Vertigo is often confused with the terms dizziness and fainting, but all three of these refer to very different phenomena. Knowing the difference and accurately communicating that to your healthcare provider can help to narrow down the possible causes of your symptoms, lead to a diagnosis, and ultimately lead to treatment.
Dizziness and faintness both generally mean the same thing. Both refer to the sensation of feeling light-headed and near to passing out. Vertigo, on the other hand, is very specific and refers to the feeling that the environment around the patient is in motion. Generally, patients complain that the room is spinning around them. With the sensation of spinning, patients often feel nauseous and are unable to maintain balance.
The basic cause of vertigo can be traced to the information that is generated by the inner ear and sent to the cerebellum for processing. The ear can actually be considered to be two organs mixed into one. One the one hand, the ear is used to detect sound waves so that humans can hear. On the other hand, the inner part of the ear plays a very important role in balance and the position of the body in space.
This idea is a little abstract, but the basic role of the inner ear should become clearer as we unravel how it works. Within the bony structure of the skull, deep behind the ear on each side of the head sit the semicircular canals of the inner ear. Within these canals are small deposits of calcium (as hard as bone and called otoliths) that sit atop very fine hairs. These hairs are attached to nerves that carry information to the brain about the position of the hairs. The hairs are able to bend and because the otoliths sit on top of them, they bend in the direction the otoliths move. As the hairs bend, they send different signals along the nerve to the brain that help the brain know what position the head is in. Here is an example.
Say you are looking straight ahead, standing very still and with excellent posture. The otoliths are positioned atop the hairs in the inner ear and are not moving in any one particular direction or the another (front, back, left, right, or any combination thereof). The signal that is sent to your brain indicates that you are looking straight ahead. Now, say you tilt your head to the left. The otoliths shift under the direction of gravity and bend the hairs to the left. This changes the signal that is being sent to the brain, which now indicates that you are tilting your head to the left. These signals, along with information from sight (visual system) and touch (somatosensory system), let your brain know how your body is positioned at all times. The system of balance that involves the inner ear is referred to as the vestibular system.
Vertigo results when the signals from the inner ear conflict with the signals from the eyes and touch. If your inner ear tells your brain (or your brain interprets) that the head is tilted to the left, but the eyes say you are looking straight ahead, then the mixed signals result in the sensation that the room is moving. Vertigo is simply a symptom of some underlying problem with the inner ear, the nerves that carry information from it, or the part of the brain that receives and processes that information. Vertigo can also result form damage to the visual system or the somatosensory system, but these are not discussed in this article. The following are some of the different underlying problems of the vestibular system that can lead to vertigo.
Harrison’s Neurology in Clinical Medicine divides vertigo into two main categories: physiologic and pathologic vertigo. Physiologic vertigo refers to vertigo in patients with no disease or underlying disorder that is causing the vertigo. In these cases, the vertigo is the result of unusual head/neck positions, spinning (remember when you were a kid, this really gets those otoliths tilited, great fun though), unusual movement (such as with sea sickness or perhaps on a rollercoaster), or when the brain is confronted with a mismatch between the inner ear, eyes, and sense of touch (such as with funhouse mirrors, or odd lighting conditions).
Pathologic vertigo is the result of disease. The disease can be in the visual system (sight), sense of touch (called the somatosensory system), or in the inner ear. We will focus only on those causes of vertigo that relate to the inner ear, the nerves that supply it, or the area of the brain that interprets its signals.
Labyrinthine Dysfunction
This refers to the inner ear and the semicircular canals. There are several types of disease that fall under this category. The most common of these is positional vertigo.
In benign paroxysmal positional vertigo (BPPV), the otoliths become dislodged from the hairs and roll around free in the inner ear. The result is that they push the hairs in abnormal ways and tell the brain that the head is tilted while the eyes and somatosensory systems disagree. The result is vertigo. BPPV is not dangerous and often comes and goes. Patients usually experience it at specific times of day, which can be related to being in specific positions (such as lying down to sleep) at the time. The vertigo in this disease results in another symptom called nystagmus. Nystagmus refers to the rhythmic beating of the eyes back-and-forth or up-and-down. Nystagmus basically means the eyes do not stay fixed, but rather jump around as brain tries to force them to concur with the information coming from the inner ear by placing them in various positions. BPPV is not dangerous and is easily treated with special maneuvers. Your doctor will be able to teach you ways of moving your head that will force the otoliths to return to their proper positions. These maneuvers can be done only when symptoms arise or as part of your daily routine to ensure that the vertigo does not return. In a select few cases, medication may be necessary to help suppress the vertigo and reduce nausea. Your doctor may provide a prescription to have on hand in case the symptoms return suddenly.
The next disorder to affect the inner ear is inflammation. Inflammation can be the result of allergy, infection, drugs/medications, or injury. Like any part of the body, bugs and germs can infect the inner ear and wreak havoc. This inflammation of the inner is sometimes referred to as labyrinthitis. According to the eMedicine article “Labyrinthitis,” viruses are the most common cause of labyrinthitis. Rarely does it cause permanent damage and it generally affects those of middle age (30 – 60). In addition to nausea, vertigo, and nystagmus, those suffering from labyrinthitis may also experience fever, ringing in the ears, hearing loss, or drainage from the ears. Medications that cause labyrinthitis include certain antibiotics (aminoglycosides), beta-blockers (heart medication), or tranquilizers. There is not specific test for this disorder, but routine blood work may be ordered. In addition, CT or MRI may be sued to rule out the possibility of other causes of labrinthitis. Treatment consists of antibiotics in the right setting, hydration, medication to suppress the vertigo, medications to suppress nausea, and steroids to reduce inflammation. Anti-viral medications may be used as well if a specific virus, such as Herpes, is found.
The above are the two main diseases of the inner ear that cause vertigo. However, Meniere’s disease is worth mentioning even though it is rather rare. According to Harrison’s Neurology in Clinical Medicine, Meniere’s disease is characterized by episodic vertigo, fluctuating hearing loss, and aural fullness (the feeling that the ears are full, such as with fluid). The disease affects roughly 1 in 2000 people, but has very different degrees of severity. In general, treatment consists of medication to suppress vertigo, a low-salt diet, and diuretics. The idea behind the low-salt diet and diuretics is that keeping th eobdy low on fluid (or at least preventing it from getting too much fluid) will draw fluid out of the inner ear and reduce symptoms. In some occasions, surgery is needed to relieve the vertigo. There is no therapy for the hearing loss, ringing in the ears, or aural fullness associated with Meniere’s disease.
Vestibular Nerve Dysfunction
The nerve that carries information from the inner ear to the brain is referred to as the vestibular nerve. Damage to or dysfunction of this nerve can lead to vertigo. Diseases of the vestibular nerve usually cause less severe symptoms than do diseases of the inner ear.
Vestibular nerve dysfunction usually results from tumors that compress the nerve. There are two locations in which theses tumors arise. The first of these locations is within the bones of the skull that the nerve passes through. These tumors are usually, though not always, schwannomas ( benign tumors that arise from the cells that surround and protect the nerve). These tumors usually are not malignant and only cause a problem because they fill up the limited space that the nerve has and compress it. The compression leads to dysfunction and vertigo, hearing loss, and ringing in the ear. Surgery is needed to remove these tumors and can be done with radiation (stereotactic surgery) or through open surgery.
The second place that tumors generally arise are in the cerebellopontine angle. This refers to an area of the brain where the brainstem meets the cerebellum. This is also the point where the vestibular nerve enters the brain. A tumor in this region also has limited space in which to grow and, if large enough, can put pressure on the vestibular nerve and cause dysfunction. Tumors in this region can be benign or malignant and are diagnosed by CT or MRI. Surgery is again required to remove the tumor in most cases.
Central Vertigo
This refers to vertigo that results from damage to the areas of the brain that process information from any one of the three systems we have mentioned: visual, somatosensory, or vestibuar (referring the inner ear). Dysfunction of these regions can be transient or long-lasting. Transient dysfunction can result from migraine headaches, mini-strokes, seizures, trauma, or medications/drugs. Long-lasting dysfunction is usually the result of irreparable damage caused by stroke, trauma, tumor, long-term drug use, etc.
Central vertigo can be a symptom alone or can be accompanied by other evidence of dysfunction of the brain, such as visual change/loss, paralysis, difficulty speaking, etc. Diagnosis is made based on symptoms, clinical exam, and on imagining through CT and MRI.
Treatment depends on the underlying cause. Stroke generally cannot be treated. Tumors require surgery, radiation, or chemotherapy. Migraines can be treated with medication. Seizures can be treated with medication and, in some instances, surgery.
Medications Used in the Treatment of Vertigo
Since we have mentioned that medication can be used to suppress vertigo, it is worth mentioning what those medications might be. It is important, however, to remember that these medications only treat the symptom, vertigo, and do not treat the underlying cause/causes.
Antihistamines: Meclizine (antivert and the most popular anti-vertigo medication), Benadryl, Promethazine (this is both an anti-vertigo medication and an anti-nausea medication)
Benzodiazepines: (Valium, etc.)
Anticholinergics: Scopolomine (used to treat motion-sickness as well)
Glucocorticoids: Prednisone and other steroids are used to treat inflammation and swelling that may be causing vertigo in specific situations.
Closing
It is important to take from this that properly communicating your symptoms to your doctor is very important. The phrase, “I’m dizzy,” is so fraught with misunderstanding that it is beneficial to avoid it altogether. Instead, it is better to describe what you are feeling. In other words, do you feel as though you are about to pass out or do you feel as though the environment around you is moving and spinning. Making this distinction is important to determine what the best work-up would be to detect what is causing the symptoms without subjecting the patient to any more pain, discomfort, or cost than is necessary. There are many causes of vertigo, but knowing that a patient’s symptoms are definitely vertigo means ruling out a whole host of diseases and the tests that would have otherwise have been necessary if it were not clear that the symptoms was, in fact, vertigo.
References
Daroff RB, Carlson MD. Chapter 9: Dizziness, Syncope, and Vertigo. In Hauser SL. Harrison’s Neurology in Clinical Medicine. New York: McGraw-Hill 2006. p 123-7.
Stasnick B, Steinberg AR. Labyrinthitis. eMedicine. http://emedicine.medscape.com/article/792691-overview
Stasnick B, Steinberg AR. Labyrinthitis: Differential Diagnosis and Work-up. eMedicine. http://emedicine.medscape.com/article/792691-diagnosis
Stasnick B, Steinberg AR. Labyrinthitis” Treatment and Medication. eMedicine.http://emedicine.medscape.com/article/792691-treatment
