A neurologist’s approach to dizziness
There’s nothing like a good screenshot from The Matrix to lure you into a blog entry on vertigo. But really, I think this is one of the most visually aesthetic depictions of the phenomenon of palinopsia. Broadly speaking, palinopsia refers to the visual illusion of a persistent image after the stimulus has subsided. It is an afterimage, and it is one of the findings you can observe in patients with dizziness.
In our latest episode, Dr. Ali Hamedani (who you may recall has given several impressive talks for BrainWaves on painless ophthalmoparesis and nystagmus) ventures into the realm of neuro-otology to bring us his approach to patients with dizziness. For those interested in more visual learning on the topic, check out Dr. Hamedani’s powerpoint on his Approach to Dizziness. But for those looking for the Cliffs Notes, here you go.
Dr. Hamedani introduces the concept of dizziness by breaking it into 4 major categories:
- Acute constant dizziness
- Transient positional dizziness
- Recurrent spontaneous dizziness
- Chronic progressive dizziness
Note that he does not use the term vertigo here, because defining vertigo can be extremely difficult for many patients. But for the sake of completeness, I will acknowledge that the dizziness he references is vertiginous–meaning the patient perceives the illusion of movement in its absence. And the movement can be that of the patient or the surrounding world. This is extremely important to distinguish from other types of dizziness, like lightheadedness or faintness which likely represents orthostatism, or imbalance which likely represents a sensory disturbance. Sometimes such features are difficult to distinguish, so in this episode Dr. Hamedani will address some of these conditions when reviewing his four major categories of dizziness.
Acute constant dizziness, like other forms of dizziness, can either be central or peripheral in origin. If the dizziness comes on suddenly and persists for several minutes or longer, you can call it acute constant dizziness. In an adult, you should be thinking vestibular neuritis (dizziness without hearing loss) or labyrinthitis (dizziness with hearing loss), or brainstem/cerebellar stroke or demyelinating event. Some rules of thumb to consider in differentiating peripheral (vestibular neuritis) from central (stroke) causes of acute constant dizziness are the character of symptoms. The nausea/vomiting of peripheral vertigo is typically far more severe than that of central dizziness, but an expanding cerebellar hemorrhage can definitely cause severe nausea and vomiting. The dizziness associated with a central process is also often accompanied by other focal neurologic deficits (long tract signs like corticospinal weakness, numbness, or cranial neuropathies). The HINTS evaluation may be useful in ruling in a central cause of dizziness, but if all elements of HINTS testing indicate a peripheral etiology, you can be almost 100% reassured you’re not dealing with a stroke.
Transient positional dizziness almost always means benign positional vertigo (BPV). That being said, rapid transition from laying to sitting upright, or sitting to standing can cause temporary cerebral hypoperfusion with resultant dizziness (orthostasis) that does not equate to vertigo. Checking orthostatic vital signs and an EKG are not bad ideas for many patients with these symptoms. But for those with subjective dizziness with head tilts or turns, you’d be more inclined to believe this is a case of BPV. Central causes of vertigo simply don’t fluctuate with positions (except rare cases of brainstem TIAs or progressive ischemic events). BPV is the #1 cause of recurrent vertigo in adults, and almost 1 in 30 of us will have BPV at some point in our lives. Abnormal stimulation of the cupula of any of the 3 semicircular canals will produce the perception of head movement in its absence (duh, vertigo), and nearly 90% of cases are due to otoconia stimulating the hair cells in the posterior canal–because it’s the lowest hanging of the 3. What is critical to recognize here is that this type of vertigo, while symptoms are severe, is very transient. Like seconds transient. If you think your patient has BPV but they still have vertigo a minute after the head is stabilized, it’s probably not BPV… But if you find someone who has it, the AAN has developed a Practice Parameter for the management of these patients which is worth reviewing. Here is a summary of the nystagmus types you will see in BPV, along with the maneuvers that induce them.
Next we have recurrent spontaneous dizziness. Several major considerations pop up when you
have a patient who meets these criteria (and the dizziness is NOT positional!). Vestibular migraine usually occurs in patients with a history of headaches or migraines–but not always–and lasts 5 min to 72 hours with symptoms of vertigo, palinopsia, nystagmus (which produces oscillopsia), and/or nausea. Vestibular migraine should be distinguished from basilar migraines (largely a childhood disorder) in that the dizziness persists throughout the episode whereas dizziness in basilar migraines is brief (minutes) and precedes the migraine headaches. Meniere’s disease, while known for its recurrent episodes of dizziness (usually >20 minutes but can last hours, just like vestibular migraine), also causes tinnitus, aural fullness, and a progressive low-frequency sensorineural hearing loss. An overview on the treatment of Meniere’s is shown to the right. Other causes of recurrent spontaneous dizziness are vestibular paroxysmia (essentially the VIIIth cranial nerve version of trigeminal neuralgia, and also responsive to carbamazepine), superior canal dehiscence, panic attacks, and transient ischemic attacks.
Finally, the category of chronic progressive dizziness. I think this was Dr. Hamedani’s favorite category, so I’ll let him describe it to you. For those who just want a differential:
- Structural (e.g. vestibular schwannoma, cerebellopontine angle meningioma or metastasis)
- Toxic (aminoglycosides, platinum-based chemotherapy, sodium channel blocking antiepileptic drugs)
- Autoimmune (rare – isolated, SLE, Susac, Cogan)
- Mal de debarquement – persistent sensation of motion after getting off boat/airplane
- Chronic subjective dizziness
As usual, Ali’s episodes are always quite dizzying. So take your time listening to this broadcast. Next time we will try a less generalizable topic.
Kerber KA. Acute constant dizziness. Continuum (Minneap Minn). 2012;18:1041-59.
Lempert T. Vestibular migraine. Semin Neurol. 2013;33:212-8.
Kim JS and Zee DS. Clinical practice. Benign paroxysmal positional vertigo. The New England journal of medicine. 2014;370:1138-47.
Kattah JC, Talkad AV, Wang DZ, Hsieh YH and Newman-Toker DE. HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke; a journal of cerebral circulation. 2009;40:3504-10.