Its functioning and the assessment of its functional integrity
Giddiness, dizziness, instability and vertigo all indicate a disorder of the balance system. Technically, the balance system is known as the Vestibular system. It is one of the most complicated and rather fragile systems of the body and derangements of the balance system are quite common.
Fortunately most disorders of the balance system are self-limiting and can be adequately managed by the enlightened general practitioner. However, in some cases proper management of vestibular disorders is difficult and these patients require specialized management by a competant and experienced neurotologist. The management of the balance disorder patient is easy, if the clinical tests and investigations point to a specific disorder like BPPV, Vestibular Neuronitis, Meniere's disease, Acoustic Neuroma, Cerebellar abscess etc. Each of these individual diseases have definite and well-defined management protocols, e.g. BPPV is treated by physical therapy, vestibular neuronitis by steroids, anti-viral drugs and B-Complex vitamins along with vestibular sedatives, Meniere's disease by diuretics and dehydrating agents, and acoustic neuroma and cerebellar abscess by surgery. The management becomes difficult when the clinical tests and investigations point to a non-specific vestibular disturbance of unknown etiology, as is usually the case. In such cases, the management of the vertiginous patient is based on 4 different modalities. In order of importance they are -
1. Reassurance to the patient,
2. Physical therapy, i.e. vestibular rehabilitation exercises,
3. Pharmacotherapy - medical management,
4. Surgery.
Reassurance
Patients suffering from vertigo and instability are usually very apprehensive - not without reason, since the sensation of falling down and /or the feeling of giddiness are very distressing and terrifying experiences. However this fear is unfounded, and though the sensation of vertigo/ instability is literally one of the most traumatic and frightening experiences that a person can ever have; yet it does not at all mean that it is a sinister or life-threatening condition. Reassurance from the doctor is hence a vital part of the management. As already explained most of the balance disorders are self-limiting conditions and most of them are amenable to treatment. Approximately 90% of the patients will respond to simple oral medication and some special exercises called vestibular rehabilitation exercises. It is however very important that the requisite investigations are done so that the management can be done on a scientific footing and the rare but potentially dangerous conditions safely ruled out.
Once the patient is reassured and his/her fears allayed, the neurotologist tries to establish a diagnosis from the clinical neurotological tests and investigations. The rest of the management depends on the findings of these tests/ investigations.
Medical, Physical and Surgical Therapy
If the tests point to a unilateral peripheral vestibular disorder (which is the commonest finding), the vestibular rehabilitation exercises are the mainstay of treatment. However, some vestibular sedative drugs are prescribed along with not only to give symptomatic relief to the patient during this acute phase but also to increase the blood supply to the vestibular system ( mainly the inner ear and certain parts of the brain) because quite often these attacks of vertigo / instability is due to a phenomenon called vasospasm. Cinnarizine is very effective in these cases, as, it in addition to its vestibular sedative effect (which reduces the giddiness symptomatically) it also prevents vasospams in the brain and thereby ensures a proper supply of blood (which carries oxygen and glucose) to the inner ear and brain. Prochlorperazine and Dimenhydrinate are only strong vestibular sedatives and does not have the anti-vasoconstrictive effect of Cinnarizine. However, there are other drugs too like Betahistine which increase the blood supply to the vestibular system by different mechanisms. In addition to drugs like- Cinnarizine, Prochlorperazine, or Betahistine some other drugs, e.g. anti-emetics like Domperidone are also needed to take care of the vegetative symptoms of the patient like nausea, vomiting etc. which usually accompany vertigo. Antioxidents, Vitamines B1 / B6 / B12 and drugs for enhancing blood supply to the brain have a big role in the management of chronic vertigo.
When one of the vestibular labyrinths in the ear is deranged, the damage is usually permanent since the vestibular labyrinth does not regenerate once it is partially on fully damaged. This of course does not mean that a person with a deranged labyrinth will remain unstable throughout life. Nature has a very efficient system, technically known as vestibular compensatory mechanism by virtue of which the balance function of the body is brought back to normal inspite of a damaged labyrinth. This vestibular compensatory mechanism is nature's way of treating peripheral vestibular disorders and ameliorating the patient's symptoms.
However, the vestibular compensatory mechanism is inhibited by drugs, which sedate the central nervous system, and by lack of vestibular stimuli. The more the vestibular stimuli like head movements, walking etc. the better does this compensatory mechanism develops. Hence, as soon as the acute symptoms of dizziness pass off, the patient should be encouraged to start his normal physical activities such that the vestibular compensatory mechanism develops properly. Neurotologists hence encourage patients of peripheral vestibular disorders to start physical exercises and resume normal activities as early as possible. Staying in a dark room (lack of visual stimuli) or lying down in bed (lack of proprioceptive stimuli) or immobility (lack of labyrinthine stimuli) jeopardizes the proper development of the vestibular compensatory mechanism. Hence, normal physical activity and exercises are a very important part of therapy in balance disorder patients and the clinician should never undermine its role in hastening early recovery.
The importance of physical therapy in the management of vertigo has been widely accepted by neurotologists as the most cost-effective way of treating peripheral vestibular disorders. More and more patients are getting better and returning to normal lives by virtue of this form of treatment. Physical therapy for vertigo, technically known as vestibular rehabilitation exercises, are a form of coordinated head, body and eye movements which help to ameliorate the patient's symptoms and help the vertiginous patient to return to normal life early.
The vestibular rehabilitation exercises act in 3 ways in the process in peripheral vestibular disorders. These 3 mechanisms are viz.- Adaptation, Habituation, and Compensation. Adaptation is the process by which the brain learns to adapt itself to the changed vestibular scenario, i.e. improper signals coming from the impaired peripheral sensory receptors. The function of the vestibulo-ocular reflex system is to stabilize the image of the surroundings in the retina and keep it at its most sensitive point- the fovea. In derangement of the visual / labyrinthine inputs, this mechanism is jeopardized. The gaze stabilization exercises in this exercise schedule helps to adapt and retrain the vestibular reflex system so that it can effectively bring about the stabilation of images in the retina and avoid the unwanted retinal-slip in spite of there being a defect in the visual / labyrinth inputs. Retinal slip means slippage of images in the retina and is one of the major causes of vertigo, which occurs because of a defective vestibulo-ocular reflex system.
Habituation is the process by which the vertiginous patient is repeatedly exposed to the mismatched sensory input. This repetitive exposure to the "error" situation induces changes in the brain such that the brain becomes conditioned to the mismatched sensory input. The head and body movement exercises in the vestibular rehabilitation exercises help to enhance habituation. Compensation means the proper and fullest utilization of the remaining sensory components viz.- the visual and proprioceptive senses and the unaffected labyrinth such that improper input coming from the defective labyrinth is overruled. In a normal subject there is redundancy of the sensory inputs and the fullest utilization of all the 3 inputs system is usually not required. But when one of these input systems is partially or wholly defective the brain is forced to use remaining senses more effectively and efficiently such that they compensate for the partial loss of function.
The patient of peripheral vestibular disorder has to understand that one of the objectives of the vestibular rehabilitation exercises is to deliberately and systematically provoke tolerable spells of vertigo so that the threshold of tolerance is elevated. Hence some spells of vertigo in the initial stages may occur during the exercises but it is bound to pass off with time. Diligence regularity and perseverance on the part of the patient is essential such that the desired results can be obtained. The exercises should be performed for 10-15 minutes twice or thrice daily till the subject becomes completely normal. However, even after the patient becomes normal there may be small phases of vertigo during period of fatigue, stress and strain, illness, long periods of inactivity etc. This phenomenon is called decompensation and occurs because the central compensatory mechanism is rather fragile. Whenever such conditions recur the vestibular rehabilitation exercises must be started afresh.
In those refractory cases of vertigo, which are not amenable to physical and medical therapy, the neurotologist has to take recourse to surgery. However, the role of surgery in vertigo is very limited. Other than in conditions like acoustic neuroma ( a tumor in the vestibular nerve) or the tumors / abscesses in the cerebellum or in vascular loops ( where a loop of blood vessel presses upon and stimulates the vestibulars of nerve), the scope of surgery is limited. The scope of surgery in peripheral vestibular disorders is only in some stubborn cases of confirmed Meniere's disease, some cases of benign positional vertigo, which is not responding to exercises and in conditions like perilymph fistula and labyrinthitis due to otitis media. In perilymph fistula the fistula is repaired and in labyrinthitis due to otitis media a mastoidectomy is done. These are relatively very simple surgical procedures. But the surgery for Meniere's disease and for benign positional vertigo is difficult and hazardous - the main problem being loss of hearing. Now -a -days some simpler surgical procedures are tried in Meniere's disease like instillation of some chemical toxins like - gentamycin in the middle ear. The results of such procedures are quite encouraging provided of course the patients are properly selected. However, one should remember that surgery in peripheral vestibular lesions whether it be selective vestibular neurectomy or sectioning of the 8th Cr. Nerve or destruction of the vestibular labyrinths or even the procedures like intratympanic gentamycin does not itself relieve the patient's symptoms. The patient's symptoms are relieved only by the vestibular compensation which follows when the offending vest. Labyrinth is totally damaged. The purpose of surgery is to convert a partially damaged unstable labyrinth into a totally dead labyrinth so that the comentsatory mechanism develops properly.
Conclusion
In conclusion, it may be said that vertigo and instability are a common but very distressing medical problem but very rarely life -threatening . however, with medicines and physical exercises most patients become normal. In a very few cases surgery has to be taken recourse to.
Caution
1. Do not perform these exercises while you have a vertigo / dizziness attack. Only the exercises may be done while lying in bed during the acute phase of vertigo. But as soon as the patient becomes a little better, which takes 2-3 days time, the full range of exercise should be started.
2. Never take any medication on your own, as there are some medicines, which slow down the adaption process.
3. Always consult your doctor before taking medicine, which is not prescribed by him.
4. Many of the medicines prescribed for the vertigenous patient have a lot of side effects and hence the patient must report immidiately to the doctor as soon as any untoward effect is felt by him / her.
5. The vestibular excercises are extremly helpful and the menistry of treatment especially in peripheral vestibular lesions. Hence, these exercises should be performed very diligently and regularly. Medicines / surgery is NOT an alternative to the exercises.
