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Dizziness is a layperson’s word. It means a whole array of different things. Our job is to figure out what the person means when they say "dizzy". If you’re the first doctor to ever see a person with dizziness and the person has not been jaded by somebody else, you have an opportunity that no one else will have dizziness. In a general population of dizzy people there’s more dizziness than there are dizzy people. The most important single cause is vertigo accounting for half the dizzy complaints and the other nonvertiginous dizzy causes make up the other half in equal thirds. Very useful little epidemiological fact about what it is that you’re facing when you’re in the general practice of medicine.
When you examine a dizzy person, and I know this isn’t something you’re going to be doing a lot, I’m not going to spend much time on it but I just want to give you an idea. You want to look for neighborhood signs. So we want to look in the ear, test the person’s hearing, look for spontaneous and positional nystagmus. I am going to show you how that’s done because it’s an elegant little trick and do a quick screening neurological examination.
By screening neurological exam I mean take a history, listen to whether the person is coherent, aphasic or not, have them write something and put a sentence about the weather or the face of a clock, look in their fundi and check their visual fields. Have them walk up and down and check their reflexes. That’s a screening neurological exam. That whole thing takes two minutes if you’re experienced with it. So there it is. Look in the ear, test the hearing, look for nystagmus and do a screening neurological examination.
Now, let’s bear down on that for a minute and see if we can find some synergy. Let’s test hearing. We test it in three phases. Is there hearing loss? If the answer is yes there’s hearing loss we decide whether it’s sensory, neural or cochlear hearing loss. If the answer is the sensory neural hearing loss, we need to decide whether the lesion is in the nerve or the end organ. Simple as that. The end organ is called cochlear. The nerve we call retrocochlear. Is there hearing loss? Is it a sensory neural hearing loss? We do that by checking the Renne test. That’s the air better than bone conduction test with your tuning fork.
Then is it cochlear or retrocochlear? We determine that by listening to the patient’s story and testing to see how their language discrimination, their speech discrimination is. Because when you have bad speech discrimination out of proportion to the amount of hearing loss that you have, that means something is wrong with your nerve – the 8th nerve itself – whereas if you had just cochlear trouble, let’s say you had Meniere’s disease, if I spoke loudly enough to you, you would understand fine because your nerve and central nervous system are intact.
Listen carefully to the pace of the illness. Again, if there’s a little rule that I can give you during my few talks with you during this course, the pace of the illness and localization is all there is to neurology. When we’re talking about localization we now want to know what is the pace of this illness. Is this an acute illness? Is this a chronic illness? Is it subacute? Is it recurrent? What is the pace. Are there neighborhood signs? Is there any hearing trouble? Is there any nystagmus – jerkiness of the eyes?
Now, I want to teach you something about the vestibular system, not too much. Just enough so that you understand this and also have an appreciation for how elegant the nervous system is. This is well worth a few minutes of thinking of how the nervous system works. So if I can ask you to indulge me with this you can put up with a little bit of technical talk about this, I hope you find it interesting and useful. The vestibular system is meant to tell the rest of the nervous system two very important bits of proprioceptive information. Those two bits of information are angular acceleration of the head. In other words, if I were to measure the movements of my head, I would measure them in degrees per second squared. Right? The head goes rightward at so many degrees/second2. That’s angular acceleration around some fulcrum. So part of this system is meant for recording that.
The second part is meant to tell us which way is down. The nervous system needs to know which way is down so it can protect itself in a fall, let’s say, to know where to make the antigravity movements. We need to know which way is down. In other words which way is gravity pulling. So the vestibular system has two subsystems, one of which does each of those two jobs.
The three semicircular ducts are three membranous ducts in your ear. They’re lined up at right angles to each other so that they can report angular acceleration in all three planes, just like an X, Y and a Z plane – a frame of reference. Watch this. Here are the two horizontal semicircular ducts inside my ear. They look like this. The fist is where the end organ is. That’s the cupula out there in front. When I turn my head in the no-no plane, fluid inside those canals called endolymph moves around, pushes on the hair cells, sends an impulse down the 8th nerve and the nervous system now knows which way the head went and how fast. Angular acceleration of the head and direction. So when the head goes rightward, this one fires. When my head goes leftward this one fires and the nervous system knows what’s happening.
Then I’ve got the right anterior and posterior semicircular duct, left posterior, which are lined up so that they can record the yes-yes plane with the head turned rightward. Then the last two, the left anterior and the right posterior, which is lined up so that they can record the yes-yes plane with the head turned left. So there’s three of them. No matter which your head goes, your three semicircular ducts can tell the central nervous system which way the head went in three dimensions – angular acceleration.
This system does not fire when the head is not moving at all or when the head is moving at a constant velocity because after all, what is acceleration when velocity is constant? Zero. The system only responds to angular acceleration of the head. So when I turn my head rightward, if I had a little electrode in my brainstem listening to the nucleus of the vestibular nerve I would hear this sound. When I turned leftward I would hear this sound and then it would stop. The moment the head stopped moving or reached a constant velocity, it would stop firing. That’s the three semicircular ducts.
The utricle and saccule are the other subsystem that’s meant to tell us which way is down. Now you remember the old Newtonian rule F=MA, don’t you? What we’re trying to generate here is force. This is a force transducer. We know what A is, don’t we? What is A through the system? It’s 9.8 meters/second2. In order to generate F, what do we have to stick in the utricle and saccule to make F=MA work for us? We need M. We need a mass.
Therefore, there have evolved little bits of calcium called the otoliths which sit in the utricle and saccule. Gravity is pulling on these things and generating this force and that force is picked up by a force transducer, goes down the 8th nerve and the 8th nerve now knows which way is down. So when I’m standing here on Earth, if I was recording from that cell in the central nervous system I will be hearing this sound. It is constantly firing. If I took you up in a spacecraft to microgravity it would fire much slower. It’s not zero up there but it’s very low.
So that’s how the system is working. Therefore, the thing that renders the utricle and saccule functional is a little bit of calcium inside. The thing that renders the three semicircular ducts immune to gravity is the fact they don’t have calcium in them. They’re just filled with water. That’s all there is to it. It’s a neat little thing. So here we are. There’s the system in real life. There’s the temporal bone of the inner ear. There are the three semicircular ducts. There’s the horizontal one with the cupula, there’s the anterior and the posterior verticals, inside them is just a fluid endolymph. There’s the utricle and saccule with their little bits of calcium in them.
Notice the hearing system is also here. It’s got endolymph and around in black here is another fluid called perilymph. Perilymph is spinal fluid and all it does is keep this system from banging up against the bone all the time. So what you have here are little balloons filled with water floating inside bone protected from the bone by another fluid. That’s what’s going on here. That’s the system.
Over here is the middle ear. Notice there is no connection between the middle ear and the inner ear. So if I put air in your eustachian tube it wouldn’t bother you. It would not make you dizzy because nothing would get inside the vestibular system. So that’s all there is to it.
When the vestibular system fires the eyes move. Why would this evolve this way? Think about it for a minute. When the head turns leftward in the wild, imagine one of our ancestors escaping from jaguars in the wild and all of a sudden a coconut comes out of a tree
Ménière's disease is a chronic recurrent illness of unknown cause, probably autoimmune which produces recurrent attacks of ringing in the ears and deafness leading eventually to very bad hearing in the infected ear. We now treat these people with steroids presumptively to hopefully settle it down. Sometimes that works, sometimes it doesn’t. In the untreatable cases, we have to just treat with vestibular sedatives. Not a very easy thing to treat.
Traumatic vertigo simply means the person bumped their head, they got a concussion in the labyrinth and they have nystagmus and/or hearing loss. It looks like labyrinthitis or vestibular neuronitis except there’s a history of trauma. This is usually a pretty big league trauma with concussion, loss of consciousness. Not minor trauma. Certainly not just whiplash.
I hope you all saw that study in the Journal of Neurology, Neurosurgery, Psychiatry on whiplash in Lithuania. The bottom line, of course, is there is no whiplash in Lithuania. If you go back a year later and looked at all the patients who had neck injuries at the time of their auto accidents including dizziness and all these other complaints in Lithuania, they don’t have it anymore a year later. We have it in the United States. We have it in the U.K. What’s the difference? The amount of trauma was exactly the same. Lawyers, of course, are the difference. That’s the only difference. So now what I’m talking about here, this is a traumatic vertigo with probably a basilar skull fracture. Blood appears in the inner ear by MRI and the prognosis is very good. It gets better in about two or three months.
Don’t confuse it with the post concussion syndrome. This is this vague syndrome where people bump their head and thereafter have trouble sleeping, trouble thinking and most importantly, of course, trouble working. It never gets better when litigation or workers’ compensation is pending. As far as I'm concerned, it will only respond to the green poultice.
Acoustic tumors are picked up when you hear about an aggressive retrocochlear hearing loss with very, very bad speech discrimination. Vertigo and dizziness are not major components of the vestibular schwannoma. People worry about it a lot. If you’re worried about it, get an MRI. The MRI will exclude it with 99.999% certainty and if you’re worried just get it and get it over with. But vertigo is not a big component of it.
When you hear about retrocochlear deafness, people that have nerve deafness, they have bad speech discrimination, vertigo is not a big component. When you hear about that that’s when you really worry about a schwannoma or a meningioma affecting the 8th nerve.
There are three kinds of nonvertiginous dizziness and I want to finish by telling you just in a thumbnail sketch what they’re like. Here now is important statistically because half of all the dizziness is vertigo but the other half is this other stuff and they’re about equally divided. So what do these people sound like when you say to them, "What do you mean dizzy?" Go right back to the original history. "I’m dizzy." "What do you mean dizzy?" These patients will say, "I feel like I’m going to faint."
The reason they know that is that every human being knows what it’s like to almost faint because at the very least at some point in one’s life virtually every person has hyperventilated to the point of dizziness. What that does, of course, is drop your PCO2 which controls vasomotor activity in your brain so you get vasoconstriction and you feel the symptom of near syncope. If you really want to exaggerate that, crouch down and pool all your blood in your lower extremities and then hyperventilate for three minutes. If you want to really exaggerate it, then stand up and if you want to really exaggerate it Valsalva at the end of that. So crouch down, hyperventilate for three minutes, stand up and Valsalva.
This is what kids call a swoon because it will actually make you lose consciousness. As you know you can lose consciousness. That feeling is the feeling of near syncope. I find it out in the office by putting the patient through the dizziness simulation pattern. I have to do this. I get down there with them on our haunches and I say, "All right. I want you to do this. Here we go. [Sound of heavy exhaling] And we do that until the patient says, "I’m very dizzy now." Then I say, "Okay. Stand up." A lot of people will say, "That’s it. That is what I get." We now know that the patient suffers from near syncope. That’s a cardiovascular symptom not a neurological symptom.
If I were force you to say among the two parts of the word cardiovascular which is more important, cardio or vascular, which is it? 100 to 1 vascular. It’s usually not cardio, it’s usually vascular meaning inappropriate vasodilation or inadequate vasoconstriction in the upright posture usually caused by drugs, toxins and environmental events like high ambient temperature, hyperventilation and excitement combined with the use of drugs that block vasoconstriction like alpha blockers which includes almost all the antidepressants which have the side effects of alpha blockade.
Gait disorder is described as disequilibrium. "I’m dizzy." "What do you mean dizzy?" "I mean I stagger like a drunk. I feel like I’m going to fall." "Have you ever fallen?" "I have fallen. Other times I’m just dizzy." Other people will say, "No, I’ve never fallen. I just stagger. I can’t keep my balance." What’s the cause? We have them walk up and down in the office and we see something. Often it’s Parkinsonism. Sometimes it’s stiff legs with bad proprioception from cervical spondylosis in the elderly person. Sometimes it’s cerebellar ataxia with a wide based gait. Sometimes it’s peripheral neuropathy with bad proprioception and Rombergism, worse with the eyes closed. Of course, myelopathy with bad proprioception. It adds up to vitamin B12 deficiency, something which is very common among the elderly. You should always consider that possibility when you see a gait disorder.
Last, ill defined light headedness. See if you recognize this story. "I’m dizzy, doctor." "What do you mean dizzy?" Pause. "Dizzy," says this patient. "Dizzy all the time. Dizzy day and night. Dizzy." So now you’ve tried my trick and it hasn’t worked, has it? They use the same word again so I try again. I say to people, "Look. The word dizzy can mean lots of things. I want you to describe your feeling without using the word dizzy." There’s a long pause and this patient, who belongs in this category says, "Dizzy. Dizzy, doctor. Dizzy in the head." This is the gesticulation which almost always goes with it. I think it’s pathognomonic. "I’m dizzy in the head. I’m dizzy all the time. I’m dizzy day and night. You don’t seem to be very sympathetic toward dizzy people, doctor. You look awfully young to me."
So then people really lose their cool and they break my rule and they say to the patient, "Does the room spin?" These patients usually say, "The room does not spin. Why do the doctors always ask me that question? The room does not spin. I’m dizzy." "Do you feel faint like you might lose consciousness?" "I’m not faint. I’m dizzy. Max, we’re not staying with this doctor. We’re going to across to the Beth Israel Hospital. This doctor doesn’t know a thing about dizzy."
What is this? People keep saying dizzy and it sounds like there’s an echo. This is what I call "true dizziness". There is no other name for this disorder. This is dizziness. This is the core dizziness within the morass of dizzy people. That’s why they can’t say anything else. It’s dizziness and the core underlying problem is anxiety. That anxiety may be an accompaniment of depression or panic disorder or agoraphobia but there’s always anxiety. These people are always anxious. Anxiety is the key there in telling you about their anxiety. It’s a metaphor. "How’s life?" "Dizzy. Dizzy all the time. Dizzy day and night." "Does if affect your sex life?" "Sex? When you’re dizzy?"
Lastly, how do you treat people with vertigo who you can’t treat with the Epley maneuver? That is, the Epley maneuver doesn’t work. Very simple. You have to give them an anticholinergic drug which crosses the blood-brain barrier. This is the central process. We must cross the blood-brain barrier and it must be an anticholinergic. That is, you’ll either give a drug that is meant to be an anticholinergic or you will give a drug which has a side effect which makes it anticholinergic. The most common ones, of course is the use of the over the counter antihistamines which have anticholinergic side effects. Meclizine, diphenhydramine – that’s Dramamine, diphenhydramine – that’s Benadryl or meclizine, that’s Bonine or Antivert. These are all over-the-counter now.
Phenergan is an anticholinergic which you could use parenterally in the Emergency Department. Scopolamine will work but it’s quite dangerous. It has serious psychiatric and cardiovascular side effects. I don’t like it even transdermally absorbed because a lot of old folks will absorb it and get very, very encephalopathic. You can use methylphenidate to reverse the drowsiness. That’s Ritalin. You can use a little bit of benzodiazepines if there’s a lot of anxiety but benzodiazepines are not the treatment. They make people go to sleep but