Neurology-RICHMOND

What is Acute Non-compressive Nucleus Pulposus Extrusion (ANNPE)?

The intervertebral discs are located between the bones of the spine (the vertebrae). The intervertebral disc is composed of a fibrous ring or capsule which surrounds a jellylike substance called the nucleus pulposus. A tear in the fibrous ring of the intervertebral disc can allow the nucleus pulposus to herniate, sometimes at a very high speed. This highspeed herniation can cause a concussive or bruising injury to the spinal cord. Since the nucleus pulposus is jelly-like and absorbable in the epidural fat, it does not cause compression of the spinal cord. Ultimately, the neurologic signs seen after an ANNPE are due to the high velocity “hit” to the spinal cord with the nucleus pulposus. This is called an Acute Non-compressive Nucleus Pulposus Extrusion (ANNPE).

Who Can Be Affected?

Both dogs and cats can be affected by brain tumors. Primary brain tumors, originating from the brain tissues themselves, are encountered more often than secondary or metastatic brain tumor(s). Primary and secondary brain tumors can occur in any breed of dog or cat and both males and females can be affected. Brain tumors are encountered more often in middle-aged to older dogs and cats, most being over 9 years old at the time of diagnosis.

A recumbent pet is one who cannot stand or walk independently, either due to weakness in the rear legs or all four limbs. These patients face several challenges, including pressure sores, muscle loss, incontinence, skin inflammation, respiratory issues, and pain management. This guide will help you care for your immobile pet during their recovery journey.

What is Intervertebral Disk Disease (IVDD)?

Intervertebral Disk Disease (IVDD) is a common spinal issue in dogs, less so in cats. It can occur anywhere along the spine but is most common in the neck (cervical spine) and mid-back (thoracolumbar region). While disk degeneration itself isn’t always problematic, issues arise when disk material compresses the spinal cord or nerve roots, leading to pain and potential mobility problems.

What is Diskospondylitis?
The intervertebral discs are located between the bones of the spine (the vertebrae). Diskospondylitis is an infection of the intervertebral disc and the portions of the vertebrae adjacent to the infected intervertebral disc. Diskospondylitis causes painful damage / lysis to the vertebral bodies. It can lead to degeneration of the infected intervertebral disc, which can cause the intervertebral disc to herniate and put pressure on the spinal cord.
Diskospondylitis can also weaken the bones surrounding the intervertebral disc, which can sometimes cause the bone to fracture.

What is Fibrocartilaginous Embolism (FCE)?

The intervertebral discs are located between the bones of the spine (the vertebrae), and these intervertebral discs contain a substance called fibrocartilage. A small piece of this fibrocartilage can exit the intervertebral disc and make its way into the blood vessels that supply the spinal cord. This piece of fibrocartilage can then block the normal blood flow to an area of the spinal cord, which means that oxygen and other nutrients cannot reach that part of the spinal cord. This ultimately leads to damage to the cells of the spinal cord. This is called a Fibrocartilaginous Embolism (v), and you can think of it as a “stroke” to the spinal cord.

What is Masticatory Muscle Myositis (MMM)?

Masticatory myositis (MMM) is inflammation of the muscles of mastication = the chewing muscles (temporalis, masseter, and pterygoid muscles). It occurs primarily in dogs with rare cases reported in cats. Masticatory muscle fibers contain unique myosin fibers, designated as 2M fibers. The inciting cause of the disease is not known but is thought to result from the body’s immune system behaving erratically and attacking these special Type 2M fibers (a type of autoimmune disorder).

What is Meningoencephalomyelitis of Unknown Etiology (MUE)?

MUE is a presumptive immune-mediated disease, which results in inflammation within the brain or spinal cord. Inflammation within the brain is called encephalitis; inflammation within the spinal cord is called myelitis; inflammation within the lining of the spinal cord and the brain is called meningitis. The most common form of MUE is granulomatous meningoencephalomyelitis (GME) hence these terms being used interchangeably in this review.

What is Myasthenia Gravis?

In order for muscles to move normally, they require energy and information from the nerves in the body. Nerves secrete chemicals called neurotransmitters. The main neurotransmitter that provides energy to muscles is called acetylcholine. There are receptors on the muscle, which are specifically made for acetylcholine to bind to them. This binding of acetylcholine to the muscle receptor is how muscles receive the energy to move.

Myasthenia gravis (MG) is a disease caused by the inability of acetylcholine to bind to the muscle receptor. If acetylcholine cannot bind to the receptor, then the muscles become weak. In the majority of dogs and cats with myasthenia gravis, the reason that acetylcholine cannot bind to the receptor is because the receptor is already bound to an acetylcholine receptor antibody.

What are Seizures?

Seizures are the most common presenting neurologic complaint in veterinary medicine. A seizure is the clinical manifestation of excessive electrical activity in the cerebral cortex. Generalized tonic-clonic seizures (‘grand mal’) are the most common type of seizures in dogs and cats. These are often characterized by a stiffening of the neck and legs, stumbling and falling over, uncontrollable chewing, drooling, paddling of the limbs, loss of bladder control, defecating, vocalizing, and violent shaking and trembling.

Seizures can last a few seconds to a few minutes (average of 1 minute) and the patient is typically unaware of the surroundings during this period. In some rare cases, the seizures will not stop or be prolonged and this is referred to as status epilepticus.

After a seizure, your pet may appear confused, disoriented, dazed, or sleepy; this is called the postictal period.

Prior to the seizure, many pets will also experience an aura stage. This stage may or may not be recognized and can last anywhere from just a few seconds to a few minutes. It is characterized by your pet appearing anxious, frightened, or dazed, as if they can sense an upcoming seizure.

Many other medical conditions or episodes may appear like seizures. These include vestibular episodes (vertigo), neck pain, syncope (fainting), narcolepsy/cataplexy, REM sleep movements and other movement disorders (dyskinesias, myoclonus, myotonia, etc.).

As such, the most important initial step for the neurologist is to determine if the patient is truly having seizures.

What is SRMA?

Steroid-Responsive Meningitis-Arteritis (SRMA) is a disease of a malfunctioning immune system, which results in inflammation within the meninges and the blood vessels (arteries) of the spinal cord. The meninges are the thin layers of tissue that surround the spinal cord. Inflammation within the lining of the spinal cord (the meninges) is called meningitis. Inflammation within the arteries of the spinal cord is called arteritis.

The immune system should normally function to help protect the body from things like infections, but in dogs with SRMA, the immune system starts to attack the normal lining of the spinal cord (the meninges).

What is Vestibular Disease?

Vestibular ‘disease’ is a broad term encompassing any problem that affects these balance centers. Clinical signs often present acutely; however, a more gradual onset is also possible. Signs of vestibular dysfunction include a ‘drunken’ gait, circling, leaning or falling to one side, a tilted head, abnormal eye position (strabismus) or movement (nystagmus), and sometimes even ‘crocodile rolling’.

In order to minimize loss of function and expedite recovery, we ask that you perform the following home exercises for your pet. Not all exercises are applicable to every patient, ask your veterinarian which exercises are best suited to your pet’s condition. All recommendations for repetitions and frequency are approximate guides and can be adapted to your pet’s personal needs.