By Danielle Eifler,
DVM, DACVIM (Neurology) Certified Veterinary Neurosurgeon
What is Vestibular Syndrome?
Vestibular Syndrome consists of a group of clinical signs that indicate dysfunction of the vestibular system. The vestibular system is part of the nervous system that is responsible for balance. The vestibular system has 2 main components, the peripheral vestibular system and the central vestibular system.
The peripheral vestibular system consists of the peripheral vestibular nerve that travels deep within the middle and inner ear. The central vestibular system is located in the brainstem. Basically, the vestibular system's control center is in the brain which receives input from the sensory component of the peripheral system in the ear.
The peripheral system senses changes in movements and head position and relays this information to the brain so that posture can be adjusted appropriately. Classic signs of vestibular dysfunction include a head tilt, circling/rolling/falling to one side, and abnormal, rapid, rhythmic eye movements (nystagmus). The type and character of these signs can sometimes give clues as to whether or not the problem involves the central or peripheral vestibular system, but it is not always possible to determine the exact location.
What Conditions Cause Vestibular Signs?
The most common diseases that cause peripheral vestibular signs are ear infections and idiopathic vestibular disease (the term idiopathic means that no underlying cause can be found). Causes of central vestibular signs include brain tumors, strokes, toxins, metabolic diseases, and encephalitis/meningitis (infection or auto-immune inflammatory diseases). Because the potential cause and therefore the prognosis is often more serious with central vestibular syndromes, it is helpful if it is possible to determine if the vestibular signs are more consistent with central or peripheral vestibular syndrome. Again, it is not always possible to differentiate between these locations.
How Can The Cause of the Vestibular Signs Be Diagnosed?
Diagnostic testing often involves multiple tests to try and rule out the other possible causes discussed above. Bloodwork may be performed to assess the overall health of the patient as well as x-rays of the chest and possibly abdominal x-rays or ultrasound if indicated. To visualize the ear and brainstem, an MRI is most useful. A CT scan also can be performed of this area though the detail that is obtained with an MRI is generally superior. A cerebrospinal fluid analysis and infectious disease testing may also be recommended.
What Is The Prognosis Associated With Vestibular Syndrome?
Prognosis depends on the underlying cause of the vestibular signs. Infections in the ear may be treated with antibiotics and surgery if necessary. Brain tumors may be amenable to surgical resection or radiation therapy depending on the tumor type and precise location. Central nervous system infections can sometimes be treated with antibiotics, however, the response to therapy depends on the particular infectious organism involved. Auto-immune inflammatory diseases such as Granulomatous Meningoencephalomyelitis (GME) may respond to immunosuppressive medications for a period of time. Patients often improve if they have experienced a stroke depending on the underlying cause of the stroke. Response to therapy for metabolic and toxic causes depends on many factors.
One of the most common forms of vestibular syndrome is Idiopathic Vestibular Disease. This is also known as Geriatric or “Old Dog” Vestibular Disease. Cats and dogs can both be affected by idiopathic vestibular disease which involves a sudden onset of vestibular signs and no underlying cause can be found. These signs often resolve over time (marked improvements are usually seen within 24-72 hours) though head tilts can remain. Nobody knows for certain why these signs can occur suddenly and then resolve quickly but relapses can occur. Idiopathic vestibular syndrome typically only causes signs that are consistent with peripheral vestibular involvement. With Idiopathic Vestibular Disease, all diagnostic tests should be within normal limits. The prognosis for Idiopathic Vestibular Disease is good.
How Is Vestibular Syndrome Treated and What Can I do At Home?
Treatment, again, depends on the underlying cause for the vestibular signs. With Idiopathic Vestibular Disease, supportive care is most important. Supportive care involves medications to help with the nausea associated with vestibular signs and sedation to calm the patient if its lack of balance is causing distress/anxiety. Providing the patient with a well-padded area will keep the animal from injuring itself due to its lack of balance control. Supporting the patient with a sling and harness when walking is also helpful. Keeping the patient in an environment that is well lit is recommended. A dark environment can make vestibular signs worsen due to the fact that the vestibular system uses visual stimulation to coordinate movements. Elevating food and water bowls can also help decrease imbalance which can occur with changes in position of the head. Using yoga mats, booties, or throw rugs on slippery surfaces can also help with incoordination.
It is also very important to watch for signs of worsening at home that could indicate an underlying disease that is responsible for the vestibular signs. The signs associated with Idiopathic Vestibular Disease generally do not worsen.
One of the most important things to remember if your dog develops vestibular signs is that even though the signs can be very severe, there are many conditions that can cause these signs, and many are treatable and may resolve on their own in time.