Vertigo: Pathology review

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.

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.

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.

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.

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.

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.

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.

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.

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.