Captain Scarlet and Captain Blue were working in the intelligence section of Cloud-base when there was a terrorist attack by the Mysterons. A bomb exploded causing the ceiling to collapse trapping both of them under the rubble. Captain Scarlet escaped with only minor injuries but Captain Blue was struck across the shoulders by masonry and piping, which pinned him down. It took several hours to dig him out and when he has pulled free he was unable to move his arms or legs. When he arrived at the Cloud-base hospital, he complained of his inability to move and of shooting/burning pains in both arms. Neurological examination revealed a left hemiplegia and right hemiparesis with a Babinski sign present bilaterally. Pain sensation was lost from the right shoulder downwards. Bladder, bowel and genital reflexes were also absent. X-rays of the cervico- thoracic region were taken and subsequently he underwent surgery to remove bone fragments and to stabilise the cervical spine.
A month later, movement of the right arm and leg had improved. Two months after surgery, movement in the right hand had improved further but there was no voluntary movement on the left. Fasciculation of the left deltoid muscle was found together with spasticity of the left arm and leg, with clonus at the ankle. A Babinski sign remained on the left side. Joint position sense was present on both sides but pain sensation was absent on the medial right aspect of the upper right arm, right side of the thorax, abdomen and whole right lower limb. Despite reassurances from his Colonel that his condition will improve further, Captain Blue feels that he will never physically recover from his injuries.
Organisation of spinal cord
In its own definition of spinal cord, Oxford medical dictionary states: “The portion of the central nervous system enclosed in the vertebral column, consisting of nerve cells and bundles of nerves connecting all parts of the body together”(1).
Spinal cord is divided into 2 regions:
The white matter: It contains the axons of the neurons that make up the descending and ascending tracts responsible for the communication of the spinal cord with the brain. The white matter can be split into the dorsal, the ventral and the lateral funiculous as seen in Figure 1.
The White matter contains the following four pathways that are essential for the scenario and that will be further discussed in the next objective. Each tract carries a specific modality (types of sensation) in the brain. The position of each tract in the white matter is seen in Figure 2.
Dorsal column medial lemniscus tract (DCML): It is responsible for conscious proprioreception and discriminative touch. It is split into the gracile and the cuneate fasiculi which carry these modalities from the lower and upper limbs respectively.
Spinothalamic tract(STT): It is responsible for the pain and temperature sensation.
Spinocerebellar tract (SCT): It is responsible for the unconscious proprioception to the cerebellum which controls the co-ordination of movements.
The above are ascending pathways i.e. they send information from the spinal cord to the brain. The following is a descending pathway:
Corticospinal tract (CST): It is responsible for sending information to the spinal cord for controlling voluntary movements of the lower and upper limbs.
Figure 1 – Spinal cord transection (2)
The Grey matter: It mainly consists of neural cell bodies and glial cells. Ten different layers of grey matter called laminae can be distinguished. it is further divided into 3 or 4 regions (depending on the level of the spinal cord) each containing several laminae as seen in Figure 2:
Superficial dorsal horn: It consists of laminae I-II and receives information from nociceptors about pain and temperature from Ac and Î´ sensory fibers.
Deep dorsal horn: It consists of laminae III-VI which receive information for touch and conscious proprioreception from the low threshold mechanoreceptors form IÎ² sensory fibers.
Lateral horn: This can be found in the spinal levels T1-L2 and is responsible for the autonomic control as it contains cell bodies of autonomic preganglionic fibers.
Ventral horn: It consists of laminae VII-IX and contains the cell bodies for Î±-motor neurons that innervate the muscles, as well as here the muscle afferents terminate.
Figure 2 – Organisation of spinal cord (3)
Organisation of pathways in Spinal cord
Each of the four pathways mentioned above will now be described:
Dorsal Column Medial Lemnsicus pathway (4):
Figure 4 – DCML tract (3)
The Information from the cuteneous mechanoreceptors travel through IÎ² fibers in the dorsal horn of the spinal cord and innervate the dorsal column nuclei.
The Axons ascend ipsilaterally the spinal cord.
They decussate in the medulla and ascend through medial lemniscuses to the ventroposterolateral nucleus of the thalamus.
Then they travel through the internal capsule to the primary somatosensory cortex in the postcentral gyrous.
Spinothalamic tract (5)
Figure 5 – STT tract (3)
It conveys information such as pain and temperature from nociceptors through C and AÎ´ fibers to the laminae I-II of the dorsal horn.
The axons decussate in the grey commisure of the spinal cord one or two segments above the point of entry.
2ndary axons ascend in the lateral lemniscus of the spinal cord and innervate the ventroposterolateral nucleus of the thalamus.
3rd order axons travel through the internal capsule to primary somatosensory cortex in the postcentral gyrous.
Spinocerebellar tract (6)
Figure 6 – STT tract (7)
It conveys information for unconscious proprioception from the muscle mechanoreceptors and through IÎ² fibers in the deep dorsal horn.
The axons ascend in the dorsal columns and innervate the Clarkes’ columns.
This pathway does not decussate.
The axons enter the cerebellum through the inferior pudencle.
Corticospinal tract (8)
Figure 7 – STT tract (3)
It curries information from the primary motor cortex in the precentral gyrous to the ventral horns of the spinal cord and from there through Î±- motor neurons to the muscles.
The axons from the pre-central gyrous pass through the internal capsule and decussate at the spino-medullary junction to form the pyramidal tract.
From there they descend in the lateral corticospinal tract to innervate Î±-motor neurons nuclei in the ventral horn.
Î±-motor neurons travel in the body and innervate the muscles.
Explain the symptoms – Diagnosis
Below are listed and explained the symptoms caused by the spinal injury giving a possible diagnosis at the end. The symptoms of Captain Blue are due to the damage of the spinal cord caused by the vertebrae bone fragments.
Initial inability to move and shooting pains in both arms
These are due to the spinal shock (9). This causes temporarily loss of function of the whole spinal cord. As a result, there is a loss of ability of voluntary control to all body giving the impression of muscle flaccid paralysis. Also there is loss of sensation and in this case there is a shooting pain in both arms. The spinal shock usually starts to face off in one day and gradually the reflexes, the control of movement and the sensation in the undamaged part are gained back.
Babinski sign bilaterally. Clonus in the ankle and spasticity of the left arm and leg
The Babinski reflex is a polysynaptic reflex evoked when there is nocturnous stimuli on the sole of the foot. The normal Babinski reflex causes withdrawal of the foot with adduction and flexion of the toes. An abnormal Babinski sign is one that shows abduction and extension of the toes of the foot when the foot is withdrawn. In neonates it is normal to show an abnormal Babinski reflex as their corticospinal tract has not yet matured (10).
Clonus is a series of contraction when the muscle is stretched.
Spastisity is increased muscle tone.
All the above are indicators of an upper motor neuron lesion and indicate a possible damage on the corticospinal tracts of the spinal cord.
Fasciculations are spontaneous, involuntary muscle contractions that can be seen below the skin. These are due to spontaneous firing of damaged Î±-motor neurons. These are caused by the damage on the ventral horn where the Î±-motor neurons synapse with the descending tracts.
Left hemiplegia and right hemiparesis. After two months right hand movements are improved.
Hemiplegia is the complete inability of the voluntary movement of the one side of the body whereas hemiparesis is the weakness in movement.
As concluded above there is damage in the CST of the spinal cord. This causes ipsilateral loss of movement below the level of lesion. Left hemiplegia indicates that there is a lesion on the left side of the spinal cord as the CST decussates in the medulla. The right hemiparesis is due to the initial spinal shock.
Pain sensation lost from the right shoulder downwards
The loss of sensation indicates damage of the spinothalamic tract. The loss of sensation is on the right side as the lesion is on the left part of the spinal cord. This is due to the fact that STT decussates in the spinal cord. The level of loss of pain sensation is an indicator of the possible level of lesion. The shoulder region is innervated by the C5 level. Therefore, this is probably the level of injury.
Bladder, bowel and genital reflexes were absent
Bladder, bowel and genital reflexes are autonomic reflexes controlled by the brain. In the lateral horn of thoracolumbar and sacral levels, autonomic preganglionic fibers originate and innervate the organs.
In more detail, parasympathetic activity in men is responsible for arousal whereas sympathetic activity is necessary for ejaculation and orgasm. Autonomic activity in bowel and bladders controls the muscles responsible for defecation and dieresis respectively.
A lesion in the spinal cord can damage the pathway and result in incontinence of bladder and impotency for men.
Joint position sense was present on both sides but pain sensation was absent on the medial right aspect of the right arm, right thorax, abdomen right lower limb.
Information for joint position is ascending to the brain through the DCML tract. This means that this pathway is not damaged. On the other hand as explained above, pain sensation travels in the CTT which is damaged.
In Figure 8, there is a body map showing the area affected as far as motor movement is concerned (solid brown area), and the area of impaired sensation. On the right, is the area of damage at the C5 level resulting in the symptoms on the left. Taking everything into concern, all the complications indicate a lesion on the left side on C5 level of the spinal cord due to injury from the bone fragments. The structures damaged are:
DCML pathway and STT
Part of the ventral horn
Figure 8 – Captain’s Blue Symptoms body map and lesion of spinal cord
Spinal cord injuries
Spinal cord injuries can occur due to trauma, infections, ischemia and other diseases. In this case the trauma was indirectly caused by bone due to vertebrae fracture. There are also direct traumas such as in stab wounds.
Damage is firstly caused due to hemorrhaging and compression of the spinal cord. The secondary complications such as hypoxia and ischemia that occur over a longer period can also cause further damage.
After the initial physical damage to the spinal cord, apoptosis of the glial cells and demyelination occur. Inflammatory cells infiltrate the spinal cord and contribute to the scaring and the inhibition of the axon growth. The injury may expand to other segments and cause grater complications (syringomyelia). Figure 9 shows a cervical spinal cord following an injury.
Figure 9 – Spinal cord after injury (11)
Figure 10 – ASIA categories for spinal cord injuries (12)
Spinal cord injuries can be classified with ASIA (American Spinal Injury Association) in Asia A, B, C, D categories. Figure 10, adapted from ASIA official website, shows the characteristics of each category.
Treatment – Prognosis
The treatment for spinal cord injuries is very complex. However, even with the best treatment, regeneration of nerves and complete regaining of functions is unlikely. The treatment mainly concerns the reduction and minimization of the damage and fights the complications caused by the injury (13).
The primary line of treatment is to relieve the pressure on the spinal cord and eliminate the cause of the damage. In this case Captain Blue undergoes surgery to remove the bone fragments.
The second line of treatment involves the reduction of the inflammatory response responsible for further damage. The prescription of corticosteroids helps with the anti-inflammatory effects, the reduction of the glial scar formation and the CNS cell death.
Furthermore, doctors must work against problems caused by the loss of movement such as urinary infection, wasting of muscles or formation of blood clots. As a result, exercises to improve bowel and bladder function and lifestyle tips to reduce the possibility of clot formation are given. Physiotherapy is the route to avoid muscle waste. Occupational therapy is needed for the patient to learn to live with his immobility. A range of non medical specialists such as dieticians, psychologists and social workers are also needed.
The prognosis for CNS damage is very poor. Regeneration of the nerves in the CNS is difficult due to:
Glial scar formation.
Release of inhibitory substances that oppose axon growth and remyelination.
However, new techniques such as electrical stimulation of the nerves with electrical devices can be used in the future to gain muscle function. Stem cells are also a promising future. Presently the most helpful and accessible way to overcome the disabilities caused by spinal cord injuries is the wheelchair with electronic devices that can be used for communication, movement and a variety of other daily jobs.