Interview with Alan L. Desmond, Au.D. Audiologist & Author
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Topic: Vestibular Function - Evaluation and Treatment, Terms and Definitions
Beck: Good Morning Alan. Thanks for meeting with me today.
Desmond: Hi Doug: Happy to do so.
Beck: Alan, I'd like to start by mentioning that you have written a book titled "Vestibular Function - Evaluation and Treatment" (Thieme Medical Publishers ISBN 1-58890-166-1) which I think is pragmatic and highly clinically oriented.
Desmond: Thanks Doug, I tried to keep the book focused on vestibular issues that the clinicians deal with every day, the fundamentals, anatomy, physiology, tests and interpretation and related items.
Beck: I think you accomplished the goal! Nonetheless, before we talk about the book, if you don't mind, let's speak about your education and professional experiences?
Desmond: I got my master's in audiology some 22 years ago from Radford University, Virginia. I was their first audiology student. It was a small program, it only lasted for about 15 years and they closed it down about 5 years ago. After graduation I spent a year in educational audiology, and for the last 21 years I've been in a partnership with two ear, nose and throat doctors. We operate Blue Ridge Hearing and Balance Clinic in Bluefield, West Virginia. I earned my doctorate at Central Michigan and finished that about two years ago, back in 2002.
Beck: Any reflections on distance education programs?
Desmond: Well, as a person who practiced for many years before earning a doctorate, I got to see, hear and feel what clinical practice was all about while practicing with my master's...but once I earned my doctorate, I understood better what it was I was seeing, hearing and feeling. In other words, the program was amazing, it was a fantastic experience. No reservations, no regrets!
Beck: OK, thanks for sharing that. Let's get back to the book...When did the book come out, and how did you become a "vestibular expert?"
Desmond: The book was released April of 2004, during the AAA convention in Salt Lake City. There was actually never a day that I said "Today I have decided to write a book."
The story is lengthy, but here's a quick version...When I finished my CFY, I didn't think I was prepared to enter clinical audiology. I went to Stanford University Medical Center for a month, as an unpaid visiting staff member. I couldn't really afford it financially at the time, but I couldn't afford not to do it from a professional competence standpoint! That was a fantastic experience and I learned a lot very quickly. Then again, 13 or 14 years ago I decided to change the direction of my career to focus on vestibular management. Once I decided to focus on vestibular issues, I took another month off and took another position as an unpaid visiting staff, but at that point I went to the House Ear Clinic. I was there for a few weeks and that greatly accelerated my learning curve by seeing how they treated dizzy patients. I observed, listened to, annoyed and badgered anyone that I thought I could learn from. So I gathered the tools and skills and made it my focus to learn everything I could about this area. I just think we owe it to our patients to become competent before we proclaim ourselves "specialists." So then after acquiring this core knowledge, and feeling comfortable professionally, I needed a way to educate the local docs and the other referral sources on these topics to make sure they knew what I did and how I offered a different and unique approach, and why they should refer to me.
Beck: So the book started as a marketing piece?
Desmond: Yes, in some respects. I actually wrote some 40 pages outlining what I did, the different tests and treatments available, screening tests and I addressed BPPV and canalith repositioning, and most of them had no idea what those things were back then! So it was exciting, and it was effective. One of the local equipment manufacturers got hold of the 40 page booklet and pretty soon the folks at MicroMedical wanted to use it too, which was fantastic, and then while I was at Central Michigan, I expanded it further into my "Capstone Project." So that was the origin of the book and how it came to be!
Beck: Alan, I know you have a list of common "vestibular-related" terms you've defined, and allowed us to reprint...So if I may, this seems like a good time to direct the reader to the end of this interview, where they'll find associated vestibular terms such as; ENG, VNG and Rotational Chair, etc, and your preferred definitions for patients, to help the patient understand what we're talking about. I'd like to mention that these terms and definitions come from your patient hand-out, titled "Blue Ridge Hearing and Balance Clinic Vertigo handout." Thanks for allowing us to use that.
May I ask you a few specific vestibular questions?
Desmond: Sure.
Beck: OK, would you please start with a basic definition and explanation of BPPV (benign paroxysmal positional vertigo)?
Desmond: BPPV is a mechanical dysfunction of the inner ear, and it can be repaired mechanically. It is not treated with vestibular rehabilitation or habituation - in the traditional sense. It cannot be cured based on CNS plasticity, as is often the case with other types of dizziness.
My description to patients goes something like this: BPPV involves sensors, which are little particles really, sometimes called "otoliths" or "canaliths," which originate in one part of the inner ear, fall loose, and settle down in another part of the inner ear. If given a chance they'll settle down ....but if they settle in one of the semi-circular canals within the inner ear, when the patient moves their head to the offending position, the particles move and create a ripple across the inner ear fluid, causing a mismatch of information between the affected ear and the normal ear.
Beck: Why do these tiny particles shake loose in some people, but not others?
Desmond: Great question. Nobody really knows the answer, but we do know that of the BPPV patients, there is a high incidence of head trauma prior to their reporting to the office. So perhaps for many of them the particles were mechanically jolted loose. BPPV is also more common in patients with Meniere's Disease and vestibular neuritis, so maybe inflammation of the inner ear is a factor too. But as far as why these same people have recurrences...we just don't know.
Beck: Thanks Alan, good points. Let me switch gears to Vestibular Rehabilitation. In general, who are the ideal patients for vestibular rehab?
Desmond: It does vary, but people with uncompensated, stable vestibular dysfunction, or people with identified vestibular injuries with abnormal VOR gain and abnormal symmetry which is detectable using rotational chair...those people are probably the best candidates for vestibular rehabilitation (VR) and they usually get good results from VR.
Beck: Is there a particular ENG profile that indicates good candidacy for VR?
Desmond: This comes up all the time. Basically, the ENG in isolation cannot tell you whether or not the patient is a good candidate for VR. The most common VR candidates are those with vestibular neuritis, not the BPPV people, and not the folks with spontaneous nystagmus. We know that VR is not a factor in recovery from the acute phase of tonic labyrinthine asymmetry.
Beck: And so, what is the primary function of the ENG test?
Desmond: In my opinion, the ENG oculomotor tracings obtained via saccades and smooth pursuit are useful as neurologic screening test. The majority of people with abnormalities on their oculomotor exams have age related, or vascular-based changes, and they don't have tumors or significant cerebellar disease. The Hallpike test is probably the most important part of the test, because benign positional vertigo is by far the most common vestibular injury. It's the easiest to diagnose and the easiest to treat. Calorics allow you to find the side and severity of a labyrinthine injury. But keep in mind that a caloric weakness may or may not be related to the patient's complaint.
Beck: If you had to pick only one tool, that served as the best and most reliable screening or diagnostic tool, what would it be?
Desmond: History! There's a wonderful quote by Dr. Joel Goebel that goes something like....
"The quality and usefulness of the history is directly related to the patience and knowledge of the interviewer!"
Beck: Alan, this is really a fascinating discussion, and I really have enjoyed working with you, but I know I need to wrap this up.
Desmond: No problem Doug.
Beck: Thanks so much for your time and efforts. I want to encourage all of audiologists working with vestibular disorders, diagnosis and treatment to purchase a copy of the book. I found it well written and again, highly pragmatic.
Desmond: Thanks Doug, I appreciate the kind words.
Vestibular Function: Evaluation and Treatment, Alan L. Desmond. Blue Ridge Hearing and Balance Clinic, West Virginia. Published by Thieme Medical Publishers. ISBN 1-58890-166-1. Published in 2004.
- - - - - - - -
Common Vestibular Terms :
ENG (Electronystagmography)
Many inner ear disorders cause an involuntary movement of the eyes called nystagmus. This nystagmus can be recorded and analyzed through ENG testing. Stimulation of the inner ear for this test includes rapid position changes of the head and body, and caloric (temperature) stimulation of the inner ear through irrigating the ear canal with different temperatures of water. The goal is to determine if both inner ears are functioning and responding equally to the stimulation. Additionally, tests of voluntary eye movement serve as a screening for possible neurologic disorders.
VAT (Vestibular Autorotation Testing)
So that we may maintain focus (or Gaze) on objects while moving our head, nature provides us with a Vestibular (inner ear)/Ocular (visual) Reflex. The impairment of this reflex action can cause imbalance or visual blurring with head movement. The VAT test determines if this reflex action is working properly at fast speeds of head movement.
Rotational Chair
Rotational chair testing allows us to stimulate the inner ear and avoid stimulating any other part of the balance system. It is a very sensitive test of inner ear abnormality. The patient is placed in a motorized rotating chair and eye movements are recorded and analyzed. The rotational chair is in our Bluefield office only, so patients undergoing screening exams in Princeton will be referred to the Bluefield office for the second appointment.
ABR (Auditory Brainstem Response)
Balance problems can come from the inner ear or the nerve pathway between the inner ear and the brain. This test involves recording the transmission of sound traveling up the auditory nerve. Hearing and balance information travel the same nerve pathway. Results of this test can help us rule out the possibility of nerve degeneration or small auditory nerve tumors that may be affecting balance and/or hearing.
SOT (Sensory Organization Test using Balance Master Posturography
Good balance depends on the efficient use of all balance information available. This test allows us to evaluate one's reaction to a variety of difficult balance situations. This is done by having the patient stand on a platform that measures center of gravity, and any sway from the center, while at the same time provoking them with conflicting balance information. By doing this, we can determine what type of situation is most likely to result in a fall. This information helps us design a customized therapy plan to enhance balance and minimize the risk of falling.
Desmond: Hi Doug: Happy to do so.
Beck: Alan, I'd like to start by mentioning that you have written a book titled "Vestibular Function - Evaluation and Treatment" (Thieme Medical Publishers ISBN 1-58890-166-1) which I think is pragmatic and highly clinically oriented.
Desmond: Thanks Doug, I tried to keep the book focused on vestibular issues that the clinicians deal with every day, the fundamentals, anatomy, physiology, tests and interpretation and related items.
Beck: I think you accomplished the goal! Nonetheless, before we talk about the book, if you don't mind, let's speak about your education and professional experiences?
Desmond: I got my master's in audiology some 22 years ago from Radford University, Virginia. I was their first audiology student. It was a small program, it only lasted for about 15 years and they closed it down about 5 years ago. After graduation I spent a year in educational audiology, and for the last 21 years I've been in a partnership with two ear, nose and throat doctors. We operate Blue Ridge Hearing and Balance Clinic in Bluefield, West Virginia. I earned my doctorate at Central Michigan and finished that about two years ago, back in 2002.
Beck: Any reflections on distance education programs?
Desmond: Well, as a person who practiced for many years before earning a doctorate, I got to see, hear and feel what clinical practice was all about while practicing with my master's...but once I earned my doctorate, I understood better what it was I was seeing, hearing and feeling. In other words, the program was amazing, it was a fantastic experience. No reservations, no regrets!
Beck: OK, thanks for sharing that. Let's get back to the book...When did the book come out, and how did you become a "vestibular expert?"
Desmond: The book was released April of 2004, during the AAA convention in Salt Lake City. There was actually never a day that I said "Today I have decided to write a book."
The story is lengthy, but here's a quick version...When I finished my CFY, I didn't think I was prepared to enter clinical audiology. I went to Stanford University Medical Center for a month, as an unpaid visiting staff member. I couldn't really afford it financially at the time, but I couldn't afford not to do it from a professional competence standpoint! That was a fantastic experience and I learned a lot very quickly. Then again, 13 or 14 years ago I decided to change the direction of my career to focus on vestibular management. Once I decided to focus on vestibular issues, I took another month off and took another position as an unpaid visiting staff, but at that point I went to the House Ear Clinic. I was there for a few weeks and that greatly accelerated my learning curve by seeing how they treated dizzy patients. I observed, listened to, annoyed and badgered anyone that I thought I could learn from. So I gathered the tools and skills and made it my focus to learn everything I could about this area. I just think we owe it to our patients to become competent before we proclaim ourselves "specialists." So then after acquiring this core knowledge, and feeling comfortable professionally, I needed a way to educate the local docs and the other referral sources on these topics to make sure they knew what I did and how I offered a different and unique approach, and why they should refer to me.
Beck: So the book started as a marketing piece?
Desmond: Yes, in some respects. I actually wrote some 40 pages outlining what I did, the different tests and treatments available, screening tests and I addressed BPPV and canalith repositioning, and most of them had no idea what those things were back then! So it was exciting, and it was effective. One of the local equipment manufacturers got hold of the 40 page booklet and pretty soon the folks at MicroMedical wanted to use it too, which was fantastic, and then while I was at Central Michigan, I expanded it further into my "Capstone Project." So that was the origin of the book and how it came to be!
Beck: Alan, I know you have a list of common "vestibular-related" terms you've defined, and allowed us to reprint...So if I may, this seems like a good time to direct the reader to the end of this interview, where they'll find associated vestibular terms such as; ENG, VNG and Rotational Chair, etc, and your preferred definitions for patients, to help the patient understand what we're talking about. I'd like to mention that these terms and definitions come from your patient hand-out, titled "Blue Ridge Hearing and Balance Clinic Vertigo handout." Thanks for allowing us to use that.
May I ask you a few specific vestibular questions?
Desmond: Sure.
Beck: OK, would you please start with a basic definition and explanation of BPPV (benign paroxysmal positional vertigo)?
Desmond: BPPV is a mechanical dysfunction of the inner ear, and it can be repaired mechanically. It is not treated with vestibular rehabilitation or habituation - in the traditional sense. It cannot be cured based on CNS plasticity, as is often the case with other types of dizziness.
My description to patients goes something like this: BPPV involves sensors, which are little particles really, sometimes called "otoliths" or "canaliths," which originate in one part of the inner ear, fall loose, and settle down in another part of the inner ear. If given a chance they'll settle down ....but if they settle in one of the semi-circular canals within the inner ear, when the patient moves their head to the offending position, the particles move and create a ripple across the inner ear fluid, causing a mismatch of information between the affected ear and the normal ear.
Beck: Why do these tiny particles shake loose in some people, but not others?
Desmond: Great question. Nobody really knows the answer, but we do know that of the BPPV patients, there is a high incidence of head trauma prior to their reporting to the office. So perhaps for many of them the particles were mechanically jolted loose. BPPV is also more common in patients with Meniere's Disease and vestibular neuritis, so maybe inflammation of the inner ear is a factor too. But as far as why these same people have recurrences...we just don't know.
Beck: Thanks Alan, good points. Let me switch gears to Vestibular Rehabilitation. In general, who are the ideal patients for vestibular rehab?
Desmond: It does vary, but people with uncompensated, stable vestibular dysfunction, or people with identified vestibular injuries with abnormal VOR gain and abnormal symmetry which is detectable using rotational chair...those people are probably the best candidates for vestibular rehabilitation (VR) and they usually get good results from VR.
Beck: Is there a particular ENG profile that indicates good candidacy for VR?
Desmond: This comes up all the time. Basically, the ENG in isolation cannot tell you whether or not the patient is a good candidate for VR. The most common VR candidates are those with vestibular neuritis, not the BPPV people, and not the folks with spontaneous nystagmus. We know that VR is not a factor in recovery from the acute phase of tonic labyrinthine asymmetry.
Beck: And so, what is the primary function of the ENG test?
Desmond: In my opinion, the ENG oculomotor tracings obtained via saccades and smooth pursuit are useful as neurologic screening test. The majority of people with abnormalities on their oculomotor exams have age related, or vascular-based changes, and they don't have tumors or significant cerebellar disease. The Hallpike test is probably the most important part of the test, because benign positional vertigo is by far the most common vestibular injury. It's the easiest to diagnose and the easiest to treat. Calorics allow you to find the side and severity of a labyrinthine injury. But keep in mind that a caloric weakness may or may not be related to the patient's complaint.
Beck: If you had to pick only one tool, that served as the best and most reliable screening or diagnostic tool, what would it be?
Desmond: History! There's a wonderful quote by Dr. Joel Goebel that goes something like....
"The quality and usefulness of the history is directly related to the patience and knowledge of the interviewer!"
Beck: Alan, this is really a fascinating discussion, and I really have enjoyed working with you, but I know I need to wrap this up.
Desmond: No problem Doug.
Beck: Thanks so much for your time and efforts. I want to encourage all of audiologists working with vestibular disorders, diagnosis and treatment to purchase a copy of the book. I found it well written and again, highly pragmatic.
Desmond: Thanks Doug, I appreciate the kind words.
Vestibular Function: Evaluation and Treatment, Alan L. Desmond. Blue Ridge Hearing and Balance Clinic, West Virginia. Published by Thieme Medical Publishers. ISBN 1-58890-166-1. Published in 2004.
- - - - - - - -
Common Vestibular Terms :
ENG (Electronystagmography)
Many inner ear disorders cause an involuntary movement of the eyes called nystagmus. This nystagmus can be recorded and analyzed through ENG testing. Stimulation of the inner ear for this test includes rapid position changes of the head and body, and caloric (temperature) stimulation of the inner ear through irrigating the ear canal with different temperatures of water. The goal is to determine if both inner ears are functioning and responding equally to the stimulation. Additionally, tests of voluntary eye movement serve as a screening for possible neurologic disorders.
VAT (Vestibular Autorotation Testing)
So that we may maintain focus (or Gaze) on objects while moving our head, nature provides us with a Vestibular (inner ear)/Ocular (visual) Reflex. The impairment of this reflex action can cause imbalance or visual blurring with head movement. The VAT test determines if this reflex action is working properly at fast speeds of head movement.
Rotational Chair
Rotational chair testing allows us to stimulate the inner ear and avoid stimulating any other part of the balance system. It is a very sensitive test of inner ear abnormality. The patient is placed in a motorized rotating chair and eye movements are recorded and analyzed. The rotational chair is in our Bluefield office only, so patients undergoing screening exams in Princeton will be referred to the Bluefield office for the second appointment.
ABR (Auditory Brainstem Response)
Balance problems can come from the inner ear or the nerve pathway between the inner ear and the brain. This test involves recording the transmission of sound traveling up the auditory nerve. Hearing and balance information travel the same nerve pathway. Results of this test can help us rule out the possibility of nerve degeneration or small auditory nerve tumors that may be affecting balance and/or hearing.
SOT (Sensory Organization Test using Balance Master Posturography
Good balance depends on the efficient use of all balance information available. This test allows us to evaluate one's reaction to a variety of difficult balance situations. This is done by having the patient stand on a platform that measures center of gravity, and any sway from the center, while at the same time provoking them with conflicting balance information. By doing this, we can determine what type of situation is most likely to result in a fall. This information helps us design a customized therapy plan to enhance balance and minimize the risk of falling.
