Dizziness is one of the most common complaints with which patients present. In spite of this the cause often remains undetermined and this is due to the complexity of the equilibrium system, the numerous causes of dizziness, and the fact that these are not confined to the area of expertise of any particular medical specialty. The general practitioner must be able to evaluate dizzy patients and be able to identify serious problems or conditions that are specifically treatable, and know when to ask for special tests or to refer. Basic Physiology.
- Balance is maintained by information received from vestibular, visual and sensory receptors, each receptor type transduces a specific form of information and sends it to the brainstem.
- The vestibular system consists of peripheral and central subsystems. The labyrinth and vestibular nerve constitute the peripheral division. The vestibular nuclei and its connection within the brainstem and with the cerebellum and cerebrum constitute the central division. The labyrinth contains receptors that sense linear head motion in the utricle (horizontal) and the saccule (vertical) and angular head motion in the semicircular canals in which each canal’s receptors are stimulated maximally with a specific direction of motion.
- The retinal neurons of the visual system provide target and surrounding information to direct gaze, to enable particular types of eye movement and to suppress or enhance the vestibulo–ocular reflex during head movement.
- Somatosensory receptors in skin, muscle and joints transduce information concerning gravity, position, surfaces, length and motion of muscles and joints.
- Information received by all receptors is processed mainly in the brainstem vestibular nuclei and the cerebellum. Interaction between these centers will set the appropriate response that will maintain balance by the vestibulocular and vestibulospinal reflexes.
- Vestibular nuclei also provide information to higher centers where conscious awareness of spatial orientation is expressed. Higher centers can modify the response of lower centers to restore a sustained mismatch (“Plasticity”) a property that is unique to the vestibular system.
Patients usually express a wide variety of symptoms as dizziness. By analyzing patient complaints some alteration of the sense of equilibrium can fall under the following terms:
- Vertigo: Illusion of movement relative to one’s surrounding, usually rotatory but may be linear. This sensation usually suggest peripheral vestibular system disorders.
- Dysequilibrium or imbalance: Usually patients complain of unsteadiness related to ambulation. This suggests peripheral nervous system or cerebellar disorders.
- Pre–syncope: Feeling of faintness or impending loss of consciousness and usually related to cardiovascular disorders.
- Light headedness: Non specific sensation of unsteadiness or floating.
- Duration of symptoms: Sudden onset or intermittent symptoms usually indicate a peripheral cause while more constant or progressively worsening symptoms indicates central cause.
- Associated symptoms: Hearing loss, ear fullness, tinnitus and ear discharge indicate peripheral vestibular pathology. Nausea and vomiting are commonly associated with all types of dizziness but may be more marked when the peripheral vestibular system is involved.
- Exacerbating factors: Symptoms that worsen with head movement indicate a peripheral and more benign etiology, symptoms that worsen with closing the eyes indicate a peripheral vestibular cause and symptoms worsened by loud noise suggest perilymphatic fistula.
- Medical history: History of autoimmune disease, hyperlipidemia, cerebrovascular accident, migraine, seizure, cancer, syphilis and previous ear surgery may be relevant to patient symptoms. All drugs taken currently should be recorded for the possible risk of ototoxicity.
The examination should include a detailed history and physical examination of the patient. The physician also examines the ear to look for evidence of infection. In addition tests of hearing should be done.
Balance and co–ordination should be tested
Investigations of Vertigo
- Screening blood tests might include a hemogram, tests for thyroid disorder especially hypothyroidism, a lipid profile.
- Audiometry to detect any hearing loss.
- CT or MRI is indicated if there is unexplained neurological findings although MRI is more sensitive for detecting acoustic neuromas and demyelinating plaques of multiple sclerosis, CT scan is the test of choice for visualization bony structures of the labyrinth.
- Treatment depends on the etiology and should include removal of the cause of symptoms if identified.
- Symptomatic therapy to reduce severity of symptoms while awaiting healing or habituation. Suitable drug or drug combination: vestibular sedatives like (cinnarzine, prochlorperazines) can be used.
- Surgical intervention, although rare, is indicated in specific situations such as perilymph fistula or in severe intolerable vertigo that is not controlled with more conservative measures.
- Rehabilitation is an effective and important alternative to surgery, medication or a life of immobility and restrictions.
Vertigo can be a manifestation of an ear ailment, brain disorders (eg. brain tumor like acoustic neuroma), or a systemic illness (eg.: vasculitis). The vertigo can also be related to migraine, head position (benign positional vertigo), cervical spondylosis, side effect of drug therapy (eg. gentamicin).