Spinal Cord Injury healthcare information in one catch

What is SCI?

Effects of SCI This section discusses what happens when your spinal cord is damaged. It describes (click on arrow to expand selection) Initial Injury Injuries to the spinal cord do not usually cut through the cord. However, they do cause damage to the thin, fibrous axon extensions of the neurones within the spinal column. SCI due to traumatic accidents may be caused by stretching or pinching of the cord when vertebrae are displaced, or by direct damage to the cord by fragments of fractured vertebrae. Non-traumatic SCI can be caused by the pressure on the spinal cord from cysts or tumours, or any interruption of local blood supply. The effects of a traumatic injury continue for some time after the initial injury, during a period known as 'spinal shock'. Spinal shock can last for up to 6 weeks.Reference 4 It is partly due to bruising and swelling (oedema) of the spinal cord, which compresses it against the surrounding bones of the spinal column and partly due to lack of oxygen, caused by disruption in the blood supply to the tissue. Spinal shock can itself result in further damage to the cord. In addition, any bleeding into the injured area can cause damage. During this period of spinal shock, the ability to send messages within the cord stops and the loss of function below the injury may appear to be total. However, once the swelling subsides, some recovery may take place and the true extent of the damage will become clearer. Over the first few days after injury, white blood cells will travel to the affected area to remove debris from the damaged cells, often causing further damage. Within a few weeks of the initial injury, the damaged tissue will all have been cleared away by specialised cells. A fluid-filled cavity surrounded by scar tissue is left behind. Molecules that inhibit the regrowth of severed neurones are produced in the cavity, so that it acts as a barrier to the reconnection of the two sides of the damaged spinal cord. This complex series of disruptive events is being studied, in the hope of finding ways to prevent and treat it. Research into forms of treatment that will enhance the normal, but often limited, recovery that can occur after a spinal cord injury, is also being carried out. Complete and incompete spinal cord damage Complete lesions A complete lesion is the term used to describe damage to the spinal cord that is absolute. It causes complete and usually permanent loss of ability to send sensory and motor nerve impulses and, therefore, complete and usually permanent loss of function below the level of the injury. This will result in complete paraplegia or tetraplegia (discussed below). Incomplete lesions An incomplete lesion is the term used to describe partial damage to the spinal cord. With an incomplete lesion, some motor and sensory function remains. People with an incomplete injury may have feeling, but little or no movement. Others may have movement and little or no feeling. Incomplete spinal injuries differ from one person to another because the amount of damage to each person’s nerve fibres is different. The effects of incomplete lesions depend upon the area of the cord (front, back, side, etc) affected. The part of the cord damaged depends on the forces involved in the injury, which were discussed earlier. The figure, ‘Cross-section of the spinal cord’ shows which parts of the cord are responsible for different motor functions. This figure has been adapted from 'Management of Spainal Cord Injury' by Zejdlik CP 1992. 3 The different types of incomplete lesions can cause specific syndromes. Anterior cord syndrome - This is the result of forward bending (hyperflexion) and usually involves the cervical vertebrae in the neck. It is often due to motor vehicle accidents, when the head is thrown forward on impact. Bending injuries can also be caused by the head being struck from behind or the injured person falling backwards, hitting the back of their head. The violent bending of the neck causes severe forward displacement of the vertebrae, which compresses the front (anterior) of the cord. The lesion this causes leads to loss of muscle control and a reduction in the ability to sense pain and temperature below the level of the lesion. Sense of crude touch, limb position (proprioception) and vibration are relatively unaffected, as these functions travel up the back of the cord (see figure ‘Anterior cord syndrome’). Anterior artery syndrome - This syndrome is similar to anterior cord syndrome but is due to interruption of the blood supply to the front portion of the cord. Because the back of the cord has a separate blood supply, it is unaffected. There is a loss of voluntary motor function and sensory function below the lesion, but sense of position, touch and vibration are often unaffected (see figure ‘Anterior artery syndrome’). Posterior cord syndrome - Forced stretching (hyperextension) of the neck, which can be caused by a fall onto the chin or face, compresses and damages the back (posterior) part of the cord. This results in the loss of sense of deep touch, position and vibration below the lesion. Muscle strength and sense of pain and temperature is relatively unaffected, but because the normal subconscious awareness of the position of the limbs (proprioception) is usually lost, the person affected may have difficulty in learning how to walk again (see figure ‘Posterior cord syndrome’). Central cord syndrome - This syndrome is due to an incomplete lesion caused by minor stretching injuries of the neck. The damage is localised to the central core of the cord. Because of the way the neurones are arranged within the cord, this leads to loss of strength of muscle and sensation in the arms and hands, with partial loss of strength and sensation over the upper abdomen and chest. Sensation and movement of the legs and feet may be unaffected and some bladder and bowel function remains (see figure ‘Central cord syndrome’). Brown-Séquard syndrome - This syndrome may be caused by a stabbing or penetration injury on one side of the cord or by the spine being forcibly bent sideways. The sensory neurones that carry pain and temperature signals to the brain cross over within the cord, so that sensory signals from one side of the body travel up to the brain on the opposite side of the cord. As a result, this type of lesion affects muscle strength and control on the side where the lesion occurred, but not the sense of pain and temperature. On the other side of the body, the reverse is true – muscle strength is unaffected but the sense of pain and temperature sensation is reduced or absent (see figure ‘Brown-Séquard syndrome’). Conus and cauda equina syndromes - Damage to the spinal column below T11 can cause a range of effects. Injury to the nerves in the conus medullaris or cauda equina cause loss of muscle strength and control below the lesion, but a variable amount of sensation. The loss of spinal reflexes caused by lesions at this level can have a severe effect on bladder, bowel and sexual function (see figure ‘Conus and cauda equina syndromes’). Sacral sparing - Even when most of the cord is affected by trauma or loss of the major blood supply, some small blood vessels may preserve the outer edges of the cord. In this syndrome, the person, although paralysed below the waist, retains some sensation from the sacral area of the cord (see figure ‘Sacral sparing’). Hemiplegia - Is a disorder in which only one side of the body is paralysed. It is defined as paralysis of half the body involving at least one arm and one leg (Greek ‘hemi’ = half). The term is sometimes used loosely to describe other partial paralysis. The most common causes of hemiplegia are damage to the brain. Generally, injury to the left side of the brain will cause a right hemiplegia and injury to the right side, a left hemiplegia. When damage to the spinal cord is localised to one side only, hemiplegia is also the result (see figure ‘Hemiplegia’). Paralysis Once the spinal shock phase is over, the level of impact, that the injury has had on sensory and motor function can be properly assessed. Paralysis is a general term used to describe the loss of sensory and motor function following damage to the nervous system. Knowing the precise level of the injury is helpful in predicting which parts of the body will be affected by paralysis and loss of function. The level of the injury also determines the severity of the effects. The higher up the spinal cord, the more severe the effects. The severity of the effects also depends upon whether the lesion is complete or incomplete. After an SCI, some simple tests are usually carried out to assess the extent of motor and sensory impairment. Paraplegia This term describes complete or incomplete paralysis, affecting the legs and possibly also the trunk, but not the arms. The extent to which the trunk is affected depends on the level of spinal cord injury. Paraplegia is the result of damage to the cord at T1 and below. Thoracic lesions (T1–T12) affect the chest as well as the legs. Lumbar lesions (L1–L5) result in paralysis below the waist. Sacral level lesions may not cause limb paralysis but will affect spinal reflexes. Paraplegia often affects bowel, bladder and sexual function. These are discussed in more detail in the Medical section. Tetraplegia (also called quadriplegia) This term describes the complete or incomplete paralysis from the neck downwards, affecting all four limbs and the trunk. This is the result of damage to the spinal cord in the cervical region. The diaphragm (a sheet of muscle involved in breathing) is supplied by nerve fibres branching from the spinal cord between C3 and C5, so that breathing using the diaphragm is maintained in all but the highest level of injury. When the lesion does affect the diaphragm, mechanical ventilation (breathing) and help with coughing may be needed. Bowel, bladder and sexual function will all be severely affected. All these factors are described in more detail in the Medical section. Spastic and flaccid paralysis Paralysis can also be divided into two categories according to the type of damage that occurs to the cord – these are termed spastic paralysis and flaccid paralysis. When spinal reflexes are still functioning, but the overriding control of these reflexes from the brain is not functioning, the person is said to have spastic paralysis. The person experiences spasms. These are sudden, exaggerated muscle contractions and jerky movements caused by exaggerated reflex reactions to normal stimuli, such as stretching, touch and pain. (Prior to injury, the brain would have sent messages to prevent these spasms. Damage to the cord hinders the ability to send these messages). If the muscle spasms continue, they can cause contractures (damage to muscle and/or surrounding tissue, causing deformity at a joint). There is also an increased resistance to movement in some muscles in this type of paralysis. Men may notice they have uncontrolled erections. During rehabilitation, people with SCI can learn how to use spasms to help with achieving some mobility. It is possible for some people to learn how to empty (void) the bowel and bladder by using the remaining spinal reflexes. People with SCI whose spinal reflexes are not functioning are said to have flaccid paralysis. They experience loss of muscle tone in the lower limbs, loss of bowel and bladder tone and, eventually, muscle wasting. Circulatory problems tend to be worse and the flaccid bowel is more likely to retain stools, complicating bowel management programmes. Damage above the sacral region of the cord usually causes spastic paralysis, while damage in this region of the cord often causes flaccid paralysis.

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