Explaining the working of the feline vestibular system and how it can lead to ataxia when it goes wrong

Let me thoroughly explain the feline vestibular system and how issues with it can cause ataxia:

The vestibular system is important for balance and spatial orientation in cats. It is located in the inner ear, along with the cochlea for hearing. The vestibular system contains two concentrated areas of sensory cells – the semicircular canals and the otolith organs.

The semicircular canals contain fluid and hair cells that detect rotational movement of the head. Cats have 3 perpendicular canals that detect movement in any plane. The otolith organs contain dense calcium carbonate crystals (called otoconia) over hair cells. This detects linear acceleration and gravity changes.

Together, the input from these structures is sent to the brainstem and cerebellum via the vestibular nerve. This allows cats to sense where their head is in space and maintain equilibrium and stability of movement.

Ataxia is a loss of voluntary coordination that can occur if the vestibular system is compromised. For example, damage to the semicircular canals or otolith organs could cause this. Vestibular disease disrupting the inner ear structures would result in ataxia through faulty neurologic signaling.

Clinical signs of feline ataxia include a wide-based stance, swaying or swirling gait, fallen/uncontrolled head bobbing, and inability to ambulate straight or balance well. This occurs as the brain cannot properly integrate sensory input without the vestibular system.

I hope this explanation of the feline vestibular system and how issues with it can lead to ataxia was thorough! Let me know if you need any clarification or have additional questions.

The feline vestibular system can cause ataxia if and when it goes wrong by Michael Broad

What disease causes the vestibular system to go wrong?

There are a few key diseases that can cause the vestibular system to malfunction in cats, resulting in ataxia:

• Vestibular neuritis: This is inflammation of the vestibular nerve, which disrupts neural signaling between the inner ear and brain. Bacterial or viral infections are common causes. Clinical signs include head tilt and circling.
• Otitis media/interna: Infection or inflammation of the middle ear (media) or inner ear (interna) damages delicate structures in this region like the semicircular canals and otolith organs. Bacteria or viruses are the usual culprits.
• Vestibular disease: A broad term used to describe any non-infectious problem affecting the inner ear balance structures. Possible causes are genetics, toxins, tumors, head trauma.
• Idiopathic vestibular syndrome: The cause is unknown for some cats. It may be immune-mediated where the body attacks the inner ear by mistake.
• Neoplasia: Cancerous tumors arising from inner ear tissues or neighboring areas can involve and disrupt the vestibular system.
• Cerebellar Hypoplasia: This is for completeness as it causes ataxia. Cerebellar Hypoplasia is a condition present from birth where the cerebellum – the part of the brain that coordinates movement and balance – is underdeveloped or malformed. In cats, this is usually due to factors like genetics, infections, or complications during fetal development. Symptoms often appear during kittenhood and persist throughout life. Clinical signs mirror those seen in other vestibular disorders – ataxia, wide stance, swaying and staggering gait, loss of motor control. However, the onset and progression tend to be more gradual with Cerebellar Hypoplasia compared to sudden vestibular diseases.

Proper diagnosis involves ruling out these potential underlying vestibular diseases through medical history, physical exam, diagnostic tests. Treatment aims to address the specific cause while symptomatically treating ataxia. I hope this overview of the disease origins of vestibular dysfunction in cats was clear!