Central Vertigo

Etiology

Peripheral vertigo may occur as a result of problems in the peripheral vestibular system from the inner ear to the vestibular division of the eighth cranial nerve. Peripheral vertigo accounts for over 90% of all causes of vertigo.

Central vertigo occurs when there is any lesion or dysfunction of the brainstem vestibular system and its connections, as described above. Central vertigo most commonly occurs due to ischemia of the central vestibular structures in the cerebellum, brainstem, or vestibular nuclei, especially in older adults with vascular risk factors. In younger patients, acute demyelination, such as in multiple sclerosis, is a more common cause of central vertigo. Migrainous vertigo, also known as vestibular migraine, is a type of central vertigo that affects 1% to 3% of the general population. The diagnosis is more straightforward when the patient presents with recurrent vertigo associated with typical migraine headaches. However, the diagnosis can be challenging when the patient presents only with recurrent episodes of prolonged vertigo.[4] The other not-so-uncommon cause is medication-induced, especially toxicity from common anticonvulsants such as phenytoin, phenobarbital, and carbamazepine. Other ototoxic agents, such as aminoglycoside or macrolide antibiotics, and the chemotherapeutic agent cisplatin, can also induce vertigo.[5] Other less common causes include infection, trauma, and posterior fossa brain tumors.[6] 

Epidemiology

In the United States, approximately 800,000 individuals experience a stroke each year. Of these, about 85% are ischemic strokes. Among ischemic infarctions, 20% affect the posterior circulation. The most common posterior circulation stroke is lateral medullary syndrome (Wallenberg syndrome), which results from occlusion of the posterior inferior cerebellar artery or, more commonly, the vertebral artery.[7] Central vertigo is the most predominant symptom of a posterior circulation stroke.

Men tend to experience cerebrovascular disease more frequently compared to women, at a rate of about 2:1. Central vertigo can also be due to multiple sclerosis, which has an incidence of approximately 10 to 80 cases per 100,000 individuals in the United States per year and affects three times as many women as men.[8]

Migraine occurs in 12% of the adult population (6% men and 18% women). Vertigo as a presentation of migraine is not uncommon, yet the actual incidence is unknown due to differences among physicians in their diagnosis. Vertigo is probably more commonly diagnosed in otolaryngology or ear, nose, and throat (ENT) practice compared to internal medicine practice. Patients typically present with recurrent vertigo lasting for a few hours without any other ENT symptoms or focal neurological signs or symptoms. Neuroimaging studies are generally normal. The diagnosis is often made when other causes of vertigo are ruled out.[4]

Pathophysiology

Any lesion affecting the central vestibular apparatus manifests with vertigo as the main presenting symptom. Often, the central oculomotor neuro-integrators (medial vestibular nucleus and the nucleus prepositus hypoglossi) are involved, resulting in the impairment of visual fixation and clinical signs of nystagmus.

The vertebrobasilar arterial system supplies blood to the brainstem, cerebellum, and peripheral labyrinths. Occlusion of the system, therefore, can result in either central or peripheral vertigo, depending on the specific artery affected. Occlusion can occur due to atherothrombosis or an embolism such as cardioembolism or plaque from the vertebral arteries.[9] The most critical difference between peripheral and central vertigo is that peripheral vertigo presents predominantly vestibulocochlear signs and symptoms of vertigo, such as tinnitus or hearing impairment. In contrast, central vertigo is often associated with other brainstem signs and symptoms.

Vertigo may occur in the setting of multiple sclerosis, generally with a waxing and waning course due to demyelination in the brainstem. The pathophysiology of vestibular migraine remains largely unknown. However, evidence suggests the activation of the trigeminal and vestibular systems during vestibular migraine attacks.[10] Central vertigo is also commonly observed in the setting of trauma, particularly as a result of shearing forces in the brain stem and resultant petechial hemorrhages in the vestibular nuclei. 

History and Physical

The most important clinical scenario is when a patient presents to the emergency department or urgent care with acute vertigo. Most patients with vertigo have a peripheral cause, including benign paroxysmal positional vertigo, acute vestibular neuritis (or labyrinthitis), Meniere disease, or even perilymphatic fistula or superior semicircular canal dehiscence. However, clinical identification of central vertigo is of utmost importance due to the serious underlying cause of brainstem ischemia or infarction.

Obtaining a detailed history is crucial, encompassing details such as the mode of onset, duration of vertigo, relationship to posture, presence of tinnitus or hearing impairment, headache, fever, skin rash, previous episodes, any recent exposure to illness, vascular risk factors, medications and their dosage, and any brainstem symptoms such as weakness, numbness, diplopia or dysarthria.

With vestibular migraine as one of the most common causes of episodic vertigo, it is important to recognize the association of vertigo with migraine headaches. In addition to vertigo, these patients also frequently experience transient auditory symptoms, nausea,  vomiting, and heightened susceptibility to motion sickness. The diagnosis of vestibular migraine is purely clinical. However, other causes of vertigo must always be ruled out before confidently diagnosing vestibular migraine.[11]

Essential elements of the physical examination include assessing vital signs and examining for skin rash, which may suggest a diagnosis of herpes zoster affecting the external ear. The presence of a neck bruit may indicate underlying carotid or vertebral stenosis. Cardiac evaluations are always important to rule out an arrhythmia, especially atrial fibrillation or valvular heart disease, which may cause an embolic event. The Dix-Hallpike maneuver is indicated to rule out benign positional vertigo or features of central vertigo. A focused and expedited neurological examination is critical, especially for Horner syndrome and other brainstem signs (see Table 1. Clinical Features to Differentiate Central Vertigo from Peripheral Vertigo).

The HINTS test must be performed on every patient suspected of central vertigo. HINTS stands for head impulse test, nystagmus, and skew deviation. This is the best bedside test to differentiate peripheral vertigo from central vertigo. The test is valid only when the patient is still experiencing ongoing, continuous vertigo at the time the test is performed (see Table 2. HINTS Test to Differentiate Between Central Vertigo and Peripheral Vertigo).

Understanding the vestibulo-ocular reflex is essential for interpreting the HINTS test results.[12][13] The afferent pathways of the vestibulo-ocular reflex started with the semicircular canals, which provide a head velocity signal. The signal is transmitted through the vestibular division of the eighth cranial nerve to the vestibular nuclei. The vestibular nuclei on both sides with the oculomotor neural integrator provide an equal and opposite eye velocity signal to keep the eyes still in space during head movements. This mechanism is essential for activities such as talking or walking, enabling individuals to maintain visual focus on objects of interest, such as road signs. Stimulation of the right peripheral vestibular apparatus, as occurs when turning the head to the right, results in equal and opposite movement of the eyes to the left (normal vestibulo-ocular reflex gain). The vestibulo-ocular reflex gain decreases in the presence of peripheral vestibular dysfunction, resulting in a corrective eye movement (saccade) visible in the bedside examination. Vestibulo-ocular reflex gain is normal in central vestibular lesions.

The vestibulo-ocular reflex test or head thrust (also called the head impulse test) forms the basis of a clinical examination to differentiate central vertigo from peripheral vertigo. During this test, the patient is asked to look at the examiner's nose. The examiner gently and quickly thrusts the patient's head about 30 degrees to one side and looks for any catch-up saccade with the eyes. The test is positive when there is a catch-up saccade to one side. The side with a positive test is determined as the side with peripheral vestibular dysfunction. A positive head impulse test indicates a peripheral cause for vertigo and is generally not as serious prognostically.

The nystagmus in peripheral vertigo is always unidirectional, often with a rotary element, regardless of the patient's gaze direction. On the other hand, the nystagmus in central vertigo more commonly presents with direction-changing nystagmus. The nystagmus is right-beating when the patient looks to the right and changes to left-beating when the patient looks to the left. Any vertical nystagmus indicates a central cause for vertigo.

The last part of the HINTS test is a skew deviation. A skew deviation (one eye higher than another) indicates a central cause for vertigo. This skew deviation can be assessed by alternately covering the patient's eyes and evaluating for a vertical corrective saccade on the affected side.

Table 1. Clinical Features to Differentiate Central Vertigo from Peripheral Vertigo

Table 2. HINTS Test to Differentiate Between Central Vertigo and Peripheral Vertigo

Evaluation

As described above in the History and Physical section, tests, such as the Dix-Hallpike test and simple screening tests for hearing, are important in evaluating potential causes of peripheral vertigo. A thorough neurological examination should be performed, including an assessment of extremity and truncal ataxia, gait, and HINTS test. 

When the examination findings suggest central vertigo, the patient must be further evaluated, often requiring hospitalization. Magnetic resonance imaging (MRI) of the brain is the imaging modality of choice for visualization of a potential infarction, tumor, hemorrhage, or evidence of demyelination that would reveal the cause of central vertigo. Computed tomography (CT) may be employed if MRI is unavailable. CT angiogram and MR angiogram may be performed at the same time or sequentially to identify any occlusion of the vertebrobasilar arterial system, which may be the cause of vertigo. Prompt evaluation is critical to improve the outcome, especially in preparation for thrombolytic therapy in the emergency department or interventional treatment. MRI has reduced sensitivity in the first 48 hours following posterior circulation stroke, and a positive HINTS result, regardless of imaging findings, is worrisome.

Treatment / Management

The initial approach to a patient presenting with vertigo involves distinguishing primary vertigo from other forms of dizziness caused by factors like impaired cerebral perfusion (pre-syncope), medication, or alcohol. Once a diagnosis of central vertigo has been established, treatment is aimed at the underlying cause. Imaging studies should be conducted as soon as possible for patients reporting vertigo. Patients should not be left unattended until a thorough examination is completed and a diagnosis is established. Most of the time, the patients must be admitted to the hospital to treat the underlying cause of vertigo.

Thrombolytic therapy should be considered if the patient is experiencing an acute posterior circulation ischemic stroke within 3 to 4.5 hours of onset. However, it is critical to be aware of any contraindications to thrombolytics, such as recent surgery, severe hypertension, evidence of acute hemorrhage or edema, or rapidly improving symptoms.[14] If neuroimaging shows evidence of large vessel occlusion within the 12-hour time window for posterior circulation, particularly in cases of basilar artery occlusion, the patient may be eligible for mechanical thrombectomy even beyond the 4.5-hour thrombolytic window.[15](A1)

Patients with an altered level of consciousness warrant an electrocardiogram, pulse oximetry, and close supervision. If a patient's condition worsens, emergent interventions may be required to decrease intracranial pressure and minimize compression of the brainstem. These interventions may include endotracheal intubation with or without hyperventilation, aggressive diuresis, and corticosteroids.

Finally, a neurological consultation is always warranted for a patient reporting vertigo, and a neurosurgical consultation is necessary if underlying hemorrhage, edema, or brainstem compression is discovered, as surgical decompression such as ventriculostomy or craniectomy may be required.

A course of an intravenous corticosteroid is indicated if the cause is an acute demyelinating event of multiple sclerosis; methylprednisolone 1 g per day administered intravenously for 3 to 5 days would be appropriate.[16]

Differential Diagnosis

The most important differential diagnoses are the causes of peripheral vertigo.[17] The most important ones in the emergency setting are acute labyrinthitis or vestibular neuritis, both of which present as acute vestibular syndromes resembling central vertigo. These patients present with an acute onset of extremely severe vertigo with nausea and vomiting, along with prominent peripheral unidirectional nystagmus.

Benign paroxysmal positional vertigo is a common cause of peripheral vertigo. The diagnosis can easily be made through the Dix-Hallpike maneuver and treated with the repositioning maneuver. Recurrent vertigo with tinnitus is indicative of Meniere disease, and low-frequency hearing impairment can be easily documented with audiometry. A gradual onset of hearing loss with infrequent vertigo and later facial paresis and ataxia may indicate the presence of a slowly enlarging tumor in the cerebellopontine angle, such as a vestibular schwannoma or meningioma. Migraine as a cause of recurrent vertigo is more a diagnosis of exclusion when other causes are excluded with a detailed history, physical examination, and normal imaging studies.[18]

Prognosis

The prognosis of central vertigo depends on the underlying cause. Vertigo due to vestibular migraine generally carries an excellent prognosis. The most common cause of central vertigo is acute lateral medullary syndrome due to occlusion of the vertebral artery or the posterior inferior cerebellar artery. Patients often recover relatively good functional outcomes with appropriate therapy. On the other hand, basilar thrombosis carries a much worse prognosis with significantly higher mortality rates. Brainstem involvement as a presentation of acute demyelination typically due to multiple sclerosis does make the prognosis worse compared to other patients without brainstem relapse. However, the acute relapse does tend to remit commonly after a course of intravenous steroids. Yet, the long-term prognosis depends on different factors, including the age, gender, frequency, and severity of relapses.