Autonomic nervous system, blood pressure and thermoregulation

First, let’s take a look at the effect on the autonomic nervous system and the implications that this gives rise to. As you may know, the nervous system can be divided into two parts: the somatic nervous system and the autonomic nervous system. The former is involved in conscious control of our mobility. For example, when you consciously decide to lift your arm, your brain will generate and send signals towards the somatic nervous system, resulting in the actual act of lifting your arm. The autonomic nervous system is controlled by the brain and is responsible for the regulation of unconscious processes in your body.

These mostly include vital functions, such as heart rate, blood pressure, and body temperature.

As the autonomic nervous system is under the control of the brain, this implies that the brain can also make adjustments in response to internal stimuli if needed. These adjustments happen unconsciously as well, you yourself can almost not control this process. That means that the responsible signals must be able to reach the brain independently, something which is impossible in people with paraplegia. As a result, the autonomic system cannot adequately be adjusted by brain signals, resulting in inadequate regulation.
For example, the signals from small blood vessels do not arrive in the brain and the capillaries below the level of the injury cannot be constricted at all. This means that, as a response to abrupt changes for example in posture and physical stress, blood pressure is slow to be adjusted, possibly resulting in lower blood pressure overall, also known as hypotension. This entire problem is further reinforced by the absence of muscle activity in the legs. As a result an important muscle pump that normally plays an important role in the backflow of blood towards the heart is missing. Usually, the body will in the end adapt to the new situation, reducing the incidence of low blood pressure.

Also the connection between the brain center responsible for thermoregulation and the skin is often (partly) disrupted. Consequently, the signals regarding skin temperature will not reach the regulation center in the brain. This means that responses to changes in environmental temperature are slow to arise. Consequently, people often experience unpleasant cold or warmth. The body temperature remains either too high or too low for the given situation.

Upper body motor functions and pain

Besides the autonomous nervous system, also the motor function of the hands and arms may be affected. This is often very dependent on the height of the lesion in paraplegics. If the spinal cord has been injured in the neck area, this will result in a loss of control over the arms and hands. When this is the case, the condition is also called tetraplegia. However, if the hands and arms can still function normally, the condition is called paraplegia. Basic treatment focuses on optimizing the remaining possible motions through training and learning new compensating movements, for example by smart use of gravity.  An important focus point is to prevent additional complications, such as edema and spasticity. This is achieved by closely monitoring the sitting position and regularly moving the limbs, either by the patient themselves or someone else.

Pain is another large and complicated problem in patients with paraplegia and is estimated to affect between 30 and 90 percent of patients. The large spread in this number mostly arises due to the various definitions of pain and the different methods of measurement. However, it is now commonly accepted that in at least 30 percent of the patients the pain significantly influences their quality of life. In order to research pain more effectively and develop a better treatment method, a classification into four groups was made regarding the type of pain:

• Nociceptive pain: pain that arises due to the stimulation of pain receptors, due to tissue damage of for instance bones, muscles, or organs.
• Neuropathic pain: pain that arises due to damage to the nervous system itself.
• Other pain: pain that cannot be classified as either of the above-mentioned groups, such as fibromyalgia or irritable bowel syndrome.
• Unknown pain: pain for which no cause can be appointed

Treatment of pain usually starts with investigating what type or types of pain a patient is experiencing. This is done both by physical examination and if needed complementary laboratory and imaging studies. Once the exact pain problems have been identified, individualized treatment will be determined. In practice, this is often rather complex.

You have completed the first part of this reading about the health complications that are caused by Spinal Cord Injuries. Move on to the next part to learn more about how paraplegia also affects the bladder, intestines, skin and sexuality. You will also learn what is meant by ‘spasticity’ in the next component.