Structure and Function of the Brain and Spinal Cord in Cats
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.
What Are the Common Diseases of the 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:
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 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 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.