of movement, especially movement that is slow or involves two different directions (for example, vertical and horizontal) at the same time.2

Three main theories exist for motion sickness is as follows

1 The Sensory Conflict Theory

1.1 Visual-Vestibular Mismatch

1.2 Intra-vestibular (Canal-Otolith) Mismatch Theory

2 The Poison Theory

3 The Postural Instability Theory 

Physiology of Motion Sickness

Motion sickness is linked to a pronounced activation of the glucocorticoid and sympatico-adrenergic stress response systems. Number of pharmacological agents could potentially affect the occurrence of motion sickness through their actions in the vestibular nuclei. The cerebral cortex and limbic system, particularly the hippocampus, are major sites of spatial orientation information processing. A number of neurotransmitters influence the activity of vestibular nucleus neurons, including acetylcholine, glutamate, glycine, GABA, histamine, norepinephrine, dopamine, serotonin, substance P, somatostatin, adrenocorticotropic hormone [ACTH] and enkephalin. The histaminergic neuron system in the brain has been supposed to play a significant role in the pathophysiology of motion sickness. Neural mismatch signals activates the histaminergic neuron system in the hypothalamus and stimulates H1-receptors of the brainstem, therefore H1-receptors triggers the development of the symptoms and signs of motion sickness, including emesis.

1 The Vestibular System

The vestibular system is exaggerated by vertical and horizontal vibrations and forces of acceleration. The vestibular system is maintaining the body balance; it records change in movement caused by motion and coordinate the position of the head through regulation of muscle tension which helps us keep our posture. The vestibular system consists of semicircular canals and otolith organs. Calcium carbonate crystals present on the otolith organs help us to detect linear acceleration and the position of the head. The otoliths are responsible for the opposite direction of visual signals when the head moves in a roll motion, which is known to be ocular counter-rolling. The part that detects angular acceleration is hair cells, called cilia, attached to the inside walls of the semicircular canals. The vestibular nuclei receive MS signals from the semicircular canals and otolith organs but also visual, auditory, somatosensory, and proprioceptively related signals and a variety of other afferents including from the cerebellum. The indication of angular acceleration tells us that our head is moving1. Individuals with a total loss of labyrinthine function are not susceptible to motion sickness.

2 The Visual System

The
visual system is crucial part of the phenomenon of MS as it coordinates us to
substantiate other organs such as vestibular, somatosensory and motor related
signals tell us to anticipate. Hence, an optical illusion of movement while
standing still, or an illusion of non-movement while moving will create a
conflict between signals to the brain from the optical vestibular system. A
conflict can also be created through an optical illusion of moving in an
opposite direction than the actual.

**RESEARCH
QUESTION:**

What will be the effect of Gaze Stabilization Therapy and Vestibular adaptation exercises in motion sickness?

AIM:

To study the effects of Gaze Stabilization Therapy and Vestibular adaptation exercises in motion sickness

OBJECTIVE OF THE STUDY:

1.      To study the effects of vestibular adaptation exercises in motion sickness

2.      To study the combined effects of gaze stabilization therapy and vestibular adaptation exercises in motion sickness.

Hypothesis

N****ull Hypothesis (H0): There will be no significant effect of gaze stabilization therapy combined with vestibular adaptation exercises in motion sickness.

**Alternative Hypothesis (H1):**There will be significant effect of gaze stabilization therapy along with vestibular adaptation exercises i

n motion sickness.

METHODOLOGY:

·        STUDY SETTING: Dr. A.P.J. Abdul Kalam College of Physiotherapy.

·        DURATION OF STUDY: 6 Months

·        METHOD OF COLLECTION OF DATA: Data will be primary collected by principal investigator.

·         **TYPE OF DATA:**quantitative

·        STUDY DESIGN: experimental study

·         STUDY TYPE: Randomized Controlled Trial

·        SAMPLINGMETHOD: simple random sampling

·        SAMPLE SIZE: 50

·        STUDY POPULATION: Patients reporting to Medicine, ENT OPD,

PMT, Loni, Ahmednagar 413736.

**Inclusion
criteria:**

1.Age between 17 – 25 years.

2.Presence
of signs and symptoms of motion sickness.

3.Normal
subjects without any pathology.

**Exclusion
criteria:**

•Individuals on medications for motion sickness.

•Individuals
with any kind of central or peripheral vestibular pathologies.

•Subjects
who are suffering from any kind of injury, fracture or any other pathology

Experimental Group

Vestibular Adaptation Exercises

1. Head fixed, object fixed and eye balls moving.

2. Head fixed, object and eye balls moving.

3. Head moving, object fixed and eye balls moving.

4. Head, object and eye balls moving

Exercises

Repetitions

Duration

|Rising while focused

5 repetitions 30 seconds

Total 20 repetitions

2 minutes  break after every 5 repetitions

 10 minutes

  |Moving head while focused

 5 repetitions 30 seconds

Total 20 repetitions

2 minutes  break after every 5 repetitions

 10 minutes

  |Focus on moving target

 5 repetitions 30 seconds

Total 20 repetitions

2 minutes  break after every 5 repetitions

 10 minutes

  |Move with moving target

 5 repetitions 30 seconds

Total 20 repetitions

2 minutes  break after every 5 repetitions

 10 minutes

 Gaze Stability Exercises Home Program

1. Stand in a corner of the room

2. Hold or tape the exercise card at eye level against a plain background

3. Keep eyes focused on the letter E

Rotate head smoothly horizontally from side to side as tolerated for 1 minute, then rest   for 1 minute

Perform this exercise for a total of 5 minutes daily during week 1

6. Week 2 through week 6, the investigator will recommend weekly exercise progression as tolerated

Please maintain a daily exercise log sheet and turn it in during weekly follow-up visit with the investigator

    Control Group

Vestibular Adaptation Exercises

Head fixed, object fixed and eye balls moving.

Head fixed, object and eye balls moving.

Head moving, object fixed and eye balls moving.

Head, object and eye balls moving

Exercises

Repetitions and time

Duration

|Rising while focused

5 repetitions 30 seconds

Total 20 repetitions

2 minutes  break after every 5 repetitions

10 minutes

|Moving head while focused

5repetitions 30seconds

Total 20repetitions

2minutesbreakafterevery5repetitions

10 minutes

|Focus on moving target

5 repetitions 30 seconds

Total 20 repetitions

2 minutes  break after every 5 repetitions

10 minutes

|Move with moving target

5 repetitions 30 seconds

Total 20 repetitions

2 minutes  break after every 5 repetitions

10 minutes

OUTCOME MEASURES**:**

1. Motion sickness severity scale(MSSS).

2. Motion sickness assessment questionnaire(MSAQ).