Initially differentiating between peripheral and central vestibular disease can be difficult. Both are characterized by a significant loss of balance with head tilt, leaning, falling, involuntary eye movements (nystagmus) and staggering. There are a few clues that can lead toward a diagnosis of central vs. peripheral vestibular disease.
The eye movements can help differentiate between central and peripheral. The involuntary eye movement is referred to as nystagmus. The eyes can go side to side (horizontal), up and down (vertical) or rotary (circular).
Peripheral vestibular disease Rolling is seldom seen
Horizontal or rotary nystagmus – not vertical
Facial paralysis may be seen with drooping of one side of the face
No mental changes noted
No body weakness
No difficulty in placement of feet
Central vestibular disease More tendency to roll
Horizontal, rotary and vertical nystagmus
When the animal is placed on his back, the nystagmus will change. This is referred to as positional nystagmus. In peripheral cases, the nystagmus does not change when the animal is placed on his back.
Possible head tremor
Poor foot placement
Excessive staggering or stumbling
Diagnosing central vs. peripheral vestibular disease can be challenging. Even with appropriate signs supportive of peripheral or central disease, additional tests are necessary to confirm the diagnosis. Unfortunately, the best diagnostic test is CT or MRI. Due to expense, this test is not available to everyone.
The importance of determining central vs. peripheral disease is to provide proper treatment and prepare for potential future problems. Peripheral disease usually resolves and the animal returns to normal. Central disease is more devastating and the animal may never recover, even with aggressive treatment.
Initial diagnostics include blood tests. These test will help determine the overall health of the animal and makes sure the animal is able to tolerate additional tests. A spinal tap is helpful to rule out infections. CT or MRI, advanced x-rays which look within the brain, can help determine if a tumor or brain abnormality is present. If all these tests are negative, the animal is diagnosed with peripheral vestibular disease.
Initial treatment of vestibular disease, both peripheral and central, is aimed at reducing the symptoms associated with a loss of balance. Some animals are able to eat and drink, show no signs of nausea and do not need medication. Those that have no appetite or vomit may require motion sickness medications. Commonly prescribed medications include: Diphenhydramine 1-2 mg per kg (1 mg per pound) twice daily
Meclizine 1-2 mg per kg (05-1 mg per pound) twice daily
These medications can help reduce the nausea associated with motion sickness and dizziness. Those animals with central peripheral disease will need additional treatments aimed at correcting the underlying cause.
Most diagnosed cases of central vestibular disease are caused by a tumor within the brain. Treatment for brain tumors include surgery, radiation therapy and, sometimes, chemotherapy. The type of tumor will determine which treatment, if any, is recommended.