Trigeminal Neuritis in Cats

This condition often manifests as mandibular (lower jaw) paralysis. All of the muscles in charge of chewing and swallowing may be compromised. The condition can affect one or both sides of the face. Unilateral (one sided) instances may be harder to notice as the jaw may retain some muscular control. In bilateral (affecting both sides) cases, the jaw will flaccidly hang open. This issue is often paired with Horner's Syndrome and other forms of facial paralysis. Veterinary attention should be sought to prevent malnutrition in the affected cat.

The trigeminal nerve is found throughout the facial structure of a cat. It branches off into three of the main facial nerves; the ophthalmic, maxillary and mandibular nerves. These nerves account for all of the motor functions and feeling sensations in the mid to lower face. Any inflammation or demyelination (disease that damages the protective sheath that covers the nerves) affecting the trigeminal nerve can lead to trigeminal neuritis.

Normal movement and appearance of the face may be hindered when trigeminal neuritis is present. Depending on where the nerve damage has occurred, either the whole or half of the face may be affected. Mild cases may not show significant change. Signs to watch for include:

• Unable to close mouth (jaw hangs open)
• Difficulty eating, drinking and swallowing
• Pawing at the face
• Excessive drooling
• Absent facial reflexes
• Corneal ulcers 

The exact reason that trigeminal neuritis occurs is unknown. It is often classified as an idiopathic (of unknown origin) disease. Often a lesion accounts for the nerve damage. As the entire nerve branch can be affected, the condition is commonly paired with other brain stem issues. Possible contributors to trigeminal neuritis development are listed below.

• Autoimmune disease
• Cancer
• Rabies infection
• Extreme trauma (such as a car accident)

To make a proper diagnosis, your veterinarian will need the cat's full medical history including if and when the cat was last vaccinated for rabies. The veterinarian will then complete a physical examination of the cat, noting all facial symptoms. An x-ray of the skull may be needed to locate the nerve damage. An MRI may be needed if tumors are suspected. Cancer may be the cause if the problem has existed for more than four weeks. The cerebrospinal fluid should be tested to identify diseases of the spinal cord and brain. 

A complete neurological examination will also be performed. This includes assessing the 12 cranial nerves and testing for regular movement and reflexes in the body. The trigeminal nerve is the fifth cranial nerve. Testing the function of this nerve may involve touching the center of the eye with a moist swab to see if the cat blinks. The nasal area should also be touched to see if a natural response occurs. The cat may be monitored while attempting to chew to see if there is symmetry in the muscles during this action. Electrodiagnostics including an EMG (electromyography) test may be used to see how much electrical activity is taking place in the muscles. 

There is no known cure for trigeminal neuritis. The issue often goes away after about a month's time, but symptoms need to be treated throughout that duration. Secondary problems can also arise and may need further treatment. 

Supportive Care 

As the cat may be dehydrated and malnourished from not being able to chew or swallow properly, a feeding tube and intravenous fluids may be administered to stabilize the animal. 

Steroid Therapy 

While more research is needed, glucocorticoid administration may help relieve symptoms. This route may be taken if paralysis is still present after three weeks.

Spontaneous recovery often takes place two to three weeks after symptoms have begun. During this time, extra care must be taken to ensure that the cat is receiving enough food and water to function properly. Your vet will most likely give you detailed instructions on how to syringe or tube feed your cat at home. Many cats lose up to 15 percent of their body weight over the course of the paralysis condition.

In idiopathic cases, there is no way to prevent trigeminal neuritis as the cause is not known. Once the cat has made a full recovery, the issue often never occurs again. If cancerous tumors are found to be affecting the trigeminal nerve, prognosis depends on the extent, aggression and location of the tumors. If rabies has been identified as the cause of mandibular paralysis, the cat will need to be euthanized. Getting your cat vaccinated regularly can help prevent it from contracting rabies.