You down with 3PD? Persistent Postural-Perceptual Dizziness
Persistent postural-perceptual dizziness (3PD or PPPD) is a non-specific form of dizziness and one of the most common causes of dizziness, second only to BPPV...remember, the crystals? (1). 3PD is a form of non-vertiginous (non-spinning) dizziness, commonly described as rocking or swaying, that has been going on for more than 3 months. Symptoms are usually present on more days than not and are generally worse with upright standing or seated posture, self-initiated or passive head or body movement, and in visually busy environments (i.e. crowds, supermarkets, driving with the windshield wipers going). Symptoms can also be constant, but may wax and wane in severity. Symptoms are often (but not always) precipitated by an acute dizzy event such as BPPV, concussion, vestibular neuritis, or even a panic attack.
Symptoms are often challenging to describe, but I've had patients do a wonderful job with their analogies saying things like "it feels like I'm walking on marshmallows" or "it feels like I'm in an elevator that is descending way too fast". I appreciate these descriptions as it not only helps me arrive at a diagnosis, but also helps me empathize with just how disorienting and scary this condition can be.
Diagnosing 3PD can be a challenge since many other diagnosis can have elements of 3PD and 3PD is precipitated by many of these other diagnoses. For example:
People with Persisting Post-Concussive Symptoms (PPCS) and Vestibular Migraine (VM) can experience dizziness in visually stimulating environments like scrolling on their computer, or driving while the sun is glinting through the trees.
People with Mal de Debarquement Syndrome (MdDS) can experience a non-vertiginous (non-spinning) dizziness described as rocking or being on a boat.
People with Postural Orthostatic Tachycardia Syndrome (POTS) can experience dizziness with upright postures.
Therefore, understanding a person's experience of dizziness and it's course through their history is of upmost importance when diagnosing 3PD. Luckily, we now have diagnostic criteria established by the Barany's Society to help facilitate this process.
Diagnostic Criteria for Persistent Postural-Perceptual Dizziness (1)
A. One or more symptoms of dizziness, unsteadiness or non-spinning vertigo on most days for at least 3 months.
Symptoms last for prolonged (hours-long) periods of time, but may wax and wane in severity.
Symptoms need not be present continuously throughout the entire day.
B. Persistent symptoms occur without specific provocation, but are exacerbated by three factors: upright posture, active or passive motion without regard to direction or position, and exposure to moving visual stimuli or complex visual patterns.
C. The disorder is triggered by events that cause vertigo, unsteadiness, dizziness, or problems with balance, including acute, episodic or chronic vestibular syndromes, other neurological or medical illnesses, and psychological distress.
When triggered by an acute or episodic precipitant, symptoms settle into the pattern of criterion A as the precipitant resolves, but may occur intermittently at first, and then consolidate into a persistent course.
When triggered by a chronic precipitant, symptoms may develop slowly at first and worsen gradually.
D. Symptoms cause significant distress or functional impairment.
E. Symptoms are not better accounted for by another disease or disorder.
It's NOT in your head, but it's not NOT in your head
So, what is actually going on when someone is experiencing dizziness from 3PD? It can be a tough diagnosis for patients to wrap their heads around...it took me lots of reading and sifting through journal articles and case studies to understand it myself. Some patients get the impression it's a psychological diagnosis and that providers are telling them "it's all in their head". It is NOT a psychological diagnosis. It is actually a functional disorder, meaning there is an issue with how your nervous system is functioning, how it sends and receives signals. Neuro-imaging has actually shown different levels of neurological activity in specific parts of the brain in people with 3PD when compared to control subjects (2). It's very common to describe functional disorders as a software problem, rather than a hardware problem, of the nervous system. Since I don't expect my patients to learn about 3PD as I did, I try to simplify it with the following:
In order for our brain (and therefor us) to understand where we are in space, it receives messages from the environment through our visual system, vestibular system, and our somatosensory system (our body's ability to feel the surface we are standing, walking, sitting, lying on). Messages from these three systems meet in the brain and the brain interprets these messages to say "hey...we're riding in a car at about such and such a speed" or "now we're walking on a beach" or "getting up from laying down in bed". The brain then reflexively sends messages back out to our muscles to respond appropriately in order to keep us upright (vestibulo-spinal reflex) and keep our visual world in focus (vestobulo-ocular reflex). It does this by contracting and relaxing certain muscles so we don't topple over while walking on soft, uneven sand or so we can keep our gaze stable on street signs or other people when riding in a car or walking. This is automatic and we don't have to think about it. I call this our "bottom-up" strategy because it originates in the peripheral nervous system through sensation in our body, our eyes, and our inner ears). It's an amazing, intricate, and beautifully orchestrated strategy...when it's working properly.
We also have the conscious ability to keep ourselves upright and balanced. For example, when you're walking on an icy street or about to step onto a rocking boat, you preemptively contract certain muscles, place your feet a little wider, walk a little slower in anticipation of this being a challenge to your balance. Unlike the bottom-up strategy, when this strategy is being used, you are very aware of it, taking stock of each step, preparing for a potential loss of balance. I call this our "top-down" strategy because it originates in our brain.
Normally, if we suddenly feel dizzy, we employ the top-down strategy to help keep us safe and prevent us from falling. This is normal. It is also normal for this strategy to dissipate once the threat of falling or imbalance is gone and we go back to our normal activity. We start using our bottom-up strategies once again and don't have to think about our balance. If you have 3PD, you are stuck in the top-down strategy loop (see infograph below) and are constantly in a vigilant, protective state...always thinking about your balance, your symptoms, why they are happening, when will the happen, what is the pattern or the cause, and what can you do to make it better or just stop. This top-down strategy is so strong, it over-rides the bottom-up strategy, preventing the bottom-up strategy from functioning properly (remember...a software problem). When this happens, you are not able to take in and process sensory information (somatosensory, vision, vestibular) correctly. More often than not, you become highly reliant on visual information and your brain isn't processing the appropriate amount of somatosensory or vestibular information to tell you where you are in space. This has been shown in neuro-imaging studies. This is why your dizziness can be provoked by visually stimulating environments or why you feel like you're walking on clouds/cotton balls/marshmallows.
NOT down with 3PD? There's treatment
While much is to be learned about the treatment of 3PD, many studies demonstrate the efficacy of a 3-pronged approach consisting of: pharmacological management of SSRIs or SNRIs (selective serotonin/norepinephrine uptake inhibitor) to calm the nervous system, vestibular rehabilitation therapy to address dizziness and balance deficits, and Cognitive Behavioral Therapy to address any anxiety or hyper-vigilance over symptoms (2,3).
Vestibular rehab for 3PD
Vestibular rehab for persons with 3PD is highly tailored to the patient and their specific symptom triggers and balance impairments. It should be delivered by a physical therapist who specializes in vestibular rehabilitation with expertise beyond treating common conditions like BPPV. Treatment consists thorough education on the diagnosis and treatment plan, habituation exercises, and balance and gaze stability exercises.
Habituation exercises can be thought of as a kind of graded exposure to visual stimuli and head and body movements which trigger a person's symptoms. These exercises are carefully graded to bring on a mild-moderate degree of symptoms, but not push the person too far that their top-down strategy takes over.
Balance exercises focus on various static (still) and dynamic (moving) balance positions which are of particular challenge to that person. For some this can be balancing postures with eyes closed, on various types of surfaces, or while performing a cognitive or motor task at the same time.
Gaze stability exercises help the person keep their world and objects in their world stable while their head is moving. This can be focusing on a small target while moving your head, while moving from sitting to standing, while getting in/out of bed, or while walking and/or running.
Again, the exercise program is highly individualized and tailored to address the specific triggers or challenges experienced by that person.
If you have been diagnosed with 3PD, or resonate with some of the descriptors of dizziness in this article, please reach out to your healthcare provider or a vestibular rehabilitation therapist. If they are unfamiliar with this diagnosis, share this article or the ones listed below. While it's a common diagnosis, it is still not well known among many healthcare professional. Education is key!
Staab JP, Eckhardt-Henn A, Horii A, et al. Diagnostic criteria for persistent postural-perceptual dizziness (PPPD): consensus document of the committee for the classification of vestibular disorders of the bárány society. J Ves Res 2016.
Popkirov S, Staab JP, Stone J. Persistent postural-perceptual dizziness (PPPD): a common, characteristic and treatable cause of chronic dizziness. Practical Neurology. 2018;18(1):5-13.
Nada E, Ibraheem O, Hassaan M. Vestibular Rehabilitation Therapy Outcomes in Patients With Persistent Postural-Perceptual Dizziness. Annals of Otology, Rhinology & Laryngology.