Structure and Function of the Brain and Spinal Cord in Cats

Below is information about the structure and function of the feline brain and spinal cord. We will tell you about the general structure of the brain and spinal cord, how the brain and spinal cord works, common diseases that affect the brain and spinal cord, and common diagnostic tests performed in cats to evaluate the brain and spinal cord.

What Are the Brain and Spinal Cord?

The brain and the spinal cord comprise the central nervous system in a cat. The brain is the center for integrating and interpreting information from all over the body. The spinal cord acts as a conducting system to relay information from the brain to various areas of the body.

Where Are the Brain and Spinal Cord Located?

The brain is located within the bony cranium or the skull. The spinal cord is located within the spinal canal that runs through the vertebral column (neck and back bone), and extends from the base of the skull down the middle of the tail.

What Is the General Structure of the Feline Brain and Spinal Cord?

The brain is a mass of soft, pinkish gray nerve tissue divided into three major compartments: the brain stem, cerebrum and cerebellum.

• Brain stem. The brain stem is located at the base of the brain and is connected to the spinal cord and cerebellum. Almost all of the cranial nerves (nerves that control various functions on the head) arise from the brain stem.
• Cerebrum. The cerebrum, which forms the bulk of the brain, may be divided into two major parts: the right and left cerebral hemispheres. The hemispheres are divided by a narrow slit or cleft called the cerebral longitudinal fissure. The two sides of the brain are connected at the bottom by the corpus callosum, which delivers messages from one side to the other.
• Cerebellum. The cerebellum is located at the back of the brain and is attached to the brain stem and cerebrum. The cerebellum functions chiefly to coordinate movement and posture.

The spinal cord is an elongated structure, more or less cylindrical, that is made up of the major bundle of nerve tracts that carry nerve impulses to and from the brain to the rest of the body. The spinal cord is connected to all areas of the body by nerves that leave and enter the spinal column through the gaps between the bony vertebrae.

Both the brain and the spinal cord are enclosed within the meninges, which consists of three tough membranes called the dura mater, arachnoid and pia mater. Cerebrospinal fluid (CSF) is produced within the brain in hollow channels called ventricles. This fluid surrounds the brain and spinal cord to protect them from injury. Both brain and spinal tissue can be subdivided into gray matter and white matter.

What Are the Functions of the Feline Brain and Spinal Cord?

The brain governs various behaviors through learning, motivation and perception. It produces nerve impulses to make muscles move, to send signals to organs, and to control numerous automatic bodily functions. The brain also receives and registers sensory impulses, such as sight, sound, taste, touch, smell, and pain.

The spinal cord acts to coordinate movement and muscular activity. It also governs both automatic and voluntary reflexes, such as blinking, scratching, twitching the ears, and wagging the tail.

What Are the Common Diseases of a Cat’s Brain?

Brain disorders can be subdivided into congenital abnormalities, infections, inflammations, degenerative diseases, metabolic disorders, vascular conditions, tumors, traumatic injuries, nutritional disorders, toxic conditions, and diseases of unknown cause. Some examples of brain diseases that occur in cats are listed below:

• Cerebellar hypoplasia is under development of the cerebellum. It is a congenital disorder, having occurred before birth. Cerebellar hypoplasia in cats is usually due to infection of the pregnant mother with the feline panleukopenia virus. Cerebellar hypoplasia results in difficulty or abnormal walking that often appears as uncoordination in the kitten.
• Lysosomal storage diseases are a group of disorders that arise when normal metabolic processes in the brain do not occur because of abnormal enzymes or deficiencies in enzymes. Examples of these diseases in cats include alpha-mannosidosis, mucopolysaccharidosis, and ceroid lipofucinosis.
• Peripheral vestibular disease is a condition that affects both the brain and the nerves that control equilibrium. Cats with vestibular disease have difficulty with balance and orientation. Signs include head tilt and falling over. The cause of peripheral vestibular disease is unknown in the cat, but may be due to the migration of a particular parasite.
• Infectious encephalitis is inflammation of brain tissue caused by infectious organisms. In cats it may be caused by viral diseases (feline infectious peritonitis virus, feline leukemia virus, rabies), parasitic infestations, protozoal infections (toxoplasmosis, encephalitozoonosis), numerous bacteria, and fungal infections (blastomycosis, cryptococcosis, histoplasmosis).
• Seizures are abnormal brain activity that may result in convulsions that manifest as odd behaviors, tremors, muscles contractions, salivation and defecation. There are many causes of seizures such as epilepsy, which is a condition characterized by recurrent seizures and which is very rare in cats. Seizures in cats occur more often from exposure to toxins, such as those found in certain flea and tick products.
• Brain tumors may be primary and arise from brain tissues, or they may be secondary and develop from either surrounding or distant tissues. Many different tumors can metastasize to the brain.
• Head trauma is a fairly common injury in cats that are hit by cars, fall from heights, or receive either blunt or penetrating injuries to the head. Clinical signs can vary widely depending upon the type of injury, but may include stupor, loss of consciousness, abnormalities in pupil size and the function of other cranial nerves, seizures, weakness, inability to walk, and head tilt.

What are the Common Diseases of the Cat’s Spinal Cord?

Spinal cord disorders generally cause dysfunction of one or more limbs and/or the tail. Spinal cord disorders may occur alone, or in combination with disorders of the brain. Like brain disorders, spinal cord diseases can be subdivided into congenital abnormalities, infections, inflammations, degenerative diseases, vascular conditions, tumors, traumatic injuries, nutritional disorders, toxic conditions, and diseases of unknown cause. Some examples of spinal cord diseases that occur in cats are listed below:

• Sacral caudal dysgenesis is malformation of the vertebrae of the lower back and tail. This condition is seem most often in the Manx cat, where it is an inherited condition. Besides missing a tail, these cats may show various neurologic deficits in the hind legs, the rear end and the bladder.
• Infectious meningitis is inflammation of the meninges of the brain or spinal cord, arising from some sort of infection. The most common causes of meningitis in cats are bacterial infections, feline infectious peritonitis infection, and systemic fungal infections.
• Spinal tumors can occur in the vertebrae, the meninges, nerve roots and/or the spinal cord itself. Tumors that arise from cells within or covering the spinal cord are called primary tumors. Tumors arising from nearby tissues that invade or impinge upon the spinal cord are referred to as secondary tumors. One of the more common spinal tumors in cats is lymphosarcoma.

What Types of Diagnostic Tests Are Used to Evaluate the Feline Brain and Spinal Cord?

• A complete neurologic examination including the testing of various reflexes provides valuable information on the function of the brain and spinal cord.
• Cerebrospinal fluid (CSF) analysis is the microscopic examination of CSF fluid retrieved via a spinal tap. The analysis often provides valuable information as to the presence of infection, inflammation, and other abnormalities.
• X-rays provide information about the bony skull around the brain, and the vertebrae that surround the spinal cord. The brain and spinal cord themselves do not show up well on X-rays, but a special procedure called a myelogram can help highlight various areas of the spine.
• Computed tomography (CT scan or CAT scan) is a special X-ray technique that provides serial images of the brain and spinal cord using enhanced computer processing.
• Magnetic resonance imaging (MRI) uses the properties of certain tissues subjected to extremely powerful magnetic fields to generate detailed images of body organs. MRI is a very useful tool in evaluating both the brain and spinal cord.
• Various electrodiagnostic tests are available to assess different functions of the brain and spinal cord. Such tests include the brain stem auditory evoked response (BAER), which is used to detect deafness; the electroencephalogram (EEG), which may detect abnormalities in brain activity during a seizure disorder; and nerve conduction velocity (NCV), which assesses the function of peripheral nerves.