Vertigo
Eyas Othman MD
Introduction
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 lack of a shared vocabulary for describing dizziness, 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 somatosensory 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.
The History in Vertiginous Patients
Quality of symptoms: 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.
- Presyncope: feeling of faintness or impending loss of consciousness and usually related to cardiovascular disorders.
- Lightheadedness: non specific sensation of unsteadiness or floating. The causes are varied, for example, hypoglycemia, hyperventilation, anemia, drugs; in addition vestibular disturbances may present with this complaint.
- Duration of symptoms: Sudden onset or intermittent symptoms usually indicate a peripheral cause while more constant or progressively worsening symptoms indicates central cause. See Table.
- Associated symptoms : Hearing loss, ear fullness, tinnitus and ear discharge indicate peripheral vestibular pathology, while CNS symptoms such as blurred vision, diplopia, dysarthria, incontinence, motor or sensory deficit indicate central 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.
Physical Examination
Otologic examination : Examine the external canal for impacted cerumen or evidence of trauma, and tympanic membrane for any evidence of acute or chronic infection, evaluate hearing by tuning forks (Weber and Rinne tests). Cranial nerve examination : Are particularly important as they are close to the neural apparatus of equilibrium, assess visual fields and ocular movement, pupillary size and reflex, facial sensation and symmetry, corneal and gag reflex. Examination for nystagmus : Nystagmus is the only objective manifestation of vertigo, and has a slow and a quick phase named for the direction of the fast phase. Start looking for nystagmus when the eyes are in resting position (Spontaneous nystagmus) then the examiner should ask the patient to follow his finger to the left and to the right (Gaze evoked nystagmus) but not more then 30° laterally so not to induce 'end point nystagmus' which is physiological nystagmus can be induced by head shaking (Induced nystagmus), by shaking the patients head vigorously 20 times in the horizontal plane, after shaking the presence of nystagmus indicates vestibular dysfunction most likely a peripheral vestibulopathy another form of induced nystagmus (Positional nystagmus) may be elicited by the Hallpike maneuver, the patient is seated on the examination table and reassured that he or she will not fall during the test, patient should keep his eyes open throughout the maneuver, the examiner hold the patients head turned 45° to the right and then swiftly moves the person into supine position until the head overhangs the table edge by 30° from the horizontal plane, after a delay of several seconds, nystagmus and vertigo may occur, the patient is brought up quickly to sitting position and then the maneuver is repeated with the head turned to the other side, this maneuver is very helpful in diagnosing benign paroxysmal positional vertigo. Balance and coordination : Balance can be assessed by performing a Romberg test. A positive test is characterized by falling, usually but not always to one direction, and indicates that when vision is absent there is only one system intact either the vestibular or proprioceptive/cerebellar, and that is not enough to maintain balance. Unless the patient has evidence of proprioceptive or cerebellar disease, a positive test indicates that the patient had impaired vestibular function. Gait assessment, finger to nose and finger-nose-finger to detect signs of cerebellar dysfunction. General examination : Look for stigmata of autoimmune disease, neurofibromatosis, auscultate for carotid bruit.
Investigations
- Screening blood tests might include CBC and differential, ESR, TSH, lipid profile, syphilis screening and serology for autoimmune disease if indicated.
- Pure tone audiometry to detect any hearing loss, and auditory brainstem response (ABR) if asymmetrical hearing loss is present.
- CT or MRI is indicated if there is unexplained neurological findings or retrocochlear hearing loss, 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
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 is based on patient symptoms: for acute severe vertigo the use of suppressant medications with good antiemetic and sedating properties is preferable, while in less severe or intermittent vertigo drugs with low or no sedating properties are preferred. 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. A rehabilitation approach uses exercises to complement the CNS compensation process for vestibular pathology and remediate symptoms of postural dyscontrol and vertigo. Differential Diagnosis of Vertigo
Peripheral vertigo: Central vertigo : - Multiple sclerosis
- Migraine headache
- Vascular insufficiency
- Temporal lobe or complex partial seizures
- Cervical vertigo
References
Arenberg IK: Dizziness and balance disorders, Kugler Publications, Amsterdam/NewYork, 1993. Jackler RK and Brackmann DE: Neurotology, Mosby, 1994
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