• Physical Examination
• Neurological Examination
• Neurological Localization and Differential Diagnoses
• Diagnostic Testing
• Treatment Options

The basic components of the nervous system comprise the brain, the spinal cord and the peripheral nervous system. For the purposes of neurological localization, these areas are usually subdivided. The brain for example is divided into three broad regions:

Figure 3A: The three main regions of the brain by photograph (left) and MRI (right). 1. Forebrain (Cerebrum or Thalamus). 2. Brainstem. 3. Cerebellum.

1. The FOREBRAIN, which comprises the cerebrum (REQUIRES LOGIN; FOR VETERINARIANS) and thalamus. These are the parts of the brain that control higher functions such as personality and behavior . They also influence motor and sensory function although to a much lesser extent than in humans.
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2. The BRAINSTEM, comprising the midbrain, pons, and medulla, controls many basic functions such as breathing and swallowing as well as providing a connection between the brain and the spinal cord. The brainstem also includes part of the vestibular system that controls balance.
3. The CEREBELLUM, which coordinates movement generated in other regions of the nervous system like the brainstem and cerebral cortex.

The spinal cord carries two broad types of information. Motor information comes from higher centers like the brainstem and cerebral cortex to generate movement. Sensory information comes from receptors outside the nervous system (such as touch and joint position receptors) and is carried along the spinal cord to the brain to be interpreted. The spinal cord is divided into four main regions for the purposes of neurological localization. These four regions are:

Figure 3B: The four main regions of the spinal cord.

1. The CERVICAL (REQUIRES LOGIN; FOR VETERINARIANS – PLEASE PUT NEXT TO LINK ITSELF, AS PER NEUROLOGICAL EXAMINATION) spinal cord that carries information from the brain to all four limbs and the bladder as well as vice versa.
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2. The CERVICOTHORACIC spinal cord that not only carries information to and from the all four limbs and the bladder but also gives rise to the major nerves of the front limbs. The reflexes of the front limbs are therefore dependent on this region.
3. The THORACOLUMBAR spinal cord that carries information to and from the rear limbs and bladder.
4. The LUMBOSACRAL spinal cord that carries information to and from the rear limbs and bladder and also gives rise to the major nerves of the rear limbs, bladder and other pelvic structures. The reflexes of the rear limbs are therefore dependent on this region.

The peripheral nervous system comprises the nerve roots and peripheral nerves – along with their associated muscles.

Figure 3C: The main peripheral nerves to the rear limb. a. Femoral nerve. b. Obturator nerve. c. Sciatic nerve. d. Pudendal nerve.

The peripheral nervous system carries sensory information from receptors to the spinal cord and brain. The peripheral nervous system also carries motor information from the brain and spinal cord to the muscles. The muscles then generate the force needed to produce movement of various body parts. Shown above are the nerves that innervate the rear limb and pelvis.

THE MAIN AIM of the neurological localization is to determine as precisely as possible what part of the animal’s nervous system has been affected by a given disease process. The initial aim is to place the problem into one of the nine areas (forebrain, brainstem, cerebellum, cervical, cervicothoracic, thoracolumbar, lumbosacral, peripheral nerve or muscle) shown above. This then allows a better determination to be made of the specific type of disease that the animal is suffering from. For example, if an animal has signs indicating that just one side of its brain is affected, then this might be caused by a tumor or a stroke. Similarly, if the spinal cord has been affected just behind the rib cage then a disc herniation would be considered likely. In contrast, if an animal has signs indicating involvement not only of one or more parts of its brain but also has a problem in its spinal cord, then some type of infectious process might be responsible.

Once the affected region of the brain or spinal cord has been determined, a list of the most likely diseases responsible can be generated. This is called the list of differential diagnoses. Diagnostic testing is then directed towards determining which of the disorders on this list is actually responsible for causing the animal’s problem. Knowledge of the region of the nervous system that has been affected allows Diagnostic Tests such as X-rays to be directed at the area of interest.