Chapter 14 - Evaluation of the “dizzy” patient
Questions
Define the following terms:
vertigo; presyncope; disequilibrium; jerk nystagmus; Meniere syndrome; benign paroxysmal postional vertigo; canilith repositioning (Epley) maneuver; perilymph fistula; Hennebert sign; fistula test; Chiari malformation; acoustic neuroma; tinnitus.
Vertigo is the illusion of movement. It may be subjective (the patient feels like they are moving) or objective (the patient feels that the environment is moving).
Presyncope is a feeling of faintness or lightheadedness. It occurs with a global decrease in perfusion of the brain.
Disequilibrium is the feeling of being unsteady on ones feet.
Nystagmus is the to-and-fro oscillation of the eyes. Jerk nystagmus occurs when the eyes move fast in one direction and more slowly in the opposite. This is named according to the fast phase and indicates imbalance in vestibular inputs. It is normal when the head is moving but abnormal at rest.
Meniere syndrome is a condition in which there is increased pressure in the endolymph of the inner ear (probably due to diminished resorption of endolymph). This may result in "blowouts" of the membranes of the inner ear, with sudden attacks of vertigo lasting hours. It usually also results in gradually progressive, low-pitch hearing loss, often with a humming or buzzing type of tinnitus.
Benign paroxysmal postional vertigo is a condition in which some otoliths are free to move around the inner ear. They provoke sudden attacks of vertigo beginning after several seconds of delay and lasting less than a minute. Looking up at the ceiling, down at the floor or turning over in bed often provoke the symptom and the Hall Pike (Nylan-Barany) maneuver often reproduces symptoms of vertigo and provokes rotatory nystagmus that also lasts less than a minute.
The canilith repositioning (Epley) maneuver is used to treat benign paroxysmal postional vertigo by moving the patient through a series of postions that move otoliths from the semicircular ducts into the utriculus.
Perilymph fistula is a condition in which there is a small tear in the wall separating the perilymph of the inner ear from the middle ear cavity. This is often near the round window. Changes in pressure in the middle ear or in the fluids of the inner ear can provoke movement of fluid and symptoms of vertigo.
Hennebert sign is the provocation of vertigo by pressure introduced to the external ear canal via insufflation. This can be seen in perilymph fistula or Meniere syndrome. This is similar to a "fistula test."
A "fistula test" is the reproduction of vertigo by changing pressure (either increasing or decreasing) in the external ear canal through an otoscope. This can provoke symptoms in perilymph fistula, but also in Meniere syndrome. This is similar to Hennebert sign.
Chiari malformation is the congenital herniation of the cerebellum through the foramen magnum. There are several types based on associated abnormalities, but it often results in vertigo and occipital headaches. There may be vertical nystagmus and, when severe, dysfunction of long tracts of the spinal cord.
Acoustic neuroma is a relatively common, benign tumor that is comprised of Schwann cells of the vestibular nerve. It is characterized by progressive hearing loss and some (usually mild) vertigo.
Tinnitus is the perception of sound in the absence of stimuli. It can be high pitched (ringing) or low pitched (humming or buzzing).
14-1. What types of dizziness are there?
Answer 14-1. Vertigo (the illusion of movement), presyncope (light-headedness or faintness), disequilibrium (unsteadiness on the feet) and "other" (usually a floating type of sensation).
14-2. What questions would lead you to suspect that the patients "dizziness" is vertigo? presyncope? disequilibrium?
Answer 14-2. Vertigo would be suggested by affirmative answer to the question: "Does this feel like you are on an amusement ride?" or significant nausea with the event. Patients with presyncope usually acknowledge that they feel "faint, light-headed or "like passing out." Disequilibrium is suggested by "feeling unsteady on the feet" or markedly improving when touching a stationary object.
14-3. What are the possible causes of vertigo?
Answer 14-3. There are peripheral causes and central causes. The peripheral causes include pathology of the inner ear or the vestibulocochlear nerve. Central causes mostly relate to conditions affecting the caudal brain stem or vestibulocerebellum. Conditions that irritate the cerebral cortex, such as migraine or very rare seizures, can produce vertigo if they involve cortical locations that are involved in perception of motion.
14-4. How can you distinguish peripheral vertigo from that caused by damage to the central nervous system?
Answer 14-4. With peripheral causes of vertigo (damage to the inner ear or vestibulocochlear nerve), nystagmus is proportional to the amount of vertigo and the direction of the nystagmus is always
the same regardless of the direction that the patient moves their eyes. Also,
peripheral nystagmus is almost never in a vertical (up or down) direction. With
central vertigo (cerebellum, vestibular nuclei and brain stem) nystagmus is
usually greater than vertigo and may shift direction depending on gaze
direction.
14-5. What conditions can cause vertigo provoked by movement?
Answer 14-5. Benign paroxysmal positional vertigo, cervicogenic vertigo and vertebral artery insufficiency all may be provoked by movement.
14-6. What conditions can cause vertigo provoked by loud noise or by pressure changes?
Answer 14-6. Attacks of vertigo provoked by loud noise or by pressure changes can be seen in perilymph fistula and Meniere syndrome.
14-7. What conditions that are associated with vertigo can be provoked by head or neck trauma?
Answer 14-7. Conditions associated with vertigo that can be provoked by head and neck trauma include: benign paroxysmal positional vertigo; perilymph fistula; cervicogenic vertigo; vetebral artery dissection; labyrinthian concussion; post-traumatic migraine; and postconcussion syndrome.
14-8. What conditions that are associated with vertigo also usually produce hearing loss?
Answer 14-8. Meniere syndrome and perilymph fistula usually produce at least some hearing loss (worse as the condition progresses). In the case of Meniere syndrome, the hearing loss tends to be a loss of ability to hear lower tones. Acoustic neuroma is characterized by significant hearing loss, although the vertigo is typically relatively mild.
14-9. What are some central causes of vertigo?
Answer 14-9. Stroke, multiple sclerosis, Chiari malformation and tumors around the craniocervical junction and cerebellum can produce vertigo. Migraine often produces light-headedness and occasionally can produce actual vertigo as part of an aura.
14-10. What are some potential causes of presyncope?
Answer 14-10. Presyncope is the result of global decrease in cerebral perfusion. This can be caused by decreased cardiac output (arrhythmia, outflow obstruction) or autonomic instability (due to drugs, conditions that damage autonomic components of the nervous system or vasovagal/vasodepressor events). Additionally, vascular instability can accompany migraine or follow head trauma, and patients with anxiety (probably through a mechanism of hyperventilation) have cerebral vasoconstriction.
14-11. What are some potential causes of disequilibrium?
Answer 14-11. This results from deficits in the sensory or motor systems that maintain the upright posture. The most common cause is loss of proprioception in the feet (associated with age and certain conditions that produce polyneuropathy). In this case, the patient has a "sensory ataxia" with a broad-based gait. They are much worse when walking in the dark (or with their eyes closed) or when the ground is rough or irregular. Vestibular disorders can produce disequilibrium as well, although these patients are typically vertiginous. Extrapyramidal disease (such as Parkinson disease) can produce diseqilibrium, particularly because postural corrections are slowed, and cerebellar disease also produces this symptom. In these cases, the extrapyramidal or cerebellar disorder is recognized by associated signs and symptoms.