Dizziness is a common clinical syndrome caused by the dysfunction of the balance system (visual, proprioceptive, vestibular system), and pharmacological and surgical treatments are the two main treatments for dizziness in China. However, these two methods have their own drawbacks, such as the toxic side effects of drugs, the trauma and postoperative complications of surgery, and the high cost of treatment, etc. Moreover, a significant proportion of patients cannot achieve symptom relief through drugs or surgery. In this context, Vestibular Rehabilitation Therapy (VRT), which is based on vestibular compensatory mechanisms, has emerged as the third major treatment for vertigo due to its non-invasive, inexpensive and definite efficacy. In this paper, we review the foreign literature and make a brief review of the application of VRT in vertigo treatment. Guo Xiangdong, Department of Otolaryngology, The First Affiliated Hospital of Henan College of Traditional Chinese Medicine
1. The concept and physiological theoretical basis of vestibular rehabilitation therapy
VRT is a physiotherapy method for patients with vertigo and balance dysfunction. There is no clear definition yet, but it can be simply summarized as a series of repeated head, neck and trunk movement training patterns developed by professionals to accelerate the production of vestibular compensation and help the brain rebuild good balance while relieving patients’ vertigo symptoms.
Vestibular compensation and vestibular habituation are manifestations of the plasticity of the central nervous system. The ability of the CNS to adapt to bilateral asymmetrical vestibular afferent impulses, a process known as vestibular compensation, is a complex process of neuronal and neurochemical reactions occurring at the level of the cerebellum and brainstem, and the recovery of vestibular function after peripheral vestibular disease depends on this adaptive change in the CNS, which in turn requires appropriate and repetitive visual and proprioceptive signals to stimulation of the central nervous system. Vestibular habituation is a phenomenon in which the vestibular system becomes less responsive to the same stimulus repeatedly over a long period of time, and VRT promotes vestibular compensation and vestibular habituation through a series of repeated vertigo-inducing movements as stimulus signals.
2.Indications for VRT
Regardless of whether the lesion is peripheral, central or mixed, any non-progressive vestibular lesion with poor spontaneous compensation or abnormal motor function such as benign paroxysmal positional vertigo (BPPV), various postoperative destructive vestibular surgeries, or patients who have used ototoxic drugs are the best indications for VRT, in addition to elderly patients with multifactorial balance dysfunction are also suitable candidates for VRT.
Volatile or progressive vestibular lesions, such as Meniere’s disease or progressive labyrinthitis, are generally inappropriate for VRT because unstable lesions produce little long-term central compensation. Therefore, VRT is not effective for acute phase Ménière’s disease with frequent attacks, and its treatment is mainly considered pharmacological or surgical. However, Richard advocates that VRT can also be performed in patients with acute unilateral dysfunction, progressive unilateral vestibular hypofunction, and bilateral vestibular hypofunction in Ménière’s disease. In the last two years, it has also been suggested that early vestibular rehabilitation should also be performed in patients with frequent episodes of acute Ménière’s disease, but the goal of treatment has changed from symptom improvement to education, prevention and self empowerment.
VRT does not apply to all patients with vertigo and is not effective for patients with vertigo due to causes such as hypotension, medication side effects (except ototoxic drugs), transient ischemic attacks, etc., because most of these patients do not have vestibular disorders.
3.Common methods of VRT
As VRT is widely used, its methods are becoming more and more sophisticated. It can be roughly divided into the following three categories according to the operation steps and contents.
3.1 Generalized Physical Therapy (GPT)
The earliest and most representative generalized physical therapy is the Cawthorne-Cooksey training method. The training method consists of a series of simple to complex, repeated eye, head and body movements, such as turning the patient’s head up and down, picking up objects with the head down, throwing a ball in a circle, etc. Through the training, the patient can become accustomed to it and eventually reduce the symptoms. The biggest advantage of this method is that it is simple, easy, economical, and effective. However, the method is less effective in improving balance and preventing falls, and the content is poorly targeted and relatively boring.
In addition, some amateur sports such as table tennis, bowling, golf, etc., which require joint head, eye and trunk movements, are also good general physical therapy. The key is their fun, safety, and a certain degree of stimulation. In addition, yoga and tai chi are also highly recommended because the state of total body relaxation they achieve can be very helpful for those patients with vertigo and balance disorders combined with anxiety.
3.2 Individualized Physical Therapy
Individualized physical therapy is a method of training that is tailored to the patient’s diagnosis or at least to the level of functioning. Because each patient with vestibular pathology has a unique combination of vertigo symptoms, head-eye coordination and balance disorders, the professional therapist needs to complete an “assessment”, i.e. a physical test, and “tailor” each patient’s treatment plan accordingly. “treatment plan for each patient.
This is a significant advance over the initial general physical therapy, the main advantage of which is that it is more effective, relieving symptoms while improving the body’s balance. However, compared with the Cawthorne-Cooksey training method, its disadvantage is that it is expensive and complex, usually consisting of 4-8 training components, and sometimes even requires 16 training components.
The training components of the method are: (1) Gaze stability exercise: let the patient look at the card in front while turning the head up and down or left and right, the speed is gradually accelerated from slow. (2) Visual Dependence Exercise: The patient’s reliance on vestibular and proprioceptive signals is increased by having the patient close his eyes or wear glasses coated with petroleum jelly to correct the over-reliance on visual signals. However, because of the lack of reliable means to detect visual dependence, the efficacy is not certain. (3) Proprioceptive Dependence Exercise: To reduce overdependence on proprioceptive signals by changing the nature of the patient’s standing support surface such as standing on an inclined board or foam, or simply walking back and forth on the beach. (4) Optokinetic tracking exercises: Having the patient turn the head to one side while tracking objects moving to the ipsilateral or contralateral side promotes optokinetic tracking and vestibular stability. (5) Others: In addition, there are otolithic exercises, postural stability exercises and virtual realty training, the efficacy of these exercises is not certain due to the lack of corresponding means to test their effectiveness.
3.3 Occupational therapy (Occupational Therapy)
Cohen et al [10] proposed the use of occupational therapy in vestibular rehabilitation on the basis of individualized physical therapy. Occupational therapy is actually a behavior with an external goal, which is manifested by performing or engaging in interesting and purposeful activities or tasks to achieve the purpose of treatment. Of course, when used in the treatment of patients with vestibular disorders, it must include repetitive head movements that increase in range, frequency and speed as the patient can tolerate. If the patient is designed to complete the nailing of a board, the board and tools are placed on one side and the nails are placed on the other side, so that the participant must turn his head to find the nails before turning his head to the other side to use the tools to nail the nails to the board.
The advantage of this method is that the patient can complete these training programs, which mimic the events of daily life, in a physically and emotionally enjoyable manner to achieve the therapeutic goal, and it emphasizes the important role of psychological factors in rehabilitation more than individualized therapy. However, this method still emphasizes that repeated head movements are the key factor for the efficacy, so there is no major breakthrough in the efficacy, but only changes in the form to make it more acceptable to patients and increase their compliance.
4.The application of VRT in various types of vertigo
A large number of studies have confirmed that VRT is effective in patients with vestibular dysfunction, and most of the patients who underwent VRT had mild to moderate relief of their symptoms, and some of them had significant or even complete relief of their symptoms, and the efficacy was not affected by the age, gender and duration of the disease [11, 12, 13]. Related studies have also shown that the treatment effect varies among different types of vertigo patients.
4.1 Unilateral vestibular dysfunction
Unilateral vestibular dysfunction caused by vestibular neuritis, auditory neuroma, Ménière’s disease, vaginitis, and surgery on one side of the vestibule is more common in clinical practice. Unilateral vestibular dysfunction can be divided into acute and chronic according to the duration of the disease. Regardless of acute or chronic unilateral vestibular dysfunction, as long as the vestibular lesion is stable and the patient’s spontaneous compensation is incomplete, they are all indications for VRT and have good efficacy.
4.1.1 Acute unilateral vestibular dysfunction
Vestibular and auditory neuroma excision surgery or vestibular neuritis can lead to acute vestibular dysfunction on one side. These patients can usually recover through spontaneous vestibular compensatory mechanisms, but some patients have recurrent vertigo symptoms due to poor spontaneous compensation, and these patients are suitable candidates for VRT. Many related studies have shown that VRT in patients after vestibular surgery or auditory neuroma resection significantly improves vertigo symptoms, improves postural stability and reduces the perception of balance disorders, and significantly reduces motor sensitivity and scores on the Vertigo Impairment Questionnaire.Tokumasu et al. found that VRT helped patients with vestibular neuritis to resume normal activities of daily living.Strupp et al. noted that VRT VRT has been shown to improve postural stability and promote compensatory vestibulo-spinal reflexes in patients with vestibular neuritis, and advocated that patients should undergo VRT as early as possible after onset.
VRT in patients with acute vestibular dysfunction due to vestibular surgery or vestibular neuritis consists of exercises to enhance vestibulo-ocular reflex (VOR) gain (gain) and static and dynamic postural stability exercises and vestibular habituation exercises [5].
4.1.2 Chronic unilateral vestibular dysfunction
VRT is a very effective conservative treatment for this group of patients. shepard et al. showed that VRT was effective in improving vestibular function in patients with chronic unilateral vestibular dysfunction with a history of more than 2 months or even 5 years, with 82% of patients showing some improvement in symptoms and 59% showing significant improvement. szturm also found that patients with vertigo with a history of more than 1 year who received VRT Cohen noted that chronic vestibular pathology can lead to a decrease in path intergration skills, which can affect daily living and work abilities, and that VRT can significantly facilitate the recovery of this skill.
For patients with chronic unilateral vestibular dysfunction, VRT also includes exercises to enhance vestibulo-ocular reflex (VOR) gain (gain) and static and dynamic postural stability exercises and vestibular habituation exercises. However, it is very important for the physician and therapist to encourage them and increase their confidence to continue treatment, as symptoms tend to recur during the exercises. Therefore, it is important to explain well to the patients so that they can understand the mechanism of treatment and establish the determination to adhere to treatment in order to enhance their compliance, which is the key to improve the efficacy of treatment. If patients can adhere to the treatment, the effect usually starts in about 6 weeks. Of course, the longer the patient’s history before starting treatment, the longer it takes for the treatment to take effect.
In general, the prognosis for VRT in patients with unilateral vestibular dysfunction is excellent. Once the assessment shows no progressive or fluctuating changes in the patient’s lesions, VRT should be preferred, and the efficacy is definitely better than long-term vestibular depressants, and it significantly improves the patient’s quality of life and ability to work. The characteristics of the patient’s vertigo symptoms, the history of previous head trauma, the degree of abnormal postural control, and the level of patient dysfunction prior to treatment directly influence the outcome of treatment. Only 30% of patients with a history of head trauma have significant results or are cured, while the percentage rises to over 90% in patients without a history of head trauma. Some studies have shown that VRT is less effective in patients whose symptoms are characterized by spontaneous vertigo, with episodes lasting 30 minutes or more and occurring more than once every 4 to 6 weeks.
4.2 Bilateral vestibular dysfunction
Bilateral vestibular dysfunction is one of the most important causes of functional disability and functional deficits, and ENG results found that about 1-2% of vertigo patients have bilateral vestibular dysfunction. Its signs and symptoms include vibratory hallucinations (i.e., vibratory hallucinations, characteristically appearing to see things swinging and swaying as if sitting in a bumpy car when the patient’s head is moving), ataxia, nausea, vomiting, dizziness, clockwise deviation when walking, tinnitus, inability to walk in the dark, and inability to read while walking, etc. Episodes of true vertigo are generally rare. The most common cause of bilateral vestibular dysfunction is ototoxicity (about 50% of cases), followed by bilateral endolymphatic sac effusion, autoimmune inner ear disease, bilateral vestibular ischemia, and primary vestibular decline.
VRT is considered the primary treatment for this group of patients, and studies by Gillespie and Krebs have demonstrated that VRT improves walking speed and motor ability as well as dynamic postural stability.VRT does help in patients with bilateral vestibular dysfunction, but the efficacy is poorer than for other vestibular lesions, being effective in only about 50% of patients, and most patients do not fully recover to their original functional level.
For patients with incomplete loss of vestibular function, the treatment plan focuses on vestibular adaptive exercises that produce habituation of the vestibular system through repeated stimulation signals, such as head movements combined with movement of the visual target, thus improving the integration of the central nervous system. For patients with complete loss of vestibular function, the treatment plan is mainly vestibular substitution exercises, in which the visual and proprioceptive system functions are replaced by a series of movements such as combined head-eye movements and head turning during walking, in order to maintain gaze and postural stability.
4.3 Benign paroxysmal positional vertigo (BPPV)
Benign paroxysmal positional vertigo (BPPV) is a kind of peripheral vestibular disorder that is self-limiting, but some patients do not recover from BPPV for a long time. Vestibular exercises can be a good way to relieve the symptoms of patients with BPPV, since repeatedly putting them in the position that induces symptoms can make vertigo and nystagmus disappear gradually.
Based on the commonly accepted theory of otolith dislodgement as the pathogenesis of BPPV, treatment methods such as Epley’s tubular stone (particulate) restoration method and Lempert’s tumbling restoration method have been developed, which have gradually replaced the original VRT due to their high effectiveness and short treatment course compared with the original VRT. However, there are also studies comparing the recent and long-term efficacy of Epley lithotripsy and VRT, showing that the recent efficacy of both methods is the same, but the long-term efficacy of VRT is better than that of Epley lithotripsy, so the value of VRT in the treatment of BPPV is still emphasized. Moreover, Pollak’s study also showed that about 63% of patients with BPPV who also had other vestibular lesions had vertigo symptoms even after the repositioning method, so further VRT was needed.
In addition, some patients with BPPV combined with severe cervical spondylosis and old and frail patients are not suitable for treatment by the repositioning method, and VRT should be chosen for these patients to relieve symptoms.
4.4 Balance disorders due to multiple factors
VRT can be very helpful for these patients, especially when other therapies are not available or are ineffective.
These patients often have dysfunction due to multiple systemic pathologies, and the chance of falling is high, so preventing falls is a priority in treatment. Complete and correct assessment by the therapist, as well as patient education and instruction, are the main focus of VRT treatment. For some patients who are particularly prone to falls, the therapist assesses their residence and identifies some risk factors in the surroundings that can cause falls, and eliminating or informing the patient of these risk factors can greatly reduce the occurrence of falls. In addition, muscle-strengthening exercises, neuromuscular proprioceptive coordination exercises, transmission training and walking exercises can also be performed. Moreover, tai chi is very effective for these patients, not only to enhance muscle strength and limb muscle coordination, and to enhance somatic proprioception and sensory perception, but also to significantly reduce the dysfunction caused by vertigo.
4.5 Vertigo due to central lesions
Because most studies have excluded patients with central vertigo, there is a paucity of literature on the use of VRT in this group of patients, and Bittar’s study showed that VRT was equally effective in patients with central vertigo, but that patients with central vertigo took longer and required more sessions than patients with peripheral vestibular lesions. Suarez also noted that VRT can improve postural control in patients with central vertigo, but emphasized that continuity of treatment is essential to ensure long-term outcomes.
In conclusion, VRT is a non-invasive, inexpensive, and effective physical therapy for many types of vertigo, and in many cases it can even replace pharmacological or surgical treatment. In foreign countries, the application of this therapy has become more and more mature and is widely used in the treatment of vertigo patients; in China, due to the constraints of equipment, technology and therapist’s experience, the related work is less carried out, which makes its clinical application also limited. It is believed that with the continuous improvement of VRT method and the increasing awareness of therapists and patients, VRT therapy will also have a better application prospect in China.