Vertigo: Pathology review

Definitions & Key takeaways

Vertigo is defined as an illusion of movement that's either self-movement or movement of the surrounding environment. Vertigo is classified into peripheral and central vertigo. Peripheral vertigo is caused by disorders like benign paroxysmal positional vertigo (BPPV), vestibular neuritis, Meniere's disease, and an acoustic neuroma. Causes of central vertigo include posterior circulation stroke, brainstem or cerebellar tumors or lesions.

Diagnosis is made based on clinical presentation and the patient's history, but sometimes imaging studies are required to rule out central causes like a posterior circulation stroke. Treatment depends on the underlying causes and may include medications like antiemetics and benzodiazepines, or even surgery.

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Case Study0:00–0:51

At the family medicine center, there’s a 55 year old female, named Juliette, who came to visit the doctor because she has had some episodes where she felt like “everything around her was moving”.
These episodes start abruptly and usually last a few hours. She also complains of ringing in her left ear and feels that she can’t hear very well from that ear.
Her medical history is otherwise insignificant. Clinical examination reveals horizontal nystagmus.
Next to Juliette, there’s a 70 year old male, named Alasdair, who is brought in by his son because an hour ago he felt that “the room around him was moving” and had difficulty in speaking.
He also complains of “seeing double”. Alasdair has hyperlipidemia and hypertension.
Clinical examination reveals vertical nystagmus. Alright, so both Juliette and Alasdair have vertigo.

Pathology0:51–2:01

People with vertigo will often say they get “dizzy,” which is an imprecise term. What they are experiencing is either vertigo, syncope or presyncope, also known as lightheadedness, or disequilibrium.
The difference is vertigo can be thought of as having an illusion of self-motion, or movement of the surrounding environment; syncope is the feeling of blacking out or fainting; and disequilibrium causes a sensation of being off balance without the sensation of the environment moving.
Vertigo arises when there’s a mismatch between other sensory systems, like sight and proprioception, and the vestibular system.
The vestibular system is made of the vestibular apparatus; including the three semicircular canals, the utricle and saccule, the vestibular nerve, and the vestibular structures in the brainstem and cerebellum.
Vertigo can be broken down into peripheral vertigo, which is due to damage to the vestibular apparatus, or damage to the vestibular nerve, and central vertigo, which is due to damage to the vestibular structures in the brainstem or cerebellum.Okay, let’s take a closer look at the causes of peripheral vertigo.

Benign PPV2:01–2:41

So benign positional paroxysmal vertigo, or BPPV, is by far the most common cause of peripheral vertigo. We normally have calcium carbonate crystals in the utricle and saccule, but the problem arises when they sneak into the semicircular canals, most commonly, the posterior canal.
The crystals obstruct the normal flow of endolymph in the canals when the head moves in a specific direction. Like stones causing turbulence in a smooth river.
Without normal endolymphatic flow, the semicircular canal can’t properly detect angular acceleration, causing vertigo. Vestibular neuritis, or labyrinthitis, is an inflammation of the vestibular portion of the 8th cranial nerve.

Vestibular neuritis2:41–3:05

These often occur after an upper respiratory infection causes an inner ear infection. A high yield fact is that unlike otitis media, which is most commonly bacterial in origin, vestibular neuritis or labyrinthitis are typically caused by viruses.
Alright, now moving onto Ménière’s disease, which is a high yield disorder! It affects the inner ear and is characterized by having excess of endolymph in the semicircular canals due to impaired resorption of the endolymphatic fluid.

Ménière’s disease3:05–3:32

That’s why it’s also called endolymphatic hydrops. The increased volume of the endolymph can lead to damage of the cochlea and the vestibular system of the inner ear.
Now, an acoustic neuroma, which is a schwannoma of the eighth cranial nerve, also known as the vestibulocochlear nerve, can also cause peripheral vertigo.

Acoustic neuroma3:32–4:26

This tumor arises from Schwann cells which are a subtype of glial cells that surround and support the peripheral nervous system neurons.
It’s usually slow-growing and benign meaning that the cells don’t invade surrounding tissue structures. Now, a small number of schwannomas are related to a disease called neurofibromatosis type 2.
In neurofibromatosis type 2 there’s a deletion on chromosome 22. This mutation inactivates merlin, allowing Schwann cells to divide uncontrollably.
As a consequence, several schwannomas develop in multiple locations. For the exams, a high yield fact is that it causes acoustic neuromas on both vestibulocochlear nerves at the cerebellopontine angle.
Finally, there are some medications like aminoglycosides, anticonvulsants like phenytoin, and the antimalarial quinine, that are toxic to the vestibular system.

Medications4:26–4:39

Alright, now when it comes to the central causes of vertigo, an ischemic posterior circulation stroke, or vertebrobasilar insufficiency are the most common and most worrisome causes.

Central causes4:39–5:15

These strokes usually involve the posterior or the anterior inferior cerebellar arteries. These arteries supply the cerebellum which helps with muscle coordination and balance.
Tumors on the brainstem such as a pilocytic astrocytoma can also compress the vestibular structures in the brainstem. Other disorders that damage the cerebellum, like multiple sclerosis, can also be a central cause of vertigo.
Alright, so whatever the cause, we end up with vertigo, so let’s go over some high yield signs and symptoms. Now, in both types of vertigo, nystagmus; which is a rhythmic oscillation of the eye, can occur.

Clinical Presentation5:15–10:32

The nystagmus can be present at rest, or they can be provoked by the Dix-Hallpike maneuver. But there are subtle nuances in the nystagmus that can help you differentiate peripheral from central vertigo on the exam!
In central vertigo, the direction of the nystagmus can be horizontal, torsional or rotatory, and vertical. In peripheral vertigo, nystagmus can be horizontal or torsional, but never vertical.
Also, in central vertigo, there usually is no lag time between the Dix-Hallpike maneuver and the onset of nystagmus, and the nystagmus usually lasts for more than 1 minute.
In peripheral vertigo, there’s usually a 2 to 40 second lag time between the maneuver and the onset of nystagmus, and the nystagmus lasts for less than 1 minute.
Finally, the Dix-Hallpike maneuver usually provokes mild vertigo in central vertigo, compared to more severe vertigo in peripheral vertigo.
Another thing associated with central causes is skew deviation where the eyes move upwards and rotate counterclockwise. This is normally due to damage to the prenuclear vestibular nerve input in the brain stem.
Other associated symptoms also provide a clue. For example, in the exams if you see the 4 Ds: diplopia, dysphagia, dysarthria, or dysmetria, think of central vertigo, whereas auditory symptoms like hearing loss or tinnitus suggest peripheral vertigo.
There are also characteristics of the symptoms that can help you identify each specific disorder. BPPV causes recurrent episodes of vertigo that are provoked by a specific and predictable change in head position, such as rolling out of bed.
Episodes last less than one minute, and can be accompanied by nausea or vomiting, which can be present in all cases of vertigo.
A high yield fact is that hearing loss and tinnitus are usually absent in BPPV. In comparison with BPPV, vestibular neuritis causes acute, severe, constant, peripheral vertigo lasting several days.
Head movement can worsen the symptoms, but the symptoms can occur at rest and don’t rely on a specific position. Also, unlike BPPV, there may be hearing loss.
Individuals with vestibular neuritis sometimes have a prior viral upper respiratory tract infection. Now, Ménière’s disease typically starts between the ages of 20 and 40.
Individuals with Ménière’s disease typically develop a triad of symptoms: recurrent episodic vertigo, sensorineural hearing loss, and tinnitus, and that’s something you absolutely have to remember for the exams!
Additional symptoms include a sense of ear fullness, also referred to as aural fullness. The onset of symptoms is usually abrupt, and episodes usually last from 20 minutes up to 24 hours.
Typically, there are long periods of remission in between clusters of vertigo attacks, and triggers include high salt intake, caffeine, alcohol, and nicotine.
Medications like aminoglycosides, anticonvulsants, and antimalarials usually affect both the right and left vestibular systems roughly equally, they balance out each other, so individuals rarely experience vertigo.
Instead, the vestibular-ocular reflex is impaired and individuals experience oscillopsia; which is a visual disturbance where the environment oscillates, moving back and forth repeatedly when the individual looks in any direction.
Moving onto acoustic neuroma. Since the tumor grows slowly, the central nervous system has time to compensate for the vertigo, making the symptoms very subtle.
Therefore, individuals with acoustic neuromas are more likely to notice symptoms like hearing loss and tinnitus before vertigo.
Alright, now let’s talk about some symptoms that can be seen in central vertigo. A stroke that involves the posterior circulation can present with vertigo and nystagmus.
If the posterior inferior cerebellar artery is the cause, then cranial nerves IX (9), X (10), and XI (11) can also be affected so there can be symptoms like dysphagia and hoarseness.
Now, when the anterior inferior cerebellar artery is involved, cranial nerve VII (7) can be affected causing paralysis of only the lower half of the face on the contralateral side as the lesion, since the upper half of the face is still receiving some information from the ipsilateral motor cortex.
The facial nerve also provides fibers to the lacrimal glands, the salivary glands and to the taste buds of the anterior ⅔ of the tongue and so there’s also decreased lacrimation, salivation, and taste from the anterior ⅔ of the tongue.
Brainstem tumors like pilocytic astrocytomas can also cause more general symptoms like headaches, a lack of weight gain, nausea and vomiting.
Alright, now let’s switch gears and talk about diagnosis. The diagnosis of BPPV is confirmed by exacerbation of vertigo or nystagmus on one side during the Dix-Hallpike maneuver.

Diagnosis 10:32–13:08

To perform the Dix-Hallpike maneuver, you have to extend the neck and turn it to one side while the individual is sitting.
Then, you have to rapidly place them in a supine position so that their head hangs over the edge of the bed. On a positive test there will be nystagmus or vertigo.
If no nystagmus or vertigo occur, repeat by turning the head to the other side. Now, the diagnosis of vestibular neuritis is based on the symptoms and the patient's history of having prior viral upper respiratory tract infection.
The diagnosis of Ménière’s disease is based on a person having the classic symptoms. Audiometry is done to assess hearing loss.
In general, if a brain tumor like a schwannoma is suspected, the next step is a brain MRI with contrast, which is optimal for identifying soft tissue structures like tumors.
But to accurately make the diagnosis of a brain tumor, a tissue sample is needed for histopathological and molecular studies.
This sample can be obtained by stereotactic biopsy or by surgical resection of the tumor. A high yield fact you have to know is that schwannomas have a biphasic appearance, meaning they have alternating regions with different cell patterns, called Antoni A and Antoni B.
Areas with an Antoni A pattern are hypercellular, meaning they have lots of tightly packed Schwann cells with elongated or spindle-shaped nuclei and little surrounding cytoplasm.
They can also have Verocay bodies, which are fibrous cell processes, between two rows of palisading, or lined-up, Schwann cells.
Now, areas with an Antoni B pattern are hypocellular, with fewer, more loosely packed Schwann cells that appear scattered.
Also, another clue for the diagnosis of schwannomas is that they’re positive for S100 antibody stain. Alright, now let’s move onto central vertigo.
Another high yield fact you have to know is that a stroke should be considered in any elderly individual with new-onset, acute vertigo without an obvious cause.
If the individual has vertigo along with other neurological symptoms such as hemiparesis, numbness, dysphagia or ataxia, then a brain MRI needs to be done to look for evidence of a stroke, because it’s more sensitive then doing a non-contrast brain CT scan.
Okay, now finally, let’s discuss treatment. The treatment of BPPV is the Epley maneuver, which aims at guiding the lost crystals back into the utricle where they belong.

Treatment 13:08–16:20

This is an important maneuver since it’s very simple to perform and is highly effective! Let’s say an individual has right-sided BPPV based on the Dix-Hallpike maneuver.
With the individual upright, grasp their head on both sides, and rapidly place them in the supine position with the right ear pointing downwards.
Then immediately rotate the head to the left side so that the right ear points upwards. Hold this position for 30 seconds.
Next, ask the individual to turn their body to the left side, and then rotate their head until their nose is pointing towards the floor.
Hold this position for 30 seconds, then rapidly lift the individual back to the upright position. Works like magic.
Because BPPV can recur, individuals are taught a modified version of the Epley maneuver that they can do themselves. First, in the sitting position, the individual should turn their head about 45 degrees to the affected side, let’s say the right side.
Then, lie down supine, and wait for 30 seconds. Next, without raising the head, turn it 90 degrees to the left, and wait again for 30 seconds.
Next, turn the body 90 degrees to the left, and wait another 30 seconds. Finally, sit up on the left side.
The modified Epley maneuver should be performed 3 times a day until the individual has no symptoms for at least 24 hours.
For vestibular neuritis, or labyrinthitis, although there’s conflicting evidence, corticosteroids can be given to help the inflammation.
In Ménière’s disease, initial treatment is to limit salt, caffeine, alcohol, and nicotine, which improves health in a number of ways.
If symptoms persist, diuretics such as hydrochlorothiazide and acetazolamide can be used. After that, surgical options like a labyrinthectomy can be considered.
Schwannomas can be treated with surgical resection or with stereotactic radiosurgery where a focused beam of radiation is used to destroy the tumor.
Alright, now when it comes to causes of central vertigo, in an ischemic stroke, the treatment of choice is thrombolysis with recombinant tissue plasminogen activator, or rtPA.
The ischemia is most severe in the core of the ischemic area, where the cells die first, and slightly less severe in the surrounding areas.
But if the blood flow isn’t reestablished within a few hours, cells in the surrounding area will also suffer irreversible damage and die, causing long-standing brain damage.
This is why rtPA treatment is time sensitive and should be given intravenously within 3 hours of symptom onset for elderly individuals or those with diabetes, and within 4.5 hours for other individuals.
Surgical treatment of pilocytic astrocytomas is often sufficient, though radiation of the tumor area after surgery may be used to prevent any recurrence.
If the tumor is located in an inoperable region of the brain, a class of medications called BRAF-inhibitors may be an option.
##SummaryAll right, as a quick recap… Vertigo is defined as an illusion of movement that’s either self-movement or movement of the surrounding environment.

Review16:20–17:00

Vertigo is classified into peripheral and central vertigo. Peripheral vertigo is caused by disorders like BPPV, vestibular neuritis, Ménière’s disease and an acoustic neuroma, while the causes of central vertigo include posterior circulation stroke and brainstem or cerebellar tumors or lesions.
A diagnosis can be made based on clinical presentation and patient’s history, but sometimes imaging studies should be done to rule out central causes like a posterior circulation stroke.

Summary17:00–17:32

Now, back to the patients! Both Julliette and Alaisdair have vertigo.
Due to the direction of the nystagmus, Julliette can have either peripheral or central vertigo, while Alaisdair has central vertigo.
Julliette has the classic triad of symptoms of Ménière’s disease; vertigo, tinnitus, and hearing loss. Now, for Alaisdair, due to his age, medical history of hyperlipidemia and hypertension, and the vertical direction of the nystagmus, a brain MRI must be done to check for signs of a stroke or a tumor.